Just out of curiosity. Has anyone gone through and tabulated bottom bracket drop relative to various bike brands?

Ridely's popping in at 57, Speedvagen is about 70, RadioFreddy's Hot Tubes was around 75.

Not that it is a ton of work, but it got me wondering if some one had already done it.

Just out of curiosity. Has anyone gone through and tabulated bottom bracket drop relative to various bike brands?

Ridely's popping in at 57, Speedvagen is about 70, RadioFreddy's Hot Tubes was around 75.

Not that it is a ton of work, but it got me wondering if some one had already done it.

The problem is that some of the manufacturers publish the number in height. Which is a pretty pointless number given your choice of tire is going to have a big impact on that measurement.

I think the Poprad is 72.

Also, if you go with the X-Fire, you get 61.

Zank claims 70 is the sweet cross number.

The problem is that some of the manufacturers publish the number in height. Which is a pretty pointless number given your choice of tire is going to have a big impact on that measurement.

I think the Poprad is 72.

Also, if you go with the X-Fire, you get 61.

Zank claims 70 is the sweet cross number.

Poprad is 74mm, for clarification. Cannondale Caad5-9 is 58mm. I ride both (caad 8) and the Poprad handles way better than the Cannondale when cornering.

Poprad is 74mm, for clarification. Cannondale Caad5-9 is 58mm. I ride both (caad 8) and the Poprad handles way better than the Cannondale when cornering.The CX Optimos and the '08 CAAD9 Optimo are 58. The '07 CAAD9 Optimo was 67. The CAAD road frames (including the CAAD8) range from 67-72 depending on size.

Just out of curiosity. Has anyone gone through and tabulated bottom bracket drop relative to various bike brands?

Ridely's popping in at 57, Speedvagen is about 70, RadioFreddy's Hot Tubes was around 75.

Not that it is a ton of work, but it got me wondering if some one had already done it.


Paul at Rock Lobster recommends 6.9-7.0 BB drop.

The CX Optimos and the '08 CAAD9 Optimo are 58. The '07 CAAD9 Optimo was 67. The CAAD road frames (including the CAAD8) range from 67-72 depending on size.

Thanks for the clarification. :thumbsup:

Yes, there was somebody here that was doing just this - putting together a spreadsheet. Do a quick search, as I don't recall who it was.

:mad2:
DOH! Right...

search...

what it is like i've just started using a ubb forum or something

but...

having just scoured the search results... and found no definative collection so i feel less like an I D 10 T than a few minutes ago. Lots of discussion with various mentions of heights but nothing that caught my eye as bunch of numbers on BB drop...

so i feel less like an I D 10 T than a few minutes ago.

I certainly don't want you to feel less of yourself than you should.

IIRC, the post jtferro referenced was actually some dude how offered to post his compiled list of bb drop for production cross bikes. However, he never actually followed through.

Poprad is 74mm, for clarification. Cannondale Caad5-9 is 58mm. I ride both (caad 8) and the Poprad handles way better than the Cannondale when cornering.

My custom cx frame has a 73mm drop (60cm frame).

Before this bike I was on a '02 bianchi axis which handled like a dog comparatively. I couldn't find what the BB drop is on the axis, but the BB definitely seems lower on the new bike.

There are a lot of reason why the new bike handles better, but I would guess the greater BB drop is a contributing factor.

I certainly don't want you to feel less of yourself than you should.

IIRC, the post jtferro referenced was actually some dude how offered to post his compiled list of bb drop for production cross bikes. However, he never actually followed through.


Ok, I found my notes. Will put together a list tonight.

Ok, Here's a provisonal list. I've tried to list for the models with TT closest to 58 cm. This is a paste from Excel so the format is gonna look kinda weird. Some of the manufacturers give BB height rather than BB drop. I'll convert these tonight and repost.

Note that the larger the BB drop the longer the chainstay. This is an important issue for mud clearance and for weight over the rear wheel for traction. Lower BB drop bikes tend to have geometry more like a road bike.

Model Seat Tube Top Tube ST Angle HT Angle CS Length Wheelbase BB Drop BB Height
Felt F1X 57 58 73.5 72 42 104.2 55
Ridley Supercross/wind/bow 58 54.5 73 72 42.5 102.8 57
Ridley Supercross/wind/bow 62 57.5 73 72 42.5 105.4 57
Ridley X-Night 58 54.5 73 72 42.5 101.3 57
Ridley X-Night 62 57.5 73 72 42.5 104.4 57
Cannondale (All 08 models) 58 59 73 73 43.3 104.7 58 29
Salsa Las Cruces 58 58 72 72.5 42.5 103.4 60
Scott CX Team (XL) 58 56 xx 71 42.2 xx 60
Ridley X-Fire 58 54.5 73.5 72 42.5 101.6 61
Ridley X-Fire 62 57.5 73 72 42.5 104.3 61
Salsa Chili Con Crosso 55 58 72 72 42.5 103.1 65
Soma Doublecross 58 59.2 72 72.5 42.5 104.2 66
Soma Doublecross 56 57.6 72 72.5 42.5 103.2 66
Surly Crosscheck 56 57 72 72.5 42.5 102 66
Surly Crosscheck 58 58 72 72.5 42.5 103 66
Spec Tricross 58 57.5 72.5 72.5 44 103.8 67 28.2
Lemond Poprad 57 57.8 72.5 72.5 43 102.5 74
Giant TCX 55.5 58.5 72.5 xx 43 104 xx xx
Kelly Knobby X 57 57 73 73 42.5 102.9 xx 29.2
Kelly Knobby X 05 52 57 73 73 42.5 102.9 xx 29.2
Kona Jake The Snake 58 57.8 72.3 71.8 43.5 xx xx 29.1
Kona Major Jake 58 57.8 73.8 73.3 43.5 xx xx 29
Steelman Eurocross 57 58.5 73 74 42.5 103.2 xx 28.6
Trek XO-1 58 57.8 73.1 72.3 43 103.6 xx 27.6

See other post.

This got me curious so I went out and measured my custom Hunter - 66.7mm drop

Ok, Here's the all-singing all-dancing expanded list. I was unable to find useful geometries for Lapierre, Empella, Orbea, Novara, Time, Guerciotti, Litespeed, Van Dessel, De Rosa, Flanders, Merckx, Alan.

For those that specified only BB height, I estimated BB drop as 344.5-BB height. 344.5 is half the expected diameter of a 35mm tire+700c wheel. As manufacturers vary in how they measure this, expect estimated BB drop to be off by +/- 3 mm or so. BB height for road bikes is usually 26.7 to 27.0 cm. Drop is typically 70 mm.

I'll find a place to upload the spreadsheet tomorrow. PM me if you want it sooner. Here's the paste from Excel, I've no idea how to turn this into something more readable. Good work PBbreath.

Model Seat Tube Top Tube ST Angle HT Angle CS Length Wheelbase BB Drop BB Height Est Drop
Planet-X Uncle John CX 57 56.8 73 72 43.5 104.2 50
Felt F1X 57 58 73.5 72 42 104.2 55
Raleigh RX 1.0 59 58 73 72 42.5 104 55
Ridley Supercross/wind/bow 58 54.5 73 72 42.5 102.8 57
Ridley Supercross/wind/bow 62 57.5 73 72 42.5 105.4 57
Ridley X-Night 58 54.5 73 72 42.5 101.3 57
Ridley X-Night 62 57.5 73 72 42.5 104.4 57
Cannondale (All 08 models) 58 59 73 73 43.3 104.7 58 29
Fort Crossmax/Carbon/LE 58 57.5 73 72.5 42 103.5 58
BMC CX Machine 58 57.9 73 71.5 42.8 104.8 59
Salsa Las Cruces 58 58 72 72.5 42.5 103.4 60
Scott CX Team (XL) 58 56 xx 71 42.2 xx 60
Rocky Mountain Solo CXR/CX 57 57 73.5 72.5 42.5 103.4 60
Blue CXC/CX6.5 57 57 73 72 42.5 103.4 60
De Salvo 57.5 58 73 72.5 42.5 xx 60
Ridley X-Fire 58 54.5 73.5 72 42.5 101.6 61
Ridley X-Fire 62 57.5 73 72 42.5 104.3 61
Moots Psychlo-X 56.5 57.6 73 73 42.3 xx 61
Yeti ARC-X 55.8 55.8 73 72 42.9 102.6 61
Voodoo Limba 58 57.5 73 72.5 42.4 xx 64 29.1
Salsa Chili Con Crosso 55 58 72 72 42.5 103.1 65
Ritchey Breakaway 58 57 73.5 72 42.5 103 65
Voodoo Wazoo 61 56 73 72 42.5 xx 65 30.5
De Salvo 56.5 56.5 73 72.5 42.5 xx 65
Soma Doublecross 58 59.2 72 72.5 42.5 104.2 66
Soma Doublecross 56 57.6 72 72.5 42.5 103.2 66
Surly Crosscheck 56 57 72 72.5 42.5 102 66
Surly Crosscheck 58 58 72 72.5 42.5 103 66
Spec Tricross 58 57.5 72.5 72.5 44 103.8 67 28.2
Fuji CX Pro/Comp 58 57 73 72 43 103 67 28
KHS CX 200 (XL) 58 57.5 73 72 43.2 xx 68
Bianchi Concept/Axis 59 58 73 xx 68
Gunnar Crosshairs 58 58 72.5 73 43 102.1 70
Scattante XRL 57 57 73 73 43.5 102.5 70
Waterford CX 58 58 73 73 43 102.6 70
Lemond Poprad 57 57.8 72.5 72.5 43 102.5 74
Giant TCX 55.5 58.5 72.5 xx 43 104 xx xx
Kelly Knobby X 57 57 73 73 42.5 102.9 xx 29.2 52.5
Kelly Knobby X 05 52 57 73 73 42.5 102.9 xx 29.2 52.5
Kona Jake The Snake 58 57.8 72.3 71.8 43.5 xx xx 29.1 53.5
Kona Major Jake 58 57.8 73.8 73.3 43.5 xx xx 29 54.5
Steelman Eurocross 57 58.5 73 74 42.5 103.2 xx 28.6 58.5
Redline Conquest/Team/Pro 58 58.5 72 73 43.5 103.2 xx 28.5 59.5
Colnago World Cup Cross 60 57.9 73 73 42.3 xx xx 28.5 59.5
Ibex X-Ray 57 57 73 72 42.5 102.1 xx 28 64.5
Kinesis Crosslight 60 58 73 71.5 43 105 xx 28 64.5
Trek XO-1 58 57.8 73.1 72.3 43 103.6 xx 27.6 68.5
Jamis Supernova/Nova Pro 58 57.5 72.5 72.5 42.5 102.3 xx 27.6 68.5
Co-Motion Lucifer/Demon 56 56.5 73 73.5 41.2 xx xx 26.5 79.5
Bianchi Volpe 58 58.1 72.5 72.5 42.5 103.2 xx xx xx
Nashbar X 58 58 73 70.5 42.5 104.8 xx xx xx

Scroll down. . .<table cellspacing="1" cellpading="1" bgcolor="black">
<tr bgcolor="#CCCCCC"><td>Model</td><td>Seat Tube</td><td>Top Tube</td><td>ST Angle</td><td>HT Angle</td><td>CS Length</td><td>Wheelbase</td><td>BB Drop</td><td>BB Height</td><td>Est Drop</td></tr>
<tr bgcolor="white"><td>Planet-X Uncle John CX</td><td>57</td><td>56.8</td><td>73</td><td>72</td><td>43.5</td><td>104.2</td><td>50</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Felt F1X</td><td>57</td><td>58</td><td>73.5</td><td>72</td><td>42</td><td>104.2</td><td>55</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Raleigh RX 1</td><td>59</td><td>58</td><td>73</td><td>72</td><td>42.5</td><td>104</td><td>55</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Ridley Supercross/wind/bow</td><td>58</td><td>54.5</td><td>73</td><td>72</td><td>42.5</td><td>102.8</td><td>57</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Ridley Supercross/wind/bow</td><td>62</td><td>57.5</td><td>73</td><td>72</td><td>42.5</td><td>105.4</td><td>57</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Ridley X-Night</td><td>58</td><td>54.5</td><td>73</td><td>72</td><td>42.5</td><td>101.3</td><td>57</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Ridley X-Night</td><td>62</td><td>57.5</td><td>73</td><td>72</td><td>42.5</td><td>104.4</td><td>57</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Cannondale (All 08 models)</td><td>58</td><td>59</td><td>73</td><td>73</td><td>43.3</td><td>104.7</td><td>58</td><td>29</td><td>xx</td></tr>
<tr bgcolor="white"><td>Fort Crossmax/Carbon/LE</td><td>58</td><td>57.5</td><td>73</td><td>72.5</td><td>42</td><td>103.5</td><td>58</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>BMC CX Machine</td><td>58</td><td>57.9</td><td>73</td><td>71.5</td><td>42.8</td><td>104.8</td><td>59</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Salsa Las Cruces</td><td>58</td><td>58</td><td>72</td><td>72.5</td><td>42.5</td><td>103.4</td><td>60</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Scott CX Team (XL)</td><td>58</td><td>56</td><td>xx</td><td>71</td><td>42.2</td><td>xx</td><td>60</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Rocky Mountain Solo CXR/CX</td><td>57</td><td>57</td><td>73.5</td><td>72.5</td><td>42.5</td><td>103.4</td><td>60</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Blue CXC/CX6.5</td><td>57</td><td>57</td><td>73</td><td>72</td><td>42.5</td><td>103.4</td><td>60</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>De Salvo</td><td>57.5</td><td>58</td><td>73</td><td>72.5</td><td>42.5</td><td>xx</td><td>60</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Ridley X-Fire</td><td>58</td><td>54.5</td><td>73.5</td><td>72</td><td>42.5</td><td>101.6</td><td>61</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Ridley X-Fire</td><td>62</td><td>57.5</td><td>73</td><td>72</td><td>42.5</td><td>104.3</td><td>61</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Moots Psychlo-X</td><td>56.5</td><td>57.6</td><td>73</td><td>73</td><td>42.3</td><td>xx</td><td>61</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Yeti ARC-X</td><td>55.8</td><td>55.8</td><td>73</td><td>72</td><td>42.9</td><td>102.6</td><td>61</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Voodoo Limba</td><td>58</td><td>57.5</td><td>73</td><td>72.5</td><td>42.4</td><td>xx</td><td>64</td><td>29.1</td><td>xx</td></tr>
<tr bgcolor="white"><td>Salsa Chili Con Crosso</td><td>55</td><td>58</td><td>72</td><td>72</td><td>42.5</td><td>103.1</td><td>65</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Ritchey Breakaway</td><td>58</td><td>57</td><td>73.5</td><td>72</td><td>42.5</td><td>103</td><td>65</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Voodoo Wazoo</td><td>61</td><td>56</td><td>73</td><td>72</td><td>42.5</td><td>xx</td><td>65</td><td>30.5</td><td>xx</td></tr>
<tr bgcolor="white"><td>De Salvo 56.5</td><td>56.5</td><td>73</td><td>72.5</td><td>42.5</td><td>xx</td><td>65</td><td></td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Soma Doublecross</td><td>58</td><td>59.2</td><td>72</td><td>72.5</td><td>42.5</td><td>104.2</td><td>66</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Soma Doublecross</td><td>56</td><td>57.6</td><td>72</td><td>72.5</td><td>42.5</td><td>103.2</td><td>66</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Surly Crosscheck</td><td>56</td><td>57</td><td>72</td><td>72.5</td><td>42.5</td><td>102</td><td>66</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Surly Crosscheck</td><td>58</td><td>58</td><td>72</td><td>72.5</td><td>42.5</td><td>103</td><td>66</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Spec Tricross</td><td>58</td><td>57.5</td><td>72.5</td><td>72.5</td><td>44</td><td>103.8</td><td>67</td><td>28.2</td><td>xx</td></tr>
<tr bgcolor="white"><td>Fuji CX Pro/Comp</td><td>58</td><td>57</td><td>73</td><td>72</td><td>43</td><td>103</td><td>67</td><td>28</td><td>xx</td></tr>
<tr bgcolor="white"><td>KHS CX 200 (XL)</td><td>58</td><td>57.5</td><td>73</td><td>72</td><td>43.2</td><td>xx</td><td>68</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Bianchi Concept/Axis</td><td>59</td><td>58</td><td>73</td><td>xx</td><td>68</td><td></td><td></td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Gunnar Crosshairs</td><td>58</td><td>58</td><td>72.5</td><td>73</td><td>43</td><td>102.1</td><td>70</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Scattante XRL</td><td>57</td><td>57</td><td>73</td><td>73</td><td>43.5</td><td>102.5</td><td>70</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Waterford CX</td><td>58</td><td>58</td><td>73</td><td>73</td><td>43</td><td>102.6</td><td>70</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Lemond Poprad</td><td>57</td><td>57.8</td><td>72.5</td><td>72.5</td><td>43</td><td>102.5</td><td>74</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Giant TCX</td><td>55.5</td><td>58.5</td><td>72.5</td><td>xx</td><td>43</td><td>104</td><td>xx</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Kelly Knobby X</td><td>57</td><td>57</td><td>73</td><td>73</td><td>42.5</td><td>102.9</td><td>xx</td><td>29.2</td><td>52.5</td></tr>
<tr bgcolor="white"><td>Kelly Knobby X 5</td><td>52</td><td>57</td><td>73</td><td>73</td><td>42.5</td><td>102.9</td><td>xx</td><td>29.2</td><td>52.5</td></tr>
<tr bgcolor="white"><td>Kona Jake The Snake</td><td>58</td><td>57.8</td><td>72.3</td><td>71.8</td><td>43.5</td><td>xx</td><td>xx</td><td>29.1</td><td>53.5</td></tr>
<tr bgcolor="white"><td>Kona Major Jake</td><td>58</td><td>57.8</td><td>73.8</td><td>73.3</td><td>43.5</td><td>xx</td><td>xx</td><td>29</td><td>54.5</td></tr>
<tr bgcolor="white"><td>Steelman Eurocross</td><td>57</td><td>58.5</td><td>73</td><td>74</td><td>42.5</td><td>103.2</td><td>xx</td><td>28.6</td><td>58.5</td></tr>
<tr bgcolor="white"><td>Redline Conquest/Team/Pro</td><td>58</td><td>58.5</td><td>72</td><td>73</td><td>43.5</td><td>103.2</td><td>xx</td><td>28.5</td><td>59.5</td></tr>
<tr bgcolor="white"><td>Colnago World Cup Cross</td><td>60</td><td>57.9</td><td>73</td><td>73</td><td>42.3</td><td>xx</td><td>xx</td><td>28.5</td><td>59.5</td></tr>
<tr bgcolor="white"><td>Ibex X-Ray</td><td>57</td><td>57</td><td>73</td><td>72</td><td>42.5</td><td>102.1</td><td>xx</td><td>28</td><td>64.5</td></tr>
<tr bgcolor="white"><td>Kinesis Crosslight</td><td>60</td><td>58</td><td>73</td><td>71.5</td><td>43</td><td>105</td><td>xx</td><td>28</td><td>64.5</td></tr>
<tr bgcolor="white"><td>Trek XO-1</td><td>58</td><td>57.8</td><td>73.1</td><td>72.3</td><td>43</td><td>103.6</td><td>xx</td><td>27.6</td><td>68.5</td></tr>
<tr bgcolor="white"><td>Jamis Supernova/Nova Pro</td><td>58</td><td>57.5</td><td>72.5</td><td>72.5</td><td>42.5</td><td>102.3</td><td>xx</td><td>27.6</td><td>68.5</td></tr>
<tr bgcolor="white"><td>Co-Motion Lucifer/Demon</td><td>56</td><td>56.5</td><td>73</td><td>73.5</td><td>41.2</td><td>xx</td><td>xx</td><td>26.5</td><td>79.5</td></tr>
<tr bgcolor="white"><td>Bianchi Volpe</td><td>58</td><td>58.1</td><td>72.5</td><td>72.5</td><td>42.5</td><td>103.2</td><td>xx</td><td>xx</td><td>xx</td></tr>
<tr bgcolor="white"><td>Nashbar X</td><td>58</td><td>58</td><td>73</td><td>70.5</td><td>42.5</td><td>104.8</td><td>xx</td><td>xx</td><td>xx</td></tr>
</table>

brilliant stuff guys - nice table and data compilations!

V.COOL!

Thanks guys, this is a big help for me.

I second that. Thanks guys. I thought it was especially nice of you to be looking for the exact frame size I am looking for.

Thor

BKW makes a convincing case for more BB drop in a post from earlier this year.
http://www.belgiumkneewarmers.com/2008/01/low-slung-fun.html

yeah - that, admittedly, was what nucleate my thinking about the BB drop...

unfortunately what it confirmed is that the biggest off the rack frame makers that have a top tube close enough to fit me also seem to have the highest BBs.

Before people pile on the thread-wagon here and take a low BB drop measurement as the key factor in a frame decision, let me just say that this is not an 'aha'- moment. There's lots more to how a frame handles than this thread implies. I'm just a mid-pack B rider, but I have been in the game for a few years and raced at least a season or two on about a half dozen different rigs over that time, and my favorites have had highish BB's, my current favorite is a custom (second-hand to me) EL-OS steel with steep (74+ deg as close as I can measure) HT and ST angles and a BB drop of about 60mm. 55cm eff. TT, slightly sloping, 53c-t ST, so it's mid to large size for my 5'10" height, middle of the bell curve. I like the 'stability' that a low BB gives on a road or road racing frame, I have several like that with what's described as"stage race" geometry, whatever that means. But on a dedicated cross racer (not necessarily designed for joyrides on dirt roads, commuting and such) give me a design that works on a (for me, Eastern US) cross course. The trickiest corners are very tight and low speed, and for me, the fastest way on those is to pedal through them while feathering the brakes if at all possible to keep the wheels powered and rolling. My higher BB allows me to maximize the possibility of doing this without clipping the turf, especially off-camber. At slower CX speeds on technical terrain, I don't think the lower BB helps much, at least not enough to offset the advantage of being able to continue to pedal through with brakes on; keeping the wheels rolling is key to avoiding too much drift/washout. Higher speed sections on a CX course are where a lower BB would feel better, but these places tend to be straight bombing descents or power sections, bike handling there is not as much of a challenge. A high BB might be more of an issue in rainy Oregon, I have experienced only a few races in apocalypse-by-mud conditions, so maybe the lower BB works better there, I defer to the Portland crowd. But on a typical CX race course that I see in New England or Mid-Atlantic, gimme my odd little high BB, steep angled, low trail beastie. The same bike handles poorly at speed on the road, too nervous; If my crosser was also my all-rounder, I'd go for a more moderate design.

I guess my main point here is, YMMV--- riding styles vary, and for the way I like to ride a course, a low BB doesn't accomodate as well. And most importantly, as has been said, and should be emphasized, BB drop measure is only one view of frame geometry. A rider's center of gravity varies with height, gender, bodytype etc and things like weight distribution between the wheels, front end trail, chainstay length, saddle setback are all big contributing factors, if not more important than BB height. One rider's dreambike can be another's albatross--- anybody want a beautiful lugged 56cm Waterford X-22 frame/fork with low BB and "stage race" geometry? It's not my favorite for cross racing for the reasons above, it's going on Ebay in mid-Summer in time for cross season.

tire choice - rider weight - rider height - pedaling style...

all affect how the BB plays into things...

Crank length even, esp for those who run 180s.

Personally I've rarely pedaled through corners. Corners that require pedaling through generally are slow enough that BB height isn't an issue.

Currently my ride is a lower middle height and I like it. I've got bikes on both sides of the BB height though, and I'd trade stability for pedal clipping on the cross bike long before I would on the crit bike. Clipping a pedal in a crit has quite dramatically different affects on ones body than clipping one in a cross race.

And yes. BB height is only part of how the frame rides, a small part, but not insignificant.

...Clipping a pedal in a crit has quite dramatically different affects on ones body than clipping one in a cross race.

Yep, been there done that... Cat V racing 101, lesson one "Testosterone can cloud your judgement"

In any case, manufacturer's geometry specs listed on a website should be taken with a large hunk of salt. Throw some of those numbers into BikeCad or something similar and they don't add up. Kinda like tire width claims... Geez when is September gonna get here?:9:

I have found pedal strike to be a real factor in CX racing if the course has extended off camber sections. Had a pretty dramatic incident with that this season.

the fastest way on those is to pedal through them while feathering the brakes

Mmm, just like left foot braking on the race track. I've done a bit of on-track sports car driving which has probably helped more than anything during cx race handling. Lacking big money and big horsepower, I've never had a fast car on the track. Momentum becomes the equalizer. If you are smooth, pick a good line, and carry your momentum, you can dog anyone in the corners. Doesn't get much better than running up the bumper of a Corvette or Viper in a perfectly balanced, yet completely underpowered Porsche 944. That said, I coast WAY too much on the cx bike.

Just out of curiosity. Has anyone gone through and tabulated bottom bracket drop relative to various bike brands?

Ridely's popping in at 57, Speedvagen is about 70, RadioFreddy's Hot Tubes was around 75.

Not that it is a ton of work, but it got me wondering if some one had already done it.

Interesting, that reminds me of a convo I had with Pager when he had just gotten his hot tube bikes the year(s) he had no cervelo. He was b*&ing about the BB being so low that he was banging pedal like crazy on his test ride. He had only just had the bikes and built them up. He thought toby had made a mistake and used a road frame dimension in a hurry to get him a bike, etc. etc.

I never found out where those bikes ended up, i really liked them, thought they were cool as hell, and super light with all the alpha q goodies he had that year. Wonder if Toby got them back...they were just my size and i suspect that I like a low BB. I would have to measure the sachs, but it has long (visibley) chainstays. i like alot in the high speed corners. I feel like its maybe not as easy to turn as the Ridley at low speed, or really tight corners, but I have not raced the Ridley, and I have the Sachs, and I like the handling overall quite alot. Many many times i have slid out and should have gone down and just didnt. It was almost a theme. Bike seems to just want to stay up.

Only problem I seem to have racing on the Sachs is sand and rut type situations, which I attribute (in my mind) to the steering, its a tad self centering, which is probably why it corners so stable, though you do need to really steer it hard. Could also be that I just suck at riding the sand. My feeling is that it tries to go straight on its own, that would be a large rake, right? So in sand, it does not follow the rut so much, and you get out into the deep and die.

What was my point? I forget...oh yah, I think Toby must use a very large BB drop as noted above, and I suspect Richard does as well. I gotta go measure. Maybe he will chime in here (and get mad at me for implying my sand ability is due somehow to his fork).

I need to look at the Ridley HT angle and rake, it seems to me to ride polar opposite to the Sachs, it steers with a very very light touch, and its a high BB. You can crank the bars back and forth at walking speeds on it. The sachs you cant. Luckily i try really hard not to race at a walking pace.

Man, i gotta do a couple races on the ridley's next season.

J

Redline claims 65mm for BB drop on all Conquest.

Interesting, that reminds me of a convo I had with Pager when he had just gotten his hot tube bikes the year(s) he had no cervelo. He was b*&ing about the BB being so low that he was banging pedal like crazy on his test ride. He had only just had the bikes and built them up. He thought toby had made a mistake and used a road frame dimension in a hurry to get him a bike, etc. etc.

I never found out where those bikes ended up, i really liked them, thought they were cool as hell, and super light with all the alpha q goodies he had that year. Wonder if Toby got them back...they were just my size and i suspect that I like a low BB. I would have to measure the sachs, but it has long (visibley) chainstays. i like alot in the high speed corners. I feel like its maybe not as easy to turn as the Ridley at low speed, or really tight corners, but I have not raced the Ridley, and I have the Sachs, and I like the handling overall quite alot. Many many times i have slid out and should have gone down and just didnt. It was almost a theme. Bike seems to just want to stay up.

Only problem I seem to have racing on the Sachs is sand and rut type situations, which I attribute (in my mind) to the steering, its a tad self centering, which is probably why it corners so stable, though you do need to really steer it hard. Could also be that I just suck at riding the sand. My feeling is that it tries to go straight on its own, that would be a large rake, right? So in sand, it does not follow the rut so much, and you get out into the deep and die.

What was my point? I forget...oh yah, I think Toby must use a very large BB drop as noted above, and I suspect Richard does as well. I gotta go measure. Maybe he will chime in here (and get mad at me for implying my sand ability is due somehow to his fork).

I need to look at the Ridley HT angle and rake, it seems to me to ride polar opposite to the Sachs, it steers with a very very light touch, and its a high BB. You can crank the bars back and forth at walking speeds on it. The sachs you cant. Luckily i try really hard not to race at a walking pace.

Man, i gotta do a couple races on the ridley's next season.

J

Question- Was the Sachs built for you or are you a second owner? Because to me, if it's custom for someone else and it's in the range that fits you but not "tailored" for you, what you have is a beautiful bike to be sure but not fully the magic that the intended owner experienced, it may be an even better bike than you know under someone else (maybe me? kidding, but keep your garage locked :aureola: ). I've never had the pleasure of taking one of his bikes for a spin, much less an aggressive lap or two around a course, but I have stared at a few close hand sitting in the pits (a Sachs PIT bike? too sad to contemplate I know). My impression is they built around loosely "classic" road bike dimensions, lowish BB around 70, with long chainstays and a trail measure around 50, which should make for handling on the light side compared to typical off the shelf cross bikes or roadies. BTW larger fork offset= smaller trail measure, steeper HT angle= smaller trail measure. So with the same HT angle, more rake would make for lighter steering, not more stability. One of these days I'm gonna attack one of those pit bikes with a caliper and tape measure. Geek out!

Bike was Page's Napa winner... we happen to be fairly close in size and shape, luckily for me his brother is like 6'-6". JP and I are both hunchy back, short legged. He is taller then me but has an even hunchier back and I have longer arms for my size. I could run a half cm less TT and ST if I wanted a small fitting bike. I think Richard has his own feelings on bike fit and it is maybe less complex then other custom builder's analyses. Not sure why I say that.

yah, the whole trail rake thing always throws me, perhaps a better description of the steering is that it is sort of wheel floppy-ish. Not in a bad way like some crazy touring bike with 75mm of rake, but the more rake you have, the more the wheel wants to translate across the ground verses just rotating on the point of contact. Since the wheel is glued to the ground by friction, it does not translate, instead the headtube and handlebars sort of pick up and move/flop, which is what I call wheel flop. A zero rake bike would essentially drill a hole in the ground spinning on the point of contact as you chopped the bars back and forth. It would also steer and like a shopping cart, right?

I could be totally out to lunch, but that is correct for a very low speed, track stand type scenario, right? similarly riding in sand. A derny bike or shopping cart is going to have zero or negative rake (dont they run backwards forks?) that would make the steering super super twitchy, and a rut could push the wheel around and the bike would follow the rut if you let it, it would follow/chase the ruts verses the bike wanting to track nice and straight, which you want in most cases, but maybe not in deep sand if you suck at riding sand.

That is how I sort of mentally define "light" vs. "heavy" steering - how it feels at super low speed. Heavy would be like "pushing" in Nascar terms. Light would be "loose". I suspect that is not the correct way to think about it, and again, I have never forced myself to sit down and understand the math behind the trail/rake/ht angle business. I am sure I will be corrected.

I wish to STATE VERY CLEARLY that I am overstating the handling of the Sachs as a way to explain the sensation vs the ridley. I like the handling, its just different then the Ridley.

Seems like I am putting alot of words in richies mouth. NOT THE CASE. I would love his input on this thread, maybe he is lurking. I have always wondered the dimensions of the bike but never bothered to try to measure, other then TT and ST.

Oh, anybody can take my bike for a lap anytime they want, if you ever see me at races. I am not stingy that way. Just dont ask during the race.

J

jerry - you just suck in the sand... it ain't the bike

oh and chainstay length - low BB and you got longer stays but maybe not longer effective chain stays.

People are used to talking about effective Top Tubs, maybe they should get used to talk effective chainstays...

ah whatever...

just ride the damn bike...
I just don't wanna wait till september...

i wanna race now... or maybe i should wait till the snow melts and the weirdo's who ski are done with that rediculous past time :D

jerry - you just suck in the sand... it ain't the bike

if it was the bike then Amy wouldn't be DEMOLISHING everyone in the sand sections ridin her RS bike...

stop it, i am trying to rationalize here. the c-stays ARE effectively long, you can see that clearly from the rear wheel position relative to the BB.

I am not a powah ridah, so I dont suppose the sand will ever be my freind, I need all the help i can get. maybe a ridley pit bike i grab just prior to the sand sections.

regardless, perhaps you should check your nemesis section (http://www.crossresults.com/?n=racers&sn=r&rID=182)over on jackie collin's site...

damn its early to be talking smack...now i know why you want me to join team big ass refunds, its so i can tow you around for the sprint and you can call it teamwork...

yeah - you beat me 6 times, i only beat you 3 times... damn I gotta work on that for next year...

join up cause skinny whitey is on the team... not for me... you riding around in that old RS skinny is good fuel to try and catch ya when i can

I asked a bunch of builders at NAHBS about bb drop. Look for an article about just that subject soon.

I asked a bunch of builders at NAHBS about bb drop. Look for an article about just that subject soon.

I'm in suspense. Who said what?

just ride the damn bike...
I just don't wanna wait till september...

i wanna race now... or maybe i should wait till the snow melts and the weirdo's who ski are done with that rediculous past time :D

In April I'm doing a local point to point race (Paris-Ancaster in Ontario). It's billed as an xc race but a lot of people ride it on their cx bikes too. There might be some races like that going on in your area.

Correct me if I'm wrong, but doesn't BB drop + BB height = Wheel Axle height (radius). Looking at the table above, I get axle heights between 347 - 370. Is there really a 23mm difference in the radius of different tires? Put another way. Not a bidg deal, but I'm trying to compare the specs on a Lemond Poprad to a Trek XO, and Trek gives BB height and Lemond gives BB drop. They run the same tires, so I should be able to get the Trek BB drop by subtracting BB height from it's wheel radius.

I used to do the Hillsborough NORBA Classic 30 mile point to point MTB race on my cross bike, back in the late 80's and early 90's until they cancelled it. It was the ideal bike, except for the punishing baby head down hill section...hah, I remember I ran a Girvin Flex Stem on it one year! I was all excited. Have not seen one of those in while.

I'm in suspense. Who said what?

A builder I spoke with talked about toe clips needed more height so they wouldn't smack the ground on remounts.

Looking forward to what Gripped has to report.

Correct me if I'm wrong, but doesn't BB drop + BB height = Wheel Axle height (radius). Looking at the table above, I get axle heights between 347 - 370. Is there really a 23mm difference in the radius of different tires? Put another way. Not a bidg deal, but I'm trying to compare the specs on a Lemond Poprad to a Trek XO, and Trek gives BB height and Lemond gives BB drop. They run the same tires, so I should be able to get the Trek BB drop by subtracting BB height from it's wheel radius.


BB drop is an absolute measure. BB height is unreliable as it will vary with tire diameter and pressure. Some manufacturers may measure it and some may calculate it. Real tire diameters cannot be trusted to be the same as ISO specifications. So, even if the manufacturers specify the tire diameter and manufacturer, the estimated BB drop will typically be off by 3-5 mm when only BB height is given.

BB drop is an absolute measure. BB height is unreliable as it will vary with tire diameter and pressure. Some manufacturers may measure it and some may calculate it. Real tire diameters cannot be trusted to be the same as ISO specifications. So, even if the manufacturers specify the tire diameter and manufacturer, the estimated BB drop will typically be off by 3-5 mm when only BB height is given.

Great explanation. It's very curious that Trek reports BB height and Lemond reports BB drop. Interesting inconsistency from the same parent company.

I measured the bb drop of my Sachs and it is 61 or 62 mm, just about the same as my Steelman Eurocross. FWIW. My bike is also a team bike (Dave Genest's from 2004 and 2005).

I measured the bb drop of my Sachs and it is 61 or 62 mm, just about the same as my Steelman Eurocross. FWIW. My bike is also a team bike (Dave Genest's from 2004 and 2005).

you are going to make me go out to the garage aren't you...

mine, i think, is the first one, or at least the first batch, that had the much taller fork crown (there is loads of mud clearance above the tire, verses a more road looking fork). Mine is Page #6, which is the Napa bike, which is the last of the bikes he built for JP, as the first year were some purple people eaters, then the Baltimore year he made a batch, then the Napa year batch.

I am curious if richard evolved the rest of the design to accomodate the taller fork.

Or I could be totally out to lunch, but that is how I remember the bikes developing (JP had forks on the brain for a while there).

I will try to measure and post a follow up.

J

Very interesting thread. In conclusion all modern CX bikes have BB drops ranging from 58 to 74mm. What about those frames from the nineties? I found a bike that has 40mm BB drop. Does it handle like a tank? Apart from the BB drop it seems to be perfect for me.
I will not use it as a pure crosser, but as an all-purpose-training machine (roads, bad roads, fireroads, trails, maybe some races). I assume I should better get something more up-to-date?!

Very interesting thread. In conclusion all modern CX bikes have BB drops ranging from 58 to 74mm. What about those frames from the nineties? I found a bike that has 40mm BB drop. Does it handle like a tank? Apart from the BB drop it seems to be perfect for me.
I will not use it as a pure crosser, but as an all-purpose-training machine (roads, bad roads, fireroads, trails, maybe some races). I assume I should better get something more up-to-date?!

try it and see. might not corner well but if you can live with that and all else is equal I wouldn't make it a dealbreaker.

try it and see is hard because it's only a frame right now. I was a bit confused because people reported different riding properties from frames that differ half an inch in BB drop, and the frame in question is more than one inch different.

try it and see is hard because it's only a frame right now. I was a bit confused because people reported different riding properties from frames that differ half an inch in BB drop, and the frame in question is more than one inch different.

do you like to ride slow? <img src="http://forums.roadbikereview.com/images/icons/icon10.gif">
a high BB <i>should</i> be a bit more stable at low speeds, fwiw. If the frame is otherwise appealing for whatever reason I wouldn't let that stop me. a lot of people ride track bikes on the road with ~5cm drop so there's precedent, sort of.

do you like to ride slow? <img src="http://forums.roadbikereview.com/images/icons/icon10.gif">
a high BB <i>should</i> be a bit more stable at low speeds, fwiw. If the frame is otherwise appealing for whatever reason I wouldn't let that stop me. a lot of people ride track bikes on the road with ~5cm drop so there's precedent, sort of.

Track frames accommodate the fixed gear drivetrain around banked corners so the BB drop on those bikes isn't representative what handles the best. Concessions have to be made for the event in questions - same logic for crit bikes.

Track frames accommodate the fixed gear drivetrain around banked corners so the BB drop on those bikes isn't representative what handles the best. Concessions have to be made for the event in questions - same logic for crit bikes.

what I was apparently unsuccessfully trying to convey was that a lot of riders are using track bikes on the road with apparently few ill effects, at least as it relates to bb drop.

what I was apparently unsuccessfully trying to convey was that a lot of riders are using track bikes on the road with apparently few ill effects, at least as it relates to bb drop.

Point taken. I have a track bike and the Poprad (lowest production BB drop at 74mm) and my view is that the Poprad handles way better on the corners and high speed than the track bike despite the longer wheelbase on the Poprad.

Are you sure your Sachs has a 60mm BB drop? I've talked to him several times as well as Paul Sadoff and they told me they normally use regular road frame BB drop for cyclocross frames. 70 ish mm's

Sachs has told me that the only reason frames were built in the "old days" with a high BB was to avoid toe clips from hitting the ground/barriers, etc. Now that there are no toe clips it is a non issue.

I think the lower center of gravity of a 70mm BB drop is much more important to riding feel and stability off road than crank clearance........

I think I like low BB's but off camber stretches suck.
Actually I think slower people benefit from a different geometry than the pro's bikes.

my zank has 7 cm of drop, and I'm 99% sure he goes to 7.2 for a road frame.

I rode an undersized redline for 3 years prior to this past one on the zank, but the difference in bb drop has not been the biggest change, being comfortable with the correct reach has. This is the first bike I've had that fits right, and only the second I've had overall so I'm not in much of a position to discuss the particularities of one drop length to another.

Overall, the zank rides more predictibly and in all but the tightest of switchbacks is far superior to the Redline. But even in those corners while it is perhaps a bit less "flickable" I know what is going to happen and can usually focus on passing another rider or setting up for the next turn rather than keeping the bike on course.

I measured my Empella Bonfire's BB drop to be 65mm for a 53cm.

one of these days I'll measure it - but...

as a Point of reference, the Giant TCX isn't listed on the charts (the bb height or drop) but it is somewhere in the lower range it seems -
~27cm high (measured approximately to the center of the BB) or so with 28 scwhable marathon tires inflated to 90 psi

and they make a nice (circus) freak size...