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Singlespeed & Fixed Gear "I still feel that variable gears are only for people over forty-five. Isn't it better to triumph by the strength of your muscles than by the artifice of a derailer? We are getting soft...As for me, give me a fixed gear!"-- Henri Desgrange (31 January 1865 - 16 August 1940)

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Old 05-08-07, 09:08 AM   #1
red house
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Track Truvativ/Sram Omnium cranks with outboard bearings?

I saw these cranks on a bianchi track bike that was for sale in my LBS. They appear to be true track cranks w/ 144bcd but they also have outboard bearings like a road crank. I've read a lot of commentary on how track cranks will never incorporate outboard bearings because it would mess up the ''Q-factor'' -(still don't know wtf that means -? ).. but anyways, anybody heard of these? Any opinions?
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Old 05-08-07, 09:31 AM   #2
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All that talk is from clueless luddites. Unfortunately as far as I can tell they are only available on new pista concepts now.

Q factor is how far apart your feet are and is a sum of bb, crankset and the pedal. Campy has done a very good job of designing outboard bearing cranks with a low q-factor. There is no reason why others can't do it as well and for a discipline that values stiffness over most other qualities outboard(or at least oversized) bearings will eventually become standard. Less money goes into developing track parts though so the technology tends to lag behind a little.
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Old 05-08-07, 02:03 PM   #3
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Trek T1 also has a hollow-spline crank with outboard bearings. Not sure if it's Bontrager or Truvativ/Sram, though.
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Old 05-08-07, 02:23 PM   #4
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I was very interested in 2-piece/external bb technology for track bikes, but it's really slim pickings out there. I was unable to find any Omniums whatsoever, and save for random cranksets popping up on eBay, the only ones you could get right away are probably Truvativ Elita track cranksets in 172.5 or 175 from On-One http://www.on-one.co.uk/index.php?mo...ge&PAGE_id=107. For reference, that would probably be around $90-100 USD shipped.

I got my hands on some Truvativ Rouleurs, which are a little nicer, but 172.5, which most people think is too big. I'll just have to see. I do believe that all the Truvativs are 130BCD rather than 144. Good luck!

Edit: T1 (at least 2006) has Truvativ Elitas that are rebranded as Bonty's, or something. GXP and all are still there.
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Old 07-23-07, 07:39 PM   #5
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Q factors, even on Campy are much larger then they were 50 years ago. I haven't heard anyone claim that this is progress. Anybody no any more?

External BB cups are solution for a non-problem. They do cantilever the bearings outside of the BB, which puts unusual forces on the bearings. So... testing has shown that expensive ceramic bearings in external BB cups manage to return the rolling resistance down to that of a decent old-fashioned ball and cup internal BB.

That said, marketers have the public convinced of the need so I'm going to try to order some Omniums from my wholesaler. Assuming he follows through, I'll give you feedback on our experience.
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Old 07-23-07, 08:44 PM   #6
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SO much of that is true...Track cranks have defiantly stuck with square taper for ages. The larger spindles of the 90's left bearing life in the dirt. Square taper bearings last a really long time, to address the shoter bearing life without changing the BB size companies went to outboard bearings. While this addressed the bearing life for larger spindled cranksets it became even more insipid for track and vintage bikes which, have for years, stuck with good old square tapers. My point...it's a solution to a problem that was really never a problem for roadies...it was the MTB world that kept snapping spindles not roadies/trackies.
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Old 07-23-07, 09:51 PM   #7
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Originally Posted by dutret View Post
All that talk is from clueless luddites. Unfortunately as far as I can tell they are only available on new pista concepts now.

QBP stocks and sells 'em.
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Old 07-24-07, 02:20 AM   #8
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omnium

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QBP stocks and sells 'em.
Yep!

http://aebike.com/page.cfm?PageID=30...d=12145&type=T
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Old 07-24-07, 02:26 AM   #9
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The Q-Factor has also been increasing due tot he increase in the number of gears. You have to make cranksets with a chainline to accommodate 10 speeds now. hence why 130mm with a stupid amount of dish is the standard instead of 126mm with reasonable dish.
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Old 07-24-07, 06:19 AM   #10
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The Q-Factor has also been increasing due tot he increase in the number of gears. You have to make cranksets with a chainline to accommodate 10 speeds now. hence why 130mm with a stupid amount of dish is the standard instead of 126mm with reasonable dish.
How much has chainline actually changed on a road double though? The rear hasn't since the introduction of 8speed. But of course none of this matters since chainline is only linked to qfactor if you are stuck with a given crankset.
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Old 07-24-07, 06:57 AM   #11
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Quote:
Originally Posted by chase. View Post
Trek T1 also has a hollow-spline crank with outboard bearings. Not sure if it's Bontrager or Truvativ/Sram, though.
One and the same. Truvativ/SRAM fabricates the cranks for Bontrager.
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