You should give triathlon a go again. If you can hold 4w/kg for an hour in your AG, you will likely crush the field unless you're at a big WTC event that draws national-class KQ competitors, and even then you'll give the guys in your AG a run for their money on the bike!

It is interesting how much more competitive pure cycling events are than typical triathlon or even running for overall field comparisons (meaning you'll place higher in the overall field), likely due to the much larger number of newbies and casual 'just-finish' participants in tri and running as compared to bike racing where almost everyone there is their to really race and thus have prepared pretty well for it.

I stopped years ago, it was too expensive. I did some duathlons a while back when my running was still ok, they were fun. Cyclocross is my favorite.

By way of comparison, I run like a 24 5k lately and when I jog around in the woods I get a VO2 of 55 which seems a gross overstatement?

Is that 24 min 5k on like minimal run training? Or are you actually running like at least 12 miles per week?

Not much running. I used to run 16 flat, but my body has aged better for cycling than running, I seem to get hurt when I run a lot.

My Garmin est. was within a couple percent of my labs....until I started running on the treadmills at the gym, where the Garmin estimates a pace that is way off so the hr/effort data is fubar.

I like that they do separate VO2max for cycling and running, so at least my cycling one is still accurate.

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My Garmin voodoo estimator figures me at 71, meanwhile golden cheetah has me in the 50's somewhere. My current training FTP is 295 (4.1-4.2w/kg), at my best my ftp might be 300-310 somewhere, so no clue how realistic the garmin estimate is.

Right now its giving me an estimated Half Marathom time that's closer to my training pace than it is to my PB.

I'll note here that I used my Garmin 945 to run that PB.

So, do you have your HR max set correctly? If you ran your "24 5k" all out, your maximum HR in that race is probably close to your HRmax. Try imputing that value into your Garmin device (second icon on the right at the top of the Garmin Connect page), sync your device and see if the VO2max estimate seems more accurate after your subsequent runs/rides.

Would a Max rate in a 5k be a bit less than a real max, like being chased by a bear?

I am no the expert, but I believe a 5K HR is typically within a few beats of HRmax. I'm not sure a "being chased by a bear" test would get the same HRmax that a more standard test would show -- maybe all that adrenaline would let you exceed HRmax -- but if so that wouldn't be relevant.

Anyway, if your 5k maximum HR is slightly below your HRmax, you will get a slightly more conservative VO2max estimate.

Whoops, it defaulted back to 185 from 160, so much for my super elite status. I can go back to getting dropped without shame

For me this problem was caused by a temporary issue with measuring HR. A couple of weeks ago my FR935 gave me a dodgy Vo2max estimate from a longer structured session on Zwift. Later I realized it used the optical HR reader rather than my old trusty Ant+ chest strap. I think the optical HR is ok until I get really sweaty, then it tends to under count HR for me at high stress. The HR stats for the ride were a little lower than normal, while power was the same as usual (erg mode on trainer). So I guess falsely lower HR at my regular FTP = abnormally high Vo2Max.

I'd love it if my Vo2Max really had jumped from 58 to 65 after one session, but sadly the benefit didn't last once I put a new battery into the chest strap.

Now I just wish I knew how to reset this 'hero' score in my Garmin profile so I could see if the Vo2Max estimate really does improve over training... It seems like I'm stuck with it as far as I can tell.

I have my Garmin Connect Fitness dashboard give me that day's computed VO2max (I actually have separate daily VO2 max -- one with no label (but it only seems to be affected by my running) and one for cycling) . And it does go up and down over a training block. You can also have it set up to give you a week by week graph and a month by month graph -- etc.

4w/kg at 135 bpm is quite strong at any age for an age group athlete. If that means your threshold is closer to 4.5, the estimated vo2 max is pretty close to what one would calculate based on the o2 needs to produce that much energy. This assumes a median aerobic efficiency and ftp that is 75% of vo2max.

71 should be around 5w/kg unless you have really low fractional utilization or low aerobic efficiency. You have your max hr set up right?

I recently did a lab VO2 Max test (where they actually measure oxygen coming in and coming out to calculate the maximum volume your body is able to process). It was 49.5ml/min vs. 58 for garmin so a good >15% discrepancy.

I think that where I'm at. I'm just not an elite 58 year old.

Same here... Garmin reports MUCH higher than Golden Cheetah for me. I have a power meter on my bike, and use Golden Cheetah's "Estimate Running Power" on my runs, for the purpose of calculating TSS. But for both running and cycling, my ego wants to believe the Garmin number because it is so much higher.

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-Mark Rebuck, http://www.markrebuck.com/