[Closed] Middleburn Chainring (only fits M760) Why ?

Might need to file a bit of the ring as there are some tabs on the crank which restrict the diameter of the ring.

Although the bolt holes are in the same place the flange on the chainset that the ring sits against differs between chainsets.

I emailed Middleburn a while back:

Was wondering if you could explain the difference between the XT hollowtech II rings and ‘normal’ arm 104/64 pcd ring?

Answer:
[i]Shimano changed the shoulder that the ring sits on to from 90mm to 88mm and the chain line is 0.6mm closer towards the outer ring.[/i]

if it dont fit yet1man I might have it off you

Ah haaa.

Well in the mean time I've fitted the ring to the crank. The shoulder length doesn't seem to be much of a problem, as the shoulder on the crank is a smaller diameter than the flanges on the ring (is indeed about a 2mm gap, which would seem to bare out the 90-88mm statement) just a little concerned about the chain line now though.

Don't know whether to chance it (I'm sure a 9 speed chain has more than 0.6mm float on the teeth doesn't it ? and/or does that statement go for the SLX crank ?) or space it out with some IS brake fitting shims ?

Going to go and try it now and see if the chain is indeed closer to the big ring and touches/catches it. (see whether I need to add shims or not ?)

Why is nothing ever simple !!!

Many thanks for your replies so far.

Cheers

Michael

This may help you. I am running the standard ring on an SLX M665 (twin and bash as I prefer a 32T that also lasts.

Sure enough, there is a gap from chainring tabs to shoulder. It's run fine for a year & whilst I would prefer the tabs to sit on the shoulders, it seems to work OK.

As it happens, same problem with the Bash guards, you can't fit current Shimano Saint or SLX bash guards to other chainsets.

As for the chainline, don't know but 0.6mm but shouldn't make any odds ?

Doh! What I just posted may be accademic, it seems middleburn only make the 'XT' 32T ring in 'slick shift' option which for my use/local conditions/whatever I have found to be pants!

0.6mm chainline isn't going to make sod all difference in the real world.

Well, its all fitted and there's no catching/scraping or other untoward interference between the chain and middle & big rings.

I'm out tonight so will test it in anger then (rather than just doing circles in the garden ;0)

[i]'it seems middleburn only make the 'XT' 32T ring in 'slick shift' option which for my use/local conditions/whatever I have found to be pants!'[/i]

ummm, thats the one I bought, ho hum, I'll see for myself tonight but to be honest there's nothing in my local woods that necessitates the granny ring anyway and the big ring is used very rarely, so very very little front ring changes anyway. (hhmmmmm thats got me thinking about running a 1 x 9 now !!)

Anyway, incase any one is in the slight bit interested... I'll report back tomorrow. ;0)

Many thanks for your help and replies.

Cheers

Michael

....Only in my experience - yours could well be completely different 😉

But then I also don't rate the 'hardcoat' either, found no discernable difference in chainring lifetime, but again I'm only reporting my own experience !

Mister P - Membe

And, more pertinently, good thread, I've often wondered this myself.

Well, it was very very muddy out last night and despite this, had no problems with the chain or chain rings.

I didn't try and front ring changes so can't comment on the 'slick shift' and as yet haven't cleaned the bike (just dried the chain) so can't comment either on the hardcoat and its durability (or not) but would be sorely disappointed if after just one ride (even if it was muddy and gritty) I could see wear on the hard coating.

I'll keep you abreast on the situation.

(que the tittering: 'flange' and 'a breast' lol)

Michael