Bottom Brackets

[schristie11]

Help choose New BB and Crank Arms
I have a Cannondale SL4 (2012) and the specs sheet says it has a Tange Seiki LN-3912 Bottom Bracket and Shimano FC-M361, 42/32/22 Crank.


I want to change my bottom bracket and crank arms but I do not know what fits my bike or what's a good replacement.


I want crank arms with shorter length and staying light weight but strong and somewhat cheap.


I want a outboard bottom bracket made to handle rocky offroad rides and occasionally crashing into rocks and hopefully light weight and somewhat cheap.

 

[alfeng]

If you do NOT see a decal on the downtube near the BB, then the BB shell probably uses a standard ENGLISH THREADED (1.37X24) Bottom Bracket ...

So, almost any English threaded Hollowtech II or MegaExo BB + crankset can be used.

• Hollowtech II & MegaExo are interchangeable -- a good thing!

It is hard to go wrong with a Shimano crankset & BB (there are some slugs, but they are typically reserved for use as OEM on low end bikes) ...

• SLX is supposed to be the bargain amongst Shimano's better MTB groups ... supposedly, closer to XT than LX ...
• plain Deore is certainly good, but may be comparatively heavy
• the better "groups" will possibly have more crank sizes available to choose from then the less expensive "groups" will have

• 'I' like FSA components because they are generally a good value + they are interchangeable with Shimano's "stuff" ...
• some people claim that FSA BBs don't last as long as Hollowtech II BBs

The GXP cranks & BB may-or-may-not be worth looking at ... they are the odd duck out as far as compatibility (i.e., they are NOT interchangeable with anything); and so, future (distant future, that is) replacement parts may be problematic.

 

[swampy1970]

Tange have always made pretty good stuff. That bottom bracket looks bullet proof. Forged steel spindle and steel cups - that ain't gonna break anytime soon. I'd take those steel cups in the durability ratings over an aluminium outboard BB.

http://www.tangeseiki.com/tangeseiki_news/bottom-bracket.php?page=1&class=4a&pic=200902051145433.png

As for the cranks, any low to mid range Shimano unit with a square taper will work with you bottom bracket. Most of the cheaper shimano mtb cranks come in 170 or 175mm. You'll have to step up to something like the XT cranks, with the respective bottom bracket, to get down to a 165mm. The older XT and XTR cranks probably used Octalink bottom brackets so you'd be out of luck there unless you went with a really old set of cranks.