Garmin Vector 3 Advice


I’ve had a search on the forum but couldn’t find the exact answers to a couple of queries I have about the Vector 3 pedals.

After deliberating on whether to upgrade my trainer to a smart one or get some power meter pedals (until I can afford both) I am erring on the side of some Garmin Vector 3s (single sided for now). I would really appreciate some advice about the following:

  1. My turbo trainer bike has 175mm cranks and my road bike has 172.5mm crank. I know that I can input the crank size when setting up the pedals. Is there a difference in power readings with different crank lengths? I tend to not use my Garmin Edge when I’m using Trainer Road, just the desktop app. Would I have to adjust the crank length on the Edge every time I swap from the indoor to outdoor bike?

  2. Will a single sided pedal power meter give an oscillating power reading as it goes through the pedal stroke or does Trainer Road smooth it out effeciently?

  3. My current non-smart trainer uses a Garmin speed sensor and the power readings have a lag of around five seconds, which means the sprints are often over before my power has reached its target. Will the Vector pedals eliminate this?

Many thanks

  1. Yes, if you want completely accurate power consistent across platforms you’ll need to enter the crank length and run a calibration each time you swap them. Both of those things can be done from Garmin Connect on your phone in about a minute. That said, crank length only seemed to change a few Watts the couple of times I’ve forgotten to do it.

  2. Power smoothing and the report time of the pedals makes this completely transparent to you and the app. There shouldn’t be a difference from a single sided or dual sided meter when functioning properly. You won’t be able to do single leg drills in erg mode, however, for what should be obvious reasons!

  3. While you won’t get instantaneous feedback, it should eliminate this issue. Even on five second sprints during workouts like Ebbetts, my power tracks accurately. Again, not instantaneous, but as good as can be expected when considering smoothing and reporting time from the power meter.

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@kurt.braeckel (I don’t know if I need to @ you in replies), many thanks for the info. That’s what I was hoping to hear. The fact I can change crank size from my phone is good news as I don’t always have my Edge1000 in my shed where the Turbo is. Your replies to points 2 and 3 are another thumbs up for the Vectors. I think I’ll get them.

You’ll find a lot of negative reviews of the Vector 3s based on their early roll out, which Garmin screwed up (akin to Wahoo’s screwup with the 2018 Kickrs and Kickr Cores). Since changing the battery covers (which you shouldn’t have to bother with purchasing today) and using their tip to apply baby oil to the batteries, I’ve had zero issues. The ability to use one power meter on two bikes has been very helpful. The reviews and feedback for the Favero Assiomas are also very good, so those might be worth looking into. As a Garmin user already, you’ll get some cool (albeit not terribly useful right now) metrics from the Vectors. I think both products are high quality. I don’t know a damn thing about the PowerTap P1s other than what I’ve read on DC Rainmaker.

A 175/172.5 crank length mismatch between the powermeter settings and reality would create approx 1.5% power difference (overstating the power if the crank length is longer in the settings than in reality). So yes, it’s important, but no, it’s not huge.


I train on rollers using my Vector 3s exclusively. I have no issues at all with the TR app and data from the pedals. it’s on par with my outside power levels.

The one thing I do notice with one sided pedals is that when I loose concentration and start spinning when fatigued my power drops significantly… since I’m right side dominant, but the 3s is left sided…so my right leg “pushes” harder than my left when on autopilot. This has no real effect on my outside but on the trainer it resorts in dips than sometimes will drop my interval average if I don’t catch it fast enough.

I also swap between crank arm lengths. The bike I use on the trainer is 170mm and the bike I mainly ride has 165mm. I can adjust and recalibrate via the Garmin app easily. I do recommend adjusting this every time for data consistency.

I have no noticeable lag on the trainer (again, I’m on rollers, so dumb trainer). I can spin up from 90watts to over 300watts in realtime.

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Good to know. If it’s easy to swap it over on my phone, it’s just a habit I’ll need to develop. Thanks.

Thanks. I think I’ll go for the single and upgrade at a later date. I’ve read up on leg power discrepancies and it seems to lessen the harder we cycle.