Need Power Meter / Crank / Chainring Advice

Derek

Derek

Active Member
3 weeks ago I suffered a severe lower left leg injury after my V20 slipped out from under me on an unsafe road surface. My foot and pedal got caught in a grate at 20mph and I suffered a compound (“I see my bone”) comminuted (twisty) trimalleolar (3 bits) fracture of my tibia (ankle) and another comminuted (twisty) fracture of my fibula (secondary lower leg bone). I am laid up for the next several weeks, but when I get back on the bike (which I intend to do when able), my plan is to work through my rehabilitation on Zwift in my garage. I will take it slow, but I would like to purchase a power meter which can provide some insight into the power output differential between my two feet - as a way to track my left foot's progress over time. While I'm modifying my drivetrain, I would also like to go to a shorter crank (currently on 165mm) to reduce the articulation of my ankle joint (read 7 screws + titanium plate have me concerned about my mobility). Ideally, I'm thinking about moving down to around a 150mm crank. And, since I'd be doing all of that, I'd also like to swap out my existing 50/34 front chainring setup in favor of something that gives me a slightly larger big-ring. So, based on a lot of reading I've done on this forum over the past few days, I BELIEVE the best setup may be:

But I'm somewhat clueless about the compatibility of components with the SRAM Rival FD + V20 frame...so I thought I'd run this past you all and get your thoughts of whether I'm heading down the right path or not.
 
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jond

jond

Zen MBB Master
Hi Derek. So sorry to hear of your terrible accident. Take time to heal great idea about zwiftin. Keep your chin up. You’ve got this.

if you have a few bikes perhaps dual side pedal power meter would suit for portability options between bikes. not sure if they cater for short short cranks but that’s immaterial as most power meters are not strictly accurate. As long as it’s consistent.

Maybe it’s possible to modify your existing crankset with larger chainring and shortening cranks. Drill and tap.

I’ve mixed sram red yaw fed with shimano chainset and fsa chainset. No issues but these are five and two year old systems. 53-39 fsa and 52-34 shimano and cobb chainset all worked fine with yaw fd.

good luck.
 
Frito Bandito

Frito Bandito

Zen MBB Master
Sorry to hear about your crash and injuries Derek, and wish you a speedy recovery. I have the 4iiii left side PM, but they also offer a dual sided PM called the Precision Pro. You simply send in your cranks and they will install them and return them to you ready to go. You can also order a set of cranks from them with the PM already installed, but they might not have the crank length you are hoping for. Buying the Wickwerks 53/34 then sending them to 4iiii for the install seems relatively inexpensive.

https://4iiii.com

I chose only the left side version because I don't need the balance, just a wattage number to not exceed for endurance rides. I went with 4iiii because (1) I don't need to swap it between my V20 and my DF, it is light, the battery is easy to change, if in the event of a crash then there is probably less of a chance of it getting damaged than a pedal based PM. The PM sits on the inside of the cranks so it is a bit protected, and you just have to make sure there is enough clearance, which on the V20 there is plenty.

The Favero Assioma is a pedal based PM that I was also considering since I do have 2 DF bikes. However, I eventually ruled it out since I don't need it at all for 1 of them, and the other is slowly collecting more and more dust.
 
Mathew Fy

Mathew Fy

GRU
I have an InSpider power meter from Rotor, but haven’t used it enough to evaluate its power metrics. Apparently you can use the data to adjust the angle of your QRings to an optimal position. I believe their 2INPower crank system has better left-right distinguishing capabilities. @LarryOz , didn’t you try this system?
A38F8911-B669-403D-BE7B-0BED5FFD5E83.jpeg
 
LarryOz

LarryOz

Cruzeum Curator & Sigma Wrangler
Mathew Fy said:
I have an InSpider power meter from Rotor, but haven’t used it enough to evaluate its power metrics. Apparently you can use the data to adjust the angle of your QRings to an optimal position. I believe their 2INPower crank system has better left-right distinguishing capabilities. @LarryOz , didn’t you try this system?
Click to expand...
I have this system, but have not tried the that part of it - got side-tracked. :)
 
TransAm

TransAm

Well-Known Member
Frito Bandito said:
Sorry to hear about your crash and injuries Derek, and wish you a speedy recovery. I have the 4iiii left side PM, but they also offer a dual sided PM called the Precision Pro. You simply send in your cranks and they will install them and return them to you ready to go. You can also order a set of cranks from them with the PM already installed, but they might not have the crank length you are hoping for.
Click to expand...

What size and type of crank did you send them?
 
TransAm

TransAm

Well-Known Member
Frito Bandito said:
Instead of sending my crank in I bought a crank with a PM already installed as I didn't have a crankset to use while waiting for the installation. Mine is a 165mm Shimano 105 though.
Click to expand...
Another cheap and dirty option for left only is the new SRAM Rival AXS Power Meter that goes down to 160mm crank length from the factory. It's only US$349 for a complete crankset in 12-speed, but only 40t, 46t, 43x30t, 46x33t and 48x35t options.
 
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