[l008com]

So I have a problem with chain skip, on my rear cassette. Its a reoccurring problem. Sometimes its because my derailer hanger is bent. Sometimes its because my derailer is bent. Some times its because my rear derailer cable needs to be adjusted. The problem is, I can never tell what my problem is. And I always have to drag my bike all the way to the bike shop just to have them look at it and tell me what's wrong. Is there some sort of trick to being able to spot which part is broken?

 

[Vermont]

i usually do process of elimination...start with simplest problem...barrel adjuster, then check chainline from behind bike...if derailler or hanger is bent you will notice it from directly behind the bike looking through the pullies....my $0.02; hangers usually break, deraillers bend

 

[trailpoacher]

backpedal and investigate each link.
you may have a single bent link.
IF this is the case then bend it back and forth until it is straight.
stiff link is the cause.
If your links are fine than it might be worn out casette.
if the teeth are pointy sharp it is worn out.
if not that then also listen to the Vermont guy with the good advice.

***ALSO CHECK FOR BENT HANGER***

 

[johnbryanpeters]

I'm in the middle of my annual bike-won't-shift-properly thrash. Rear shifting started acting up at the Monkeyfest. So far it has gone like this:

Symptoms:
Can't adjust so both down and up shifting work reliably in rear.

Verify that dropout's not bent.
Inspection shows missing tooth on middle chainring. replace.
Check rear derailleur adjustment.
Check cables for dirt, kinks, binding. None found.
Replace chain.
Note that pivot pins on the rear deraileur seem worn and loose - replace derailleur.

Tonight's exercise will be to replace the cables and housings.

J

 

[BikeGeek]

^ all good advice. Of course for me it never fails that once the problem is "fixed" on the repair stand, it starts doing it again on the trails.

PM me your email address and I'll send you two chapters from the Barnett manual, one on chains and the other on rear derailleurs. The troubleshooting sections at the end of each may help you narrow the problem down.

 

[oldfart]

Rule of thumb is to check for the obvious stuff first, bent and or damaged parts, worn parts. Next is to clean and relube. I believe 99% of all shifting problems not caused by obvious damage is due to dirty slow to react shift cable and housing. JBP your problem sounds like classic fouled cable 'n' housing. But it might also be a "B" pivot which is seized, but you replaced the derailleur so that's not it. When the "B" seizes, the top pulley will get too far from the cogs so that there are a couple links between the pulley and cogs. The chain flexes sideways before it shifts, so the tendency is to adjust the cable to overshift one way and undershift the other. Same thing with dirty cable n housing. Spring isn't strong enough to return the derailleur when you click once so it gets set to overshift a bit which causes and undershift the other way.

I think modern shifting systems are more finicky simply because there are more funky shapes ramps and pins which affect shifting when worn. Thing is, old friction 5 speed setups were never very good. Not compared to the latest and greatest anyway.

But people ignore that old cable and housing. I do it too. I start getting poor shifting and because the degradation is a slow process, the shifting feels the same so we tend to look other places. I just recabled the road bike after working on the wifes road bike. Her shifting was so much lighter, I realized how gummed mine was. Now I can one finger shift again easily.

 

[johnbryanpeters]

Thanks. That may very well be it. However, I have to wait for tomorrow to try the cable, because I heve been tied up fighting with fractious shifters this evening.

J

 

[Dartman]

So I have a problem with chain skip, on my rear cassette. Its a reoccurring problem. Sometimes its because my derailer hanger is bent. Sometimes its because my derailer is bent. Some times its because my rear derailer cable needs to be adjusted. The problem is, I can never tell what my problem is. And I always have to drag my bike all the way to the bike shop just to have them look at it and tell me what's wrong. Is there some sort of trick to being able to spot which part is broken?

If you've got a good eye you can sight down the chainline from the rear and top of the bike and see if the hanger or derailleur is bent. If it's just a cable adjustment you can see if the top pulley is in line with the cog as you move the barrel adjuster. Pull that rubber boot up from time to time and see if the housing/ferrule is kinked at the barrel adjuster. Sometimes that causes lots of shifting problems.

Mike