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Swapping FSA chainset / bottom bracket for Shimano

HenryTheHooverHenryTheHoover Posts: 126
edited June 2014 in MTB buying advice
Evening Gents and Ladygents

I have a Boardman Team Urban with Sram X7 gearing, FSA mega exo bottom bracket and a 42 \ 27 tooth chain set ( 386 comet I think).
The bottom bracket has really not done me proud and I am reluctant to spend 40 nicker on another one so I am thinking of possibly switching over to a Shimano chain set / bb.
My issue is that the chainring offerings from Shimano seem quite different tooth wise. I swap from slicks for my commute to knobblers for off road and find I spin out downhill with 44-11 gearing on my slick tyred commute but need the 27-36 off road.
Options from Shimano are 38\26 or 40\28. Neither of which seems ideal. I have tried to persevere with the mega exo bb to keep my gearing but even carefully dismantling the cartridge bearings and re greasing doesn't seem to work and I am reluctant to spend £40 every 400 miles or so ( which is all I seemed to get out of it).

Any input / experiences / solutions would be appreciated because I am procrastinating like a don't know what about what to do and my bb is rapidly deteriorating. Ta

Posts

  • If you are only getting that distance I wonder if you are setting the bearing preload correctly. Check it out if anything like mine you need correct spacers with a wavy washer that needs to be only lightly compressed.
  • If you are only getting that distance I wonder if you are setting the bearing preload correctly. Check it out if anything like mine you need correct spacers with a wavy washer that needs to be only lightly compressed.

    Thanks for replying. It could well have been tightened too much. My left crank fell off mid ride a couple of times so maybe I over did it wacking it back on?

    However the main issue I seemed to have first was it just got crapped up with soms sort of silt \ clay. Its not cleaning related as I don't clean it as a rule.

    There are two spacers on the drive side and one on the non drive. No wavy washer from what I remember. The issue I have now after stripping it could be due to tightness because its hardly gone off road since.

    Its a bit hard to justify spend 40 nicker on what seems like a censored bb when a slx chain set and bb can be had for £72. An xtr bb is only £22. The gearing is the issue with this plan as at 38-11 I loose 10% top speed. A 40\28 looses me 5% top and 3 ish % bottom but I' m 92kg and use my 27-36 fairly regularly off road.

    I think the X7 mech is rated as having a 15 tooth capacity. I was wondering whether one of my options was to buy a 38\26 and sell the 38 and get a 40,41 or even try to push to a 42 and see if the mech will deal with 16 teeth difference?

    A new FSA bb would be the easiest option though. I just want it to last better than my current one.
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