NeilGunton

I'm in the process of swapping out parts on a 2009 Rocky Mountain Sherpa 10 which I'm purchasing from my local bike shop. One of the items that is being changed is the crankset/bottom bracket, to a mountain range (24/34/44). I'm probably going for either the Shimano SLX or XT. The XT is over $100 more than the SLX. I'm wondering if anybody here has knowledge of whether the current XT is functionally better, more durable etc than the SLX for the touring application. I know it's a little lighter, but I'm wondering about stuff like, oh I dunno, different materials that will be more robust or better seals etc. The bottom bracket is something that I don't really like to have to mess with in the field, so I'd like to get a good one, but if SLX is very similar and the differences are mainly branding and a few grammes then maybe XT is not worth the extra bucks. My main desire is durability, not weight.

Any thoughts?

Thanks!

Neil

kayakdiver

Just go with the SLX. You will never know the difference.

lancele

Someone please correct me if I'm out of date, but the XT probably saves some weight from having all alloy chain rings, while the SLX's small chain ring is steel and the middle chain ring is partial steel. Also, the XT should have alloy chain ring bolts, and I'm assuming the SLX has steel chain ring bolts. The XT also has more crank arms lengths available.

A long time ago, the XT crank arms were cold forged (good), but not sure about today.

You probably won't notice the difference.

You can get either the SLX triple or double (the double comes with a bashguard) from Wiggle for $135, while the XT crank set is $191. This should qualify for free shipping to the USA.

https://www.wiggle.co.uk/p/cycle/7/Sh...et/5360031021/

If you're interested in a Brooks B17 saddle, it's about $77 shipped. Prices change based on the exchange rate.

https://www.wiggle.co.uk/p/cycle/7/Sh...et/5360031021/

-Lance

NeilGunton

According to Shimano's website, the FC-M770 XT has aluminum outer chainring, steel + composite middle chainring, and aluminum inner chainring. The FC-M660 SLX has aluminum outer, steel + composite middle (on the 32T), and steel inner. The XT weighs 853g, SLX is 889g, so not much in that. So the difference seems to be that the SLX has a steel inner chainring, as opposed to aluminum on the XT.

Is steel better as a material for a chainring for touring? More durable? Anybody know?

Thanks,

Neil

kayakdiver

Chainrings... I'm guessing you will get approx 20K miles minimum from either one. They are both good choices Neil. It's really a matter of bling and how light you want your wallet.

36 grams is nothing. Both are going to be robust.

NeilGunton

Yeah, I know they'll both be good. I'm just one who likes to dig into the differences between the options, particularly when there is a choice. Nice to be educated for future decisions. I believe, from a cursory google search, that a steel chainring might be a bit more hard wearing than aluminum. So my current impression is that you might go for XT mainly for reasons of weight, whereas the SLX will be a little heavier, but also a little longer lasting. I was wondering if there are any other differences, such as better seals on the XT or better axle or whatever. I know they're both ok, I just like to know what the real functional difference is. If it's mainly in the bling factor, and a little weight savings, then that's good to know too.

Thanks,

Neil

sstorkel

I doubt you'll get 20K miles out of an aluminum chainring. The aluminum chainrings on my SRAM Red road crank didn't go a quarter if that distance before i was thinking about replacing them... I would expect steel to be significantly more durable.

Bekologist

boy, its too bad shimano thru the tourist/trekking LX groups to the wayside in north america. its a shame.but the XT771-K does look schweet. this crank has allloy for all 3 rings.

certainly shimano's steel/"carbon" middle ring on their new slx/xt mountain cranks is a response to most of the wear on mountain cranks taking place in the middle ring. a cyclotourist concerned about ring wear (and affordable replacements if ever needed) would get a sugino XD300(?) series with the steel rings or the shimano DEORE cranks. the new ones look pretty sharp, not clunky like earlier deore, are hollowtech, and with steel for the middle and granny ring.

perhaps the SLX/XT 771K look more bling but the DEORE is where i'd put if for touring drivetrain longevity and cheap replacement rings. i doubt you would ever need to replace the steel rings on that crank, maybe after a decade of hard touring? you can still get the Deore in a 48-36-26 and easily replace the 26 with a 24 for a nice wide range touring triple with adequate granny.

NeilGunton

Yeah, I may actually end up going with Deore. I don't really need a carbon-steel composite chainring on my touring bike, do I. According to the Shimano site, the current Deore doesn't mention Hollowtech, it just seems to have solid cranks, but who cares. This isn't a racing bike after all. The M590 has steel chainrings for inner and middle, and aluminum outer:

https://bike.shimano.com/publish/cont...-L.-type-.html

Anybody aware of any big deficiencies in this Deore M590?

Shimano even mentions "trekking" in their blurb for Deore, whereas the SLX and XT pages seem to go on about stuff that seems more relevant to racing. Maybe M590 is "good enough"... if anybody's tried this and found it noticeably inferior to LX or XT, please let me know. Just trying not to overspec my bling factor here, while keeping it real with quality components that will last and not let me down in the middle of nowhere.

Thanks again,

Neil

Bekologist

sorry, i thought deore went hollow this year, it was late last night and i didn't factcheck. It is the two piece with external BB. I kind of like having bearings inside the BB itself, but hey. progress. better seals? no, the DA bottom brackets have a 'modified' seal for lower rolling resistance, As far as i can tell having looked at a lot of the shimano cranks, they use the same spindle material.

there's nothing in deore that is going to fail by design and the steel rings will last fer sure. i put an LX on my heavy tourer as an upgrade last year, maybe I should have taken a closer look at the deore!! doh!

kayakdiver

There have been a ton of LX cranks on ebay with bb for under $100 all spring. It's what I would suggest for bang for the buck. Simple and effective.

kayakdiver

I really have a hard time believing that Red chain rings last only 5K miles unless abused or someone doesn't maintain/replace chains when needed. Maybe those aluminum rings on Sram aren't as durable as Shimano? Must be the 1700 watt sprint power you're putting out in at the town line

Bekologist

oh, i think a dirt tourer could chew thru aluminum chainrings in a couple of seasons. And if you've ever used your outer chainring as a log assist, you can blow a few teeth out pretty easy (have done). an easy way for the consumer to ensure replacing chainrings EVERY TIME their bikes goes in for service is to: never check chainwear!

Of course, those that tour on sram red are likely exceeding the maximum wattage specs on the rings

Just an FYI though, i think even Deore level replacement big rings are about 50 bucks full retail.

cyccommute 

For the small inner ring, steel has always been the choice for mountain biking. Dumping the chain to the inner ring in high torque situations puts a lot of stress on the teeth. Aluminum rings can bend easily and that will effect shifting. In mountain biking, a bent or damaged inner ring can lead to the dreaded 'chain suck' where the chain catches on the teeth and gets sucked up between the chainstay and the crank. In certain situations, that can lead to frame damage or the chain wedged in so tight that you end up walking back to the car

Touring bikes can experience the same high torque situations. If you can be smooth (a couple of chain suck incidences and you'll learn to be smooth), you can get away with an aluminum inner. Just be aware of the limitations and look at the teeth on the ring if you experience any kind of hesitation while shifting to, or from, the small ring.

That said, the SLX would probably work fine. I'd go with an external bottom bracket over a traditional bottom bracket, however. The set up on Shimano is dead simple and can be fixed in the field with a 5 mm allen wrench. It really is...Damn you Shimano!...a superior system.

If you want the XT trekking set up (larger outer and middle rings), Blue Sky Cycling currently has the M771 for a very reasonable $190 with the bottom bracket. The inner ring is too large but a 22 inner is cheap and easy to replace. That gives you a very wide range of gearing (118 to 18 gear inches). If you went with an SLX 12-36 rear cassette, you have a bit lower high and a lower low.

NeilGunton

I just got off the phone with Shimano. I was asking about the real differences between the levels. It was kind of hard to extract information from the dude, who actually sounded kind of bored with my questions, but eventually I think I was able to get this:

1. Deore has stamped chainrings, and solid stamped crank arms.
2. SLX and XT have Hollowtech II crank arms, which are stiffer and lighter than the solid Deore.
3. SLX chainrings are stamped, XT are machined. Also a different alloy on XT.
5. The aluminum alloy chainrings on XT will be stiffer, giving better transmission of power to the drivetrain.
6. The main difference between the FC-M770 (mountain XT) and the FC-M771-K (trekking version) is the number of teeth on the chainrings - the trekking version is a little higher geared, 26-36-48, which they believe tourists want for riding on the road vs mountain biking (22-32-44).
7. The trekking version of the LX is called FC-T661 (but it's not on their site for some reason). It has stamped chainrings, apparently.
8. The actual innards of the bottom bracket, according to the dude, is the same on all of them (though I don't know if I can trust this, since at this point I believe he was just getting kind of tired of all my questions).

So the upshot of all this, in terms of real differences, seems to be that Hollowtech II is worth going for because the crank arm is two machined and bonded pieces which will be both stiffer and lighter than the single solid stamped piece of the Deore. And the XT is differentiated from SLX mainly by the machined vs stamped chainrings, and the alloy used on the XT chainrings may be different too. The only difference between the MTB and "trekking" versions seems to be the number of teeth on the chainrings, no other construction differences according to him.

Summary: Machined vs stamped chainrings, different alloy, Hollowtech II vs solid crank arms. Same bottom bracket innards.

Now I'm not sure all over again, I'll go see what Sean at the bike shop thinks about all this...

Thanks again,

Neil

cyccommute 

FYI, the Hollowtech cranks aren't two pieces that are welded together. Shimano uses a super secret forging process that makes the crank arms so that they are hollow and one piece. I've seen the innards of one and I'm pretty sure that magic...evil black magic...was involved

Either the XT or SLX will work and you'll likely not be able to tell the difference.

NeilGunton

Ok... evil black magic... check. Thanks, I'll add that to the list.

What do others think? Is it worth getting the evil black magic, or is that more just for racing?

badger1

FWIW, I'm now going in to my 4th year on LX Hollowtech II (direct ancestor of current SLX). It's on my only bike, an mtb hardtail (heavily) modified for commuting/light touring/occasional non-technical off-road, used pretty much daily March through December.

I have had exactly 0 problems; just (a couple weeks ago) replaced the big/middle alloy rings, simply wore 'em out.
Original bb unit (which is not as good/well sealed as the current ones) still smooth as silk.

IMHO, for your/'our' purposes there's no point to current XT unless you want the miniscule weight saving and the 'bling' (not that there's anything whatsoever wrong with either reason). SLX (or 'old' LX) light, durable, functional, and considerably less expensive than XT (let alone XTR). In fact, according to the British mtb press, SLX is if anything slightly 'stronger' than XT (again, marginal -- but worth thinking about).

imi

Isn't this a bit weird? From Shimanos N.America site:

"New SLX, Tough, Aggressive and Light, for a modern mountain bike group. Deore LX, has been functionally re-designed into two groups: New SLX for MTB and new Deore LX for Trekking."

... but Deore LX is not to be found? It can be found on european sites... Is this just a web thang or good for a BF conspiracy plot discussion?

FWIW I rebuilt my bike with Deore LX drive chain last year and am totally happy this far (after a 2K mile tour)

NeilGunton

I'm going with the Shimano XT M770:

https://www.wiggle.co.uk/p/cycle/7/Sh...et/5360031021/

No really compelling reason for this, except that wiggle had a pretty good price and I was ordering some other stuff from them anyway. Sean, my bike shop guy, was very impressed with this price ($189), much less than he would have been able to source it.

I figure since I can't really make any compelling arguments for or against any of the levels, I can't really go wrong with XT. This is the 44/32/22 version.

Should work, let's hope.

Neil

sstorkel

Red chainrings have a reputation for wearing out quickly. People who want longevity rather than light weight often buy a Red gruppo but use a Force or Dura-Ace crankset. I guess it's the price for having such a light crank?

kayakdiver

I was thinking about Red for my next build... Might be rethinking this now...

TurbineBlade

Just got SLX 22/32/44 crankset this past December on a LHT. I love mine -- long-term reliability of the external BB not realized yet.

sstorkel

Red is really nice! Though these days most of it's advantages, other than weight, have migrated down to Force and Rival.

Hybrid setups seem common over in the Roadie forum: Red levers, brake calipers and rear derailleur, Force front derailleur, Force or DA cranks, KMC chain, and cassette of your choice. The Force FD is supposed to be slightly stiffer (and heavier) than Red which leads to crisper shifting. Lots of guys claim that Shimano chains, chainrings/crank, and cassettes lead to quieter/smoother shifting.

When I built my Red bike, I went with a Force FD, PG-1070 cassette, and the non-ceramic bottom bracket. If I had it to do over again I'd probably buy a Force crank. Mostly because I think it looks better than Red and Red's lighter weight doesn't justify the significant cost increase. That said, even though the Red chainrings are starting to look knackered they still shift beautifully...

ricohman

I did the same to my Sherpa. I choose the Trekking crankset.