Forum home Road cycling forum Workshop

Raleigh Mercury chainring problem

daffyavfcdaffyavfc Posts: 237
edited May 2010 in Workshop

Raleigh Mercury, early 1990’s, pink and white 12 speed.

Bought this the other day second hand. Lovely bike, just need to change bar tape and fine tune gears.
I’ve just noticed a problem with the front chainrings though. When it spins it has some sideways movement, in other words it firstly catches the front derailleur when it spins and I’ve noticed that the small chainwheel has eaten into the paintwork on the chainstay tube. It is not loose as BB is fine and tight, it’s just that somehow it’s been ?bent with obvious sideways movement into and out of the bike frame.

How do I get the right size replacement to ensure it fits onto the BB without major changes needed??




  • bill57bill57 Posts: 454
    Unfortunately you're a bit censored for elbow here. Most would buy a chainset and buy the appropriate BB for that model - you've got the BB and want to choose a chainset to fit. You could measure the length of the axle and scour the web to find a suitable chainset, but you've also got to know whether it has JIS or ISO taper - I'm assuming it's a square taper? Also, have you considered the possibility that it's the BB that's not straight?

    Personally I couldn't be bothered with this, and would just choose the chainset I liked best and buy the appropriate BB to go with it. You'll save yourself a lot of hassle.
  • daffyavfcdaffyavfc Posts: 237
    I've stripped the BB today and it's the old school Cup and Cone BB.

    The axle is so thick I doubt it's that that's bent. I've re-greased the lot and put it back and looks/appears to be fine. I'll look at the chainrings, if I cannot bend them back how do I know what to buy to replace it so that it fits the same?? What I mean is that if its a different width compared to the first one I could have the same problems or it could be wider and then the derailleur may not work properly.


  • bill57bill57 Posts: 454
    You can take a horse to water...................
Sign In or Register to comment.