Help me choose proper stem length for my new bike. (All other measurements inside)
I am in the process of putting together a second bike. I have nearly everything ordered except for the stem. I am unsure what length I need. I like my position on my current bike, so I want to replicate it. The measurements of my current bike are as follows:
Frame is a 54CM Felt F75 2006
Stem is 7 deg. 100mm and I am running 35 mm of spacers and headset stack combined. Stem is flipped.
This means my current bike measures in at:
Horizontal TT: 545mm
Stem Reach: 88.2mm
Handlebar Reach: 110mm (I have measured multiple times. I keep getting this, though it seems very long for a handlebar reach)
New bike has a Head Tube Angle of 72.5 deg. It will have FSA Pro Wing Compact bars. I plan on running no spacers, only the headset stack, which is approximately 10 mm. The new bike has the following dimensions:
Adjusted TT (adjusted using Seat Angle for comparison): 537.8mm
Stem Reach: ??
Handlebar Reach: 80mm
Based on the above information, before taking into account handlebar reach, I had estimated that I was in need of a 110 degree stem on the new bike to put me close to my current position. However, once I take into account the handlebar reach, my estimates tell me I would need a 130mm. According to my calculations here is how it would break down.
With a 110mm stem:
Stem Reach: 106.1mm
With a 120mm stem:
Stem Reach: 116mm
With a 130mm stem:
Stem Reach: 125.9mm
With a 140mm stem:
Stem Reach: 135.8mm
I know it is a little more complicated than just adding up Horiz TT, Stem Reach, and Handlebar Reach, but if I do so, it would seem that the 130mm stem puts me 5mm under and the 140mm stem puts me 5mm over my current reach.
My current bike also has Shimano 105 while the new bike will be running Sram Red. The difference in reach on the shifters is about 5mm, with the Sram Hoods being shorter, so that could make up the difference on the 140mm.
I am almost considering ordering a 110mm, 130mm, and 140mm and trying them all out. What do you guys think I should I do?
thats all way too complicated for me. i just buy the length that puts my bar dead center over the front hub when gripping the bars and looking down.
1999 Gary Fisher Procaliber Red/Yellow SRAM X9
2001 LOOK KG281 Blue/Black 10sp Ultegra
2002 Specialized Allez Red 9sp Ultegra
Quintana Roooooo! TT bike (dura ace friction)
2008 LOOK 586 Mondrian 10sp Ultegra
Build the bike and then take some measurements, much simpler than doing all that math. Get the stem that will give you the same reach as your current bike.
I suspect that you have measured your handlebar reach incorrectly. There are several methods used by various manufacturers. Although you can find bars with a listed reach of 110mm, that dimension is not comparable to those listed as 80mm.
According to this, I am measuring A for my current bars. Measuring this same for my new bars gives me 79.5 mm or so, which leads me to believe I am measuring it correctly. I had turned up my bars slightly to compensate for a higher lever position without unwrapping and moving my levers up the bar, so perhaps that is why the reach of my current bar is so high. It is probably lower in reach in the properly mounted position, but as currently mounted I am confident that the reach of the bar is 110mm.
The more I think about this the more I feel like I am going to need to just experiment with stem length.
As shown by the illustration you posted, "reach" of a bar is a dimension inherent to the bar. It always remains the same regardless of how you rotate the bar.
Originally Posted by Vee
If you're talking about "reach" as defined from where you sit to where your hands normally are, then rotating the bar does in fact make a difference. But that's an entirely different kind of reach than "the reach of a bar" stated in the bar's spec sheet.
I see. What I am looking for is to replicate my current position. For that reason, I guess I need to be less concerned with the actual measurement of reach for the handlebar, and more concerned with the reach provided as the bar is currently mounted. This is 110mm. With that in mind, am I right that I would need a 130mm stem on the new bike to replicate my current position?
Originally Posted by wim
First, with all the changes you're making it's virtually impossible to calculate on paper. Are the seat tube angles the same? I don't see any mention of this and you want to try and duplicate your position over the pedals first. Same saddle? Same post?
Originally Posted by Vee
The different shape of the bar and shift/brake levers will affect your position. Even if you are able to exactly duplicate your old riding position it will still feel different with these different components.
Personally when building a new bike with new and different components from the old bike I start with my position over the pedals and try and duplicate this on the new bike. Distance from tip of saddle to bottom bracket using a plumb bob then adjust for different saddle length if necessary if using a different saddle. You want where your sit bones meet the saddle to be the same distance fore and aft of the BB and the same vertical distance from the BB as your old frame. May require a different post too. That establishes my starting point, then through various measurements I figure out what length and degree stem and the amount of spacers needed to put the bar at the right height and distance from the tip of my saddle (adjusting for changes made if there's a new saddle). You're complicating things by using a new bar and shift/brake levers too so you'll never be able to exactly duplicate your old setup because the shape of the bar and levers is different. I basically take it one component or group of components at a time, start from position over pedals and work from there. I order and install as I go along and what I order and install is determined by the result of the previous work, moving from back to front. Takes longer to build this way but I find it works better than trying to order a bunch of stuff at once and hope it works. Invariably you'll be returning and ordering some parts but that happens more often if you buy them all at once.
"Those who can make you believe absurdities can make you commit atrocities." Voltaire
There are your fog people & your sun people, he said. I said I wasn't sure which kind I was. He nodded. Fog'll do that to you, he said.
We are all ignorant about most things.
Stop with all the angle crap, build a bike, put a stem on, ride it and make your mind up.
Fitting bikes is NOT HARD, you just have to engage your brain.
Much appreciated! This is good advice.
Originally Posted by Mel Erickson
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