Chain Whipped

[toonces]

I broke my chain for the third time (different rides). Now I'm pretty sure it's too small for safe use so it's time to get a new chain. I currently have a SRAM PC-59 and I'd like something other than that. Anyone have good experience with other chains? I'm using a 9-speed super-weakling drivetrain. Thanks.

[carlos]

how, and where are the chains breaking?

[toonces]

Exhibit A, Broked Chain Link:

http://home.austin.rr.com/warmgrey/brokie.jpg

Here's how the chain has broken on the three separate occasions.

1. Walnut Creek. Dipping into the Powerline Hill thingee I crank in a really high gear for the downhill but wait too long to shift back down for the uphill and end up trying to go through too many gears at once and snap. I'm not sure, but I think that's what the broken link looked like.

2. City Park. I'm climbing near the middle loop and my chain skips and makes a loud clanking noise. It doesn't sound good, but I check the chain and it looks fine so I ride on. A few hundred yards up the trail on a slight uphill, I start cranking, already in an easier gear and it snaps. Above is how it looked then.

3. City Park. I'm getting to the base of a climb near the same spot as number two but when I shift (not too late this time) my gears slip again and go <i>down</i> the cogs instead of up. I don't know how as I've been riding for several years and am positive I know how to shift. Anyhow, I get the loud clanking, but again, the chain spins freely and looks good. So I walk this hill since I've already lost momentum and cruise at the top of the trail which is flat. I get to a short climb/ledge and start to crank and as I'm going over the ledge, snap. That's the broken link above.

From the looks of it, I'd say the chain is twisting. Kinda like when you cross the chain. But the weird thing is that this has happened twice when I was in a good gear. My theory is one that involves the suspension in the rear causing the chain to sag when it's (suspension) is compressed therefore taking the tension off the chain allowing it to move freely down the cogs. Either that, or the movement of the suspension is slackening the rear derailuer cable and causing it to shift back into the smaller cogs. Reason I suspect this is because of the dozens if not hundreds of times I've compressed the rear on a big ledge, then the next pedal stroke cuases my chain to skip and me to flail. Evil. That's why I was asking about full housing a while back.

Any thoughts?

[TechniKal]

Definitely check your cable housing length and routing - if it's too short or gets kinked up during compression, it can cause the derailler to activate.

For chains, I have mixed feelings. I think Shimano chains shift better and run a little smoother than SRAM, but I really like the little powerlink thing on SRAM chains. I usually just end up buying whatever's on sale, though.

[carlos]

1. seems to match the busted link.

2. could have been a skip.

3. i'm not sure on 3.

how old is the whole drivetrain. also, what front and rear der, cassette, and rings are you using?




as for full housing. i don't think that will fix it.

techniKal has a good. point, check your lengths. they might be too short.

what kinda bike?

[toonces]

Exhibit B. The Bike:

http://www.bikes.com/images/bikes/detailview/large/slayer-large.jpg

Here's the specs on my drivetrain:

• XT Rear Der
• LX Front Der
• SRAM 7.0 Cogset
• SRAM PC-59 Chain
• Race Face Prodigy Crankset 22/32/BlackSpire Bash Ring; 104 BCD
• LX 9-Speed Shifters

It's all stock and was brand new with the bike purchase in early February. The first busted chain happened prolly around May or so. Second in late June, and the third today.

The bike is a Rocky Mountain Slayer 2002 size 18. It's got 4.75" of rear wheel travel on a Fox Float RC shock that is 6.5" with a 1.5" stroke. I'm set at about 25% sag in the rear.

The rear derailuer is routed as follows: from shifter to first stop on top tube near the front... from that stop it's exposed cable (with plastic sleeve) to the rear stop on the top tube near the seattube... housing gaps from top tube to the seatstay stop a few inches down... exposed cable from there to the last stop on the seatstay right above the rear pivot... then the housing loop to the rear derailuer.

I've always suspected something fishy about the shifting setup. For one, the middle piece of housing has 'ejected' two strands of it's casing and is starting to lose it's shape. Two, the rearmost housing (rear der loop) looks a bit short. I can't really say if that's affecting my shifting or causing these problems, but I have a few feet of SIS housing and new cable about to arrive so we'll soon see. I prolly should have ordered a new chain too.

On that note, any suggestions for chains? Have you had any problems with the Shimano stuff Kyle? Will 8-speed make a miraculous comeback? Tune in next time for these and other exiting adventures...

(Thanks for all the help!)

Exhibit C. Rear Loop:

http://home.austin.rr.com/warmgrey/mtb/loop.jpg

Exhibit D. Stray Strand:

http://home.austin.rr.com/warmgrey/mtb/stray.jpg

Exhibit E. Kinked Housing:

http://home.austin.rr.com/warmgrey/mtb/getbent.jpg

[carlos]

the set up seems kosher. nothing weird.

the one thing, that strand coming out of the housing like that......it's time for a new rear derailleur housing and cable.

the last loop the the rear der looks good. kinda short though. of course, the cool thing is, you could add 2", and then, if you feel it's too long, you can always cut more.

in the future, you may want to switch from the SIS (4mm diameter) housing to the standard 5mm housing. it's much more stout and the ferrules are made of metal so the strands won't punch through.

as for the chain, do you ever shift under load?

[toonces]

Cool. I'll change the housing/cable and see how it goes. As far as the chain, I'll see what I can find locally.

I really, really, really try to avoid shifting under load, but I also try to avoid stopping even more so inevitably, I end up shifting with load every once in a while. I know this is bad. I've slapped the back of my hands a few times already.

[carlos]

as for chains, SRAM seems to make a good chain.

as for alternatives, the new Shimanos should hold up to a beating a little better.

but here the warning in BIG RED LETTERS (well, at least they're big):

before you buy it, take th chain out of the package and look at the ends of the pins. the new chain that are supposed to be stronger, have these little cupped ends. also, make sure when you break the chain, these new pins are so much stronger that they've been breaking the tip on some chain tools.

[toonces]

Don't Shimano chains require the use of new pins when the chain is broken? If so, do a few come with the chain?

[carlos]

yeah, it's a two peice tapered pin.

you should get two pins per package.