Chain Skipping/Missing

[ireadbooks]

Hi everyone,

I have a Diamondback hybrid and it is about 3 years old. I have only ridden the bike consistently this year so its still relatively "new".

Last year, I noticed that about 1-2 months after a tune-up my chain would miss or skip whenever I need to exert extra torque.

This occurs both when I start out and/or when I try to trying to gain speed on a flat run. Whenever I receive a new tune-up the problem goes away until about a month afterwards and then returns again, becoming more frequent as time goes by (thus it might be theorized it is something addressed in a tune-up?). It also makes a horrendous sound, at times can cause me to lose some control of the bike (as it is a rather violent and unexpected event), and even causes the pedals to rake my leg. It lasts for just a split second--a release and then it "catches" again.

My mechanic says that he can't find anything wrong with it, and that the bike doesn't do it to him when he rides it. I have not had a chance to ride it in front of him. An experienced rider told me I might be stretching the chain, or that my size might be affecting it--I weigh about 240.

Any help would be greatly appreciated.

[1FJEF]

Perhaps you are severely cross chained?
Derailleur hanger alignment? Is the rear wheel straight in the frame, both top to bottom & front to back?

[ireadbooks]

(08-24-2013, 04:28 PM)1FJEF Wrote:  Perhaps you are severely cross chained?
Derailleur hanger alignment? Is the rear wheel straight in the frame, both top to bottom & front to back?

Would this be something the average mechanic would easily recognize?

[bikemanfred]

Des it happen in all of the gears or just a few?

[ireadbooks]

(08-24-2013, 05:10 PM)bikemanfred Wrote:  Des it happen in all of the gears or just a few?

In all gears, though less often in higher gears. The common element is always amount of torque.

[bikemanfred]

I would say to check to see if the chain stretched. Also make sure the rear derailleur has a good pull and holds the chin tight and returns back quickly when you push it forward.

[DaveM]

Sounds to me like it is either:
- worn chain/cassette and the chain is jumping over the top of the teeth.
- pawls in the freehub are starting to wear out and skip under heavy load.

If you can get someone to job along side you while you ride slowly uphill (or with your brakes on) so you can put a lot of torque on it without zooming away, they may be able to see what's happening. But this kind of skipping is hard to diagnose because it only happens when you put a lot of force on the pedals.

[1FJEF]

(08-25-2013, 12:55 AM)DaveM Wrote:  If you can get someone to job along side you while you ride slowly uphill (or with your brakes on) so you can put a lot of torque on it without zooming away, they may be able to see what's happening.

Excellent idea. See if the chain is slipping over the rear teeth, across the rear teeth to a different gear, or see if the chain stays engaged with the rear teeth & it's the entire rear gear assembly (freewheel/cassette) that's slipping.
I would swap the rear gears & chain simultaneously also.
Also note that he says the problem goes away for awhile after the bike is serviced.

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(08-24-2013, 05:02 PM)ireadbooks Wrote:  

(08-24-2013, 04:28 PM)1FJEF Wrote:  Perhaps you are severely cross chained?
Derailleur hanger alignment? Is the rear wheel straight in the frame, both top to bottom & front to back?

Would this be something the average mechanic would easily recognize?

Not if he didn't watch you ride it.