Bottom bracket advice needed please?

[Preston-m3]

Hi All, I am looking for someone to explain what bottom bracket I need. I have a white industries crank currently fitted, fits fine. I recently bought a lovely set of retro middleburn cranks fitted with PACE chain rings but they dont fit onto my current bottom bracket on the drive side. Its as if the bottom bracket need to be wider? What bottom bracket do you think I need to change to so the new cranks fit. I am not at all technical by the way so you may need to explain in simple man terms?
Thanks guys.

 

[d8mok]

Re:

I’ve just changed my middleburns for some XTR. I was running a 118 bb and worked fine. I might of got away with slightly less (116) but didn’t want to take the risk of having to buy 2.

 

[Preston-m3]

Re:

Thanks, i need to get my bb out i think and see what width it is. What is the maximum size they come in?

 

[d8mok]

Re:

No idea of a maximum size. But anything too wide will mess up your chain line.

 

[jimo746]

Re:

DO you know which model of Middleburn cranks you have?
Good idea to remove the current bottom bracket first and see what length it is.

http://www.retrobike.co.uk/forum/viewto ... mp;t=86278

 

[Preston-m3]

Not sure on the model of cranks?
They look like these though.

 

[pazaudi]

^^^ Those are RS-2's. I had a set of RS-1 cranks (which I suspect you have Preston as I know the chap who was selling the cranks with Pace rings a couple of weeks ago) with 1 outer chainring only which were running ok on a 121mm Hope titanium bottom bracket but when I swapped over to a 3 ring RS-3 chainset I had to swap over to 113mm.

 

[FluffyChicken]

Preston, it's all don to the 'profile' of the cranks, each profile needs its proper length. Frame may alter the chainline to use the wider one. But that fat alu or maybe full sus frames.

They vary from 107 for M900 crank (up to it max 113)
to M730 crank that use 122.5 up to it's max of 127.5.
and everything in between (and possible for a few a bit either side.

Also just because it is Shimano or Middleburn or Raceface, doens't mean you can tell. You need to know the model.

It's a good chance you have a 113 bottom bracket fitted for the Sugino? White industres crank.

An RS2 I think will be 122.5 (would need to check, it could be the odd 118 size, I forget)
But an RS3 will be a 107-113 crank.

 

[Preston-m3]

Re:

Thanks all. Yes that’s me that bought the cranks. so I will look for a bb at 122.5 or 124? Either should be ok? It’s going on a hardtail stumpjumper frame.

 

[pazaudi]

Have a look at this thread:

viewtopic.php?f=1&t=86278

Cheers