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Discussion Starter · #1 ·
I have a road bike, a Renovo Elwood, which is built up with a Gates belt and Alfine-11 hub. To get the gearing I want, I need to use a 4-bolt 104 BCD spider, but I would like a low Q-factor road crank. The 68 mm outboard bottom bracket takes a 24 mm spindle or SRAM GXP, and I want 175 mm arms in black if possible. Any ideas?

Best,
David
 

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Discussion Starter · #3 ·
Thanks for the suggestion. But that crank has about the same Q-factor as the Truvativ Stylo I'm using now: about 175 mm. A road crank like the SRAM S300 has about a 145 mm Q-factor, a substantial difference, and if I can't get close to that, then it isn't worth the effort and expense to swap.

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David
 

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The SRAM XX1 crankset is available in a 156mm Q factor version with a GXP BB spindle.

It doesn't come with a 104 BCD spider on it (I believe it has an assymetrical 76mm BCD spider). The spider is removable though and you could install a 104BCD spider from an X0 or X9 cranks. Or, I'd bet that Gates may make chainrings (belt wheels?) to fit the XX1 spider as is.
 

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You'll need to go to a square taper BB. There are no <145 qfactor cranks with 24mm spindles. Check out White Industries. They use a trick spider that allows multiple chainring sizes and they're square taper so you can go as narrow as your chainstays allow. Middleburn also has some options that might work for you but their official road cranks are MIA.

The other option is to go on Ebay or scour the LBS's for old square taper mountain bike cranks that you could go double with. I have a set of Race Face square taper 94 bcds that are bad ass.
 

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Check out White Industries.
It would be hard to get a belt drive ring on a White Ind cranks...they don't really have a spider perse...the ring is the spider. In the case of the road cranks, the big ring is the spider.

You could have someone make you a 104 bcd spider for the White Ind spline pattern though. Probably a one-off and expensive.

I don't think the Gates Belt Drive rings come in 94mm BCD either...not sure about that though.
 

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To the OP:

What tooth count are you going for on the chainring? A quick perusal shows that the only tooth count from Gates that is limited to the 104BCD is the 39tooth. It might be easier to achieve all you're looking for by going slightly bigger on the chainring as well as the cog on the Alfine. Assuming there is a belt length that works for your cog/chainring/chainstay length combo.
 

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Discussion Starter · #8 ·
To the OP:

What tooth count are you going for on the chainring? A quick perusal shows that the only tooth count from Gates that is limited to the 104BCD is the 39tooth.
I have a 42-tooth front and 24-tooth rear. Unfortunately, the bike has a Philcentric bottom bracket that only gives a little more than +/- 3 mm, and 440 mm chainstay length. The only combination of existing Gates components that allows are 42/24 with a 113-tooth belt, or 46/24 with a 115-tooth belt. I had hoped to be able to use a 46/26, but it would require a 116-tooth belt, which they don't make. I had actually purchased the parts, including an SRAM S-300 crank that does have a GXP spindle and 144 mm Q-factor, but when we went to install it we realized that it couldn't be tensioned. I will check out the XX1 option. Thanks for the help.

Best,
David
 

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Discussion Starter · #11 ·
To answer my own question, in case it helps anybody else: the SRAM S900 cranks are 145 mm Q-factor. The spider is indeed removable. The spiders that North Shore Billet makes for the Truvativ X0 cranks have the same spline interface and base curve, and fit perfectly. I got the 1x10 one, which gives me exactly the chainline I need, but Chris at North Shore Billet said they had a customer who used the 2x10 one on an S900 crank to get a double setup on a touring bike with smaller chainrings than the stock 130 mm BCD would allow.

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David
 

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David, thanks. I don't understand all about your config, I' m french, but the important thing is that I could fix a 104BCD ring on road cranks! Maybe there are other possibilities than S900 and NSB?
Do you know if every S900 cranks have the removable spider, considering the year of fabrication?
My plan is to put a single 34t O'Symetric ring on my 10spd cyclo-cross bike (same measures as a road bike), so only in 104BCD, and I don't know about chainline details and other stuff, but I think it will be close to perfection compared to a single MTB crankset! What do you think?
 

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Discussion Starter · #13 ·
All the S900 cranks have the removable spider, but the ones manufactured before 2012 have arms whose base is a different shape. It looks like the spiders that NSB made for the X9 cranks would fit, but I have not tried it. Having now ridden the combination for about 1K kilometers, I am very pleased with the way my setup worked out, and can highly recommend it. It is very easy to feel the difference between the 175 mm Q-factor of mountain bike cranks and the 145 mm Q-factor of the S900, especially when out of the saddle.

Best,
David

Best,
David
 

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Thanks, it looks like a vital info! (for the "before 2012" no compatibility)
I've just asked many confirmations of that to dealers.. One response, for a french store: uncompatible anyway 'cause cranks are carbon and NSB spider is metal! But NSB just told me they had several customers that did like you (XO or X9 spider).. So before buying I wait for more answers to be sure.

For the Q-factors, I constantly switch from MTB to TT road (triathlons cross or road) and 30mm QF + larger pedals on MTB, not cool! But can't do anything for the MTB, my heels come already close to the rear tubes!
 

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Discussion Starter · #15 ·
One response, for a french store: uncompatible anyway 'cause cranks are carbon and NSB spider is metal!
I'd avoid that dealer. The S900 crank has carbon arms and a removable aluminum spider that is attached with three screws and a spline. That is what allows the NSB spider to be used: it has the same spline pattern as the stock spider.

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David
 

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I insist a lil', I have trouble finding infos to confirm that the S900 cranks are for sure compatible with the NSB spider (mono for XO or X9) only if the S900 is manufactured 2012 or later (cause of interface change). I've eMailed many shops saling those, to know wich year are the cranks from, no respond.
Thanks
 

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Discussion Starter · #17 ·
They are fairly easy to tell apart. The older one, which you can see here, has a rounded end to its arms. The newer one, here, has a squared-off base to its arms. The former might work with the X9 spider, the latter definitely does work with the X0 one.

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David
 

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Thanks again, David. Your last post completely re-assured me, plus a vendor confirmed his S950 was 2013, so I've bought the combo. I'll write again when it's installed
You're the best in deed, David :thumbsup:
mV
 

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I still need help!!
(The 1x10 XO NSB spider and 2013 S950 cranks: compatible, thanks again)
But now I' m in trouble with the S950 instal:
the cranks won't fit my Shimano GXP BB, cause they are flat, I mean they totally come in contact with the all BB, not only the rolling surface, but the metal circle too. And it's the same with both the original and the NSB spider.
Do I have to put a "spacer" (not included in the box)? or must I buy a Sram GXP BB (I don't see how it will be different, Sram GXP BBs look all flat too)?
Thanks
mV
 
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