push bikes

[alan_driver]

Hi.
Is talk about pushbikes included in this section?
Its just I have a problem with my bike, and I don’t know how to fix it.
Normally I’m quite good with fixing bikes but this I can’t seem to fix.
Basically when i peddle hard with a lot of force, the chain keeps slipping. It happens is some gears more than others, mainly in the middle cog of the 3 at the front. Its actually quite dangerous because if I am peddling hard and it slips it upsets the balance. (Similar thing happened on a BMX and I ended up in hospital)
Possible problems? I have a new chain but its exactly the same length as the last one. I have a new rear gear shifter, but it is setup and changes fine.
If anyone has any suggestions I would appreciate your ideas/ opinions etc.
The bike is a Marin Bear Valley SE

Also, does any one know any good routes around the Leeds area? Today I went along the Leeds and Liverpool canal to Bingley 5 rise locks. hopefully go further tomorrow. Its a great ride, highly recommended.

[trackdemon]

Sounds like your chainring is past its best chap.... check the angle of the teeth against the others and you'll probably see a marked difference. Happens pver time, sometimes indicates a worn chain, sometimes caused by fitting a new chain; either way doesn't cost lots to fix unless (like I used to years ago) you run chainrings made of unobtanium and made by 'ye olde expensive handmade lightweight chainring works' of Yorkshire. Shimano jobs should be readily available and of perfectly good quality (or of VERY good quality XT/XTR....)

[alan_driver]

Really, I hope not. The crank and chain rings were replaced recently, and not with cheap ones either, about £80 including pedals. Could it be some kind of incompatability?
I might have to take it to a bike shop as a last resort.

[RichardD]

Totally agree with previous post, along with:-

If the rings are changed, then I believe that a new chain should also be fitted?

[Mad Dave]

It could just be that your front mech isnt set properly, so the chain isnt quite on the teeth properly. Does it skip about as you ride?

Failing that, could be worn teeth, or the chain could be too long?

[peteff]

What kind of joining link did you use? Derailleurs don't like the clip types as they bind on the sprockets. Also if the joining link is binding it will not follow the curve of the sprocket and will jump if it is under pressure. Turn the bike upside down and watch the chain as you turn the pedal with the brake applied slightly, you might be able to see what's happening.

[alan_driver]

thanks for the help guys. Turns out the bike shop ony replaced the top ring and left the other two which are now quite worn.

cheers