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  1. #1
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    Chainring Question: 52/36 or 50/34?

    Hi All,

    I'm a female, 5'5", 120 lbs, riding a Felt F75 wit a 50/34 crank. I'm thinking of upgrading to a BMC Teammachine SLR02, but it comes with 52/36 gearing. I've been at my physical limit on 15% grades with my 50/34, and am worried that I might not have the oomph to push a 52/36 up same, especially during the endurance rides I prefer, from 60–100 milers. With the trade-off of a lighter carbon frame vs. my current aluminum frame, what do you all think? Will the difference in chainring size be noticeable with a lighter bike?

    Thanks!
    Tammy

  2. #2
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    Same cassette? Gearing isn't just a chainring. Assuming your largest cog is the same, your 36 will give you a gear about 6% higher than with the 34. That's "noticeable," but whether it's a problem depends on too many things to say definitively. The lighter bike will reduce the weight of bike/rider total by maybe 3 or 4%, not a huge deal. So if you're at your limit with your present low, you might want make sure you have at least that low on the new one. But you can possibly do that by changing the cassette rather than (or in addition to) the chainrings.
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  3. #3
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    Ah, good point. The Felt cassette is 10-speed, 11-25; and the BMC is 11-speed, 11-28.

  4. #4
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    The 36/28 new gearing would be a little lower (about 4.5%), than the 34/25 you have now. So worth a try.
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  5. #5
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    Quote Originally Posted by bikerjulio View Post
    The 36/28 new gearing would be a little lower (about 4.5%), than the 34/25 you have now. So worth a try.
    Right. Or actually about 5.5%, but I'm quibbling. So, OP, your concern was misplaced. You'll have a lower low gear with the new bike.

    Ratios are what matter. All the talk of compact and standard, etc., can lead people to forget that. When you're going up that hill, you're not "pushing a 52/36"; you're pushing a 36/28 (or whatever).
    Last edited by JCavilia; 05-05-2016 at 12:28 PM.
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  6. #6
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    Fantastic! Thanks for sharing your insight! Truly appreciated.

  7. #7
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    If you do endurance rides with lots of climbing or steep climbs, I suggest the 50/34 and 11-28 cassette. You'll have a lower gear than you have now, and the same high gear. It helps to have low gearing on steep climbs, to keep from tiring your legs out as fast.

  8. #8
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    Quote Originally Posted by ericm979 View Post
    If you do endurance rides with lots of climbing or steep climbs, I suggest the 50/34 and 11-28 cassette. You'll have a lower gear than you have now, and the same high gear. It helps to have low gearing on steep climbs, to keep from tiring your legs out as fast.
    Yep, I agree. I do quite a few 100+ milers each year and you are better erring on the side of lower gearing. I also like closer spacing on the cassette than an 11/28 provides. 50/34 and 12/25 would make more sense in my opinion. You might be able to get the shop to swap the crank for free (or a small fee) if you are buying it new.
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  9. #9
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    Quote Originally Posted by ericm979 View Post
    If you do endurance rides with lots of climbing or steep climbs, I suggest the 50/34 and 11-28 cassette. You'll have a lower gear than you have now, and the same high gear. It helps to have low gearing on steep climbs, to keep from tiring your legs out as fast.
    I agree with this as well with two notes:

    1] If you ride where the are big mountains - see if the dealer will install a long cage rear derailleur which will allow you to go up to a 32 if you every want to.

    2] I would put on the 28 and find if you don't need the 28 then you can always install a 11-25 or 11-23 for closer ratios if you want them. I really like close ratios for group rides where you'll fine tune what gear you are in to optimize cadence etc. For touring or just riding with some friends that is much less of an issue.

  10. #10
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    Quote Originally Posted by Jon D View Post
    I agree with this as well with two notes:

    If you ride where the are big mountains - see if the dealer will install a long cage rear derailleur which will allow you to go up to a 32 if you every want to.
    It is not the cage that determines if a derailleur will accept a larger cassette. That is a common misconception. The 11 speed derailleur might accept a 32 as is. My Domane with DA 9000 can take a 32. It depends on the derailleur hanger and the geometry of the derailleur motion.

  11. #11
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    She would only need to ask the shop to put on different chainrings, not a new crank. It's probably not an unusal request.

    I have done a bunch of endurance rides and races with lots of climbing. I generally try to have one gear lower than I think I'll need. There's been enough times where it's been harder than I expected or I was not feeling well late in the event and needed that low gear.

    For Sram road derailleurs the spec is 28t but they can almost always handle a 30t. On newer Shimano road derailleurs the spec is 30t and they can often handle 32t.

    BTW I looked up the SLR02 and for 2016 it looks like it comes with 50/34 and a 11-32 cassette. Shimano 105.

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    Hey All,
    Just wanted to thank everyone for chiming in. Super helpful! I ended up getting a Cannondale Synapse 3 WITH 50/34 and a, 11-32 cassette. Then I promptly signed up for two Gran Fondos in California this summer/fall. I should be sitting pretty.
    Cheers!

  13. #13
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    I am on a 52/36 with an 11-28 (11 speed) carbon frame. I do some hilly rides, and have been on gradients as excessive 15-20%, i do just fine. I am approx 5 foot 8 185 lbs.

    Really you could get different chainrings, for different events. A 52/36 may be better for flatter courses.

  14. #14
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    My gearing works fine for me so it should be fine for you. Doesn't matter that I have no clue what climbs you're doing or your fitness or your pedalling style. No one could possibly need gearing different than what I use.


    BTW we have actual mountains here in California. One of the races I do has three 6000' climbs and three 3000' climbs, over two days. There are tons of organized rides with 10,000' or more total climbing.

  15. #15
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    Quote Originally Posted by TammySalyer View Post
    Hey All,
    Just wanted to thank everyone for chiming in. Super helpful! I ended up getting a Cannondale Synapse 3 WITH 50/34 and a, 11-32 cassette. Then I promptly signed up for two Gran Fondos in California this summer/fall. I should be sitting pretty.
    Cheers!
    perfect gear ratio for almost anything, it's what I use on 3 bikes now

    but then for someone old and heavy as me, I would even want lower gear for a tough real mountain climb. in my youth I would climb in the alps with a 39-28,and I could not do that today. In my youth did all my racing with a 53-39, 13-21 in midwest terrain

    it's one thing I agree with Durianrider about: have low gears, high cadence and ride a lot of mountains. I think he even put on a 36T or 40T on his Giant Defy to climb Mt Baldy recently (10k ft), though he is as fit as a strong young racer.

  16. #16
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    Definitely go with a compact crank and an 11-32 cassette.

    Ah- I see you did this.

  17. #17
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    My Bianchi came with a 50-34 compact and an 11-25 10 speed cassette. I changed out the big ring on my crank to a 46. This is a fairly common cyclocross setup. Now I have a 46-34 crankset with a 12-28 10 speed cassette. With the 34-28 I can pretty climb anything I am likely to encounter. I can also spin the 46-12 on the top end. Previously with the 50-34, I wasn't using the smaller cassette cogs except downhill or downwind. Get what works for you. That's why they make so many different combinations.

  18. #18
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    You may find the 11-32 to have large gaps between ratios. If so and you consider going back down to an 11-28 or 11-26, know that these two options only differ in the largest 3 cogs so given the choice, I'd recommend the 11-28.

    Good luck with the new rig. Nothing like that "new bike ride".

  19. #19
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    To give you a better idea of the gearing ratio. Download the app Gear Calculator, it allows you to compare different gear setups. You can adjust crank arm length, cadence, etc.

  20. #20
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    Quote Originally Posted by davidka View Post
    You may find the 11-32 to have large gaps between ratios. If so and you consider going back down to an 11-28 or 11-26, know that these two options only differ in the largest 3 cogs so given the choice, I'd recommend the 11-28.

    Good luck with the new rig. Nothing like that "new bike ride".
    The gaps occur on the larger cogs - on 11 speed cassettes most of the smaller cogs are similar in their spacing/# of teeth. I recently went from 50/34 w/ an 11/26 cassette to 52/36 w/ an 11/32 cassette. I found the 52 helping with downhills, but hurting me on flatter areas. I'm going back to the 50/34 or possibly a 50/36. I feel as if I'm only using the 5 larger cogs on my cassette a majority of the time.
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