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 Post subject: Hollow axle cranks.
PostPosted: Sun Feb 12, 2012 11:24 pm 
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Wondering what the spacing is on an 83mm bb hollow axle crank? And where to meausre from.
Amd what are the lengths for the others? (68/73).


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 Post subject:
PostPosted: Sun Feb 12, 2012 11:33 pm 
Moderator /Lincs, E & S Yorks Deputy AEC
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What exactly do you mean by spacing?

What do you want to do?

68 & 73mm hollow axle cranks generally have the same length axle & use spacers to make up the difference between 68 & 73mm BB shells

83mm BB shells are usually on DH bikes and require a different crankset to a 68/73mm BB shell


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PostPosted: Mon Feb 13, 2012 12:03 am 
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I see what i did there!

I mean the LENGTH of the axles?

Im guessing theyre 5mm different but where to measure from? (Guess the end to the other end, doh!) but, is it different to measure between different brands?


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 Post subject:
PostPosted: Mon Feb 13, 2012 12:38 am 
Moderator /Lincs, E & S Yorks Deputy AEC
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cyfa2809 wrote:
I see what i did there!

I mean the LENGTH of the axles?

I'm guessing they're 5mm different but where to measure from? (Guess the end to the other end, doh!) but, is it different to measure between different brands?
Axles are the same length for 68 & 73, the plastic spacers make up the difference in BB width

83mm needs a different chainset entirely & is a different axle length, not compatible with the 68/73 variant

Dunno how the axle lengths are measured to determine the difference between a 68/73 & a 83 as it's only the BB with that determines which of the two you'd need

Different manufacturers may have different axle lengths as they can use different crank arm fitments

What are you trying to do? Which cranks on what frame? I'm assuming you're trying to fit some cranks to a frame or need to know which cranks to buy?


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PostPosted: Mon Feb 13, 2012 1:14 am 
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Yes i have some raceface evolve dh cranks and i havent been able to get them setup properly. On maintenence today i realised one the the plastic bits which sits inside the bearing and 'guies' the axle through, is crushed into the cup slighlty.

This is with a 68mm shell and i measured the amount of spacer i have on there, its 80mm between the 2 cups! Soooo im guessing thats not right, right?

I had suspicion with these before but managed to get them setup ok on the other frame i had them on but dont think it will happen on this frame.

All being said and done though, should it matter? I thought you could space out a bb to whatever? (Although obviously its not ideal and not best practice, just theoretical for me as if they are 83mm i will probably be looking for others).


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 Post subject:
PostPosted: Mon Feb 13, 2012 1:21 am 
Moderator /Lincs, E & S Yorks Deputy AEC
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As far as I know those cranks are only compatible with a 83mm BB shell


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 Post subject:
PostPosted: Mon Feb 13, 2012 1:31 am 
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Ooooooooo really?! Are you pretty sure about that?

Bugger. Solves my predicament though!


Appreciate your help.


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 Post subject:
PostPosted: Mon Feb 13, 2012 1:44 am 
Moderator /Lincs, E & S Yorks Deputy AEC
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I think there's an X-drive variant which works on a 68/73mm BB shell, but without knowing exactly which ones you have it's hard to be 100% sure

How you'd tell the difference between the 83mm variant & X drive I'm not sure right now as I'm falling asleep at the monitor!

Did the other bike have a 83mm BB shell?


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 Post subject:
PostPosted: Mon Feb 13, 2012 1:54 am 
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Nope was aaaa eerrrrrr 68 again i think. And who i gt them from was running a 73 i believe (dead rats).

Theyre x type if that helps anything haha.

Go bed!


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