BSA30 Bottom Brackets

Discuss light weight issues concerning road bikes & parts.
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KWalker
Posts: 5892
Joined: Mon Dec 28, 2009 8:30 pm
Location: Bay Area

by KWalker

I've been switching my Rotor 3D+ back and forth between a road and TT bike, but recently got an S-Works Power2Max and want to sell the now redundant Rotor unit.

So I realized that the S-Works crank might not work on the TT bike I'm using, which has a standard threaded BB (S-Works Transition). I know Rotor makes a BSA30 BB, but would that be too wide for the Speci spindle? From what I gather they're both 68mm? Or am I incorrect?

Also, RaceFace now makes this: http://www.raceface.com/components/bott ... nch-bsa30/ which has a 68mm width.

Anyone know if any of these will work for what I am trying to do- i.e. use my S-Works cranks on both bikes?
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Nefarious86
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by Weenie


stormur
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by stormur

Rotor BSA30 require "UBB30" spindle length. In human language : same as "Shimano" and BB386. So if your S crank has shorter axle than that, then it will be to short.
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glepore
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Location: Pa USA

by glepore

Shimano default width is roughly 86mm (shell is 68mm plus the external cups). If the sworks cranks have a length of that plus the nds arm engagement area it should be a go with the Rotor or any other thread in 30mm BB. Shims are your friend if it doesn't preload correctly due to an overlength issue.
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ooo
Posts: 570
Joined: Sat May 21, 2016 12:59 pm

by ooo

Anyone know BSA30 bb with low profile caps around 9-9.5mm each (18-19mm total width) ?
I have found token BB386BSA which have 9.25+0.5=9.75 caps (with sealing) is almost what I need
but for most other bsa30 I can't find any info on caps width (please share, if you know anything)

Is it possible to use FSA 386 BSA bottom brackets (like Evo8681-Di2) with BSA30 cranksets?
FSA BB have 30mm inside diameter and same caps width around 9-10mm
But one of reviewers on crc posted that 'INCOMPATIBLES TO MOST CRANKSET OF DIFFERENT BRAND' without any details
Attachments
token-BB386BSA.jpg
token BB386BSA
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hambini
Posts: 296
Joined: Tue Nov 15, 2016 8:13 am

by hambini

Shimano default axles are about 90mm between the crank arms.

If you add in the width of the cups to the edge of the bearing onto a BSA frame you get 68+11 + 11 = 90

True BB386 cranks have an 86.5mm spindle length and will not fit as they come up short. However, BB30 axles with a 90+mm effective length (BB30 extended) are often marketed as BB386 hence they fit.

You just need to check what you are getting or have. I have some drawings of common bottom bracket setups here

https://www.hambini.com/technical-suppo ... re=default

ooo
Posts: 570
Joined: Sat May 21, 2016 12:59 pm

by ooo

Axle length between 2 installed crank arms: 99 mm
Total width outside of 68mm bb shell: 99-68=31 mm
Width outside of 68mm on each side: 31*0,5=15,5 mm

Plastic threaded Sram preloader width is 6,4 mm - compatible with ≤9,0 mm BSA30/BB386EVO-BSA left bb cap
Metalic threaded Cane Creek preloader is 6,0 mm - compatible with ≤9,5 mm BSA30/BB386EVO-BSA left bb cap
Wavy washer (instead of threaded preloader) - compatible with (any) ≤15 mm BSA30/BB386EVO-BSA left bb cap
'

ooo
Posts: 570
Joined: Sat May 21, 2016 12:59 pm

by ooo

I figure out how to fit cranks to frame and get correct chainline.
Now I want to find best setup for winter/bad weather use:

1. Narrow bsa caps for 30mm axle with simple sealing + sram plastic or cane creek metalic preloader (axle not exposed)
caps93.gif
plastic-preloader.jpg
2. Wide BSA caps for 30mm axle with better sealing + wavy washer instead of plastic preloader + spacers to make exposed axle as little as possible
caps100.jpg
wavy-washer.jpg
3. Wide BSA caps for 30mm axle with better sealing + left BSA cap reduced 0.5-1.0mm to fit plastic preloader + plastic preloader (axle not exposed)
caps100reduce.jpg
last one look good in theory, but it may result in creaking?
@hambini, what is recommended precision for this mod?
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hambini
Posts: 296
Joined: Tue Nov 15, 2016 8:13 am

by hambini

ooo wrote:
Sat Aug 18, 2018 9:30 pm
I figure out how to fit cranks to frame and get correct chainline.
Now I want to find best setup for winter/bad weather use:

1. Narrow bsa caps for 30mm axle with simple sealing + sram plastic or cane creek metalic preloader (axle not exposed)
caps93.gif
plastic-preloader.jpg

2. Wide BSA caps for 30mm axle with better sealing + wavy washer instead of plastic preloader + spacers to make exposed axle as little as possible
caps100.jpg
wavy-washer.jpg

3. Wide BSA caps for 30mm axle with better sealing + left BSA cap reduced 0.5-1.0mm to fit plastic preloader + plastic preloader (axle not exposed)
caps100reduce.jpg

last one look good in theory, but it may result in creaking?
@hambini, what is recommended precision for this mod?
Best modification is your choice of bearings. The external seals will have limited effect in winter. I would suggest you get FAG 2RS or NTN LLU bearings, the seals on these are good. Use of an O ring on the periphery is not a good idea, dirt and fluid naturally gets expelled outwards so you block this path.

Hope that helps

Hambini

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ooo
Posts: 570
Joined: Sat May 21, 2016 12:59 pm

by ooo

Thanks for advice, I will look for caps without o ring and find better bearing
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