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Scooterist
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Discussion Starter · #3 · (Edited)
After looking at your 2 bikes and the fact that I will be doing some "serious" racing in 2009, I was wondering if I should buy an Air9 and transfer the parts over from my Sir9.

This way I could pick up cheap parts during the year and build a dedicated singlespeed as a bit of a project.

The question about bb shell size, has to do with my economy because I dont have enough money for a new crank and would like to use my Tune bigfoot with 29-42 rings and my tune 113mm axel 68mm width titanium bottom bracket.

Obviously, if I had the cash I would go for a jet...

Niner are putting my marriage at risk! I hate those guys!

So, does the 2009 Air have a 68 or 73bb!
 

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While we are on the Topic, I have a Phil Wood Square Taper 68mm./113 for a WI ENO Crank Set which I was hoping to put on my new '09 Air9. Any chance of this working?
PF
 

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hi,
i have a question.

I planing building up my Air 9 XL and i want to use the smallest possible q-factor.

The new Hollowtec XTR Cranks(FC-M970) have a q-factor of 170mm, but the older FC-M952, FC-M950 with the old and heavy octalink bb have a q-factor of 163mm. Not mutch better but ill try it.

What octalink bb (BB-M952) should i buy ? the 112,5 mm or 116mm?


I will drive 24-32-48.

anyone has an idea plz?
 

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Nompton, OK
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141 Posts
So is the "New and Improved" 73mm bottom bracket that everyone is going to really going to be that much of an improvement. I mean we are talking 5mm here, come on! It seems like if all else on the bike tubing stays the same (tube diameter that welds to the BB etc) than that would only move the cranks further out, increasing their leverage which contributes to flex of the BB where it is connected to the frame due to the twisting forces when you crank. But thats my arm chair call, my job is not designing bike frames haha
 

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to above poster. This doesn't move the cranks further out! They moved to 73mm BB so that the chainstays could be a hair further apart to aid in tire clearance and it adds more weld area. Most newer (outboard bearing) cranks, XT, XTR, etc.. use spacers on the BB bearing cups with a 68mm BB, so on a 73mm you just take out the spacers. This does not move the cranks out further.

This is a move for the better for 99% of people that use outboard bearing cranks, for the few people above that use square taper, isis, octolink, they might be out of luck.
 

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Vortechcoupe said:
to above poster. This doesn't move the cranks further out! They moved to 73mm BB so that the chainstays could be a hair further apart to aid in tire clearance and it adds more weld area. Most newer (outboard bearing) cranks, XT, XTR, etc.. use spacers on the BB bearing cups with a 68mm BB, so on a 73mm you just take out the spacers. This does not move the cranks out further.

This is a move for the better for 99% of people that use outboard bearing cranks, for the few people above that use square taper, isis, octolink, they might be out of luck.
I had a TA Axix square taper BB on my Jet.
It could be used with a 73 mm BB shell by adding two 2.5 mm spacers in the cups.
I guess this would be possible with other Square tapers also.
 

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Some handy work on an XT could make the Q-factor lower and the chainline better:
-Use no spacers at all, thread the cups without them in the frame.
-Make (Dremel) the grooves on the axle 2.5 mm longer and shorten axle 2.5mm.
-Grind 2.5 mm away from the left crank.
-Get rid of the granny bosses, you could leave them but a chain drop might damage the frame...
-crankset is only usable now on middle and/or outer position with a better chainline (i.e 1X9 setup).

I have an old XT on my 'road mtb' and plan on using this crankset for the alteration...
 
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