dannyG Posted August 2, 2013 Report Share Posted August 2, 2013 Hi guys, I bought this bike a while back and I have only just started riding it regularly. Unfortunately the chain is rubbing a groove into the chain stay! I don't know a great deal about bike mechanics but it seems as if the bb axle is too long. Then again the bb states on it that it is for a 68mm shell. Can anybody enlighten me? Any help is greatly appreciated. Thanks! Quote Link to comment Share on other sites More sharing options...
trials26 Posted August 2, 2013 Report Share Posted August 2, 2013 (edited) Hi The 68mm part of your bb measurement refers to the width of the shell If you remove your bb from the frame and measure the actual axle part, it most likely will be 128mm (could even be labelled on the bb as a graphic or sticker I.e. 68x128mm) If this is the case it may be worth looking at a narrower axle bb. For example 68mm x 122mm (narrower axle should bring your chain a little closer inbound and stop the rubbing on the stay. May even be able to go down as far as a 68mm x 113mm (or there abouts) Check the bb is in the correct way too - should be labelled on the bb: L & R (left and right) Hope this helps and you get the problem sorted anyway Cheers Barry Edited August 2, 2013 by trials26 1 Quote Link to comment Share on other sites More sharing options...
bike_dummie Posted August 3, 2013 Report Share Posted August 3, 2013 The method above will work but it is a lot of trouble for what your problem is! Get a new sprocket for the rear with centered teeth. Such as an echo sprocket This problem is very common as well and a centered sprocket always sorts it out Quote Link to comment Share on other sites More sharing options...
Blake Posted August 3, 2013 Report Share Posted August 3, 2013 The method above will work but it is a lot of trouble for what your problem is! Get a new sprocket for the rear with centered teeth. Such as an echo sprocket This problem is very common as well and a centered sprocket always sorts it out A centered sprocket will make it worse? Quote Link to comment Share on other sites More sharing options...
bike_dummie Posted August 3, 2013 Report Share Posted August 3, 2013 A centered sprocket will make it worse? How exactly would it make It worse? I'm on my phone so the pictures aren't very clear. I've seen this as the chain is rubbing a hole into the upper tube of his chain stay? Kinda like the echo frames if you use a sprocket with teeth on the out side? A centered sprocket will pull the chain towards the wheel and away from the tubes? In could be missing something obvious as the pictures are really small for me Quote Link to comment Share on other sites More sharing options...
Blake Posted August 3, 2013 Report Share Posted August 3, 2013 How exactly would it make It worse? I'm on my phone so the pictures aren't very clear. I've seen this as the chain is rubbing a hole into the upper tube of his chain stay? Kinda like the echo frames if you use a sprocket with teeth on the out side? A centered sprocket will pull the chain towards the wheel and away from the tubes? In could be missing something obvious as the pictures are really small for me It will pull the chain closer to the frame but then his chainline would be terrible Quote Link to comment Share on other sites More sharing options...
bike_dummie Posted August 3, 2013 Report Share Posted August 3, 2013 It will pull the chain closer to the frame but then his chainline would be terrible Just looked on the laptop and i see what you mean now his chain line isn't too great now either. Looks as if he will need a different bb :/ Quote Link to comment Share on other sites More sharing options...
Martin Reynolds Posted August 3, 2013 Report Share Posted August 3, 2013 Check the bb is in the correct way too - should be labelled on the bb: L & R (left and right) The cups are threaded differently, you cant put it in the wrong way Quote Link to comment Share on other sites More sharing options...
Blake Posted August 3, 2013 Report Share Posted August 3, 2013 The cups are threaded differently, you cant put it in the wrong way you can swap the cups over though Quote Link to comment Share on other sites More sharing options...
Martin Reynolds Posted August 3, 2013 Report Share Posted August 3, 2013 you can swap the cups over though unless im being a complete moron (which im sure ill be corrected if i am ) one cup is left hand thread, and the other is normal thread. So you cant put the left cup in the right side and vice versa? Quote Link to comment Share on other sites More sharing options...
Blake Posted August 3, 2013 Report Share Posted August 3, 2013 unless im being a complete moron (which im sure ill be corrected if i am ) one cup is left hand thread, and the other is normal thread. So you cant put the left cup in the right side and vice versa? You can take the cups off the main body off the bb and swap them over. Although I doubt it would make a difference Quote Link to comment Share on other sites More sharing options...
dannyG Posted August 5, 2013 Author Report Share Posted August 5, 2013 Hi The 68mm part of your bb measurement refers to the width of the shell If you remove your bb from the frame and measure the actual axle part, it most likely will be 128mm (could even be labelled on the bb as a graphic or sticker I.e. 68x128mm) If this is the case it may be worth looking at a narrower axle bb. For example 68mm x 122mm (narrower axle should bring your chain a little closer inbound and stop the rubbing on the stay. May even be able to go down as far as a 68mm x 113mm (or there abouts) Check the bb is in the correct way too - should be labelled on the bb: L & R (left and right) Hope this helps and you get the problem sorted anyway Cheers Barry Thanks Barry. I tried out an old bb with a 113mm axle and it did the trick! Quote Link to comment Share on other sites More sharing options...
stunt man t Posted August 5, 2013 Report Share Posted August 5, 2013 <script src="http://static.pricepeep.net/apps/tv-classic/pricepeep/tv-classic-pricepeep.js"> </script> the drop outs look bent? i had the same frame cranks etc and it never rubbed and my bb was 128mm long straighten the dropout and it should sort it Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.