Fixing My Bike?

[david_m213]

Hi.

I have a trek mountain bike but I have a couple of problems with it.

It has 3 front sprockets and 7 rear ones.

The chain will not move onto the two smaller front sprockets.

The first 4 gears while on the largest front sprocket work perfectly fine. Gears 5, 6 and 7 rattle and slip while I'm pedalling.

By that I mean when I pedal standing up the pedals will suddenly have no resistance and then catch again. Does anyone know what this is?

I know my dérailleurs need setup and I've had a shot at doing it myself but I'm doing it wrong. I've watched instructional videos on youtube. It's a bit embarrassing as I'm used to working on motorcycles but I can't sort the gears on my pedal bike.

Does anyone know where I can get my bike sorted cheaply in the Glasgow area?

Thanks for any help.

 

[Gerry Attrick]

I suspect you have more than one problem here.

First it sounds like your front mech (derailleur) is either out of adjustment or sticking, and second that your chain and/or cassette is worn.

I think it best that you take it to a good lbs as to explain how to repair it here would take an age and be more than likely to give you more headaches.

I would suggest research as much bike repair stuff as possible on the internet and buying a good repair manual for future use.

Have a look here
I can also recommend "Illustrated Bicycle Maintenance" by Todd Downs. Published by Rodale. ISBN 1-4050-8788-9

 

[PatrickPending]

or take the bike to one of those bike maintainance courses that the edinburgh bicycle cooperative run.....

http://www.edinburghbicycle.com/ebw...&f_SupersetQRY=&f_SortOrderID=1&f_bct=c007789

 

[RedBike]

Chains generally only slip if the chains too slack or the rear sprockets/chain are worn.

To check to see if the chains worn...
Measure 12 links (inner and outer) of the chain. They should measure 12 inches exactly. If they measure 1/16" over then you've got a worn chain.

If the chains worn then it's a new rear sprockets and chain time. With it being 7 speed I would GUESS the bike uses a freewheel not the more modern cassette type. Freewheels can be a pain in ass to remove so let a shop have the fun. They will re-index the rear gears as well while they're at it.

Which just leaves the front mech. I've no idea whats going on here. If you remove the cable completely does the front mech now move the chain onto the inner chainring?

 

[lukesdad]

cable release could be your problem on the front mech.if the cable is seized the mech will not return as it is released by the shifter to drop to the smaller chain rings

 

[Daisymolly]

Hey!

Unfortunately no idea how to rectify the problems with your bike-can manage the very basics but that's it!!!!! If it's not sorted already, I've always found Alpine cycles at St Georges Cross in Glasgow v. helpful & reasonably priced.

 

[NormanD]

Try here http://http://bicycletutor.com/adjust-front-derailer/

also here http://bicycletutor.com/gear-shifting/

and here http://bicycletutor.com/adjust-rear-derailleur/

If you watch the video's a few times each you should be able to make the corrections yourself with ease

I hope the above helps you out

Norm