XT Cranks - Boost -...
 

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[Closed] XT Cranks - Boost - 165mm

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Posts: 1967
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https://bike.shimano.com/en-EU/product/component/deore-xt-m8100.html

Which ones am I after? My current 175mm SLX cranks get pedal strikes, I’d like to try a shorter crank but am a bit confused by shimanos numbering.

Thanks

 
Posted : 07/02/2021 8:24 pm
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You want the ones with the B suffix

FC-M8120-B2

 
Posted : 07/02/2021 8:33 pm
Posts: 1967
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Thanks very much scotroutes.

 
Posted : 07/02/2021 8:54 pm
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Not necessarily.

Check the back of your crank arm towards the pedal thread and you’ll see the model number.

7100 work with boost and non boost (52mm chainline)
7120 are boost only (55mm chainline)

I’d buy the crankset with the same chainline.

XT use the same 00 or 20 at the end of the model number so if you have 7100 cranks buy 8100, if you have 7120 buy 8120.

 
Posted : 07/02/2021 9:49 pm
 poah
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try not pedal over rocks. its only 10mm difference.

SLX crank arms are the same weight but cheaper.

 
Posted : 07/02/2021 10:03 pm
Posts: 1967
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Okay, thanks I’ll have a look and buy the same. I’m sure the codes are useful on their stock management system.

I would try and not pedal going up hill but I’d be walking 🙂

 
Posted : 07/02/2021 10:17 pm
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10mm is night and day when pedalling over rocks. The difference between a very solid whack on a rock versus a glance or compelte miss. Made a huge difference for me when I made the same change. Not pedalling is not an option, especially when riding up rock gardens.

 
Posted : 08/02/2021 7:58 am
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Yes, it is surprising how much difference 10mm makes. Pedal strikes went from constant to almost never on the same bike for me.

Didn’t notice any other real difference though. Like torque, or cadence etc:

 
Posted : 08/02/2021 9:06 am
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Pretty sure Shimano don't make 12 speed non-boost cranks. As above, slx is great value compared to xt as the weight difference is almost nothing. I think merlin have them at a decent price.

 
Posted : 08/02/2021 9:13 am
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+1 if the chainring clears the chainstay then a 52mm chainline is superior to a boost chainline, in my experience. Some frames are very tight on clearance though, particularly BB92/pressfit designs, so be aware of that.

 
Posted : 08/02/2021 10:07 am
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Shimanos new 12sp normal is only 1mm closer to the chainstays than the 10/11sp boost, I'm running XT 12sp with 52mm chainline on 148 rear, don't think I'd want 55mm. Seems like shimano are pushing the q factor as the important bit and trying to dump the boost tag cos its confusing if you're mixing old with new parts.

 
Posted : 08/02/2021 4:14 pm

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