I have a new Lynskey GR300 frame on the way and my LBS is going to build it up with GRX Di2. Due to clearance issues, I can’t run a left side crank power meter as I did on my old bike. Both my current bikes have 4iiii crank power meters and as far as I can tell they read very closely to each other (did some testing with my Kickr and swapping the PMs on the same frame to look for differences).
For the new frame, my options are a right side GRX install for $300 on top of the crank so roughly $550 all together, or a Power2Max for $820. The GRX install would be cheaper, but could take a while to get installed. If I have a big L/R imbalance, it might really show up using left side on one bike and right on the other.
On the other hand, I think the P2M will give L/R and is in stock now. My frame should be here early March and I want to build it as soon as I can (patience is not my strong suit!! )
Yeah if you get the NG eco (the cheaper one) then you have to pay $50 (I think) to get the L/R measurement. It’s also good to keep in mind that it won’t be a true LR measure like a dual power pedal would give. It just looks at your crank position and then assigns the power to each leg. So it won’t know if you pull up with your left and push with your right or just push with your right.
So if you don’t get the upgrade, but it’s measuring at the spindle, does that mean it’s still effectively giving you the right total power (as opposed to left x2 on a crank) even if they don’t split L/R?
Yeah it’ll still be measuring total power that is transmitted between the crankset and the chain. But if you don’t buy the upgrade it just won’t be spitting out the LR split. I’m sure it’s still calculating it but it probably just isn’t transmitting it.
To break it down just do be clear. If you pedal 100W with your left leg and 110W with your right, it will still say you are pedaling 210W. It just won’t say you are pedaling 49%/51% LR.
Honestly, I don’t really measure L/R on the mountain bike. I’ll do an L/R balance check from time to time with my pedal based power meters (road bike) on the trainer just to make sure I’m not getting out of whack for some reason – but other than that I haven’t found a ton of use for it, so I can really say. Sorry.
If you want to use the 4iiiiiiii on the GRX, you can try just spacing it out 2-3mm shouldn’t be a big deal https://amzn.to/3qtlUgg (affiliate link)
I wouldn’t bother with the L/R - both side measurement, yes, but L/R specific data, no.
The P2M is solid though. What rings are you looking to use? 1x or 2x? I’d get 110bcd rather than the “gravel” build unless you are running a ring less than 34t.
That PowerMeter City $$ looks too high - Gravel NGeco Rotor ALDHU 24mm/30mm 2x Chainring Package – Power2Max North America Order from P2M directly. I’d get the Aldhu or Power2Max budget version (same just less machining for weight) - those are light and built like tank.
$612 all in with BB and rings for the Gravel
-If you want to do the road 110bcd, you can space it out 2.5mm easily for GRX spacing (or not - I think the GRX just gives you 2.5mm of frame spacing and lets you run a 30t ring, but matters for the front deraileur)
-If you use P2M’s 1x rings, ask for 12sp rings. The 12sp chains work on 11sp, but offer more side to side “swing” clearance and the SRAM Eagle higher end ones last a long long time. 12sp > 11sp chains on 11sp 1x.
PMCity usually has the same pricing. Not sure what’s up.
If you have all the parts, I’d suggest trying to shim your existing 4iiiiii first and share it between bikes if you don’t mind 5min of work moving back and forth between bikes.
Otherwise, the 2x P2M Gravel, GRX Stages arm, or Assomia Uno pedals would be the better buy over DS only GRX. The pedals would be the most portable for vacations / loaning to friends, but might not play well with your preferences for cleats. If you can’t find a GRX arm, an XT left arm would work and be +2.5mm over the GRX arm (so the road arms are +0, GRX +2.5mm, XT +5mm - you can run mis-matched sets)
I asked Lynskey about clearance and they said it would be too tight (can’t fit a AAA battery between the crank arm and frame). I’m a little worried that it’ll be too tight even with a few shims (maybe no room for debris etc.)
I’m going with the slightly cheaper P2M since it’s in stock.
I asked PMC about the pricing and they said theirs includes the crank arms and the discounted ones @ P2M didn’t. I haven’t had a chance to double check but I’ve had great experiences with PMC in the past so I’ll stick with them.