Middleburn RS2 bb length... Fitting probs

[H]

Re:

Hi guys, I've measured the chain stays at their widest point (nearest the bottom bracket). The distance is 97 mm the bb shell is 68 mm and the bb is NOS, so the tapers are fine. What does everyone think? I could try and borrow a bb tool and assemble if that's what's needed next. Thanks, H.

 

[secret_squirrel]

Your other option is a compact spider for the RS2's. There are a few knocking around on here but mostly NOS and pricey - plus you would need different rings.

 

[Gaddmeister]

Re:

Think I can see the problem. The rear stays are welded very near to the end of the shell, thus causing them to protrude more than other frames. I think you will need a longer axle or smaller rings?

 

[My_Teenage_Self]

^^^ think he might be on to something there...

I actually meant are the tapers in the cranks 100%?

 

[H]

Re:

Hi guys, I really appreciate your insight thus far.
I've since spoke with Neill Orrell (the frame builder) and he thinks on paper at least it should be okay. I've tried Middleburn too and they are unable to send me a technical drawing for Orrell right now.
In frustration I've mounted the 127.5 mm bb myself tonight and offered the drive side RS2 cranks up. They do touch and do so very early on the tapper (see pic 1). Put it this way, I did't bother to get the bb bolts from the packet. Interestingly, I offered them to the non drive side and they didn't touch, although I reckon on tightening with the bb bolt I think it might (see pic 2). What do you think should be my next steps? Should I use a spacer on the drive side (is this even a good idea) or swop this bb out for a 134mm bb instead? All help, gratefully received. Peace and love, H.

 

[Gaddmeister]

Re:

Looks like the frame was designed around compact drive. I would look at smaller rings or different chainset. What year was the frame made?

 

[itscervo]

You really need to sit down & think about this, you have TWO options :shock: .
A) go ahead, disregard any thoughts on chainline with its associated & gear change issues by trying to fit a non compact crankset on a frame that was built to accept a compact :facepalm: .

B) Do it right, fit a compact crank with the correct length bb & enjoy the ride .

 

[H]

Re:

Curiosity got the better of me. I threw three rings (44,36,26) onto an M900 chain set and finger tightened them on the axle. Check out the results. I'm really keen to mount the RS2's, but is this telling me to go for a newer style crank with a lower Q factor (?). All the best, H.

 

[secret_squirrel]

Swap the RS2's for RS3's which look even better. Job done.

 

[H]

Re:

My final midnight fettling. Compact RS2 with chain rings 46,36,26 as bad (pic 1). So I switched out the 26t chain ring for a 22t and voila (pic 2). Now, what's best? Change chain set as per m900, swop out the bb for a longer one, or change the rings for something smaller, namely 22,32,42? Comments please, H.