What size chainring for DH ???????- Mtbr.com
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  1. #1
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    New question here. What size chainring for DH ???????

    Hi,
    we are currently building a project for our first DH rig. It's a Kona Coiler Dee-Lux.
    We're not sure what size chainring to fit?. We want to go single speed on the front but 9 speed on the rear.
    Can anyone help as we're pretty new to DH.

    Cheers,
    The Shad & Gingy G

  2. #2
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    38 is what ive been running, but with a road cassette. Enough that i wont spin out, but i can still climb to get in shape

  3. #3
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    I'm running 36 F 11-23 R for only DH. It really depends on what trails you're riding.

  4. #4
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    I was bringing extra rings to the races just so I could swap out for course conditions. I'd have a 38 on most of the time and run the 40 if there were more high speed sections. What size ring you run is also going to depend on what chainguide you decide to go with.
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  5. #5
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    36 or 38s are the most common.. if you ride really fast smooth stuff i'd go with a 40, more tight technical stuff i'd rock a 36.
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  6. #6
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    Thanks so far guys.

    We need to be able to use the rig for DH, but also for XC now and again, which is why we were going for a 9 speed rear, but if anyone has any better suggestions we'd love to hear them.
    Please remember we are newbies to DH, so any advice you can give would be great. It might seem basic to you, but to us you could be a DH Guru!!.

  7. #7
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    We've been thinking of getting the RaceFace Diabolus chain guide as it seems to have some good reviews, but we'll decide on which chairing to go with then get the guide to suit it.

  8. #8
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    if you are doing both xc and dh on a coiler, i'd suggest either a 34 or 36. honestly a whole season of shredding keystone and i topped out the 36 on my demo maybe a dozen times.

    as far as guide would go, since this it's a fairly lightweight bike you're building, i'd go with an e13 lg-1. or an e13 srs.

    the diabolus is ok, but isn't quite as good as the e13 (both as a mechanic and a previous owner of both.)
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  9. #9
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    38 is a good starting point for DH. I run a 33 but then I ride my DH rig on a lot of trail riding.

  10. #10
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    I run a 36T with a XT 11/34t what is the benefit of going with a Road cassette I know they are lighter but what else??
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  11. #11
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    Quote Originally Posted by El Gordo
    I run a 36T with a XT 11/34t what is the benefit of going with a Road cassette I know they are lighter but what else??
    closer ratio, better for racing.
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  12. #12
    Meh.
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    The RaceFace guide is like a knock-off of the old e13 guides. Go for the LG-1 with Taco.

    Road cassette offers closer ratios and snappier shifts.

  13. #13
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    Quote Originally Posted by XSL_WiLL
    The RaceFace guide is like a knock-off of the old e13 guides. Go for the LG-1 with Taco.

    Road cassette offers closer ratios and snappier shifts.
    Whats a good road casette Shimano? I am running a XT shifter with a 9 spd 11/34T XT cassette. I know you are a sram guy, but what shimano road casette would I get for my setup.
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  14. #14
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    Quote Originally Posted by El Gordo
    Whats a good road casette Shimano? I am running a XT shifter with a 9 spd 11/34T XT cassette. I know you are a sram guy, but what shimano road casette would I get for my setup.
    I'm a "Sram guy" but I run a Shimano Ultegra road cassette. From what I remember the Shimano is slightly lighter and has a stronger lock ring according to some reviews. Also I think the comparable Sram cassette didn't come in 11-23 which is what I wanted (I can't remember if that was the case or not for sure though). And lastly I didn't like the plastic ring spacer deal the Sram had.

  15. #15
    Meh.
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    Ultegra is similar to XT. DuraAce is like XTR. Do make sure you use a 9 speed and not a 10 speed...

    The Shimano XT is lighter than the comparable SRAM 990 (has aluminum spider too). The 990 uses an aluminum lock ring. People tend to go gorilla with the torque and strip it.

  16. #16
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    34t with a 27-11t in the rear
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  17. #17
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    I worked it out and found out that a 34t front ring with a 12-27 road cassettee has the same ratio as a 36t front with 11-34. I was thinking of using the the first set up. what ya think.
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  18. #18
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    So i would need a 11/23 for my 36T setup? Thanks for the help
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  19. #19
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    very sick and light colby
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  20. #20
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    Quote Originally Posted by CountryBoy
    I worked it out and found out that a 34t front ring with a 12-27 road cassettee has the same ratio as a 36t front with 11-34. I was thinking of using the the first set up. what ya think.
    No. No it doesn't.

  21. #21
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    Have you considered dual ring setup with bashguard? if you want xc/dh and youre not that gnarcore then you would probably be better off with a dual setup...


    just an option. so don't flame me for it
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  22. #22
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    Quote Originally Posted by The Shad & Gingy G
    Thanks so far guys.

    We need to be able to use the rig for DH, but also for XC now and again, which is why we were going for a 9 speed rear, but if anyone has any better suggestions we'd love to hear them.
    Please remember we are newbies to DH, so any advice you can give would be great. It might seem basic to you, but to us you could be a DH Guru!!.

    32 for xc.......34/36 for dh
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  23. #23
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    I ride my bike up and down the hill and I've found that 32 tooth front 11-34 rear works great
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  24. #24
    Rb
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    Currently running a 38 front with 11-32 XTR rear. I don't think I'll switch over to a tighter cassette anytime soon...

    My slalom bike however, is a 32 front with 11-21 Dura-Ace rear...

  25. #25
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    it really depends on the course, for some i use a 38 but then for others i use a 42. big difference. but always if racing use a road casatte closing gear ratio for smoother shifting.

  26. #26
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    New question here.

    Thanks for all this help guys.

    Averaging it all out so far, it looks like a 38 might be the best bet. We've not done any proper DH other than very basic stuff, and we're nowhere near racing competent, so I think we'll go for the 38 setup to start with, then look at it again once we're a bit more confident at throwing our bones down a mountain!!.

    Maybe should have asked this before, or started a new thread, but what sort of chain guide do you suggest?. The E Thirteen SRS has been mentioned and we've been looking at the RaceFace Diabolus, but if you've any better ideas we'd love to hear them.


  27. #27
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    run a dbl front with a E13 DRS chanin guide.

  28. #28
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    lg-1 + taco = secure chain heaven
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  29. #29
    StraightOuttaCompton
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    lg-1 + taco = secure chain heaven
    yes and no bent chain rings
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  30. #30
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    38t has been my favoured setup.
    Im using 11-32 in the back now... i never use first gear
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  31. #31
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    Not sure where you live and what constitutes DH and FR etc to you, nor how steep you plan on rididng the bike 'up', but either way, 38 is a lot of gear (more than you will ever need) if you have an 11 on the back as the smallest cog.

    As a comparison: a good chunk of world cup DH racers are currently running 36's or 34's on the front of their dedicated DH race rigs. (think 2X worlds champ, world cup champ, etc) I have seen several pics of guys running as small as 32 (Atherton) on some tracks (mostly for ground clearance).

    This trend is certainly a by product of lower frames and the need for ground clearance, but if you have spun out a 36/11 then you are better off standing and pumping terrain (unless the trail is completely smooth), keeping speed, than trying to pedal through the rough at that speed.

    I would seriously think about a double in front with a e-13 DRS as a guide (you say you want to pedal a bit, and this bike is not really a true DH bike). somthing like 24-36 up front and 11-32 in back with the 32 locked out to protect the rear wheel. This will give you all the gearing you could ever want as well as a rock solid chain guide that will not drop a chain.

    really depends on how much and what type of pedaling you plan on though.

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