Unsane

recently got an '04 Tassajara. It's my first "real" mountain bike. I took it to the shop to have the derailleurs adjusted because I noticed this skipping problem. They said they fixed it but I'm still having the same problem. It doesn't do it in all the gears just in the lower gears and only when I am peddling like normal (when I pick the back tire up it doesn't do it). I am hoping that someone here knows more about derailleurs than I do. I am trying to learn how to fix it myself so I don't have to rely on the LBS for simple fixes. I appreciate any help you can give me.

btadlock

Is the bike new or used? the skipping, front or rear? if the bike is used, could be worn cassette, chainrings or the chain. If the bike is new, or barely used, it sounds like an adjustment issue.
Is it just skipping or is it changine gears on you?

Unsane

It's a new bike. I think that it's not shifting fully into or out of the lower gears. When I am pedaling it is very jerky like there are teeth missing on one of the sprockets and makes an awful sound but I checked them out and all seems fine. I know its going to make noise, but this seems unsafe because my feet coming flying off the pedals when it does this.

Portis

Click the link below to learn how to repair your bike. It lists every bike repair known to man kind. With pictures!!! BTW, the other guy asked you if it was the front or rear derailleur. that is sort of important to know before we can help you. Go to the link and study. Then come back and ask questions.




https://www.parktool.com/repair_help/FAQindex.shtml

Unsane

Sorry about that.

I think it's the rear derailleur because when I switch the front I don't seem to have any problems.

Deanoldo

Make sure your deraillure hanger isn't bent too. I fiddled with my rear deraillure for 2 weeks until one of my buddies noticed that it wasn't straight. It only skipped gears when I was putting a lot of pressure on the pedals. Make sure your two pulleys and whatever cog your chain is in are in a straight line. If they're not, have the LBS straighten it and buy a spare.......

Dean

Unsane

Well I thought it was the rear derailleur but now I think it is the front. I adjusted to rear derailleur as described on the park tool website just in case and all seems to be fine. Only when I shift to the largest chainring and begin going through the gears the chain starts to rub after about the 3rd or 4th gear and that is when I notice the skipping that I had mentioned before. I'm going to try adjusting the front one now. I will let you know how it goes.

Unsane

Still no luck. I improved it somewhat but it still jumps over those 2 gears. I got it so that it shifts smoothly from one gear to the next until you get to the 3rd from the outermost cog. Then it is almost like the chain is not meshing with the cog properly and the chain is riding on top of the teeth of the cog. Has anyone had anything like this happen to them? Let me know what you think please.

blue_neon

So your chain is skipping when you go into certain gears. This might not be the problem but I had a probelm with my bike, that the chain always rubbed against the derailer. This happened when i was in front 3 and rear 6 or 7. The chain is on such a diagonal to get from the back cog to the front, it rubs against the derailer. But in 2 front 4 rear its fine, because the chain is in a straight line from front to rear.

I also experience a rough feel sometimes when riding. It is from the contact with the chain and the teeth and it is a rough contact which creates an uneven feel in my feet when pedaling, traveling through the pedals. That is most likely because my bearings are bent in my front cog. Also this can be a problem if the chainrings are loose, or the cogs or crank is a bit loose, the chain wont smoothly fit in the teeth.

Not sure if any of these are the problem, but I took a look at my chain, gave it a clean and removed grim ect, and then tightend up my crank and performence and feel improved. Although my bike is not knew, 2 years old so I'm not sure why its happening to a new bike?

Dannihilator

Don't eat the yellow snow. Ok, really, you need a new cogset, chain rings, chain and pulley gears.

blue_neon

I've noticed with the more expensive cog sets, and chain rings that i've tried out on some bikes that it is extreemly smooth changing and contact with the teeth. I suspected that on my bike and my LBS told me that the chain does need replacing, or links removed after time when it stretches and falls out of place.

Unsane

Would this be possible on a new bike? I bought it brand new from the LBS and I have only had it about 3 weeks. I haven't been going on the trails because they are so muddy so I have only been going up and down the road to build up my stamina. I think I have only ridden the bike about 7 or 8 times since I had it.

Unsane

Blue Neon - I have adjusted the deraileurs so that I don't have any rubbing now. No matter what front chainring I have the chain on as I move through the gears I notice that the chain doesn't seem to seat onto the same two gears in the rear. I dont know if that is helpful.

blue_neon

Well then it must be a problem with those two rear chainrings or whatever you want to call them. The teeth are probably bent, and the chain is slipping to catch them. It seems like the chain is fine, but on those rear to gears / chainrings there must be a problem. If you 100% sure that this ONLY occurs on the two mentioned rear chainrings, then it must be a problem with them. You probalby look like you need a whole new cogset, so either the ones that you have on now are faulty and you should take the bike back and explain the problem, and see if they can be replaced. Just make sure everything is tightly screwed and that the chain is clean and all the links are correct, then try it out again. Your derailer wouldn't have anything to do with this, so my best guess is replace the rear cogset/chainrings.