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Delicious - One for you mate (or any other knowledgable nobmobbers)
NB: Originally posted elsewhere on the Global Riders Network and appears via syndication.
I have XTR M970 cranks and need to replace the inner and middle chainring. XTR is too expensive, and I wanted to know what other chainrings I can fit.
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They are a popular replacement for the uber expensive xtr cogs.
http://www.blackspire.com/
available from the usual suspects (OS).
....the website has a set which it says are for Shimano XTR FC-M960, but not one for M970. Will they fit either?? Also, it says "For best performance use only Blackspire SuperProX rings as a set. These chainrings will not work if mixed with other brand rings." and I don't need the outer ring changed yet and given it is the most expensive, I am not superkeen to change it (although will it if I have to).
http://www.blackspire.com/qs/product/83/5948/263...
is compatible with the M960 and you don't need to replace all three. I replaced inner and middle only and they shift ok.
I think the standard xt rings will fit the 970 crankset, but check BCD first. Just make sure you get the ones to suit hollowtechII cranks http://www.chainreactioncycles.com/Models.aspx?M... as the ones for the hollowtech I will need to have the lugs filed off to fit. That said I don't own the 970's so am not 100% certain
I get this question from time to time. And I'm not going to mince my words on this. If one can afford to get xtr in the first place, then one needs to allow for replacement parts. This day was always going to come. It was inevitable. Dearer kit means higher performance and lighter weight, not more durability. Usually.
The rings of any crankset are engineered to work as a unit, so it's always best to continue to use the proper rings. An xt middle will work fine and shift fine also. All the the HG spikes and pins are present. It's just that you miss out on the titanium/carbon composite of the xtr. Only choose xt M770 though and not older generation xt. Saint/slx is fine also.
Don't mix brands ever. This means dropping a middle and granny from say Blackspire onto an xtr crank with big ring. Poor shifting will result. One can however purchase a complete set of rings and install them on their crank, then reset the FD, as all three rings are spaced nicely, provided the manufacturer designed them for that purpose (eg a Blackspire Pro Ring set for XTR ) Otherwise, simply use Truvativ rings on Truvativ cranks, RaceFace rings on RaceFace cranks etc. This way the best available shifting is obtained.
I expect a flurry of comments confirming many personal experiences of folks using ring brand A with crank brand X and all is merry. That's cool and all however my opinion on this ( and this time it was invited ) refers to best available shifting, not simply what will function.
The truth is stuff wears out and parts cost money. For those of you who feel that your stuff is wearing out to quickly then possibly you're doing something wrong, such as not replacing the chain often enough or not lubing enough.
Here's a tip; ride in the big ring everywhere for longer drivetrain life. Normal correct chainline rules still apply. More tooth engagement. Spread the workload. Even the drive inside the rear hub will last longer.
Delicious, thanks for all the input, I really appreciate it. One statement which is a bit harsh though is "If one can afford to get xtr in the first place, then one needs to allow for replacement parts." This is not fair for a number of reasons:
1) We are in changed economic times with a lot of people having lost jobs, and many others tightening their belts due to job uncertainty etc.
2) It ignores individual circumstances surrounding the purchase of the bike. I bought my 2008 bike after the 2009's were released and Netti were sitting with excess stock in the 2008 Scott Spark 10's in a SMALL frame, but had no Spark 20's in a SMALL. As a result I bought the XTR equiped 2008 Spark 10 for around $1,000 LESS than it would have cost me for a Spark 20. Kind of obviuos choice givent he generally better spec and frame differences on the Spark 10.
3) XTR is a complete rip-off and unless you are a pro (and therefore are probably sponsored), IMHO you need to be nuts to pay up for the difference over XT given the weight and performance difference. Simple example. I needed to replace my jockey wheels. The XTR jockey wheels were $90 at the shop, so I bought BBB for $25.
That said, I appreciate your advice, enthusiasm, and help.
My initial comment was most harsh and I totally understand the present economic times, and your deal on your Spark is excellent. It just so happened that I spent a greater part of my day fielding customers who are whinging about their expensive parts from Bike Accessory Provider A which is attached to their bike made by Global Bike Manufacturer X that has now worn out in a time frame represented by this formula ( date installed - not bloody long enough ) which in turn means that both manufacturers A and X are shit, robbers and con artists and that the shop that did the work is crap and could the shop of my employ organise a better result. The fact that these guys ride around in the filth all weekend long in the same chainring seems to matter not.
And how's this? A road rider telling me that it's ridiculous that their chainrings have worn out after just one year. "How much do you ride mate?" asks I. "Oh, just to and from work, about 15km each way."
So I whip out my calculator. "So that's 7200km in one year." says I. "Yeah", he says, "they should last longer than that!"
Well, no they won't. Furthermore, he'd never changed the chain to at least get a bit more life form the cassette and rings.
After explaining my chainring logic to several throughout the day I then found your message, and I guess you just copped my frustration and for this I apologise.
I read a lot of stuff on this site of all sorts of parts wearing out in really short time frames, yet none of these things seem to happen to me and I reckon I ride plenty. It's not all roses here though. Recently I broke a drive side crank, snapped it on the spider near a bolt. I won't mention the brand here because many will twist it and get the wrong message. What I will say is that I put in excess of 12000 km on it and was using it as a single speed which it most certainly wasn't engineered to be. And I weigh a lot. So no, I don't think that crank or that parts maker is shit. I just exhausted the cranks usable life time.
The sport we have all chosen is one of high maintainence.
If it has wheels or wears heels it'll cost you money.
I didn't know specialized now made cranks
Jokes aside, I am interested to hear your theory on running the big ring. Fair point, more teeth, greater contact area, less wear per tooth etc but doesn't the additional load pushing the dog as opposed to spinning the granny also have a negative effect? (Praying that shouldn't have been affect)
There isn't more load on components when pushing the dog. It feels harder to push from the perspective of the human doing the work, yet the load is less because of the spread across more teeth.
F'instance, Shimano has just revamped the Deore groupset and very nice it is too. Within said collection there is a new cassette size available which features a 36 tooth bottom gear. It's aimed directly at 29er riders due to the bigger radius of those wheels and the increased effort required to get 'em a turnin'. So it's percieved that these princesses required an even lower gear in order to ascend.
Alongside this cassette option is a new hub set which is the only rear hub rated to handle the high torque of using a combo of 22t granny and 36t lowest gear. No other hub at present is cabable of handling that high torque load.
However, when using the cassette, should one avoid the aforementioned gear position then the special hub is not required.
You see, using extreme low gears is what wears stuff out.
Look at this from another perspective. The new Sram XX system. Make your own, cheaper version and call it a 2x9 system. Simply ditch the granny, space the crankset to the left a bit and spread all the work across the entire remaining system and I firmly believe that longer component life will result, and one will still succesfully climb every mountain.
Lots of people use this type already and Cannondale had it as a Coda product some years ago.
.... based on the cost of the big ring vs the middle ring (XTR at random bike shop) you would need to get approximately 35% longer life from the big ring to break even. I have no idea what difference it would make to the replacement mileage, but a wild guess would be 20-40%, so I would think that it is unlikely to make MUCH difference from a cost perspective.
Just a question to followup Delicious' comment about the 2x9 setup: since i don't need the granny and rarely ever use the 11 tooth cog, is there a spacer available between the spokes and the biggest cog (34 tooth) so on can take the smallest cog (11 tooth, rarely ever used) off to give a better chain line for 2x8 setup?
Many thanks.
Tien.
Its the 11T you've taken off the outside and put against the wheel.
Ok I have no idea if that would actually work and I'm thinking it will depend on how the spider is built but you have the pieces so you can try
I have a 7 speed casette I'm not useing, I had it on the Hardtail for the 2008 Dirtworks and it was fine.
would be better than spacers and so on, I think. ..... 2 x 7 !!!!
Bernd