FSA SL-K light MegaExo Shimano BB mixing parts

Discuss light weight issues concerning road bikes & parts.
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drotos
Posts: 12
Joined: Sat Nov 10, 2012 11:34 pm

by drotos

I've just got a second hand FSA SL-K light chainset. I've read many discussion about the MegaExo bottom bracket, but have some specific questions...

- Could I use an FSA-style wave spring washer with Shimano bottom bracket? (Beacause of the preload of the FSA SL-K light cranks...)

- Is that possible to use the FSA tube between Shimano bearings? (Again, the preload...)

- Are the outer dimensions of the BBs the same?

Thanks!

by Weenie


bobones
Posts: 44
Joined: Mon Aug 12, 2013 11:19 am

by bobones

The spindle will be very tight on a Shimano BB. I always use the BB8681 for mine but you may get it to work. Here is the definitive answer which states they are not compatible:

http://www.bikeforums.net/showthread.ph ... ost8412886

Answer from FSA’s Dae Oh

The short answer; no, the FSA K-Force Light Rd. Crank is not compatible with a Chris King bottom bracket (made to Shimano compatible dimensions). Also, the K-Force Rd. crankset will not be compatible either.

The FSA BB8200 (meant for K-Force Light) uses a 6 mm width bearing. This allows us to make the bottom bracket outside to outside dimension more narrow providing room for a wave washer. The BB8000 (meant for K-Force) does indeed use a 7 mm width bearing, yet its design does not allow for use of a Chris King bottom bracket.

However our popular alloy cranksets, the Gossamer Rd. and the Energy Rd. is compatible with the Chris King bottom bracket (made to Shimano compatible dimensions). These cranks use BB6000, this BB's dimensions are compatible with Shimano.
Dae Oh
Full Speed Ahead

Marin
Posts: 2662
Joined: Wed Jan 22, 2014 11:48 am
Location: Vienna Austria

by Marin

After the Mega Exo on my FSA Gossamers seized on my commuter, I replaced them with a Shimano HT II unit I had. The fit is a tiny bit tighter, but it works perfectly, unlike the original, which either had play or was too tight. YMMV, though.

The Shimano unit is only like 10€, so the experiment is cheap.

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ms6073
Posts: 2370
Joined: Fri Jul 23, 2004 8:24 pm
Location: Houston, Texas

by ms6073

FSA Energy/Gossamer cranks have ~25mm OD spindles which are compatible with Shimano Hollowtech spec'd bottom brackets (25mmx37mmx7mm) and don't incorporate crush washer or wave spring washers for proper pre-load. The FSA's 'Light' variants (K-Force Light/SL-K Light) incorporate the wave spring washer for proper pre-load and spacing so have narrower 6mm bearings but these cranks also have a slightly larger spindle diameter (~25.5mm) which makes for an overly tight fit which will most likely result in damage of the bearings if a Shimano compatible bottom bracket is used - been there, done that with lots of $$$ attached!
Michael - The Anaerobic Threshold is neither...

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