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Thread: 29er Gearing

  1. #1

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    ... and if we just ... Best gearing I found for 29er

    Never found more happiness on my 29er than when I figured out the gearing. Seems a 29er moves about 11% further for each revolution of the crank than a 26. Since the gearing is designed for a 26, the 29er really never gets to use the range of the gearing effectively and seems a bit slugish on acceleration. I changed the front chain rings to a 42, 30, 20 set up. Now, I have a 29er that pedals like a 26 with all the benefits of a 29er. Best race set up I've ever had. 4 wins and 2 2nd place finishes on the bike this season. The 2nd place finishes were before I figured out the gearing set up. Rings are Salsa Pro's with Race Face cranks.
    Last edited by stevenseltz; 06-18-2004 at 09:52 AM.

  2. #2

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    I think you are right.

    I had a discussion with one of my co-riders the other day, about setting up our SS rigs, he has a 26" and I have a 29" (soon).

    He thinks that it would be a bigger (harder to turn) gear required to get the same on a 29".
    32 x 18 feels comfortable on the 26" bikes, and I was thinking about a 30 x 19 on the 29" to get the same effect, or close to.

    Just confirmed on Sheldon Brown's site, assuming same crank arm length.
    This gives you about a 46 gear inch ratio.

  3. #3
    jl
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    I know some Monkey riders who are riding 32x20. Which I probably easier to setup than a 30x19. It to is around the 46 gear inch ratio.
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  4. #4
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    Did you miss the 22/32 gear, than, in racing?
    Otherwise, in theory, it's just a matter of shifting one cog larger in the back, in eveyy circumstance.

    I like smaller rings better as well, but have no clue as to why.
    Klok - XC - Skate - Ski

  5. #5

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    To me it's really very simple, adjust your gearing by about 10% lower than you would run a 26 and your have fairly equal gearing, whether this be single speed or multispeed. The beauty is you better efficiency than the 26 due to the nature of the 29er. You can outclimb, out decend, out sprint and be more technical than any 26 I've ever raced.

  6. #6
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    32X20 on a KM

    I am new to the 29er thing and SS thing, about a month of riding now. The 32x20 is good off road but I find my finger phantom shifting on the road when I spin out.
    blah blah blah

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    Running a 32/22 on a 29er is almost like running a 36/24 on a 26. And rather than changing the rear cassette it's easier to change front rings. This way you can use all nine gears on the rear and have all three at you disposal in the front. Why waste gears because some are just to big to to be effective and maybe not have a small enough gear when you need it. There is just to much effort required trying to push to big a gear to have anything left at the end of a race.

  8. #8
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    Below is the gearing difference illustrated.

    26" travel is calculated as front-teeth / rear-teeth * (559+55+55) / 1000 * 3.14
    29" travel is calculated as front-teeth / rear-teeth * (622+55+55) / 1000 * 3.14

    55 mm is the tire height over the bead seat (measured on my pair of Mythos).

    Whether the standard 26" three-ring gearing is ideal for everyone is another story.

    For me and my riding, I have found that I only need the big ring for the 44/13 gear, which is just one step heavier than the mid ring's heaviest gear (32/11). I would practically reach 44/13 with the mid ring if I swapped it for a 36T (36/11 is close to 44/13). I could then lose the big ring (and get a bashguard perhaps) but the 22-to-36 front gap may be unpractical, corresponding to jumping 4 rear cogs, so it may not be such a good idea.

    The really steep climbs that I run here aren't such long that I miss a lighter gear than 22/34. But I could imagine those climbing up a steep peak in the Alps or Rockies wanting something lower to get a lower prolonged high power output.
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    Last edited by anden; 06-19-2004 at 08:03 AM. Reason: Graph was wrong (no-one noticed? or cared perhaps;))

  9. #9
    jl
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    Quote Originally Posted by ozlongboarder
    I am new to the 29er thing and SS thing, about a month of riding now. The 32x20 is good off road but I find my finger phantom shifting on the road when I spin out.
    Isn't this MTBR and not roadbikereview . I'm not talking about anything roadie here.
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  10. #10
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    For the 2x9 folks...

    I've found that 28/38 (or even 26/36) shifts well and covers a decent range of possible trail conditions, for those folks who want just 2 chainrings. You'll seldom be spun out unless you're on slightly downhill fire roads or something, likewise you'll seldom need a lower gear (if you're in decent shape) when climbing.

    For me, the issue with 29er gearing isn't that you need to go a bit lower (which is common knowledge and probably doesn't need to get rehashed for the 800th time here) - it's that it changes the front chainring shifting significantly - you've got to bail to an easier chainring sooner, assuming you're running the same rings and cassette. I found this quite difficult to adapt to, hence the 2x9 to simplify things.

    -Walt

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    If running a 10% lower chainring group in the front on a 29er is the same as a compact (44/32/22) chainring set on a 26, why are you having to bale sooner? I've never had trouble shifting my 3 ring set (set it up correctly) with the smaller gearing. There have been a few who have tried to run a 2 ring set ups, the pro's tried it for a while, but depending on the terrain, the results have not been spectacular. I'll take to task anyone who wants to run a long, steep, rocky grade during a race effort, or for that matter just out for fun with only a 28 small front ring. Let's see who get's to the top faster and more important, with something left. And in a sprint to the finish, give me a big ring 42. The 29er with a 42 front, 12 rear will out sprint any 26.

  12. #12
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    Please re-read my post

    As I said, with the SAME chainrings and cassette, one has to shift sooner to a lower chainring on a 29er. If you use smaller rings, that won't be the case.

    I had a UCI elite license until recently (which "pros" tried 2x9 setups "for a while"??!?), so the 26 tooth (or heck, 32) isn't going to make me run up the hill after you, trust me. 29ers are great, and I'll never ride a 26" bike again, but it's the rider that wins races, not the hunk of metal underneath them.
    Last edited by Walt; 06-18-2004 at 03:35 PM. Reason: Grammar correction

  13. #13
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    Hmmm.. What about chainsuck?

    When I read this stuff about using a 20 for a granny, I keep hearing a strange "sucking" sound in my head. I remember the 20/32/44 set-up I used to run.... not good! We used to make do with 28 or 32 for a low gear out back on a 26 inch bike, now we have 34's available, (again, after a looong hiatus!) Isn't that low enough? Do you really have to go with those-shudder- compact chainring sizes to get the gearing low enough? I've always been a fan of the traditional 110/74mm cranks. What would the suggestions be for chainrings on that sort of crank, with a 34 for a low gear out back?
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  14. #14
    mcd
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    29er anticipation...

    having made the decision to go 29, but not yet having it(due very soon though), i have quit using my 30 and 34 on one bike, and on my older fully rigid(which I've been riding a bit lately since my 29er will be rigid), i only have the option for 24/28, and even on that i try to stay out of the 28. i figure at least when i get the 29er it won't feel like i'm pedaling any harder when i go to the 22-34...
    incedentaly, i might actually be losing some weight doing this...which means more beer apres ride!

  15. #15
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    Maybe some day the cassettes have been 29" adjusted, and the rear derailleurs have got correspondingly higher capacity?

    A 29" bike with the classic front chain ring set gets the old 26" gearing with cog set 12-14-16-19-22-25-29-33-38.

    That would also keep the chain force at 26" level, as opposed to going to smaller front rings which increases the chain force (which doesn't have to be a problem though). But the chain would need to be slightly longer.

  16. #16
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    Yeah, gears will all feel the same as with 26" NOW, but do we really need that? Back in the days, we ran 26/36/48 * 12-28 and it worked fine. As long as we have an x number of gears with a nice spread, why the need to 100% immitate 26"? Every rider has it's unique fitness level. I'll be forced to go to the middle rings 10x more per lap than say, an Olympic contender. Someone slower than me may not even have a good reason to even get an outer ring, other than to keep pedal pressure on superfast descends.
    Right now, everyone from the Olympic champ to Slow Joe uses the same 44/32/22 * 11/32. Would that be the ideal setup for all humans on 2 wheels?
    Klok - XC - Skate - Ski

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    Gearing Diatribe

    In answer to Walt. I'm sure your an exceptional rider and your right, it is the rider that makes the bike, but together you make a machine and you are the engine that drives that machine. Unfortunately it the gearing that connects you to that machine and like every machine, whether it a race car, race motorcycle, everyday car , truck, bicycle racing, washing machine, they all rely on the proper gearing to get the needed effeciency out of the engine. It's really is all about the gearing in every machine! You wouldn't put road rings on mountain bike and vise versa. Maximizing the effeciency of the gearing is a decision everyone has to make for themselves, I have found something that works for me in the various conditions I ride which change drastically during the race, I need that 42/12 and I need my 20/34 to maximize my competitiveness.

    And yes the front smaller rings can be a little tricky to set up and the chainstay on some bikes can be a problem. But I've never encountered any problems since I set it up correctly, never had chainsuck and love what's it's done for the bike and it's engine, me. I have to use a 94/64 race face to make it happen and Salsa seems to be one of the few to make the rings. But what a difference it has made for me

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