Lightest crank + bb solution for a bbright frame (like the s5)

Discuss light weight issues concerning road bikes & parts.
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alcatraz
Posts: 862
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

Hi ww!

I'm considering buying an s5 frame to use as a tt bike. It's a bargain and perfect size.

I know weight isn't life or death but I am still a weenie.

Has anyone been in this situation and researched the matter?

Is the solution gxp bb and sram red or to go standard 24mm and get a duraace/kforce/slk crank?

I often see rotor cranks but they aren't that light. No need to suggest ridiculously exotic cranks that are in limited small production.

There is also the option to get a bb386 crank. I would avoid getting a bbright crank.

Thank you for your help
/a

alcatraz
Posts: 862
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

Noone? :D

glam2deaf
Posts: 657
Joined: Mon Apr 27, 2015 4:36 am

by glam2deaf

Most of Rotors cranks are UBB which is more or less the same dimensions as bb386. The 3D+ is quite a bit lighter than the 3D. There is also the new Rotor crank (I forget the name) which they're claiming as a massive weight loss.

I was running 3d + SRM on mine as that was the best solution, also not WW at all. Maybe looking at Sram force GXP + a Direct mount ring for x1 would give you a reasonable saving. It's probably not where you want to go, but you'll also save on the FD weight.

androidavies
Posts: 74
Joined: Sun Sep 29, 2013 4:34 pm

by androidavies

If you've saved money on the frame, then surely a THM Clavicula and their BBRight specific bottom bracket is what you should be getting?
I've had that set up on an S5, works well….

Also had a Rotor 3D+ with a C-Bear ceramic BBRight, worked well, and super smooth.
Also fitted up Dura Ace 9150 with Wheels Mfg angular contact "screw together" bottom bracket, surprised me how silky smooth it felt.

I'd say that the Shimano rings are the stiffest, and give the best front shift, if that's a concern, the Rotor aero rings are pretty solid as well, although you might not be bothered if it's flat TT's…...

alcatraz
Posts: 862
Joined: Mon Aug 29, 2016 11:19 am

by alcatraz

This might sound crazy but what about MTB bb30 cranks.

They are supposed to be 73mm long but lets say you get one with a preload adjuster that you then remove. Could that fit a 79mm wide pf30 shell like the s5?

How will the asymmetry affect the riding feel?

I'm ok with going to a 46-48t big ring.

/a

Valbrona
Posts: 1484
Joined: Fri Oct 28, 2011 3:25 am
Location: United Kingdom of Great Britain and Northern Ireland

by Valbrona

alcatraz wrote:This might sound crazy but what about MTB bb30 cranks.

They are supposed to be 73mm long but lets say you get one with a preload adjuster that you then remove. Could that fit a 79mm wide pf30 shell like the s5?

How will the asymmetry affect the riding feel?

I'm ok with going to a 46-48t big ring.

/a


If SRAM, removing the pre-load adjuster and replacing with wavy washer is possible.

But bad idea to use MTB crankset. Q Factor might be up to 2cm greater; that be 1cm extra sticky-out either side.

morganb
Posts: 517
Joined: Wed Mar 15, 2017 5:30 pm

by morganb

You should check your fit before getting the frame if you already haven't, Cervelo road bikes have such slack seat angles I can't imagine riding one as a TT bike, you may have much longer femurs than me though.

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prendrefeu
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by prendrefeu

Your absolute lightest option: THM Clavicula SE
Your lightest yet affordable option: Lightning Cranks
Your lightest 'mainstream brand' option is SRAM BB30 Force level - it has a longer axle than their Red level and won't need the GXP adapter, which adds additional mass.

Rotors are nice cranks, I personally don't like them and never have. I've yet to be impressed, but to each their own. :shrug:
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uraqt
Posts: 815
Joined: Mon Apr 03, 2006 8:53 am

by uraqt

what about Eason ? That crank has to be in the top three if you include price!!

C

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prendrefeu
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by prendrefeu

That's a good point - those are some light arms at a good price.
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