[Twiggy]

I previously had a Shimano XT M785 Crankset, which does have a wider Q-Factor of 176mm (apparently, from what I've read).

TwoTone - to answer your question, I did actually order another M9020 Crankset (ie: I currently have two!) and it has the exact same clearance or lack thereof. I also wondered whether the arm was bent but that doesn't seem to be the case.

I haven't checked frame alignment, so maybe I'll bring it back to the shop today or tomorrow and see if I can have that done! I can't imagine that being the case - wouldn't misalignment be pretty rare and quite noticeable?... At the same time; I can't see any other reason why this clearance would be so bad. If this crank is this close then I guess I also couldn' t buy any of the sram Carbon cranksets (Q-factor is also 168)...unless they flex less than the shimano somehow? This would limit my high-end crank choices quite a bit.... I doubt Scott would make such a mistake.

I was wondering last night - Are these shimano PF BB's symmetrical? could my shop have installed the cups on the wrong sides, and could there be a slight variation in bearing placement caused by that?

 

[TwoTone]

One thing I do notice in the picture is the difference in tire clearance from one side to the other- again could just be the angle.

You need to find another shop- it never should have left that way in the first place, they don't give the impression of being competent.

 

[c8stom]

What is the history of the bike ? Are you the first owner ? Any crashes ? Strip downs ? warrantied replacements parts ?

As a user of M98x series XTR cranks on a couple of bikes, I found them to be stiff, very stiff and if they flex at all, it would be tiny < 1mm. Most flex comes from my frames under load. Although I have not used the M9020's, I seriously doubt they would flex that much especially at that particular crank position

I suspect your frame has an alignment issue and when you pedal under load, the chainstay moves closer to the drive side crank as the rear is compressed

If you don't how to check the frame, find a seasoned Scott mechanic to take a look.

I agree the rear wheel does not look centered. May or may not be related.

 

[Twiggy]

Dropped the bike back off at the shop last night - they had spoken to some technical reps at Scott and Scott had requested an alignment check (as you guys had suggested) and a ton of pictures. I dropped the bike off minutes before closing and the shop was busy prepping some donated bikes for a charity event, so they didn't figure they'd have a chance to look at it until late today.

I'll let you know when I hear back!

I wonder if the Spark RC frames (carbon rear triangle) on the Spark Premium (the one that is spec'd with this crank) are stiffer and thus offer less chance of the frame flexing against the crank?

To answer your questions, c8stom, the bike was a demo bike that I purchased off of the Scott rep. It had been demo'd but in reality, it was ridden very little....it was like new when I got it, although thats not to say that it couldn't have been crashed before I got it! (luckily I got full warranty coverage)
I guess time will tell!

 

[J.B. Weld]

I wonder if the Spark RC frames (carbon rear triangle) on the Spark Premium (the one that is spec'd with this crank) are stiffer and thus offer less chance of the frame flexing against the crank?

I can't tell exactly how close your crank is to the chainstay in the pic but IME even a hardtail frame needs at least 2-3 mm clearance to avoid contact during hard pedaling. Your's definitely looks a bit too close to me,

I'd be a little surprised too if the frame alignment was that off but I have seen it before and as mentioned it's easy to check.

 

[Twiggy]

Still waiting for an answer...

The shop (the only Scott dealer anywhere near me) had a bit of an issue last week with 3 of their normal 4-5 mechanics getting sidlined by serious injury (broken leg, broken arm, and a bad concussion) so they haven't even had a chance yet to look at my bike, and they're closed today (Monday).

On the weekend I stopped by another shop and they took a quick look but couldn't diagnose the issue. The mechanic I spoke to dismissed the idea of checking alignment. I texted the head mechanic at that shop and he agreed it would be worth checking the frame alignment but he wasn't in....I'll have to go back. In the meantime I'm hoping the original shop will be in contact with Scott and help me diagnose/fix the issue.

Other interesting tidbits:
- Last night I flipped the bike over and took some of my own measurements, although I have little confidence in their accuracy. I assumed (likely wrongly so) that the visible seam in the middle of the rear tire tread should be roughly in the middle of the bike, and measured from there to the inside of the crankarm on both sides. Oddly (or not) the dimension from that "pseudo-centerline" to the inside of the driveside crank arm was 72mm, and it was 70 mm to the inside of NDS crankarm. These are exactly the same measurements that Sram lists for their XX1 Cranks in a 168Q factor. From this I deduce that switching to a Sram XX1 crankset wouldn't help me any....odd since its a fairly 'standard' crank.

- I measured the thickness of an XX1 crank (at the pedal spindle) and my XTR crank and they were within 0.5mm of each other; thus it would make sense that they would have the same clearance issues. Less clearance if I used the crank boots.

- I considered experimenting by buying a set of used Raceface Next SL cranks from a local seller and seeing if they'd fit, but since they also have a Q-factor of 168mm I'm doubtful.

- I realized that the thickness of the cranks is within 1mm or so of the depth of threads on my pedals.... so I'm guessing that most cranks are likely almost the same thickness, and thus likely to have the same issues unless they have a qider Q factor to begin with.

-I can't help but think that this HAS to be a frame issue. There is no way in my mind that Scott, in 2014, would have designed a bike that had to be used with lower-end cranks with wider Q-factors (say, over 170mm).

 

[scottg]

Still waiting for an answer...

The shop (the only Scott dealer anywhere near me) had a bit of an issue last week with 3 of their normal 4-5 mechanics getting sidlined by serious injury (broken leg, broken arm, and a bad concussion) so they haven't even had a chance yet to look at my bike, and they're closed today (Monday).

On the weekend I stopped by another shop and they took a quick look but couldn't diagnose the issue. The mechanic I spoke to dismissed the idea of checking alignment. I texted the head mechanic at that shop and he agreed it would be worth checking the frame alignment but he wasn't in....I'll have to go back. In the meantime I'm hoping the original shop will be in contact with Scott and help me diagnose/fix the issue.

Other interesting tidbits:
- Last night I flipped the bike over and took some of my own measurements, although I have little confidence in their accuracy. I assumed (likely wrongly so) that the visible seam in the middle of the rear tire tread should be roughly in the middle of the bike, and measured from there to the inside of the crankarm on both sides. Oddly (or not) the dimension from that "pseudo-centerline" to the inside of the driveside crank arm was 72mm, and it was 70 mm to the inside of NDS crankarm. These are exactly the same measurements that Sram lists for their XX1 Cranks in a 168Q factor. From this I deduce that switching to a Sram XX1 crankset wouldn't help me any....odd since its a fairly 'standard' crank.

- I measured the thickness of an XX1 crank (at the pedal spindle) and my XTR crank and they were within 0.5mm of each other; thus it would make sense that they would have the same clearance issues. Less clearance if I used the crank boots.

- I considered experimenting by buying a set of used Raceface Next SL cranks from a local seller and seeing if they'd fit, but since they also have a Q-factor of 168mm I'm doubtful.

- I realized that the thickness of the cranks is within 1mm or so of the depth of threads on my pedals.... so I'm guessing that most cranks are likely almost the same thickness, and thus likely to have the same issues unless they have a qider Q factor to begin with.

-I can't help but think that this HAS to be a frame issue. There is no way in my mind that Scott, in 2014, would have designed a bike that had to be used with lower-end cranks with wider Q-factors (say, over 170mm).

If your Scott dealer is amenable to it then maybe you could do a trial fit with your crankset on a Spark that they have in stock and measure the clearance to see if it is any different than the clearance when fitted to your frame. A crank swap only takes a few minutes anyway and you wouldn't even have to ride it to gauge whether there's a difference.

 

[Twiggy]

If your Scott dealer is amenable to it then maybe you could do a trial fit with your crankset on a Spark that they have in stock and measure the clearance to see if it is any different than the clearance when fitted to your frame. A crank swap only takes a few minutes anyway and you wouldn't even have to ride it to gauge whether there's a difference.

Not a bad idea - maybe I'll ask them if they can try that!

 

[Harold]

Measuring anything relative to the tire isn't going to tell you anything useful. I've never seen a tire built perfectly. They all have some kind of wobble to them. Wheel dish can also affect the results of any measurements. If you want to do some home checks on frame alignment. Run a piece of string from one rear dropout forward to the headtube, go around the front of the headtube, and go back to the opposite dropout.

Measure from string to seat tube to check alignment. Most modern bikes have asymmetrical chainstays, so make sure the string is not hanging up on a chainstay after is leaves the rear dropout. I'd also run the string to the inside of the dropout, rather than the outside. Obviously remove the wheel for this.

 

[Twiggy]

Still waiting for a response from Scott - my dealer sent them pics this weekend as they requested.

In the meantime, I threw a set of XT cranks on there that I borrowed from a riding buddy.... used those to win a 24 Hour race .... still PO'd though that I can't get to the bottom of this clearance issue!

I'll let you know when I know more!