I’m not sure why you don’t think Quarq will do the gearing you currently have, seems you’re only thinking of the SRAM options which have smaller big chainrings and a smaller tooth jump. The Quarq DFour uses the Shimano bolt circle so you can use 50/34 Shimano chainrings, that’s what I have on my tri bike and was my choice as I have a Shimano drivetrain and I think they make the best chainrings.
Warning: Long post ahead!
I have a slightly different quandary. I have a second, older Quarq with 50/34 rings and was going to put it on my gravel rig, which I purchased last year. I have a 46/30 GRX 600 crank on my gravel bike and while I thought the top gear wouldn’t be high enough, in practice I’ve found that with the larger tires it’s actually adequate even though I’ve ended up also using my gravel bike as my main road bike with a second set of wheels. And given my age, the very hilly gravel terrain I ride, and that I’ve also been using the bike on easier MTB trails, I’ve come to really like the 30t inner ring. It’s going to be very challenging to get the same low since my old Quarq can’t run smaller than a 34t inner ring. If I run an 11-40 tooth cassette then I run into problems with chain wrap and big gaps in the gears. Plus the existing chainrings on the older Quarq need to be replaced, ideally I’d go with a smaller front chainring to help the wrap issue, but nobody makes paired sets that match a 34 inner with a smaller than 50t outer anymore. And I’ve test fitted the older Quarq on my gravel rig and wasn’t crazy about how tight the clearance was with the 50t large.
I can’t run a single sided meter due to a leg discrepancy. And while I know that weight doesn’t really matter that much, it has entered into my thinking, it would be nice not to have a significant weight penalty over my old road bike when in road mode and it’s nice to not have a heavy bike when you’re hefting it over technical sections on the trails.
So here’s my own personal take on what’s available based on my needs, but might be of some use to others.
Power2Max NG Eco gravel version - Plusses: Reliable, accurate, good reputation. Available with a wide variety of crankarms of varying prices and weights some of which are significantly lighter than my current 600 series crank. Retains my existing gearing, and supposedly uses the same GRX chain line.
Minuses: Uses proprietary chainrings only available from them. I haven’t had a single chain drop on my GRX and reluctant to go with non-Shimano rings. Lighter options are pricey.
Favero Assioma with Xpedo SPD hack - Plusses: Reliable, accurate, good reputation. Adds simplicity since no more pedal swaps for road use.
Minuses: The pods seem very vulnerable to rock strikes on the trails and I have some scratches on the ends of my crankarms. Adds significant weight in road setup over the Speedplays I’ve been swapping for road use; also, I prefer the feel of the Speedplays for the road.
Garmin Rally XC200 - Plusses: No pods like the Assiomas. SPD pedal out of the box without the hack necessary on the Assiomas.
Minuses: Really pricey for a pedal that gets rough treatment. Past Garmin pedals have had bad reliability reputation. Kinda heavy.
Two sided 4iiii installation on GRX 810 crank with 48/31 rings - Plusses: Preserves nice Shimano chainrings. Saves some weight over my 600 cranks. The 48t outer chainring gives better road gearing than I have now.
Minuses: Questionable accuracy of PM installs on Shimano cranks; accuracy is very important to me, if it isn’t accurate, I’d rather just train with PE. Takes a few weeks for installation process. Lose 1 tooth of low gearing, which is not too big a deal.
Well this is probably more than any of you wanted to know.
I think if it weren’t for the pod issue I’d go with the Assioma SPD hack. I’m leaning towards Power2Max but concerned I won’t have as good shifting with non-Shimano rings. Still pondering.
