New frame bottom bracket and crank compatibility and general stupidity!

Question

I recently bought a Scott CR1 SL 2012 frame to replace a crash damaged frame on my 2009 Boardman Team Carbon road bike. The intention being to move as much as possible across from the old bike on to the new bike. Mostly all went well, I even managed to cut the fork and install the headset. I didn't have any specific tools and the press-fit went in by firm hand pressure.

Anyway, on to the BB and crank. The old bike was running SRAM Rival and SRAM GXP cranks. New frame came with Shimano press-fit BB already fitted (I believe to be Shimano SM-BB91-41B). From a lot of internet searching it was still unclear whether the BB is compatible with GPX crank so I gave it a go to see. Once fitted it actually seemed fine but after a short test ride there was a bit of play that no tightening could get rid of. I left it for a week then went back to it to remove when I had a spare 5 minutes...... Oh dear, in my rush I forgot that to remove I need to leave the outer 'screw' in and loosen the inner one to push the crank arm off. Instead I screwed a crankpuller in to the crankarm and kept tigntening and managed to strip it. So now left with a stuck crank arm.

So first things - need to remove the crankarm, I have tried hammering it outwards and it seems to have budged a bit but now none further. Going to try a gentle ride soon to see if that helps. The arm is knackered so also could cut it off but how easy is that? Any other suggestions. I'm not sure riding it is going to work but it may.....

Once it is off what to do next? I think options are:

1) Swap BB to Sram BB86 GXP and stick with my crankset after buying a new crankarm. Problem here is removing and fitting the BBs, new tools etc

2) Go Shimano crankset, the 'off the shelf' bike uses Dura Ace but could use a lower range crankset that would fit the BB I suppose.

I'm leaning towards (2) as it involves less fitment work on my part although will cost a bit more but at the same time I don't mind upgrading anyway.....

Any thoughts on first of all removing the old arm? Then what would you do given my options?

Thanks

Answer 1

Now all sorted and working.

As described above, the pedal crank was removed by sawing of corners/chunks etc.

I then managed to successfully knock out the Shimano press fit BB, this was quite easy with a decent sized screwdriver and hammer.

Then fitted the new SRAM BB86. I used a headpress tool bought off ebay for around £7 to £8 delivered. Worked a treat - a simple threaded rod with plates and bolts. Did one side at a time which seems to be the recommended technique.

New pedal crank also bought and chainset fitted and all nice and solid, no wobbling!

Answer 2

I did something similar years ago with my first bike.

I was replacing the stock square taper BB and ended up tearing out all the threads. The BB was fried and it was the left side arm so I cut it off.

It took about two hours since the arms were hardened steel, I used a hack saw and a grinder. Once I had removed a chunk I still had to hammer it off. I completely jacked up the bottom bracket, but I was replacing it so it didn't matter to me.

So, I would advise against cutting it. I would try: Heating the arm with a heat gun and tapping with a hammer, penetrating oil around the splines and light riding, or maybe re-threading the arm with a tap, I'm not sure what size you need but since you've moved it a bit already you may not need many good threads.

You may have to bite the bullit and go the the bike shop...