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crank question.... and bottom bracket
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crank question.... and bottom bracket
Postby pembo6 » Tue Dec 04, 2012 2:25 am
If I purchase a new cranksset for square taper, will it fit the larger nuts? Or do the newer cranksets only fit the axles with the smaller Allen bolts. My existing BB is the right size (68mm). I am just worried that the nuts won't fit into a new crank arm.
Or will I need to also purchase a new BB?
I hope I have explained that clearly??
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Re: crank question
Postby BRLVR.v2 » Tue Dec 04, 2012 12:51 pm
Dan wrote:They'll fit.
But the issue will be the axle length, if its an old road double it maybe toolong. A new bb that matches your crankswill get a better chainline. Have a look at sheldon brown's info . 68 mm is the shell width,the axles come in many lengths,and thats the important bit
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Re: crank question
Postby slidetaker » Tue Dec 04, 2012 1:41 pm
which you can aim to match with the cog in the rear wheel....
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Re: crank question
Postby Dan » Tue Dec 04, 2012 1:49 pm
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Re: crank question
Postby pembo6 » Tue Dec 04, 2012 3:04 pm
So it seems that the cranks will fit my existing BB, but it may not be at the ideal chainline. It is an old road double chainwheel.
I will be running a new flip-flop rear wheel/ hub (in the mail) and will be using a fixed track cog. So a little limited in changing the chainline at the rear (without moving wheel over and re-dishing).
It sounds like my best option is to get the new crankset and check the chainline. Fingers crossed it will be OK. If not, I will measure the BB/spindle width and see what I need to get the correct chainline.
The crank I am looking at does specify the chainline (42.5 I think??) but it does not specify what BB size that is for. The specs are......
Chainline: 43.5mm
BB Axle: Square (103) NOT included
Is "103" the BB/spindle length? How can it state the chainline without knowing what BB is being used?
Thanks again for your help.
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Re: crank question
Postby Dan » Tue Dec 04, 2012 3:32 pm
pembo6 wrote:
Chainline: 43.5mm
BB Axle: Square (103) NOT included
Is "103" the BB/spindle length? How can it state the chainline without knowing what BB is being used?
that's the chainline you'll get using a bottom bracket with an axle/spindle length of 103mm - cranks can only sit so far in on the axle before they bind, as they're tapered. Look at the link to Sheldon posted earlier. If you want a chainline that's lesser, you need to get a shorter axle, and vice versa.
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Re: crank question.... and bottom bracket
Postby BRLVR.v2 » Tue Dec 04, 2012 4:21 pm
- Mulger bill
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Re: crank question.... and bottom bracket
Postby Mulger bill » Tue Dec 04, 2012 10:47 pm
London Boy 29/12/2011
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Re: crank question.... and bottom bracket
Postby BRLVR.v2 » Wed Dec 05, 2012 7:52 am
Mulger bill wrote:It'd be worth trying the single ring in the small ring position too, it won't look as neat but it may solve the problem.
I think OP is purchasing a new single ring specific crank which only has one mounting option any way.
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Re: crank question.... and bottom bracket
Postby Mulger bill » Wed Dec 05, 2012 11:38 pm
BRLVR.v2 wrote:Mulger bill wrote:It'd be worth trying the single ring in the small ring position too, it won't look as neat but it may solve the problem.
I think OP is purchasing a new single ring specific crank which only has one mounting option any way.

London Boy 29/12/2011
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Re: crank question.... and bottom bracket
Postby BRLVR.v2 » Thu Dec 06, 2012 10:49 am
Mulger bill wrote:BRLVR.v2 wrote:Mulger bill wrote:It'd be worth trying the single ring in the small ring position too, it won't look as neat but it may solve the problem.
I think OP is purchasing a new single ring specific crank which only has one mounting option any way.
Comprehension fail.
Old age,bud.....

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