Mountain Bike Chain Repairs, the Dummies Approach

rear barrel adjuster

Around ANHQ, we think it's bad enough when a clueless n00b can't figure out how to ask a question, but it's a lot worse when someone who claims knowledge doesn't know enough to answer that question. For some reason, we seem to run across that situation a lot on the niches that used to be eHow.com. Take, for instance, "How to Fix Slipping Gears on a Mountain Bike" on SportsRec.com, tossed up there by one Abby Roberts.

Roberts, whose bio says she "produces a blog for female cyclists," blew this one big time. For starters, she waxed eloquent about bicycle drivetrains, but she never gently corrected the OQ by saying that chains don't "slip," chains skip. Once that was over, Abby went into excruciating detail about how to adjust a derailleur. As eHowians are wont, she started with the high and low limit screws and the tension screw, telling her readers that,

"These are marked by an 'L,' a 'B' and an 'H.'"

Except for a confusing change in the order (she should have kept them in the same order: H, L, and B, she was right... assuming that the derailleur was new or you'd just had a wheel rebuild. After all, her reference (Sheldon Brown, of course) clearly states that,

"Normally, the limit stops need to be set when a new derailer is installed, and should not require any further attention."

Roberts also claimed that the derailleur hanger is,

"...a cheap and easy part to replace..."

...which flies in the face of our experience – especially the "easy" part, since it requires removal of the derailleur, with all the necessary adjustments. Then again, Abby was talking through the proverbial hat.

Roberts' instructions were for adjusting the limit screws and the B-tension (something nobody ever does). She finished by telling her readers to,

"...run through all the gears to ensure the derailleur will not shift into the axle."

We guess she meant "into the spokes," but one can never be certain of the ignorant.

Why ignorant? Because almost every mountain bike has indexed shifters, and a skipping chain is most likely caused by a stretched shift cable. You correct that with one of the barrel adjusters, a phrase that appears nowhere in the post; not by monkeying with the limit screws – those rarely need any adjustment once the bike has been (correctly) built.
We also found some more "slop" earlier in her post, when she told people to check their chain for wear:

"Using a chain tool, slip each of its ends through the links of your chain and check your chain against its wear indicators."

No, Abby, you're thinking of a chain gauge, not a chain tool. So, we ask you, dear reader: who's a Dumbass of the Day? Abby is!

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