Power meter on a budget, multi bike solution, dumb trainer, is one even necessary

Hello, I am a light TR user but planning to ramp up more now that my marathon is over.
I currently use a dumb trainer with virtual power, wahoo speed cadence sensor combo.
I have a retro cannondale I use on the trainer and got a new to me, used Cervelo S3 this spring I am using for my outdoor rides. I have no power meter on this bike.
I am thinking it would be nice and make sense to have the same power meter for both bikes so I can have power on outdoor rides as well as it be the same power meter I use for indoor rides so the data is comparable?
This leads me to believe power meter pedals are the best option?
However, I am not sure how necessary, for me, a power meter is for outdoor rides as I am mostly using them now for getting in longer duration rides 2.5-4 hours.
I am also tight on a budget.
My questions are:
-Should I do nothing, keep current set up and just focus on my TR workouts to build fitness with virtual power and use outdoor rides to build seat time?
-Are pedals the way to go? If so can I get away with one sided power to save money? Buy used? If so what is a good make and model to go with?
-Pedals don’t seem the most common way to go, cranks seem more popular. If my observation is right, why? Obviously switching cranks is not easy, I am sure the cranks on my vintage cannondale are not the same as those on my cervelo, I don’t even know how to tell what cranks are compatible with my bike.
-Should I ditch my cannondale and just use 1 bike, the cervelo for both indoor and outdoor riding and get an “blank” style power meter for it (and just get a 2nd wheel, tire and cassette to easily swap out between indoor and outdoor)?

Any feedback or advice is welcomed.

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Short answer: yes.

Longer answer: PM is very useful outside when you need to pace below, at or above threshold. Long slow distance can be paced by heart rate.

Have a look at these cheaper Chinese power meters: https://www.youtube.com/watch?v=5JTBtDxA5Ss


In my view, pedals are the best option. So easy to swap between bikes, and having the same powermeter indoors and out is the best option if you are able. If I were to start again with powermeters, I’d buy the single sided Garmin pedals.


Power pedals are great, so long as you are using road shoes for everything (I have P1s, and I miss power on my MTB!). I think all the current pedals are easy to swap around - the older style Garmin Vectors had those pods that were vulnerable, and they needed to be installed at a specific torque and so were a bit more hassle. I don’t think that’s a problem with the Vector V3. Also, if your cranks are a different length then it’s a bit of a pain changing the crank length settings every time you switch the pedals over.

Having said that, if you don’t have a power meter but want to use Trainer Road indoors, Virtual Power is fine. How valuable the power data is on the outside rides depends on you and your riding.

FWIW, the reason crank arm meters are more popular is that they are cheaper (to manufacture and to buy), more sturdy (no moving parts, not so exposed), and you can use whatever pedal you like (including MTB pedals). They aren’t suitable if you want to move them between bikes on a regular basis though.



You get the same power meter, same saddle, same position indoors and out. Changing over a wheel takes 15 seconds where changing pedals can be a faff even without specific torques required. You should be able to pick up a cheap rear wheel and cassette on Ebay, and put a trainer-specific tyre on it (and pump it up hard!).

And this way you can take your pick of crank or pedal based power meters. IMO you can’t go wrong with Stages, but get whatever suits your needs and budget best.

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+1 for using the same bike on the trainer and the road. A stages single-side is a great option, and if you want dual-side power the power2max NGeco is not that much more expensive. Just gotta make sure you have crank/chainring/bottom bracket compatibility. Once you get a power meter on your cervelo, I’d recommend using that on the trainer for the reasons @martinheadon mentioned above: consistent position, consistent power measurement, and it’s really easy to switch wheels to your trainer-specific wheel. You don’t need a trainer tire, you can just use last year’s worn out road tire. I swap out my tires every couple thousand miles and just switch the old one to my trainer wheel, I’ve never had an issue with this.

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What are you training for?

If your going to do any type of racing (including triathlons) a PM is both useful during your event and it does improve the overall quality of your training. If you are riding for recreation you don’t need a PM but it is nice to have. A PM basically makes a dumb trainer 80% of the way smart so it will put a nice edge on your training and make something like Zwift more usable.

I went from a dumb trainer to dumb trainer + super cheap used PowerTap wheel ($150) and it was a huge improvement. I’ve since gotten a Quarq but after training and racing with a PM, I’d never ever go back. If I was on a tight budget, I’d pick up a closeout Stages if my bottom brackets matched. https://store.stagescycling.com/closeout-cosmetic-blems Otherwise pedals.

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Wow - some interesting deals in there. Many oddball crank lenghts, but still - not bad. And between moving a pair of pedals from one bike to another, to moving a left Hollowtech crank arm, there’s not much of a difference…

I would go for crank based. I’ve got 2 X 4iiii (105 and Ultegra), you can pick them up cheaply and mine have always been spot on. They’re easy to swap, picture shows my keys as it has the tightening nut on so I always have it handy as they get swapped between 5 bikes (tt, road, commuter, etc). I have often thought that I would get pedal based power meters but after two large crashes where the pedals got trashed I’m glad I didn’t. The 4iiii’s survived the crashes without issue. Another problem is getting the right cleats, I prefer Time so no pedal based meters for me

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If you go with say a 4iiii crank PM or some Favero Pedals, both of them have a scaling factor you can use so they can roughly match the power readings of your dumb trainer… Obviously not ideal though as you will be anchoring your power to an inaccurate bit of kit but you wouldn’t have to be taking your be on and off the trainer and you would get some consistency of sorts .

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Assioma single sided $450 and easily swappable. I have dual sided and swap between road, fixed gear and SS Gravel bike. Just wish Assioma would made SPD type off road pedals for MTB.

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I also have a 4iiii crank based power meter on one bike only. I use this bike for all the indoor workouts and outside ones where close tolerance to a pre-determed wattage is required. Otherwise I use HR to monitor how hard im working and despite HR fallabilities, it works well enough for me.

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I’d go with one bike as well, use it indoors and out, then do whatever you want with a power meter. Keep an old wheel with a trainer tire. Swap that before outdoor rides. That was my setup for a while. Easier than swapping pedals.

That said, if you stick with two bikes… I have a TT (tri) and a road bike right now, and went with dual-sided pedal-based power meter after using a PowerTap hub for a long time in training. Happy with the pedals, particularly the ability to easily swap bikes with one accurate PM, but if I had to do it again, I’d look at a swappable crank-based meter or single-sided pedals. Then again, since I’ve had dual sided power, I know my legs are well-balanced. If there’s some other reason you might have an imbalance, dual sided can have value. Otherwise, single-sided is the best value whether crank or pedal, IMO.

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When I got a TR setup on a budget, I opted for a used direct drive fluid trainer (Elite Volano) for $210 as it is more quiet and it did not require me to buy a second rear wheel (which is not strictly speaking necessary, but I don’t want to use up my fancy Vittoria tires on a trainer). And I got a 4iiii crank-based power meter for $325. However, unlike you, I did not have a second bike.

Regarding pedals vs. crank: I think it’s a nice luxury to have a dedicated bike for your trainer — provided that your body position on both bikes is quite similar. But practically, even if you go for pedals, they will in all likelihood stay affixed to one bike all the time. One-sided crank arm-based power meters are still the cheapest option (unless you want to wait for the IQ^2 pedals …), so if you are really on a budget, this is what I would recommend. They are really easy to install, all you need is a torque wrench (very important to get the torque settings right) and a $4 Shimano tool to remove and install the plastic locking nut thingi.

If you opt for a pedal-based power meter, IMHO it makes no sense to go one-sided. With crank-based ones it is a different story, simply because one-sided power meters have become so affordable.

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I only use virtual power with a dumb trainer.

I’m not very tech-literate and whilst I’d love to have some power measurement, I completely understand the difficulty in needing 2 power meters because you need 2 bikes.

I know someone will say you only need 1 bike, just swap a wheel, but I think that the chain would be dirty from an outside ride, so you’d need to be quite consistent at keeping things clean.

It has been worrying seeing how many complaints there have been with the Wahoo Kickr.

I am happy to stay dumb and virtual. Thanks to TrainerRoad for making it easy.

That is one reason (the bike that stays inside requires surprisingly little maintenance, we under-estimate the effect of road dust and grit on a drivetrain). The hassle of moving the bike back and forth is another; and the need to re-align the rear derailleur when moving to a direct-drive trainer is yet another (the probability that the cassettes align perfectly between your rear wheel and your trainer is pretty low).

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I’ve a Hammer Trainer with a SRAM PG-1130 11 speed (11-42) fitted. My MTB has an XD 10-42 11 speed cassette… have never had any alignment issues.

I would think they’d only occur if you have a different cassette size (obvious) or didn’t set up you trainer with the correct spacing for the cassette you are fitting. Think mine required spacers if cassette was 10 speed or less, that long ago I can’t remember.

It takes me a couple of minutes to go from my bike being on a smart trainer to setting it up for outside, and same the other way around. Drive train is continuously lubed by my Flaer system.

It’s something I’ve never thought about, am I one of the lucky ones who is fortunate enough to not have any alignment issues?