Chain Slipping when pedaling up hill or with a lot of resistance

[Vilhelm_84]

So, I have recently constructed my first bike from hand me down components (with some help from a friend at a bike store and some help from this rockin' site). Everything was working well for about a week until I started biking to work (about 3 miles, pretty hilly). On these work-bike trips when I pedal hard going up a hill and resistance increases, my chain slips, the gear doesn't change usually (thought this does occur sometimes spent many an hour with your video's here), it just slips and makes a horrible noise. Possible issues: My bike has a 9 speed rear derailleur (shimano tiagra) and an 8 speed cassette and shifters (shimano sora shifters). The chain looks a little worn in some places but aside from that everything looks like its in good shape (had them checked by the bike store) before I put it together. Any help you can offer would be appreciated.

[Skyguy9999]

How does this bike shift and handle on flat ground? Still well?
Generally with bikes you don't want to try shifting them when there is a lot of resistance on the chain. Basically this means that you don't want to shift a bike while on a hill or pedaling (too) hard.

[Alex Ramon]

It sounds like a worn chain. Cassettes/freewheels usually wear together so when they don't match up you end up with skipping problems like you've described. If you don't have a chain-wear indicator, your local bike shop will be able to check the wear for you for free.

[Vilhelm_84]

It generally shifts well on flat ground. The chain is new, and the wear is minimal on the cassette/freewheels (only used for 1 year before I got them). I will get it checked anyway. Thanks! I will let you know how it turns out.

[DaveM]

A new chain on a used cassette can actually cause skipping like this. The old chain and cassette wore into each other. When you change one without the other, the wear on one means the teeth don't line up as well anymore and you get skipping. It is also possible that the ratchet in the freehub body is actually skipping, but this is more common on old freewheels than on cassettes. Finally, it is possible, though quite rare, that it is skipping on the front chainrings. This only happens on VERY worn chainrings (when the teeth look like sharkfins instead of being symmetrical), but I've seen it happen.
These problems can be tough to diagnose. Sometimes you can have someone jog next to you on a steep hill and see if they can see what the chain is doing. But this requires good friends.

[Alex Ramon]

Here's a new a video that shows how to <a href="http://bikeride.com/chain-wear/">check for chain wear</a>.

[hemi426]

I have a full suspension mt. bike bought bought from a friend last year , the problem I'm having is chain skipon the up hill or w/ any resistance. I have rplaced the complete drive train, including cables and housing, and have had no luck fixing this problem. I am pretty descent at repairs and maintaining my bike and have taken it to a mech. I trust at the local shop and everything checks out fine on the stand. Could the length of the housing between the frame and swingarm not be the right? The new housing is cut same length as the old ones when I bought it.

[stickboy]

I had the same problem: chain slipping when I would apply a certain amount of force, usually when humping it up a hill. Mine mostly only happened in a particular gear, though. Turns out I had a bent tooth on one of my gears. I had eyeballed the gears before but didn't find the problem until _thoroughly_ cleaning my drive train. After that it was so obvious, I was surprised I didn't see it before.

[DaveM]

If it is not the chain, cassette, front chainrings, or a combination of them, then the next likely problem is the cassette ratchet body which is part of the hub. These can be replaced but it is a little more complex as you have to remove the axle, etc.

[steelmill]

This seems to be a problem with cheaper department store bikes. I bought a Quest Omega (Dicks Store Brand) as a second bike and the chain slips in higher gears and while peddling hard or up hills. It has less than a 100 miles on it. The bike tech at Dicks cant get it adjusted. I have an Ironhorse Maverick 1.2 that is my main bike. I don't experience any problems with it. For $200 on sale (Dicks price)it cant be beat. They cost about $249 now. It is rated as good as a similar TREK.