[dwnwrd]

I haven't been downhilling much yet. I have a 2002.5 Bullit and XT derailler. It sounds like my derailler is flapping so much it's about to catch in my spokes and send me flying.

Part of it may be that my chain is extremely close to my rear tire (2.5 weirwolf). What can be done to dampen that derailler flapping? Tightening the B screw? Putting on a chain guide? Stronger spring in the der? Just shutting up and dealing with it?

Would putting a chain guide on do much for that or would it just make it less likely I'll drop a chain? I figure at the least it will keep some tension on and make it less likely the chain could swing over and catch some tire tread. I don't know about the bounce though.

If I did go for a guide I definitely need something for 2 rings. I do a lot of climbing. Recommendations?

 

[JohnMc]

Just some ideas
1) shorten the chain - this may prevent you using the big/big combination but you shouldn't be using that anyway

2) Tighten the b-screw

3) Shift to a bigger chainring when bombing down rough stuff. This isn't a half bad idea anyway because having the chain on the outside chainring just might save you from a 'shark bite' should you crash...

I remember seeing supplementary spring tensioners of rthe derr (pulled it backwards from the bottom) but that was a few years ago and I don't see them for sale anymore. Kore sells a chain tensioner that hooks to the chainstay and pulls the 'loose' section of chain upward, that might help.

 

[peter6061]

I ran into the same thing on my Titus Quasimoto last summer.

I hate noise on my bike. It's one of the things that makes riding my singlespeed so much fun...back to the quasi...

I tried riding in a bigger ring combo - better

I tried tightening the B screw - better

I tried shortening the chain. - better (a few accidental shifts into big big combos - whoops)

I put an old elastomer on the front of the derailleur with a zip tie to dampen the sound. - better until it myteriously disappeared. hmmm

Finally, removed the derailleur and took out the main pivot spring. I put a large flat plastic washer under the derailleur and bolted it back on. The derailleur now does not move at all from the pivot. It still shifts...good. (not great, but good -it's XTR) I get very little chain slap and no derailleur bumping. Overall, it's been a good fix and has been going strong since about September.

If interested, I'll see if I can dig up a pic somewhere.

 

[peter6061]

Here's the pic for your viewing enjoyment.

 

[Matt D]

what's the red plastic washer for?

 

[Brian HCM#1]

Originally posted by dwnwrd
I haven't been downhilling much yet. I have a 2002.5 Bullit and XT derailler. It sounds like my derailler is flapping so much it's about to catch in my spokes and send me flying.

Part of it may be that my chain is extremely close to my rear tire (2.5 weirwolf). What can be done to dampen that derailler flapping? Tightening the B screw? Putting on a chain guide? Stronger spring in the der? Just shutting up and dealing with it?

Would putting a chain guide on do much for that or would it just make it less likely I'll drop a chain? I figure at the least it will keep some tension on and make it less likely the chain could swing over and catch some tire tread. I don't know about the bounce though.

If I did go for a guide I definitely need something for 2 rings. I do a lot of climbing. Recommendations?

Go with an Evil DRS guide, they work great. As far as the noise, its just part of the game. Using a short cage derailleur alot of times quiets the noise.

 

[peter6061]

Originally posted by Matt D
what's the red plastic washer for?

Without the Spring setup inside the pivot, the derailleur just spun around. With the washer, I can position the derailleur at any angle I want, and it just STAYS there. I worked with it in the stand until I found the ideal location for derailleur shifting, and tightened it down on to the washer.

 

[MisterMental]

i found that my roox rollercoaster did wonders for reducing chainslap
when it broke me chians all over the place
u dont know how good sommat works till you break it

 

[auntesther]

had the same problem really bad on my Iron Horse SGS DH with the Horst pivot right near the rear derailleur. I took an old manitou elastomer, trimmed it a bit, and zip tied it to the bottom side of the horst pivot through the center of the pivot. no noise at all. no downsides

 

[TrueScotsman]

DON'T shorten your chain so you can't go big/big!

Since the bike is full sus, make sure the chain is long enough to go into the biggest at front AND back and also when the suspension is fully compressed. I know you shouldn't ride in big/big but it invariably happens (accidental/friend having a shot/etc) and it will wreck your mech.
It is worth taking the spring out of your shock so it is easier to set the chain length up at full suspension travel.

 

[MikeD]

-Maybe use a roadie derailleur; much stiffer springs and the short cages stay out of the way (if your gearing allows such a short cage to be used).

-Increase the spring tension in your existing derailleur by tearing down the man and cage pivots and moving the springs' tips into the other retaining hole; it'll be stiffer when you reassemble the thing.

-The old bullit-bros. style chain tensioners are fairly ghetto, but they do the trick until the spring explodes and wraps up in your cassette. Also make your rear wheel a pain to remove.

-The DRS guides are great; I recommend one heartily.

MD