Workaround to get VO2Max reading for cycling without a power meter.

honestly this just sounds like a bdas idea in my opinion. Reasons why:

- Biking at the same effort level as running gives you a lower heart rate. (Max effort sprint will result in higher heart rate then max effort on bike)
- Your bike speed won`t correlate to running speed. It will probably tell you that you have in impossible high Vo2max if you suddenly start running at more then 30kph :p
- Because of that the Training status will also be completely out of whack and you`ll also lose your proper running Vo2max indication

what i suggest you do is:

- Forget about your cycling vo2mx for a while, its not that important anyways, and focus on your FTP improvements. They also might also be hard to gauge without a powermeter but, if you have some long flat roads without to much wind or obstacles you can try to do 20min efforts there (just google on how to do an FTP test) and use the Strava watts prediction. It won`t be spot on, but it will give you an idea!

(then you can also use your FTP to better define your training zones)

Dear forum team members,
I've read that VO2Max for running is estimated from speed and HR and, for cycling, a power meter is required (i guess due since shift ratios make speed measurement unreliable).

I've not found a workaround to get a cycling VO2Max reading (e.g. chosse a fixed shift ratio configuration), so, what would happen if I cheat using a 'running' activity when cycling to get a VO2Max reading?. -purchasing a power meter is out of budget in the short/mid term-

I know it will not be precise, but at least it may serve as an index of training status/evolution trend over time. In my case, I do cycling much more often than running, so VO2Max for running reading is not very useful.

What do you think? will this approach work to get a 'trend reading'?. Do you foresee any side effect / collateral damage on readings that I need to consider?.

Thank you very much in advance!

Sorry to say, this won't work... at all - for pretty much the reason you indicated. There is essentially no way for cycling speed to reliably represent an external workload.

And even if you were able to somehow trick your watch into giving you a reading (possible I suppose, maybe) - the analytics engine would, then, not be able to make sense of any runs you perform with the device... and you would also lose out on a host of other personalization aspects that rely on a reasonable accurate VO2max estimate. These would include bad calorie counts and your Training Effect scores and more would be all out of whack... not just for running, but for everything.

I do admire the ambition... and yeah, it would be great to get your fitness data without a power meter.

On the plus side, it doesn't take much running to update your VO2max... a quick 10 min jog is enough in many cases.

I'm primarily a runner and was interested in maintaining my VO2Max readings when using a bike while recovering from an injury. I picked up one of these: https://www.powertap.com/product/powertap-powercal. I got the $70 BLE/ANT+ unit, which works great with my Fenix 5, but they also have a $50 BLE only unit. While it's not a perfect power meter when it comes to instantaneous measurements, the average power over any given activity seems reasonably accurate. You can check out an in depth review here: https://www.dcrainmaker.com/2012/11/cycleops-powercal-in-depth-review.html. I've found that my cycling VO2Max is in the same ballpark as my running VO2Max (50 vs. 54). So, for a runner interested in cycling VO2Max, this product fits the right price to performance ratio.

The main issue is that speed does relate to the amount of effort you make.

Strong wind? That can make you go faster or slower.
Heavy bicycle or luggage? That means more effort to start and going uphill
Incline or declining? That will affect your effort as well.

Etc etc so that is why you need a power meter. Any "workaround" will give you data that is of no use.