deacon mark

I have runner’s dystonia so cannot run full out for any length of time as gets get tied up. Cycling not an issue. I want to know what my estimated VO2 would be based on cycling time trial. I don’t have a power meter. Does some know of a chart that might provide this estimate. Running calculators do this pretty eas

RChung

Sorry for your dystonia.

The reason why you don't see rules of thumb like that is because power for a cycling time trial depends much more on terrain, wind, and aerodynamic position than running. However, if you do have a some way to convert your time trial into a power estimate, then given average metabolic economy for an average-sized adult a rough rule of thumb is about 75 watts per L of O2 per minute. So if you have an estimate of VO2 from running in terms of mL/min/kg, you can multiply by your mass to get mL/min, then divide by 1000 to get L/min, then see whether the power estimate from O2 is consistent with the power estimate from your time trial. It's a tad convoluted and there are several fudge factors in there, but it should put you into the right ballpark. Alternatively, you can go the opposite way and if you have a power estimate for the time trial you can do the calculation backward and see how your VO2 in terms of mL/min/kg for cycling compares with that for running.

deacon mark

Well that is what I would like to try and do. Say some time trial over a relatively flat course with wind issue being minimized. I am have never strictly done a real time trail. I do however sometimes go out on a measure course I do and just go hard for say 25 miles. I can solo ride 25 in maybe 70 minutes. I now I can relatively easily do 25 miles at 20 mph. Frankly my issue is aerobically I am in good shape for age 59. I have huge endurance and resting pulse is like 40. I have been averaging 700-1000 miles riding a month for past 6 months. I just would like to figure my VO2. As you say running it is easy. I am runner first but over past 5 years the dystonia makes running for any length hard. I can actually sprint for say 1 minute hard but then have to walk or I will trip. I just cannot run long enough to get in my limit. My best 10ks at age 30 were 38 minutes. I think back when I could do this in my prime it was in the mid 50's. I am a total lone ranger riding but at times when around groups I do find that I can kick it and a lot and that surprises me although it should not since running with others much easier.

RChung

Well, if it's flat and there's minimal wind, then the only thing left is the aero drag. Unfortunately, for an average-sized rider on a road (not TT) bike, the CdA can range from maybe 0.275 m^2 up to maybe 0.40 m^2. If you can ride in the drops, probably mid to low 0.3x m^2. Then given your time you can figure out what your average power was. I suppose you could bracket it by assuming something like 0.3 and 0.4, and that would give you a range.

Here's another rough rule of thumb for getting from running speed to power: for an average-sized runner on flat firm ground, running speed in m/sec ~ watts/kg. So, if you used to run 10k in 38:00, that's about 4.4 m/sec, and you would have producing, ballpark, 4.4 watts/kg.

Dean V

Why do you want to know your Vo2 max?
Aside from all the variables with aero drag etc that have been mentioned I thought it wasn't a direct indicator of cycling performance anyway?
In other words, someone could have a higher Vo2 max than someone else, but a lower power/weight ratio.

RChung

Although the OP mentions "max" in the subject line, the post itself makes clearer he's asking about VO2. You can't really maintain VO2Max in a TT. TT pace is lower than VO2Max pace. TT pace is closer to VO2 at LT (lactate threshold), or MLSS (maximum lactate steady state).

The OP wants to be able to estimate VO2 from cycling because he can't use the Daniels formula from running anymore.

deacon mark

Exactly! Has nothing to do with my cycling ability I just wanted to figure it now and some estimate at my age. As far as cycling is concern I ride fine and thank goodness the dystonia has no effect on my cycling. I am a decent rider for sure but of course I have long background. Cycling is just so much more complicated to make comparisons to each ride and other factors. Running is straightforward you run and can make pretty fair generalizations. On the bike is all goes out the wind. Rarely would two rides on the same course exactly each day be the same. The other aspect is the even the same course can yield drastically different data on given days.

gsa103

Hill climbs are much better for estimating power, aero drag is basically one giant fudge factor. If you can find a nice long (a couple of km) 6% grade, time yourself. Weigh yourself & your bike, you should get a decent estimate for time. There's a some fudge factors for rolling resistance and aero drag, but at slower speeds those introduce MUCH less error.