You're going to have to have a crank arm for your specific crank. So you'd need an Ultegra (or maybe 105) arm for your Ultegra crank. That arm won't fit your Truvativ crank. Not sure if anyone makes a PM for Truvativ, although if it's a GXP interface, you could use a SRAM GXP arm.

On the Shimano front, to clarify, you can run any hollowtech 2 left side crank arm meter on any hollowtech 2 crankset. There may be super limited exceptions.

Meaning, if on a budget, you could find a 5700/6700/9000 left crank meter a lot cheaper than an 6800 or r7000/r8000 left crank meter and run it just fine.

So, if you own a hollowtech you aren't limited to the same generation or groupset level for the left crank arm power meter.

Cause, you gotta ask, is a couple grams and some vanity worth probably a couple hundred dollars in cost difference?

Not sure if this answers your question, but I think a few of the crank arm power meter companies will put a power meter on your crank arm if you send it in to them. Check with 4iiii and stages maybe.

---

- Jordan

My Strava

I'm grateful you guys are sharing this info, as I find the powermeter world to be very overwhelming. Do you have any recommendations for where to cross-check compatibility? I have two bikes I'm considering outfitting with single arm PMs but they aren't clearly compatible (at least through my lack of experience). My P2 is 105 (can I put a single Ultegra crank on?) and my Cannondale SuperSix Evo seems to have specific Cannondale requirements for crank arms? I hate this feeling of the compatibility being totally over my head.

Thanks a ton for sharing this expertise.

---

KJ
Swim and Triathlon Coach
AllTerrainEndurance.com
KJ@allterrainendurance.com

You have to think about this as needing a non-drive-side arm that fits the spindle of the the crankset that's already in the bike. Generally (but not always), the spindle is attached to the drive side arm. That's what makes a power meter on a the non-drive-side arm a fairly inexpensive and easy-to-install option. But spindles come in different diameters, and different crank systems have different ways of attaching the arm to the spindles. Then there are different spindle lengths for different systems, with arms that have different degrees of curvature to get the pedal width correct.


Pretty much all the Shimano Hollowtech II cranksets have the same type of spindle, so there's a lot of cross-compatibility when it comes to Shimano single-arm power meters. A 105 non-driveside crank arm will fit on the spindle of an Ultegra crankset. The left and right arms might not match, color-wise, but it would be perfectly functional .

The Cannondale crankset uses a proprietary spindle. To put a single arm power meter on a Cannondale, you have to use a Cannondale specific crank arm. That does NOT mean that's the only power meter you can put on a Cannondale bicycle. Other crankset systems will fit in the Cannondale frame (some may require different bottom bracket bearings).

---

"They're made of latex, not nitroglycerin"

THANK YOU so much. This is exactly the kind of information I've been looking for, I truly appreciate you taking the time to write that out! This is awesome and makes looking at Quark/Stages so much easier.

---

KJ
Swim and Triathlon Coach
AllTerrainEndurance.com
KJ@allterrainendurance.com

For the Supersix Evo, you might consider a Power2Max NG eco, 2-sided, too. They make one for the Cannondale SI/SISL/SISL2 cranks. Depending what chain rings you have on your current crank set, you might be able to reuse them which would make it only $590 US to upgrade.

https://power2max.cc/...cts/ngeco-cannondale

---

"They're made of latex, not nitroglycerin"

Oh that's a great find, thank you!

---

KJ
Swim and Triathlon Coach
AllTerrainEndurance.com
KJ@allterrainendurance.com

I've installed a few left side only crankarms on more than a few bikes now...

If your bike has under the chainstay brakes, be careful. They may not clear. I know my buddy's Madone didn't by more than a red **** hair. Heck! That thing wouldn't even fit Zipp 404s without lots of fiddling with the brake. Zipps with the power meter is a serioius no-go.

HTH

M

Noted, thank you!

---

KJ
Swim and Triathlon Coach
AllTerrainEndurance.com
KJ@allterrainendurance.com

Unless you have some sort of special gearing I would just take the Truvative off and swap on a Shimano bottom bracket and switch the whole crankset between bikes, or just buy a used 105 and swap the left arm between bikes, it's very easy

Have you considered power pedals? Favero single sided are one the $400 range.