balto charlie

Hey folks: I know a worn rear cassette and chain will cause skipping. What other parts can cause this problem. I rebuilt most(but not all) of this bike last winter and don't feel it should be skipping this badly. I can't stand and hammer at ALL. The RD is very old as well as the right shifter. Could either of these cause the problem?? Thanks for your time, Charlie

DiabloScott

bent derailleur or hanger
clogged up cables

shifter: unlikely but not impossible
Also, check for broken frame tubes - especially the chain stays, surprisingly hard to notice.

slowandsteady

A maladjusted RD

San Rensho 

Tight chain link.

Falkon 

All of the above. A worn out chainring CAN cause skipping as well. It does happen.

First check whether the hanger or RD are bent. Next shift to the highest gear and check cable tension on the RD. Then, check limit screws.

DiabloScott

Am I the only one who has his reader set for reverse sorting? Newest posts on page 1 at the top?

Falkon 

must be. I set mine to view standard. In this case, all of the below [or above]

Gravity Worx

The above reasons can all cause skipping.
So can an overly dirty chain as well as a chain that's not lubed at all.
The one bigger or more probable thing I noticed missing from possible reasons though is the possibility of a worn front chain ring.

Mr. Underbridge

Couple of other questions/ideas to add to those already thrown out there:

1) Has the bike been cleaned well (particularly the cassette)? Not sure what kind of bike it is or what kind of riding you do, but I've had a gummy combination of lube/road detritus get stuck between two cogs and prevent the chain from seating correctly on the cog, leading to slip. Cleaning worked.

2) Does it autoshift when it slips? Would indicate some RD issues. Even if it doesn't, could be less severe RD issues - if it's off enough to pull the chain up out of the teeth some but not enough to shift, you can get slip. This probably isn't safe, but I've experimented with the barrel adjuster while riding and gotten rid of some minor slip before.

3) Does it slip in all the gears? Could indicate a bad/bent/worn cog.

4) Are the chain/cassette mismatched? You're not using a 10-speed cassette and 9-speed chain, right?

5) Not sure if this would cause slip, but how about the spring in the RD? If that's too weak you could end up with fewer links actually on the cog and a lot of slack in the chain.

If you've cleaned it and checked the chain/cassette and they're new and matched, then that old RD of yours might be a POS.

Quijibo187

If your freehub is mucked up with grease and dirt, the teeth may be having a troubles engaging. There's little springs that push the teeth out (makes the clicking noise in your rear hub when coasting). It's gonna ba a little harder to diagnose because you can't see it. If everything else looks fine, this might be your problem.

Alphonso

+1

Niles H.

A few years ago, Giro made a helmet that had an extra piece that came down and wrapped around the chin. It wasn't a downhill helmet, but a more or less standard-looking bike helmet, with an extra piece attached. It looked light and airy -- not like a downhill helmet. And it looked as if it would provide much better protection for teeth, jaw, and face than a standard helmet.

Does anyone know if anything like this is available these days?

Gravity Worx

Now there's a big change in subject.

That Giro helmet was called the Switchblade. It had a removable snap on chin guard.
The snap on chin guards are worthless for protection as they just snap out off on impact and then the plastic cuts up your face.

Niles H.

Is there anything that will work? (in protecting teeth, jaw, nose, etc.)(short of a full-face downhill helmet) -- and is still well ventilated and light?

Niles H.

Charlie,

I've had this happen too. One thing you can try: stand over the bike, as if you are about to take off from a stop, with your take-off foot at the three o'clock position or so. Apply both brakes, so the bike won't go anywhere. Gently apply more pressure to the pedal, until it skips (if it does), then back off. Now do it again, this time watching the chain.

If the chain moves forward as the skipping occurs, it is probably not the chainring (may be the cog). If it does not move at all, it is probably the chainring.

You can repeat the test in a different chainring. And you can test in different cogs.

You can actually see the slipping as it occurs.

I once filed the teeth in a worn (middle, 36T, aluminum) chainring, and it completely fixed the problem. It takes a little testing, but it worked fine. It is best to use a round file that has a diameter close to that of the rollers on the chain. I used about fifteen light to medium-light strokes with the file. That wasn't enough (when I tested it), so I repeated the process, and it worked.

Putting a new, unworn ('unstretched') chain on the bike, along with somewhat worn chainrings or cogs, can cause this problem (skipping when force is applied). The chain climbs up and over the ramps. If you file them (the ramp sides of the (roughly u-shaped) chainring valleys, the ones that engage or pull on the chain) back into the right shape, the chain will not climb up.

balto charlie

Thanks everyone for all the advice. To answer some Q's:
Chain lube is white lightning. I do need to clean it but looks ok, not real mucked up
chain does not have a bad/tight link, checked it
looked at the rd hanger, looks straight but did replace the RD. The original RD had 13,000 miles. Will fine tune it a lunch and we'll see if this helps
I oiled the freehub.
Doesn't shift gears just slips.
Chain and cassette match.
Bike is used as an everyday commute from the train to work. Does not get tons of miles anymore but does get a tough treatment and is kept in a bike locker overnight.
Front chainrings are recent upgrades
Does slip in all(at least most)gears
I will play with it at lunch to see what I can or cannot make it do after the rd replacement.
Giro helmet: I have no clue
Thanks again and will report back, Charlie

balto charlie

I return, sheepishly....After trying many of y'all solutions I still had issues. I rode to the LBS and had him measure my chain. 'Twas the problem. I apologize for my foolish ways. I guess I rode more than I thought. I bought a rear cassette and chain. Repairs will begin soon. I cut and pasted all of your comments and printed out for future use. I'm sure I'll need them at some time.

So now I want to buy a chain measuring tool. Which one is the best/easiest to buy/use.

TurdFerguson2

A ruler. Your chain should be 12" from pin to pin. If it is 12-1/8" it is worn out. Lots of people replace at 12-1/16" to save the cassette. Most people just ride until it skips then replace.

balto charlie

That's me. Thanks for the info

TurdFerguson2

That's not to say that's the most efficient or cost-effective way. It can be, depending on the quality of your components, especially with lower end grouppo's.