Trek Check Point with GRX / Stages power meter

 I swapped my wife's crank from ultegra to GRX ( for lower gearing).  My measurements made it look unlikely that a stages power meter would fit on the checkpoint with ultegra.  But the GRX appeared to have more room. After measuring the gap, I pulled the trigger.  Here is a photo of the gap between the stages power sensor and the chain stays.  

Is this the 810 or the 600 crank? Although I'm not sure if they are any different in terms of spacing...
I've been thinking of getting on one of these. On the original R7000, I couldn't even fit a cadence sensor

All SHimano Hollowtech arms use the same interface, so you can throw a MTB arm on a road crank. The GRX and Road are made for BB86 (BB92 for trek) which dictates the spacing of where that arm connects to, so it wouldn't matter. The GRX is different in that it holds the rings 2.5mm out further and the arms pull away from the frame 2.5 further on each side.

@jfranci3 yes, I'm aware that all Hollowtech II Spindles use the same interface. The reason I was asking which crank it was is because the last time I looked into it Stages was only installing their pms on the 810 cranks, and I have a 600. I'm not sure why they aren't doing 600, and I also haven't checked with Stages in a while, guessing a it's testing thing  ¯\\_(ツ)_/¯

Ahhh...  There is a 100gr difference between the two and they're both AL, so you can assume the rX600 has solid arms and the 800 has hollow arms. I don't see Stages trying to make hollow and non-hollow PMs here since they haven't for MTB or road and the hollow is at their bottom price point.

jfranci3 wrote:All SHimano Hollowtech arms use the same interface, so you can throw a MTB arm on a road crank. The GRX and Road are made for BB86 (BB92 for trek) which dictates the spacing of where that arm connects to, so it wouldn't matter. The GRX is different in that it holds the rings 2.5mm out further and the arms pull away from the frame 2.5 further on each side.

Sure it'll fit, but there's a difference in Q-factor that can't be ignored.  On top of this, Shimano has changed the thickness of the splined interface amongst their mountain crank arms.  So while it may fit on, it may go "too deep" along the splines or "not deep enough" depending on your combination.  This is not a problem for their road line (yet), as all the HTII crankarms are universal amongst the road cranksets.  This does not count Tiagra.

clarksonxc wrote:

Sure it'll fit, but there's a difference in Q-factor that can't be ignored.  On top of this, Shimano has changed the thickness of the splined interface amongst their mountain crank arms.  So while it may fit on, it may go "too deep" along the splines or "not deep enough" depending on your combination.  This is not a problem for their road line (yet), as all the HTII crankarms are universal amongst the road cranksets.  This does not count Tiagra.

It can easily be ignored.

For the q-factor impact on the body - Go look at a 2.5mm hex key, that's a very small difference you'll never notice. Your legs are probably more than 2.5 different and you've never noticed. Your saddle is 2.5mm offcenter too. No one has ever noticed the difference when someone did or didn't install a wave washer between their crankarm and bottom bracket (unless it started making a noise or rubbing).

As for the crank fit, it fits. Both road and and GRX cranks use a 86.5 mm wide bottom brackets. Only 12sp mtb has the change,right ?The otherwise the  difference between the road, grx, and MTB units is that the grx and MTB crank arm zigs further out. and the chainring spiders move the chain lines further out.