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....before I throw the bike out of the window...
Bike been parked up for a bit with the cranks off, X1 1000 as fitted originally, Sram GXP bottom bracket, 73mm shell so no spacers as per the instructions.
I have just fitted a new n/w chainring, "assisted" the cranks in with a rubber mallet then done them up from the non drive side until there is no play (and a bit more) but the chainline just seems wrong, it is straight in the 7th cog (11 speed, 142 rear as when bought). There is only 12.5mm axle exposed on the non drive side and on the drive side there must be a 5mm gap between the cranks and the shell.
Google suggests a gap is reasonably common but it just seems wrong, especially the chainline ie when in the 42T. I have tried hammering a bit more and swearing and applying FT + 3 to the 8mm bolt along with lots of grease but this is as far as they go in.
Is this normal or should I take it into the wood, dig a hole and leave it there? I can't remember what it was like before but I had a lot of wear on the original ring after 350 miles and it used to rumble and make a right racket when in the larger cogs in the mud. Chain is barely worn using a gauge
Pics here,
[url] https://goo.gl/photos/3Tz4WqVSgqtPTQdv9 [/url]
[url] https://goo.gl/photos/YcTX3dGdR6QZfgDEA [/url]
Chainline should be 49mm on a standard SRAM setup.
Boost is 52mm.
Dimension is from centreline of bike to chainring tip.
No tolerance is given.
Of course, the position of the crank is of course reliant on the position of the non driveside cup. So you can move things further inboard by adding extra spacers to that non driveside cup to pull things in closer.
I have seen cranks with seemingly longer than normal axles and a gap on the driveside between the crank and the drive side bearing cup.
There's no space on the drive side of my sram gx 11 set up, 73mm BB shell too so no spacers.
Cheers for replies. Chainline is coming out at 49mm which suggests it is right, maybe I just didn't notice the gap before, just surprised the chain lines up with the 7th cog (11 speed)
12.5mm is correct for the NDS axle exposed, suggesting the cranks are fully 'engaged'. The DS gap should be 4mm (or thereabouts). I cant comment on the chainline though as that would be frame specific, or rather dependent on the alignment of the frame(!), only to say that I've measured the chainline on GX1000 cranks and the ones we run are definitely 49.
Yer I just took them back out and you can see in the photo below, it is going in as far as to fully cover the silver part where the bearing seats, the rest between that and the outer park of the crank is left exposed so all seems fine. Perhaps it is just that the frame is designed for double chainring as well and hence ends up with a slightly off chain line
[url= https://goo.gl/photos/KbgmB17koPNPQxQr9 ]Crank photo[/url]
cheers everyone, will just ignore it 😀
Mine's a 73 mm shell with one spacer on drive (as it came from bike shop) straight chainline on 7th cog never had any trouble
Tagging add I have similar "issue" on a 1x gxp build. Chain line looks way too far out on my also but seems to acceptable is the consensus.
Just want to be able to reassure myself by reading this thread late at night on occasion.... when things like this come in to my noggin when I turn in for the day!
No, not kidding, wish I was! Lol
7 cog is about right. If you wanted to run it in properly in the middle of the block you'd actually need a chain-line of about 45mm (lower again for Shimano I believe). One of the advantages of boost is that you can actually get close to this by running non-boost cranks if your frame / tyre allows clearance for the chainring. Not that you have boost, just sayin' like.