46T chainring and XTR front derailleur on a K2 4000 issues

[signalMTB]

I may have royally screwed up, not sure.  In my rebuild, I went with Blackspire 46T large chainring up front with a FD-M950 XTR derailleur.  It's a pretty tight fit in there.  I'm worried the swingarm may hit it on the downstroke.  Has anyone had any experience with this?  Suggestions? I don't have the manual for the derailleur but I assume there is adjustments that can be made.  Is this 46T ring just too big?

[kiwi]

i think 46 t is about as big as you can go...other s with more exerience on the evo frame will chime in I am sure..

[Colin]

I may have royally screwed up, not sure.  In my rebuild, I went with Blackspire 46T large chainring up front with a FD-M950 XTR derailleur.  It's a pretty tight fit in there.  I'm worried the swingarm may hit it on the downstroke.  Has anyone had any experience with this?  Suggestions? I don't have the manual for the derailleur but I assume there is adjustments that can be made.  Is this 46T ring just too big?

I have a 44T on my 4000se (22/34/44) and a Shimano Deore XT derailleur, This is as per original spec.

There is about 15mm of clearance between the adjustment screws on the derailleur and the bottom of the carbon swing arm when the standard NR-4 shock is fully extended, so the slight increase of diameter for a 46T should be OK I should think?
The bigger issue is getting a Derailleur to cope with such a big spread of gears isn't it?

Col.

[shovelon]

I also run a 44, but the swingarm travel is 6 inches, so it kind of relates. Never had a problem so far.

Terry

[signalMTB]

I may have royally screwed up, not sure.  In my rebuild, I went with Blackspire 46T large chainring up front with a FD-M950 XTR derailleur.  It's a pretty tight fit in there.  I'm worried the swingarm may hit it on the downstroke.  Has anyone had any experience with this?  Suggestions? I don't have the manual for the derailleur but I assume there is adjustments that can be made.  Is this 46T ring just too big?

I have a 44T on my 4000se (22/34/44) and a Shimano Deore XT derailleur, This is as per original spec.

There is about 15mm of clearance between the adjustment screws on the derailleur and the bottom of the carbon swing arm when the standard NR-4 shock is fully extended, so the slight increase of diameter for a 46T should be OK I should think?
The bigger issue is getting a Derailleur to cope with such a big spread of gears isn't it?

Col.

thanks for all the replies...I'll build it out and see what happens, and post with pics maybe.  From what I heard on MTBR, the 950 was designed to handle up to a 46T so I hope it'll work.  Sure wish Speedgoat would carry the 44T Blackspire Super Pro

[Colin]

I believe........that XTR or XT FD's will work for up to 26T unless they are designed for the compact chainset, in which case they will only do 22T.

Col.

[signalMTB]

OK, here's the deal now...the issue isn't with the derailleur.  My big ring is too big.  It measures approx. 190 mm across, and upon trying to change to the big ring, the chain will not clear the the ring and the swingarm (right by pivot bolt).  My old big ring was ~171mm diameter.  Holy cow, all this work and this happens. 



Anyone want to buy a brand new never used 46T Blackspire Super Pro ring??

[Luke]

Don't give up!
I've run 24/24/46 on my 5500 for 8 years!
I just checked the gallery, they're the same swingarm.
What crankset are you using?
I've just measured mine, I have 7.5mm from the pivot to the inside of the tooth (where the ring's not too warped) and that seems to run fine.
My chainring is a Specialités TA with pins and ramps and the odd short tooth, on the bike stand I once managed to twist the chain and jam it, but it rarely sees a bike stand so that's ok.
Try to shim the drive side out until it clears, I did this with some 0.1mm shim stock on TWO of the tapers of the BB, held in place in the crank with a drop of araldite until I got the crank on (the little bits of shim just don't want to stay where you put them) Be sure to have enough length to cope with the taper sliding as you tighten the bolt.
If you've got one of those modern external BB sets, I beleve they come with all manner of spacers, one wafer thin after din...
er, sorry.
One of the thinner ones should get you spaced out correctly.

One day I'll get that front mech adjusted to go down onto the granny...

Happy tinkering
Luke

[shovelon]

OK, here's the deal now...the issue isn't with the derailleur.  My big ring is too big.  It measures approx. 190 mm across, and upon trying to change to the big ring, the chain will not clear the the ring and the swingarm (right by pivot bolt).  My old big ring was ~171mm diameter.  Holy cow, all this work and this happens. 



Anyone want to buy a brand new never used 46T Blackspire Super Pro ring??

I can't see why it would not work either. But my legs are too weak to push a 46t ring. If ya had some pics, maybe we could see more. As far as 171/190mm difference, I think something is wrong.

Terry

[Thunderchild]

I have an 8-speed Race Face 46 tooth compact drive on my Oz.  I have been using it for almost two years without a problem.  I raised the front derailleur ~10 mm higher than Shimano instructions and it works well.  I also run a 20T (five-arm cranks) for my granny gear.

Thunderchild