[Closed] Need a new SLX double chainset - can anyone clarify my options?

built my new bike last week set it up 10 speed with all new 10 speed slx parts except the crankset which is the 9 speed slx double and bash from my last build( although ive removed the bash) works flawlessly, so yes you can:)

[i]will it work perfectly well with my new 10-speed XT[/i]

Yes

Your options are:-

1. Buy the new 10sp SLX double cranks - M675. Comes in 24/38, 26/38 or 28/40 combinations. However, there's no place to fit a bash so if you really must have one then you either need a BB/frame mounted one or the Blackspire Defender which is specially made for Shimano doubles.

2. Buy the new 10sp SLX triple cranks - M670. Discard the big ring and fit any 104 BCD bash in its place. But then you're left with 24/32 or 26/36 rings, so you'll need to replace one of the rings to get a decent spread of gears.

3. Buy an old 9sp SLX double - M665. This has 22/36 rings and a bash, and will work perfectly well with an otherwise 10sp drive train (as others have said above, and I'm also running one in just this way). I would suggest also getting the M665/7 double FD to go with it though, as this will match better than the new M675 FD.

Very interested in this as was looking to 'upgrade' to 10 speed with minimum spend and run SLX '9 speed' twin and bash on both trail bikes.

perthmtb - do you still use a 10 spd front shifter with the '9 speed' front mechs quoted ?

theraggyone - similar question, did you use a 10 spd front shifter AND 10 speed front mech ??

Cheers.

perthmtb - do you still use a 10 spd front shifter with the '9 speed' front mechs quoted ?

Yes, I use the 10sp M670 shifters cos I like front & rear shifter to match, and the I-spec function so I can mate them to my SLX brakes.

Shimano 9sp and 10sp front shifters both pull 11mm of cable on the first shift and 7mm on the second, so they are interchangeable. Only thing you gotta watch out for is that the 10sp double FD (M675) uses the second shift (7mm pull) whereas the 9sp double FD (M665) uses the first shift (11mm pull). If you set the mode selector switch on the 10sp shifter to 2x it forces you to use the second shift, so if using a 10sp shifter with the 9sp FD you leave the mode selector switch in 3x and use the first shift. Sounds complicated, but it isn't really 😀

Cheers all - very, very helpful.

Perthmtb - what's this you mentioned "I would suggest also getting the M665/7 double FD to go with it though, as this will match better than the new M675 FD"

Thanks again.

im using a 10 speed sram x7 front mech( needed a low direct mount with clearance and sram gave the better option) with a 9 speed slx shifter and 10 speed slx clutch rear mech with a 10 speed slx shifter

Perthmtb - what's this you mentioned "I would suggest also getting the M665/7 double FD to go with it though, as this will match better than the new M675 FD"

Well its not a big deal, any FD will work Ok with it - 9sp/10sp, double/triple, Shimano/SRAM. Front shifting isn't rocket science, you're basically just yanking the chain off one chainwheel and sending it in the general direction of the other 😀

However, the M665/7 FD was specifically designed to match the M665 cranks, so has a slight advantage in a couple of areas.

1. The curve of the outer plate exactly matches the curve of the bash, whereas the M675 has to accommodate up to a 40T outer ring, so has a different curve on it. Mostly cosmetic, but it means the M665 FD looks better with the M665 bash.

2. The M665 FD is designed to mount a little higher up the seat tube than the M675 as it has to clear the bash, but still have clearance for the chain when its in the 22 ring. The M675 FD when mounted as designed can foul a bash. You can of course lift it up a few mm to clear the bash, but then the chain can rub on the bottom of the cage when in the 22 ring.

Cheers. I already got a 10-speed SLX 'dyna system' front mech to stick on, so I'm hoping that will be ok. Fingers crossed!

Cheers. I already got a 10-speed SLX 'dyna system' front mech to stick on, so I'm hoping that will be ok. Fingers crossed!

Yeah, it'll be fine. Just be aware you can't mount it 1/2mm above the big ring teeth like the instructions say, it needs to be a little higher than that to clear the bash. Only issue this might cause is a little chain rub on the bottom of the FD cage when in 22 front and the smaller sprockets in the rear. If you don't intend using these combinations much, and/or its a FS bike so has some rear suspension sag, then it shouldn't be a problem while actually riding 😀

Cool. Until someone just told me I can't run a 36 on the front of the bike - it's a Five. So, back to square one I guess. Anyway, thanks for your help perth - still been very useful and I appreciate it.

Until someone just told me I can't run a 36 on the front of the bike - it's a Five

Don't know about the Five. Is that a chainstay/suspension clearance issue when running a 36T ring in the 'middle' position? If so, is it possible to space the BB out a little on the driveside to get enough clearance?

Think you might be right. Just attempting to find out exactly that, once and for all. Someone else has said 'yes'. It's a minefield out there!

Sorry, can't be much help with the specifics of the Five, as I've no direct experience of them. I can tell you the difference in radius between a standard 32T middle ring and a 36T is only 8mm. So hopefully you'll be able to find a way of spacing the BB out a little to give you enough clearance. Will set the chainline off a bit, but just have to avoid using big/big if that becomes an issue.

Cheers again, perth. Just put a thread on here and dropped Orange a line. Will see what the replies say.

Ok, good luck 😀

Cheers perthmtb - very good information and your set up would suit me as I also like my shifters to match and fancy the ispec as it's compatible with my Deore brakes !!!

And thank you to raggyone as you also answered with even more proven options 🙂