"old fashioned" stationary bikes...

No idea exactly how the speed would compare (it depends on the bike and how it calculates "speed" or "power", but if you have improved your "speed" consistently on the same stationary, then that ought to be reflected in improved speed/strength on the bike outside, since both depend on power. Exactly how much will depend on your position on the bike, etc. Before I got my bike trainer, I did 90% of my training on a gym stationary. That one was a bit more modern than the one you describe--it had a watt meter--but similar in terms of resistance levels. Improvements in speed/power on that stationary did correspond to improvements in speed on my road bike; it just wasn't really possible to compare speed (or power) very precisely between the stationary and a real bike outside.

As I recall, the computer on the stationary seemed to overestimate my speed relative to my road bike (saying I was averaging 30 kph for a 2-hour ride, when in fact it was more like 27 on my road bike), but underestimate my power. (I did a 20-minute FTP test on the stationary and on my road bike with a Computrainer with only a few weeks of minimal training between them, and the Computrainer test was about 20 watts higher.) There was clearly some kind of algorithm that the stationary's computer was using to calculate "speed" and power based on resistance level and cadence, and in my case it overemphasized my cadence (which tends toward the high end when pushing for high watts on a test) when calculating speed, while it seemed to put more emphasis on resistance than the Computrainer (and the power meter I have now) did when calculating power.

If there was really a close match between stationary speed and outdoor speed, might want to look into getting your pro card. 29 minutes for a sprint tri bike split sounds really fast! Definitely top age-grouper level for women. My guess is you have improved substantially, but the stationary is giving you higher speed numbers than you'd get outside. Guessing that as a lightweight woman, you're also a fairly high-cadence rider and the computer is playing the same tricks it played for me. But it would not surprise me if, after getting used to the outdoor bike again, you could push closer to 19 mph now.

Edited by Hot Runner 2016-02-08 6:24 AM

The speed never correlates to riding outside. Even on your own bike on a trainer the speed will not be the same.

Your making improvements, so when you go outside you will see the improvements there too. You just don't know how much until you hit the road.

Thanks Hot Runner! I would be very happy with 19mph!

The speed never correlates to riding outside. Even on your own bike on a trainer the speed will not be the same.

Your making improvements, so when you go outside you will see the improvements there too. You just don't know how much until you hit the road.

I also ride one of these bikes a couple time a week at the gym at my office. The previous comments are spot on. It certainly helps your fitness for road cycling, but the data doesn't transfer.

I don't know if you use a cadence sensor and/or HRM when you ride, but I've been using both at the gym (I put the cadence sensor in my shoe) so I can at least carry over a similar cadence and heart rate when I get back on the road. It isn't much, but at least I'll know I'm giving roughly the same level of exertion.

I did that at my local gym years ago...So it was definitely an old fashioned gym bike. Did 2 - 3 rides per week ...by the spring I had developed some real leg/hip pain...the setups on the old bikes seem to be much different from road and especially tri bikes. I do all my winter bike training now on one of my tri bike in my cellar

Thus the pro card comment! I think most likely it is overestimating her "speed" due to high cadence, as it did for me. Although it wasn't a question about training, heart rate can be a good way to compare workout intensity of indoor and outdoor riding (although it may be off if there are big differences in temperature), and to structure workouts. Another thing would be to check cadence and aim to do most riding at a resistance level where one can sustain a similar cadence at a similar effort level (or heart rate) to riding outdoors, regardless of what feedback the bike is giving about "speed" or "power". This was basically how I chose cadence/resistance on the stationary bike.

This makes it less likely that one will simply be spinning away madly in pursuit of high "speed", or pushing gears that are too hard. The resistance levels on those bikes and the position that many of them have make overdoing the resistance and injuring knees, etc. a real concern.

As people have already stated above, there is not much correlation between indoor stationary bikes and actually riding outside. But just staying on top of everything during the cold months where you aren't able to ride as much outside should still show some improvements once you do get back to outdoor riding.