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PostPosted: Sun May 01, 2011 10:30 am 
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Joined: Sun May 01, 2011 8:06 am
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Location: Knutsford
Does anybody have any advice on getting a 'perfect' chainline using Middleburn cranks RS8 X-Type Uno 3, or RS8/7 square taper bb (what size?).

I'm building a Hummingbird, haven't used a Alfine before but know it's chainline is 42.7mm - a bit of a newbie so any guidance would be most welcome.

cheers.


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PostPosted: Sun May 01, 2011 6:34 pm 
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Location: Odense, Denmark
X-type:
Original Alfine Chainset is similar to a road compact and runs on a road BB. RS8 X-type uno will have different offset so you would need to fiddle around with spacers till it's right - which precludes using a Road BB.

Square taper: no idea. Sorry.


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PostPosted: Sun May 01, 2011 8:54 pm 
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Joined: Sun May 01, 2011 8:06 am
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Location: Knutsford
Thanks for replying.

dbmtb wrote:
X-type:
... you would need to fiddle around with spacers till it's right...


Do you know if an external BB can offer this level of adjustment?

Apols if these are basic Q's - I've read that the hub sprocket can be turned round to get the line closer to 47 so that might be a better starting point with the Uno.

If the square taper can offer a better line then I'll be tempted to go down that route.

thanks


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PostPosted: Sun May 01, 2011 9:53 pm 
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Location: Platsa, Messinias, Greece
I'm using an Alfine 8 on my Hummingbird with Middleburn RS7 cranks (square taper) and Uno chainring. With the Alfine sprocket fitted to give the wider chainline (ie dishing inwards) the chainline is perfect with a 113mm BB (SKF 600 series) which is 47.5mm.

You might also findthis interesting.Maybe this too.

And plenty more stuff here too.........


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PostPosted: Mon May 02, 2011 10:22 am 
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Joined: Sun May 01, 2011 8:06 am
Posts: 3
Location: Knutsford
Andy R wrote:
I'm using an Alfine 8 on my Hummingbird with Middleburn RS7 cranks (square taper) and Uno chainring. With the Alfine sprocket fitted to give the wider chainline (ie dishing inwards) the chainline is perfect with a 113mm BB (SKF 600 series) which is 47.5mm.

You might also findthis interesting.Maybe this too.

And plenty more stuff here too.........


Thanks Andy. If I went with a shorter spindle then, in theory, I wouldn't need to turn the sprocket over but I'd have to look for something like a 103mm bb which are available. Of course I'd have to consider the chain ring clearance, any idea how tight this would be on the Hummingbird?


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PostPosted: Mon May 02, 2011 6:43 pm 
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Joined: Tue Aug 07, 2007 12:22 pm
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Location: Platsa, Messinias, Greece
splane wrote:
Andy R wrote:
I'm using an Alfine 8 on my Hummingbird with Middleburn RS7 cranks (square taper) and Uno chainring. With the Alfine sprocket fitted to give the wider chainline (ie dishing inwards) the chainline is perfect with a 113mm BB (SKF 600 series) which is 47.5mm.

You might also findthis interesting.Maybe this too.

And plenty more stuff here too.........



Thanks Andy. If I went with a shorter spindle then, in theory, I wouldn't need to turn the sprocket over but I'd have to look for something like a 103mm bb which are available. Of course I'd have to consider the chain ring clearance, any idea how tight this would be on the Hummingbird?



I couldn't get away with a shorter BB than 113mm, not an SKF anyway. As it is, there is only about 1mm clearance between the drive side bearing and the inner face of the crank, chainring clearance with a 32 tooth Uno is about (well exactly, as I've just measured it) 6.5mm.

Turn the sprocket to give you the better chainline is my suggestion.


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