Banzai

Building a new rear wheel to replace that POS Alfine I had.

I'm finding numerous SLX hubs cheaper than even the Deore hubs. Is there a problem with that model? Looking at the exploded views, they look darn near identical.

Darth Lefty 

Just marketing, probably. SLX M7000 is out now but M610-615 Deore is still current.

Deore, Saint, and Zee are due for updates. Deore dates from 2013 and the other two 2012, all 10-speed era

Metaluna

Some of the Shimano hubs designed for 29'er bikes are supposed to have beefed up freehub bodies to withstand higher torque loads that 29'ers supposedly exert. I *think* the 675 is one of these, and is supposedly nearly identical to the earlier 629 and 665. This thread has some details:

XT vs SLX rear hubs- Mtbr.com


Also, when I was researching hubs for a new wheel build, I found that the 675 has the NDS flange a bit further inboard than many similar MTB hubs. This sacrifices a bit of lateral strength but results in less dish offset, for a bit more even spoke tension. I recently built a wheel with one and it seems to be a good hub so far after ~2000 miles or so.

jsdavis

Dunno about the SLX/LX series, but for Deore there was M525 and M529 hubs. The M529 had stronger freehub for 29er because at some point there was a Shimano cassette with 36 big gear on the cassette that did not play well with the M525 (and probably other hubs). It was stronger material or design to handle the greater torque from the larger gear, not because of the wheel. The 36 low was supposed to make 29er have the same or similar low as 26er.

Bike Gremlin

IMO Deore is as strong and as tough as Shimano makes. Higher end stuff is mostly just lighter.

HillRider

Very interesting. I wonder how most freehub bodies are coping with the 40T and 42T cogs now being used on 1x10 and 1x11 drivetrains.

Darth Lefty 

All the 42 cassettes have a spider that spreads out the load for the big cogs. My guess is that the next Deore will have a 1x10 option, but then it will be interesting to see how they handle that, because Deore/Tiagra has been the level where they stop doing spiders.

HillRider

I wasn't wondering about the cogs gouging the splines on the freehub body, I was wondering if the freehub pawls have to be strengthened to handle the extra torque.

Banzai

Examined both hubs. Weigh about the same in my hand. Hardware/nuts that secure the cone in place subtly different. One major difference though:

SLX: I counted 32 engagement points when rotating the freehub body.

Deore: I think I counted 16. Maybe 18.

Andy_K 

I've got a set of wheels that I built using SLX hubs. I chose them over XT hubs specifically for the reasons given in the MTBR thread linked above. They've been great.

Metaluna

Just to follow up my own post with some references, the FH-M675 does appear to use the same freehub as the 665 and 629, i.e. the 29'er one that's supposed to be stronger in some unspecified way (possibly splines, pawls, or both)

https://si.shimano.com/php/download.p...M675-3402A.pdf

The interchangeability chart lists the "Freewheel Body Unit" as having A-level interchangeability with both the FH-M629 and FH-M665.

Here's more information about the ISO torque standard that Shimano had to meet.

https://bikemagic.com/bike-component...ific-hubs.html
Shimano "29'er" 12-36 cassette « Singletrack Forum


P.S. I switched to a 675 for a wheel build after reading some horror stories about the freehubs on the XT 770/780-series, one of which I had originally purchased for the job. That's how I ended up going down the rabbit hole of freehub bodies and ending up on the M675.