Maintenance

Bike Skills Skills Maintenance Installing Bottom Brackets and Cranks
 

Installing Bottom Brackets and Cranks Installing Bottom Brackets and Cranks Hot

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This post covers the installation of a Shimano XT M761 Bottom Bracket, Crank and Chainring combination. There was no pain involved at all! hmnhhh! Enjoy

First some specifics:

  • This covers the installation of a Shimano XT M761 Hollowtech II triple chainset. It is an integrated bottom bracket, crank and chainring combination. Recommend you do work like this whilst checking your manufacturers guidelines (specifically on spacer insertion and torque requirements: NB see comments below for full details on Torque))
  • Also new component often come pre-lubed hence you don't see me using much lube ( I also could not lube and film..doesn't mean I didn't lubeSMILEYS_WINK but check first the state of what you are using and lube as required.
  • My bike specifically has a 68mm bottom bracket. Other bikes can differ. For mine I required a particular spacer combination. Don't wing this check it out first.
  • Finally when all is done check your gears through especially if the chainrings are a different size. I actually kept my Raceface chainrings (i.e. I swapped them over from the Shimano ones as they are quite new). You do not see this on the video.
  • Putting this piece of kit on was a lot easier than taking the old lot off in the other tutorial. All in all straightforward. Any questions please do post them in the forum using the link above or in the comments section below.
  • I did all this with one hand as the other hand held the video camera. I used a Nokia N95. Cool phone but need some type of standSMILEYS_WINK.

OK... step by step

  • Get bike and tools ready. I used a tape measure, a bottom bracket spanner, Allen keys, pedal spanner and lube. I should, will soon and recommend you also use a custom torque tool to check out how much you tighten everything.
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  • Get the adapter ready and the number of spacers together . Mine used  3 spacers each different sizes 1) 2.5mm, 2) 0.7mm 3) 1.8mm on the drive side making up 5mm in total and then one spacer on the non drive side.
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  • Put in the adapter drive side first first and use the bottom bracket spanner to tighten
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  • Put the smaller adaptor in on the non drive side and again tighten up with the BB spanner tool
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  • Pick up the drive side crank integrated with the chain rings and the BB spindle. Push through the drive side adaptor until flush. You may need to use a bot of brute force. Tip: I used a hammer gently but I put a towel over the crank to protect the surface. I couldn't do this and video at the same time.SMILEYS_WINK
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  • Once on go insert the other crank arm (note that they need to be at 180% to each other as when we ride.
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  • Insert the cap into space in crank arm facing the BB and use the other part of the BB spanner tool with an Allen to tighten up.
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  • At the top of the crank arm on the drive side is a stopper plate. Makes sure this is pushed in and flush (you may need to loosen side Allen bolts first.). In the video it isn't flush and I had to redo this later (but not on film I'm afraid) so make sure it is in right)
  • Once in position then turn each Allen bolt gently bit by bit on one side then the other. DO NOT do one side tight then the other or you will damage the parts. CHECK your manufacturers Torque requirements.
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  • Lube your pedals and attach with pedal spanner.
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  • Go ride.
  • Ride faster.
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