Crank-arm fit problem
11-23-11, 01:29 PM
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Crank-arm fit problem
I'm building up a Cyclocross bike using a frame that has the tire clearance of a MTB.
The build sheet states that 48 & 38 or smaller chainrings fit.
My problem isn't the chainrings, It's the crank-arms.
I was going to install a 44t single chainring in the outer position of a Sram 130bcd GXP road crankset. The crank-arms won't clear the chainstays;
I have not even tightened the non-drive side arm and the arms won’t clear the chainstays. I know that using this crank is impossible. I’ve given up on using any road crankset, and will go to a 10-speed MTB triple.
My question is: will a Sram GXP X7 MTB crank fit? Is the problem the fixed axle that comes with a GXP style crank? Should I use an crank with a 118mm old school BB instead? These are (mostly) not designed for 10-speed chains.
The build sheet states that 48 & 38 or smaller chainrings fit.
My problem isn't the chainrings, It's the crank-arms.
I was going to install a 44t single chainring in the outer position of a Sram 130bcd GXP road crankset. The crank-arms won't clear the chainstays;
I have not even tightened the non-drive side arm and the arms won’t clear the chainstays. I know that using this crank is impossible. I’ve given up on using any road crankset, and will go to a 10-speed MTB triple.
My question is: will a Sram GXP X7 MTB crank fit? Is the problem the fixed axle that comes with a GXP style crank? Should I use an crank with a 118mm old school BB instead? These are (mostly) not designed for 10-speed chains.
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When I ride my bike I feel free and happy and strong. I'm liberated from the usual nonsense of day to day life. Solid, dependable, silent, my bike is my horse, my fighter jet, my island, my friend. Together we will conquer that hill and thereafter the world.
When I ride my bike I feel free and happy and strong. I'm liberated from the usual nonsense of day to day life. Solid, dependable, silent, my bike is my horse, my fighter jet, my island, my friend. Together we will conquer that hill and thereafter the world.
Last edited by Barrettscv; 11-23-11 at 01:51 PM.
11-23-11, 01:47 PM
#2
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If I were in your shoes, I'd stay with the cranks of my choice, and switch BBs or just the spindle to one long enough to make the system work. It rpbably wpouldn't take more than a few millimeters to get the job done, especially since the right side seems to clear already.
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11-23-11, 01:54 PM
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If I were in your shoes, I'd stay with the cranks of my choice, and switch BBs or just the spindle to one long enough to make the system work. It rpbably wpouldn't take more than a few millimeters to get the job done, especially since the right side seems to clear already.
I'm concerned that the MTB Sram GXP cranks will also not clear. Or are these designed with wider crank arm spacing?
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When I ride my bike I feel free and happy and strong. I'm liberated from the usual nonsense of day to day life. Solid, dependable, silent, my bike is my horse, my fighter jet, my island, my friend. Together we will conquer that hill and thereafter the world.
When I ride my bike I feel free and happy and strong. I'm liberated from the usual nonsense of day to day life. Solid, dependable, silent, my bike is my horse, my fighter jet, my island, my friend. Together we will conquer that hill and thereafter the world.
11-23-11, 02:14 PM
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Most mtn cranks use wider BB spacing, or at least have arms that are wider at the ends. Crank design involves an assumption about the chainstay width of the bike they're fitted to. Road cranks assume narrower tires, hence narrower stays, while mtn crank crank design assumes that the stays are wider to accommodate wide mtn tires.
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An ounce of diagnosis is worth a pound of cure.
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“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
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FB
Chain-L site
An ounce of diagnosis is worth a pound of cure.
Just because I'm tired of arguing, doesn't mean you're right.
“One accurate measurement is worth a thousand expert opinions” - Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance.
11-23-11, 02:57 PM
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Yes, Thats what I would expect. I need about 5 to 10mm wider spacing between the arms to clear. I'll do a little more research and order the MTB crankset.
Thanks for the opinion & Happy Thanksgiving.
Edit, I found the data I needed on page 20 of this doc: https://www.sram.com/sites/default/fi..._-_rev_c_0.pdf . I have 130mm of chainstay structure (see picture above) between where the arms need to pass. The Sram X7 Triple gives me 141mm. I'll be ordering these.
Thanks for the opinion & Happy Thanksgiving.
Edit, I found the data I needed on page 20 of this doc: https://www.sram.com/sites/default/fi..._-_rev_c_0.pdf . I have 130mm of chainstay structure (see picture above) between where the arms need to pass. The Sram X7 Triple gives me 141mm. I'll be ordering these.
__________________
When I ride my bike I feel free and happy and strong. I'm liberated from the usual nonsense of day to day life. Solid, dependable, silent, my bike is my horse, my fighter jet, my island, my friend. Together we will conquer that hill and thereafter the world.
When I ride my bike I feel free and happy and strong. I'm liberated from the usual nonsense of day to day life. Solid, dependable, silent, my bike is my horse, my fighter jet, my island, my friend. Together we will conquer that hill and thereafter the world.
Last edited by Barrettscv; 11-25-11 at 11:28 AM.
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