[Closed] SLX M665 v M660

I read that the double-specific SLX crank might have a different chain line and a burlier spider than the triple, as being double-specific it was designed and made to be used more like a cheaper Saint than regular SLX/XT, but there is nothing wrong with triple SLX that would prevent you running it with double and bash*.

Remove big ring, replace with bash, and fit something like a blackspire Stinger. No need to change 'middle' ring unless you want a different gear range but Ive kept 22/32. And obviously set the front mech stop screw. You might be able to drop the front mech a few mil to get it to run closer to the bash (which will be smaller diameter than the big ring) and it will then serve a little like an upper chain guide.

CRC had stingers cheap last time I looked.

*This is the marketing blurb describing the differences

The SLX group includes two types of Hollowtech II cranksets for different types of riding styles. The first is an all-mountain compact drive crankset with a double chainring 36/22T combination, designed to give more range over the traditional 32/22T setup. It has a reinforced construction with increased axle and spider strength to meet the rigors of all-mountain riding. This crankset includes a “honeycomb” bash guard, a steel pedal thread insert and is claimed to be 100% stronger than the XT crankset.

In addition to the double/bash guard chainset, there will also be a triple SLX crankset for cross-country riding where a larger gear range is required. Using technology from the current generation of XT and XTR chainsets the triple will come with a composite/steel middle chainring that doubles durability over the standard middle ring and improves the shifting performance. It will be available in a chainring combination of 44/32/22T.

For info the SLX bashguard does NOT fit the triple spider.

oddly shimano's doesnt (I think there are issues with Saint bashs too?) but a few other manufacturers do- I have a blackspire C4 and a raceface alloy bash on shimano cranks.

I read that the double-specific SLX crank might have a different chain line

Nope - the two rings on the M665 are in exactly the same place as the middle and inner on the M660.

You might be able to drop the front mech a few mil to get it to run closer to the bash (which will be smaller diameter than the big ring) and it will then serve a little like an upper chain guide.

...but will also cause chain rub in the extremes of the cassette, because your chain is now running in a narrower part of your front mech. And in fact, if you replaced the 32 with a 36, for best shifting & least chain rub, you would [i]raise[/i] the FD a few mm, as the 36T ring is larger diameter than the 32T it replaced, and therefore the chain is running higher in the cage. In fact, if you're staying double, you may want to consider the double specific FD - M665/667, as its smaller, looks much neater, and contains the chain better.

For info the SLX bashguard does NOT fit the triple spider.

True - the spider on the M665 is different to the one on the M660. Here's what I've found thru trial and error...
- M665 bash doesn't fit M660.
- M660 32T middle doesn't fit M665.
- M665 middle ring fits M660 but doesn't seat properly on spider 'lugs'.
- Any third party 'standard 104BCD bash' will fit the M665 but won't sit on the spider lugs, so when you bash it, the chainring bolt surrounds take all the force instead of the spider. If it's ally probably not a problem, but the plastic ones soon crack around the chainring bolts if you bash them regularly.
- The 22T granny is identical between M660 and M665.

the difference between the M665 middle ring and M660 middle ring will be something to do with shifting pins

M665 middle is 36T, all alloy, and yes, it has very different ramps/pins/tooth phase to help jump the 14T gap between 36 and 22. The M660 middle is 32T and steel/composite.

Remove big ring, replace with bash, and fit something like a blackspire Stinger.

That's what I did, no problems.

For info the SLX bashguard does NOT fit the triple spider.

You can bodge it by filing it down, but TBH the Shimano SLX bash is big and ugly. The Hope ones are sleek and light and fit without messing around.

As I'm changing a M660 it looks as if this will give me more options.
I will ditch the outer ring for a Hope Bash, depending on which middle ring I settle on (32,34,36) and get a Blackspire Stinger. I'll try the existing FD but if I get any issues I'll swap for a double specific.
Thanks for the advice everyone.

faint - Member
As I'm changing a M660 it looks as if this will give me more options.
I will ditch the outer ring for a Hope Bash, depending on which middle ring I settle on (32,34,36) and get a Blackspire Stinger. I'll try the existing FD but if I get any issues I'll swap for a double specific.
Thanks for the advice everyone.

I changed a M660, and after a bit of trial and error ended up with a Deore 36t, heavier but fits the lugs better than a M665 36t, an E thirteen turbocharger bash. I used a double specific topswing F. mech, because, as the post above says, it looks neater and it can be set to contain the chain properly, and a Deda Dog Fang to prevent shipping the chain inwards. I then used an old rear reflector bracket to make a bionicon-style chainstay mounted chain tensioner. Thus six quid's worth of chain retention goodies, even better than a 15 quid Blackspire.

perth, obviously dropping the mech was on the basis of keeping the 32! Done this on both my bikes with no problems (the RF bash is labelled as taking up to 34T but is tiny, only just bigger than the 32T with a chain seated, compared to the blackspire which is significantly larger).