chainring compatibility
 

Hi all,

I have a shimano slx m660 crank and it seems that the middle chainring is worn, my question is..Is it possible to put a deore middle chainring onto this crank. I would prefer a steel chainring which i think the deore one is, as i do alot of touring and thus appreciate durability. If this is possible what bcd will i need.

Thanks for your time guys.

Rich:)

The 600 crank's bcd is 130 mm and Deore, or any other MTB crank's, chainrings are not compatible with it.

Edit: Whoops, I read this as a "600" series crank implying an Ultegra level road crank. Not right. Sorry.

chain rings need to have the same BCD and the same number of bolts. most mountain stuff is 4 bolt, most road stuff is 5 bolt. ok, the SLX M660 is 104mm 4-bolt. Deore M590 is too. so yes, they'll fit.

next time spend more time on the big ring (with correspondingly larger sprockets in back), and ALL your gears (and chain) will last longer. keep your chain clean and lubed, and your chainrings and sprockets and chain will last longer, too.

Just curious- which chain ring set do you have? 22-32-44 or 26-36-48.
I'm assuming your largest ring is too big to be useful enough of the time, thus spend most your time on the middle. That's the same with me BTW.

Have you considered going to a smaller BIG ring that may be more useful?
I changed my 22-32-44's to 22-32-36/38 on my 2 bikes.
A bad knee, emphysema and old age prevent me from turning more gear inches. I use the 32 around town and shift to the big ring when I get the opportunity to "cruise".
Shifting isn't "pristine", but it shifts.

I deplore this trend towards 11T cassettes for everything. even with a 44T front, 11T is rather tall gear, and running rings and sprockets that small is guaranteed to wear stuff out faster. its a proven fact that using larger sprockets at the same ratio is more efficient... instead of a 32:12, running a 48:18 is smoother, quieter, and less friction. there's also less force in the chain for a given effort using the bigger ring, so the chain has less wear which leads to 'stretch' which leads to eating sprockets.


I have a 'hybrid' with a 48-38-28 front, and changed the back from an 11-32 to a 13-26 (8 speed), which provides more useful gears to me. I'm overweight and out of shape, and have 58 year old knees that ache if I mash on them, but I can't maintain a very good spin rate either.

Pierce- I agree a lot of bikes have some ridiculous gearing off the dealers floor. Apparently Shimano makes the "factories" a good deal deal on the 11-32 8 speed cassettes, since that seems to be what comes on so many mountain & hybrid type bikes.

However, you are making a lot of assumptions about what the OP is using, terrain & physical conditioning.

weell, I would /hope/ bad knee rules out actual mountain bi....... oh wait, I'm mixing up your response and the OP. k, I'll shaddup now :)

he /did/ say touring.

Thanks very much for your replies much appreciated.
It looks like ill be going for the deore rings after your comments, interesting what you say about the big(ger) chainring9s) as i always thought grinding out bigger gears lead to more wear, what with the chain running at increased angles. At the moment the rings are 22,32,44, but i may go up to the higher tooth possibilities if it would increase longevity.
When i say that i do touring i mean very long distances (last ride = Alaska to Argentina) and im getting ready for norway to new zealand via the Stans and tibet, as such i need things to last due to spending alot of my time on dirt roads in less developed countries where getting old of quality replacements is a full on drama ( i had to wait in bolivia for a tyre to come via a friend in the US for three weeks, three fu==ing weeks):). If anyone has more to say about the bigger toothed options i would be keen to hear opnions.
Thanks very much for your help, its really is appreciated.

Rich

what is your rear cassette gear range ?
when you're in that 32T middle gear that you said you spend so much time in, what range of those rear gears are you most typically using when not climbing hills ?

Hi,
My cassette is 11-34 and i usually use the 15, 17, 20 or 23 tooth sprockets when on the flats depending on the weight im carrying.

cheers

Rich

phew, with a 32T front, them are some low gears. to think I used to tour with a 52-42 front and 13-26 rear, often carrying 70 lbs or more of gear, food, water (yes, big hills were painful).

pierce, sounds like you remember those with fond memories, mind you i might move up to 36 just to get a feel of the pain you mention on the hills.

pierce

I tend to agree with you that the 11 tooth high gear is really too high for most people. With a 26" rear wheel, at a cadence of 70 rpm and a 52 tooth chain ring your speed would be aroung 25mph. Most regular riders cant maintain that level of effort. On my trike that does still have an 11 tooth high altho the new cassette has a 34 tooth low, and with the 48 tooth large chain ring I still have a gear inch over 110 for down hills. IMHO most bikes and trikes are geared too high for the ave rider. The way I feel is that 100 gear inches if great enough for most people. If you are on a steep hill, and you wind out with a bike that has a gear inch of 100, stop pedaling and just enjoy the ride.

these days, I'm pushing 60, and way out of shape, and my rides are maybe 10-15 miles around the bike trails in town on a flatbar hybrid 'city bike'. on the flats, I'm usually in somewhere between 68 and 86 gear-inches. my TOP gear is 99 inches and I need a tail wind to even think of getting up there. medium hills that are maybe a block long, I can usually keep in a 40 inch gear, but I have a 30 inch for the longer steep ones. of course, longer/steep to me means 1 mile of 8% grade... and yeah, totally concur re: downhills. if I'm going faster than I can push down a hill, I just relax and enjoy, like you say, but I'll probably keep the pedals moving just to keep the blood circulating :).

the bike I did my touring on in my misspent youth was a 1970s steelie '10 speed' (2x5) with campy NR gearing, 42:26 was about the lowest gearing it could cope with. I *wish* I'd had a wide range triple, then I might have done more touring as I really did like getting places on my own power. my longest tour was 9 or 10 days round trip up and back the northern California coast.

crossing whole continents, wow, that boggles my mind. I've never even been able to make the time and commit the effort to doing a trip like that on my motorcycle.

OH! re chain rings and compatibility (the original question, having drifted sideways quite a bit).... Shimano chain rings have an "A" and a "B" version, some are A, others are B, and I'll be darned if I know what distinguishes them.... I suspect it has something to do with ramping and pinning. You should use A rings with other A rings, and B rings with other B rings for the best shifting. the letter should be stamped on your existing rings.

hmmm. http://techdocs.shimano.com/media/te...9830728283.pdf doesn't indicate if a M660 is A or B or what. maybe this only applies to road bike rings?


anyways, if you're running in the middle of your cassette now, you're probably fine with the rings you have. if you wear out your cassette, you might consider replacing it with one that starts with a 13 instead of an 11, this will give you closer gear spacing in the mid ranges, and you might also run 44:20 instead of the 32:15 (its the same gear, but with the bigger ring there is less drive train loss and wear). ditto 44:24 instead of 32:17.