Hope you are all well. I am looking to buy a dual side power meter for my Shimano 105 (Crankset: FC7000 50/34, black 170mm, Cassette CS-HG700, 11-speed, 11-34).
First I looked into pedals but unfortunately the options for SPD pedals are limited. The Garmin XC200 are fairly pricy. Main reason for pedals would be that there are easily transferable to a new bike (planning to upgrade my bike next year, currently considering a SRAM group set)
If it comes to crank-based power meters I am looking into the InPeak or 4iiii. InPeak is my current favourite. 4iiii seems to have only an outdated model with dual sided power meter.
The InPeak Powercrank Ready Twin2 looks great at a fair price. Now I’ve been reading that Shimano Dual Sided power meters have issues with accuracy and consistency. Is this still the case? Should I go only one sided?
Favero Assioma pedals are compatible with pretty much any bike, however they are 3 bolt LOOK as standard, does it need to be 2-bolt? You can convert the Assiomas to SPD with some DIY.
TBH if you are planning to go SRAM then a spider/crank PM will be wasted money.
Quarq Dfour PM crankset and move the 105 chainrings across? Very consistent and reliable power and would guess similar price top the other options you’re looking at. Would mean changing your bottom bracket as well though.
Power2Max makes a great PM that’ll work with your 105 rings and Shimano bottom bracket.
There have historically been accuracy issues with right side power meters due to the way Shimano builds the cranks. Not sure if they’ve been sorted out, but I wouldn’t want to take the risk for that kind of money.
Love mine. They’ve been beat to hell with zero issues. Three seasons of XC racing and three BWRs.
Dual sided power meters are totally overrated.
Also, unlike cranks, you can actually calibrate your power pedals to match your trainer. It takes some trial an error but you basically fudge the crank length in your head unit. So let’s say your cranks are 172.5mm. Your power meter reads high, so you now you adjust the crank length value to 171mm or 170mm. Bingo.
At the risk of opening a can of worms, you won’t know if you have a significant L/R imbalance unless you measure total power. I run Assioma Duo-Shi now and found I typically have a 52% L/48% R balance. My prior rides on left side PM’s were therefore reading high and I was blissfully unaware thinking my FTP was higher than it was
I’d argue that total power is preferable, which you can get from spindle or dual sided PM’s. Nothing wrong with single sided PM’s if that’s your main source of power or if you don’t have an imbalance.
I’d say dual sided can be very useful for some people. E.g. I’ve had various injury issues over the years including a herniated disc which have affected my L:R balance. When I’m healthy, fit and on top of my exercises I’m usually in the 48:52 to 50:50 range. But if I’ve got a niggle or am tired it’s not uncommon to see 45:55 and at times following a crash or injury I’ve had rides at 42:58.
Having dual sided means I’m at least aware that something is out of whack and needs working on, and that my power measurements are accurate regardless of L:R imbalances. Single sided for me would hugely underestimate my power at times. Even my “normal” variation of 2-3% difference in contribution from each leg from one ride to the next would double up to 4-6% variations in recorded power which is quite a lot. No idea how common it is for people to have the same sort of variability I do, could be I’m a complete outlier.
The Power2Max seems to be a bit pricy (890€), especially if I am planning to change my bike in 1-2 years. For +50€ I could get the Garmin XC200.
The Quarq DFour spindle seems to be the more budget friendly option (330€ for the spider, 530€ with a full crankset) (suggested by @cartsman)
Right now I am leaning towards Assioma DUO-Shi + SPD pedals (which seems to work fine, if you can deal with the q-factor).
It is not cheap (650€) but it would give me all the flexibility in the future.
I picked up the Duo Shi last fall and have been really impressed. I thought I’d only use them on my gravel bike, but in the past two weeks I’ve swapped them onto a backup road bike and a backup MTB. Really handy and adaptable, having power meter pedals.
I put the SPD pedal bodies on and they’ve been great.
Im testing Inpeak Twin2 now, but on Shimano R8200 crankset and results may be worse, than on 105. 105 crankset aren’t vulnerable in matter of metering inaccuracy, they are constructed in different way, than Ultegra/DuraAce (tested with Ronde on R7000/R8000 I own). If you need to buy crankset, buy 105 with Inpeak. If you have crankset, buy Assioma Duo powermeter.
I just bought a pair of Assioma DUO-Shi and Shimano SPD pedals. Will try this first, if it doesn’t work I think I will get the 4iiii Precision 3 (one sided) and then upgrade to two sided with a new bike.
@HLaB The original hack is not required anymore if you buy the Assioma DUO-Shi (it’s just the spindle, but more q-factor). A couple of Shimano SPD pedals work (while not officially supported), I created an overview here
If you want a Rotor crank set or other options, it gets iteratively more expensive. I’m using the Rotor3D24 crank set which used to ship for 680€. The cheapest Rotor option now is a bit more expensive.
