Gears for a DH bike
- Thread starter isaacchdh
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rear 11-34 front 40 life longer than the small stuff
quite sure this has allready been discussed so next time use the search thingy.
i run 40 or 42 and 12-24/26 depending on the track.
i run 40 or 42 and 12-24/26 depending on the track.
Exactly, it'll all depend on the terrain and preference. There is no one answer.
Dont forget individual leg speed and power.
11-23 cassette and a 38 in the front
more importantly powerband range
11-32 with a 38t in front. Road cassettes require too much shifting with the close ratios IMO. If you can learn to pedal efficiently in too high or low of a gear, you'll save time by not having to think about shifting as much as you do with a road cassette.
i run the same...
11-23 with a 36 is the best ratio so you are never between gears and get bogged down
The absolute best for downhill is a single speed setup with a 46 T ring. Then there isn't much to break. All the top guys are doing it. 
I have a 12-34 w/ a 34 T ring so it can still climb..but I need a 36 for races.
I have a 12-34 w/ a 34 T ring so it can still climb..but I need a 36 for races.
I run a 11-27 ultegra cassette with a 36 tooth ring up front.
I constantly top out though at Whiteface. I think I need a 40 tooth ring, but then I need a new chain guide as mine (medium) accommodates only up to 36 I think?
I bought the 36 because someone said the fastest racers use a 36.
But you certainly can't pedal when your going 40 mph.
I constantly top out though at Whiteface. I think I need a 40 tooth ring, but then I need a new chain guide as mine (medium) accommodates only up to 36 I think?
I bought the 36 because someone said the fastest racers use a 36.
But you certainly can't pedal when your going 40 mph.
and shifting just becomes natural once you learn how to do it properly. are you saying that having the wrong gear for a situation can be just as fast as having the correct one?
I'm saying I don't have time in races to click through a whole bunch of close gears on a road cassette. I'm in a hurry, and want just a couple of shifts to get to a gear that's close enough to what I need. The less shifts I make, the more concentrated I can remain on pedaling and riding. I might try a road cassette again some time, but for now the MTB ones are nice and widely spaced. I ride a lot on my DH bikes, and don't mind pushing a little higher than normal gear for a short ways. I've found it faster to push a little harder than to let off the gas and try to get into exactly the perfect gear. Usually it works.
to each their own. i just find that shifting becomes second nature after a while
Amen.
But if it matters, Im running a 11-34 with a 40 up front. After having a 40 for half a year, I've gotn used to low RPM and once I get down a hill...oh man I can fly.
I have just changed from an 11-34 to a 12-27 and i have to agree with bikenweed, i have been finding that i have to push 2 gears where i used to push only 1, i am finding the ratios too close and im having to shift more often.
11-23 & 34T ring for racing and 11-32 for trails. Works great but I am going with an 11-34 for trails this year.
I'll be using a 38t with a sram 12t-26t cassette this year.
11-23 and 38 im gonna try a 11-21 on the 4x bike w/ a 36
Agree as well.
Now I can see why some one on a DH race specific bike might not need the easy gears (big cogs), the pedaling that you do on a DH bike is very different than on a road bike. The majority of pedaling on a Dh bike is done in short burst over undulating terain, while standing...constantly changing velocity.
Road cycling is VERY different. Long stints in the saddle on the exact same slope. The fine ratios on a road cassette are there for just these very long continious/monotinious uphill slogs at a very steady speed. Something rarely encountered on a DH bike. An increase in slope on a DH track can usually be overcome with a simple stand-up burst. When facing a mile or 5 or more of constant uphill tarmac, a stand up burst is not an option, it will get you no closer to the top of the hill, but can dramatically sap your strength to continue. The key is to find the exact ratio that allows speed BUT also allows you to continue the same output for HOURS. This does not happen on a DH course.
For a pure race bike, I think the best bet is fewer gears (5 or 6) over a reasonable spread.
That is what i was thinking of doing. I find the spread of gears perfect but the jumps too fine, i thinking i might grind the 3 largest cogs off an 11-34 xt cluster and use that.
My question is, can the limit screw move the der over that far?
38t-12-27 cass. Works for most all courses. I like the close-ish gear ratios when I'm racing. For me, shifting is extremely important in a race. I think it's super cool coming into a corner sprinitng in the smaller cogs then breaking/pedaling/shifting before the apex so you can have a perfect gear to spring/sprint out of that corner.
I feel vindicated. I tried the roadie cassette thang and was shifting too much. Whats the point of closely spaced gears if you skip 3-4 gears to get to the combo you need?
I use a 11-32 cassette with a 38 up front.
I can't lock out that many gears. I run a 11 - 32 with the 32 locked out, and that works for me. I think a you would have to set the stop via cable tension (not a great option). What der are guys running with the profile 6 speed hub?? BCD runs some 5 speed set up as well...but I cannot remember the specifics.
I agree, downshifting while breaking in a corner is super fun. This is one of the reasons that I run Sram shifters (all shifting with the thumb), I just have not found a place on an 11-32 where I feel like I cannot find the 'right gear'....
definately think that the use of the bike (race only or DH freeriding) and terrain makes a difference in the gears needed.
Keep in mind that the smaller the front ring, the smaller the jumps will be between rear cogs
I felt compelled to reply to this thread for some reason
I find that my favorite combo is a 7 speed 11-23 cassette with a 36t ring. I ran it all last summer. 9 speeds is just excessive for me so 7 seemed the way to go. The 36t chainring provides for a lot of ground clearance on bikes with low BB's.
exactly, im gonna try to run an ultegra 11-23 with a 34 up front this season. it seems that you can either run a big cassette and a big ring, or a small road cassette and a smaller chainring, saving more weight, better ground clearance, and close to the same ratios
shifting with a roadie is a lot easier than shifting a big ass mtb cassette
I run a roadie with a 40
works for me
works for me
Everyone has their own preferences. Take into account that some people are beasts and will spin at a low cadence in a hard gear. Others will stay in a somewhat easy gear and pedal as much as humanly possible without succumbing to cardiac arrest. It's whatever floats your boat.
11-30 8spd Xt level cassette (spider but no ti), 8spd chain, 38 up front, Sram Attack Trigger, and an Ultegra short cage rear mech is my dream drivetrain.
Look at a gear inch chart and you'll start to see that some of the big differences aren't that really that big at all...running a smaller chainring (34 vs 36) and smaller road block cassette (11-23T vs 12-26T) can actually give you more range, shorter chain, more clearance, and weighs less...
34T w/ 11-23T = 80/38
w/ 12-26T = 74/34
w/ 11-32T = 80/28
w/ 11-34T = 80/26
36T w/ 11-23T = 85/41
w/ 12-26T = 78/36
w/ 11-32T = 85/29
w/ 11-34T = 85/28
38T w/ 11-23T = 90/43
w/ 12-26T = 82/38
w/ 11-32T = 90/31
w/ 11-34T = 90/29
40T w/ 11-23T = 95/45
w/ 12-26T = 87/40
w/ 11-32T = 95/33
w/ 11-34 = 95/31
-ska todd
34T w/ 11-23T = 80/38
w/ 12-26T = 74/34
w/ 11-32T = 80/28
w/ 11-34T = 80/26
36T w/ 11-23T = 85/41
w/ 12-26T = 78/36
w/ 11-32T = 85/29
w/ 11-34T = 85/28
38T w/ 11-23T = 90/43
w/ 12-26T = 82/38
w/ 11-32T = 90/31
w/ 11-34T = 90/29
40T w/ 11-23T = 95/45
w/ 12-26T = 87/40
w/ 11-32T = 95/33
w/ 11-34 = 95/31
-ska todd
DHR - 38t, 11-23t
RFX - 36t, 11-23t
i <3 nice tight drivetrains.
RFX - 36t, 11-23t
i <3 nice tight drivetrains.
exactly my angle, thank you ska todd!
Take the L screw out of any derrailleur and put in a longer one
A mate of mine runs a 11-34 cassette with the top 3 cogs taken off and replaced with spacers, giving the same range of gears as a roadie cluster and a decent step between each cog.
My new bike came with a roadie cluster and after the first race I couldn't stand it, I would get onto a ski road and have to pedal, so I'd shift up, find it was still too easy...shift again....still not right...shift again...ahh **** it I'll coast
Yes and no..if you go down to a 34 in front from a 38, you only heed to pick up an 11 in back to make up the difference. Does not matter if it is an 11-23 or an 11-32...it is the 11 that will give you back your gear inches.
just need to figure how low you need to go as well..that will determine the large cog. This is the part that I think changes with a 'race only' machine versus a local use DH bike.
I do agree that a lot of folks who are running a 40 with a 12-26/7 would be better off with a 36 and a 11 - anything. Dropping the ring size will close the gaps in the back. So you could run a MTB cassettte with an 11 and the jumps between gears will not feel as big due to the smaller ring in front....(see ska todd's chart above)
pretty simple to do the math to figure gear inches or just ratios..also becomes obvious how rediculous a 3 ring set up is when you see all the repeat ratios...
On my X9 the screw is attached to the parallellogram in such a way, that when the screw is far out, it is at an angle to the perch/stop. If the screw was much longer, it would angle so much as to fall offf the perch, and not work. Maybe if you turned the screw around so the larger diameter head would contact the perch...Take the L screw out of any derrailleur and put in a longer one
for now, 11-28 works for me!!! and hwlps protect the back wheel.