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PostPosted: Thu Mar 04, 2010 11:02 pm 
retrobike rider / Gold Trader
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ok, so im going to run an alfine hub on a steel frame.

trouble is im not used to s/s type set ups and the alfine runs (a fairly weird?) 42.5mm chainline. by flipping the rear cog you can achieve 47.5mm, so my question is about suitable chainsets.

Ive sized things up and it looks like the biggest ring I can manage is a 39t up front, can anyone suggest some new model chainsets I can go for that will give me around 47-48mm chainline?

im presumming ill need a shorter axle, like 108mm? what about external b/b's? how do I measure them up?

can I pick up any old chainset, say for example, an XT hollowform, then remove to rings, fit a 39t in the middle and hope for the best?


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PostPosted: Fri Mar 05, 2010 2:19 am 
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Assuming your 39t ring is on the middle ring mounts. If you try putting it on outside on the big ring mounts, you'll get about 5mm adjustment there, right?


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PostPosted: Fri Mar 05, 2010 8:31 am 
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Middleburn RS-7's with a 113mm square taper BB will give you spot on 47.5mm, either with the Uno chainring (the better option IMHO) or a chainring on the middle ring position on a spider.


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PostPosted: Fri Mar 05, 2010 9:53 am 
retrobike rider / Gold Trader
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Andy R wrote:
Middleburn RS-7's with a 113mm square taper BB will give you spot on 47.5mm, either with the Uno chainring (the better option IMHO) or a chainring on the middle ring position on a spider.



really? not on a 108mm BB? thats very interesting as I was looking at the new larger UNO rings last night.
Its a pricy option but I may just plump for it


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PostPosted: Fri Mar 05, 2010 10:51 am 
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47.5 mm to the middle ring is usually what you get if you're running the BB they specify and a mountainbike chainset.


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PostPosted: Fri Mar 05, 2010 10:59 am 
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Just double checked (to be sure that I wasn't making it up...)

RS-7s with Uno chainring (in this case 32T, but that's neither here or there). 48mm chainline with SKF 113mm BB.

Just a quick pic. for illustration - I did actually measure it more accurately than this, using a pair of verniers.


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PostPosted: Fri Mar 05, 2010 11:13 am 
retrobike rider / Gold Trader
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legend.

thanks pal


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