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Just wondering, is it possible to convert a GRX double crankset to a single ring set up? If so what rings out there fit in the 36 or 38t range?
Yeah, easy to do. I just used the Shimano GRX single ring. Still need to sell the double rings I took off.
If the 2x bolt pattern is the same as the 1x which I believe it is then it's different from all other Shimano Cranksets (because otherwise it would be simple!). It's a 4x110bcd but asymmetric.
Smallest Shimano one is 38T or Wolftooth do a 36T or 38T Round and that's about the only option I could find that anyone actually stocked which bolts in place of the outer chainring, and it's more expensive than just buying a GRX Single Crankset from the likes of Merlin etc. normally. With shipping it's £92!:
I think that Shimano only do 2x GRX cranks, it's just a matter of how many rings are fitted.
There are Shimano's own 1x rings & TA Specialites do nice ones (possibly others available too).
I saw this asked elsewhere as well, so do the Shimano 1x rings have the offset built in?
For some reason I had it in my head that I had to buy specific offset rings so I use Garbaruk offset rings (38t oval).
Recon the offset must be accounted for with the Shimano 1x rings. Can't remember if I went 40 or 42, but it's been sweet all summer. Anyone after an unused 48t, they cost a daft amount new.
https://share.google/lkUhSIuMYR5eNiM5 j" target="_blank" rel="noopener">110G BCD for GRX - Stone Bike Chainrings https://share.google/lkUhSIuMYR5eNiM5j
Recon the offset must be accounted for with the Shimano 1x rings.
I must confess to being a bit clueless when it comes to chainline. I assume that with a 2x it's measured to a point between the two rings and I'd have thought that the ring on a 1x would be at the same position. However looking at Shimano's GRX pages, the 2x chainsets have a chainline of 47mm whilst the 1x are 49.7mm.
It's the same cranks with different rings. The 1x has the 2 sets of tabs. The 1x ring has some offset but it still gives a crap chainline (IMO). garbuk are I think the only company making an increased offset ring for better chainline, or you can use spacers.
I've used these on mine and they work fine. They're cheap enough to have a choice depending on expected hilliness of the ride.
Yeah I have one of those deckas ones linked above and they work, fine, never dropped a chain yet
I have a non-GRX one of the above Deckas ones bought on eBay on an old set of Ultegra cranks on my other gravel bike as a stopgap, all seems good so far and I just mounted it backwards so you can't see the silly anodised patterns all over it
I didn't think that the chainrings in that link would fit a GRX crank, I'm sure that there is a difference between GRX.and all other Shimano road cranks.
It's the inner ring spacing that's different. The outer ring is just the same.
There is a difference in the outer ring. All the suppliers do different models for road and grx. The BCD might be the same but there are other differences, not least that they fit in different sides of the tabs (road outside, grx inside).
I've got a specialitès TA 38 ring on one bike and a blackspire 38 on the other