Bicycle Mechanics - Chain slippage on rear cog

Some people say, "Hey, Nate, why don't you just take your bike to the bike shop and let them fix it once and for all?"

I say, "Hog wash!!! I can fix anything."

This problem is related to all the others, but I thing it deserves its own thread. The whole reason I am having trouble with my bike derailleurs/chain is because I decided to replace the cranksets on my two bikes. A few months ago I stripped out a crank arm on my Mongoose and had to buy a non-matching replacement. Ever since then I have wanted to take that crankset and put it on my Hardrock and get a new one for the Mongoose. Then recently the chain on the Hardrock started slipping. So, I figured this would be a good time to make the switch. And due to the fact that both bikes are 8spds, I did not want to upgrade to a 9 on the Mongoose and have to spend a lot of money. So, now that I have replaced the crankset and put the old one on the old bike, I have had nothing but problems. Currently the only bike I have that works is my 1973 3spd.

Well, the chain on the Hardrock still slips even with the new (old) crankset. After closer inspection, I am thinking that it is slipping on the rear cog, not the crankset. But, the cogs look totally fine and they were replaced one year ago. I am correct in assuming the slippage is occuring in the rear?

I am out of breath now, so I will be going. Does anyone know the number to the LBS?

Sounds like you need an order of shimano cogs, and a side of chain! Isn't it amazing how short a lifespan they design into these things? That's part of the reason they shift so well-the chain is just barely held by the teeth!

The chain is brand spanking new, so I just find it hard to believe that the rear cog would be worn out after a year. The teeth on the cog do not look worn at all, not that they aren't just enough to cause a problem.

I was going to suggest a worn out chain or a seized link, but if the chain is new, it rules out the former and all but rules out the latter. You may want to check each link to make sure it flexes freely in the hopes that it might not be the cog???

Good luck.

Steele-bike

One question; are the cogs and the chain both the same age ?
No; thats your problem, cogs and chain belong together and aren`t exchangeable, replace the cogs and chain.
Yes; follow Bubba`s advice

I hope it works out,

How much did the previous chain "stretch" before you replaced it? If you permit a chain to stretch by more than 1/2 percent (using Sheldon's 1/16" per 24 half-links formula), it will wear our cogs and chainrings rapidly. Also, change your riding style, to reserve the smaller cogs for high-speed riding; 11-, 12-, and 13-tooth cogs do not hold up well under load. I hope this helps ...

Cogs and chain do wear together, thats why you should replace the chain before things get too bad. A new chain will work OK and prevent further wear.
If you leave it too late, the worn out chain will have re-shaped the cogs. The new chain will slip. The only solution is new cogs.
The slippage and wear at the rear is not affected by anything at the front of ther transmission.

If you are replaceing rear cogs it may be worth checking out 3rd party cogs. I use Marchisio cogs on my Campagnolo. They wear OK, and are available individually. You can use them in any transmission setup, and chose your own combinations.

Sorry to break the news to you, but 1 year is pretty good for hyperglide index-ramped clusters. It's planned obsolescence, ya know!

Originally posted by D*Alex
It's planned obsolescence, ya know!

Its sad when the marketing & sales departments get to do the engineering.

Chains can slip on chainrings too. Do you have any "sharkfins" on cogs or chainrings?
Ride sans sharks
Pat

The whole microdrive fad, with 42-32-22-ish chainrings and 11-tooth high cogs, also accelerates chain and cog wear significantly. I am staying with old-fashioned 110mm and 130mm BCDs and higher tooth counts front and rear.

Does the slippage occur on any particular cog, or all of them?

I have since brought the bike into the shop, but it was slipping on all the cogs. I checked for stiff links, worn teeth and I found nothing. I will soon find out what was the problem.