52 or 55mm chainlin...
 

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52 or 55mm chainline? SC nomad

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Hi folks.

I'm putting some shorter cranks on my nomad 5, but not sure what cranks to get. 52 or 55mm chainline? Both are apparently compatible, but will one work better than the other?

The cranks in question are Shimano xt, with Shimano 11peed drivetrain which I probably won't be changing any time soon.

Edit: frame is 148 boost

TIA!


 
Posted : 19/04/2023 8:46 pm
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52mm every time as long as it gives you chainring clearance on the frame.

52mm works much better in the lower gears offering better chainline.

I think Q factor increases by 6mm on 8120's compared to 8100's if that bothers you.


 
Posted : 19/04/2023 8:50 pm
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I'm on 11speed 148 boost and 55mm chainline and it's absolutely fine


 
Posted : 19/04/2023 8:52 pm
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To add to my confusion, I think my rear hub is a 142mm hope with boost adapters. I'm guessing the cassette is spaced a bit further out on the boost hub? So I would be best getting the 52mm chainline cranks?


 
Posted : 19/04/2023 9:21 pm
 DanW
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Echo qwerty

52mm for me too, provided you have chainring, crank and heel clearance on the frame.

52mm is already lined up far closer to the smallest sprockets so I wouldn't want to be pushing the chainline any more to the drive side. People say they notice no difference but ride a SS with perfect chainline then go back to 55mm and the largest sprockets and tell me it is smooth.

The plus 6-8mm Q-Factor on cranks is a definite no go for me too with sensitive knees. I couldn't adjust cleats/ pedal axles/ etc to get comfortable with even the lowest Q-Factor 55mm chainline cranks. XT cranks are already wide as it is. Maybe you won't notice.

If your current setup has the hub spaced correctly for Boost width hub then choosing 52 or 55mm chainline should work. Bikes like a Trek Top Fuel or Scott Spark have 148 Boost rear ends and 55mm chainline cranks


 
Posted : 20/04/2023 9:18 am
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Thanks chaps, I've gone with the 52 🙂


 
Posted : 20/04/2023 11:55 am
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If the rear hub is 142 running hopes boost conversion then 52mm will work like a 55mm chainline due to the cassette running 3mm inboard, a 55mm would've been like 58mm and awful.


 
Posted : 21/04/2023 9:13 pm
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Sorry to hijack. I am also on 52mm and happy with it on 12 speed 148mm. However, if there is enough frame clearance for the ring, I wonder if swapping the 1.5mm spacer to the ND side and therefore go down to 50.5 wouldn't be even better with an even greater bias towards the largest cogs. I rarely use the smallest cog off road and shifting to or away from it seems far less chainline sensitive anyway. Good idea or not ? Unequal q factor might be an issue I guess.


 
Posted : 21/04/2023 10:08 pm

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