Help with lower gears
03-15-20, 04:26 PM
#1
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Help with lower gears
I'm thinking about finding a complete bike and modifying it to get lower gearing. The goal is to be around 20gi. Thinking about this bike below:
https://www.jamisbikes.com/usa/renegades2.html
Can I swap the GRX crankset for a sram nx? Iwould have to change the BB too, but from what I've seen the lowest chainring for a GRX is 38t. The nx has a direct mount chainring, so after shortening the chain, I should be able to run almost any chainring.
Dave
https://www.jamisbikes.com/usa/renegades2.html
Can I swap the GRX crankset for a sram nx? Iwould have to change the BB too, but from what I've seen the lowest chainring for a GRX is 38t. The nx has a direct mount chainring, so after shortening the chain, I should be able to run almost any chainring.
Dave
Last edited by bonsai171; 03-15-20 at 04:33 PM.
03-15-20, 11:36 PM
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Assuming 1x without front derailleur, sure a MTB crank/BB can work on a road frame, but the chainline may not be optimal.
03-16-20, 03:36 AM
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03-16-20, 04:03 AM
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Traditionally road BBs were 68mm wide and MTB BBs were 73mm wide. Correspondingly, MTB cranks will have a longer slightly spindle and slightly outward chainline. No exrience with your exact planned setup but just throwing it out there that it could potentially be an issue.
03-16-20, 04:10 AM
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GRX 1x chainline is 49.7mm and the NX is listed as both 49 and 52mm. I would assume that the 52 is the boost chainline, so the standard chainline is actually slightly less than the GRX by an insignificant amount.
03-16-20, 03:59 PM
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03-16-20, 08:10 PM
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The S3 Renegade has a 30-36 bottom gear right from the factory which gets you pretty close to your GI goal, but you have to go to 2x for that. The S3 has about the lowest stock gearing of any gravel bike I am aware of...
03-17-20, 11:11 AM
#8
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Another consideration is that MTB cranksets have a highter Q factor to allow for a wider tire, personally I prefer this others not so much.
03-17-20, 03:27 PM
#9
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The difference in q factor between my mtb and road bike is noticable. I prefer the road bike q factor, but it's not a deal-breaker.
03-17-20, 10:30 PM
#10
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Could just save get the S3 version that comes with a 2x 46/30 crank or install a 46/30 crank and FD on the S2 version. Sounds like the S2 has a front shifter already
"Shimano GRX ST-RX600 Dual Control STI, 22-speed."
"Shimano GRX ST-RX600 Dual Control STI, 22-speed."
