Author Topic: Bottom bracket confusion.  (Read 1077 times)

tiermat

  • According to Jane, I'm a Unisex SpaceAdmin
Bottom bracket confusion.
« on: August 23, 2011, 02:27:54 pm »
At the risk of getting boring, I am going to ask another question regarding the InBred I am building.

It has a 68mm BB shell, and I have fitted a 105 external cup BB.

Today I took delivery of a RaceFace Evolve chainset, along with BB, which apparently are carp and the Shimano BBs are compatible, so I left it in there.

When I came to fit the chainset I found that the ring fouled the chainstays.

So I RTFM and find I need to fit spacers, 2 on the DS and 1 on the NDS, which makes the chainset fit nicely.

I then try out the 105 chainsets I have in the garage, and they fit, no fouling!  However I seem to be unable to get the NDS crank on far enough to engage properly.

So my questions are:
Am I doomed to failure if I want to use the 105 chainset?
If not, should I just remove the NDS spacer, see if it fits ok, if not remove one of the DS ones and see if it fits (without fouling)etc etc.  this would mean I have just wasted £109 on a new chainset I didn't need :(
Should I just stick with the Race Face chainset and try to ignore the nice, shiny 105 cranks wasting away in my garage bike shed?
I feel like Captain Kirk, on a brand new planet every day, a little like King Kong on top of the Empire State

The Mechanic

Re: Bottom bracket confusion.
« Reply #1 on: August 23, 2011, 02:55:12 pm »
If you have 105 BB cups I would suggest you may not need the spacers to fit a 105 chainset.  Just because you need spacers for one type of C/set does not mean that you will need them, or the same spacers, for other types.  BTW, why have you bought a race face C/set if you have a "nice, shiney 105 cranks" wasting away in your garage.  I suggest you stick with the 105 stuff and send the R/F c/set to me for safe keeping. :thumbsup:

tiermat

  • According to Jane, I'm a Unisex SpaceAdmin
Re: Bottom bracket confusion.
« Reply #2 on: August 23, 2011, 03:00:09 pm »
From what I can see, 105BBs expect the bike to have a 73mm BB, but the InBred has a 68mm BB.

I have measured the BB on the Ridley (Ultegra) and it comes to 89mm, on the inbred, with spacers, it comes to 97mm.

So to make it fit I would need to remove all spacers (7.5mm of spacers), which of course would then mean that the middle chainring would foul the chainstay.....

So I haven't wasted my money, so it would seem.

However it would appear that the cups on Shimano BBs are slightly wider than the RaceFace ones, which *may* mean I need to replace on of the 2.5mm ones with a 1.8mm one.

This is not going to be a simple build, is it?
I feel like Captain Kirk, on a brand new planet every day, a little like King Kong on top of the Empire State