... I guess you won't be
I just got back from my 12 hr race, and the conditions were absolutely miserable [2" of rain the night before - and light rain the day of, w/ clay like mud mixed with gravel/sand - for a nice abrasive stingy mix, all on a twisty woodland forest trail].....I had some of the worst chainsuck problems ever, but what compounded it was the swingarm design of my Spot......that big wide shelf of aluminum which connect the two BB pivot arms together is a really really good collector of mud piles.....anyone else ever get this situation...and I started thinking how would one design something with similar strength, yet allow mud to clear out and off of this critical zone....
did I mention chainsuck....luckily backpedalling freed it, but I was wondering what other 5-spotters are running up front that has been relatively free of chainsuck problems.......I may have contributed to the cause. I'm running a RF Northshore crank w/ RF granny, shimano xt middle [w/ appropriate spacers!], and RF big ring.......and a shimano XT chain.....that said, I never got out of my middle ring the whole day.....
I guess I'm puzzled as to why the chain continues to follow the middle ring even with the derailleur pulling on it.....can mud be that sticky that would allow it to glue the chain to the chainring and cause chainsuck, or is there a metal/mechanical issue, or combination....?
[I'm very frustrated by this situation!] Maybe running a chain with a whole section of links removed would create more drivetrain tension, allieviating the suck problem?
You mentioned the components, but not their relative ages.
I find that runnig a minimalist, 2-ring chain guide causes the chain to detatch itself in a more orderly manner, and I have never had a single bout of chainsuck since installing guides on my bikes (I only rarely had suck before that though). I used to be able to tell when my chains were worn out because when pedaling on smooth climbs the chain would bounce and oscillate as it left the rings. Newer components release smoothly. The chainguide sort of peels the chain off the chainring in a much more regulated manner. Try a Heim guide arm with a MRP LRP roller. They work muy fantastico.
On the crap accumulation thing, I would try one of crutch zip-tie-plastic-parts-all-over-your-lower-link creations that you see on the Santa Cruz board all the time that they employ to keep their pivots from dissolving. Take a relatively flexible chunk of plastic, cut it into a tall triangle, zip tie the upper point to the back of the seat tube above the f-der clamp, and zip tie the lower two points to the inside of the chain stay yoke. Curve the lower end of the plastic so it follows the radius of the inside of the yoke. That will form a "chute" of sorts which will guide crud right down past the yoke. It may take some experimentation to find something that works when the suspension moves.
The "chute" can be made from a cut section of inner tube stretched between the yoke and the seat tube, as Tscheezy suggested your middle ring is proably goosed,I only get chainsuck on the hooked teeth of old rings.
... I guess you won't be
all great suggestions! I never thought of making some sort of rubber/plastic inner fender/deflector type thing. I thought about going to a guide type device, but that probably would have been torn clean off with the heavy clay mud we were riding [walking] thru.....as for a two ring setup, I probably wont go there since I ride on the road some miles to get to trails and it's much nicer to be able to put it into "overdrive" with a big ring.....
I believe I put the middle ring on sometime last summer sometime, but I think it may be an LX ring, which probably wore out a lot faster [I'm not going to try to save a few bux next time....when you buy second best, you buy twice - why do I always forget that!].
I'm going to order up a new RF middle, and throw on a new xt chain and new xt cassette, since that mud race probably wadded up whatever live was left on it anyway...
anyway - here's a pic of my GF's racer-x after a lap.....that's what we were dealing with....