I've got a turbo and I'm trying to calibrate it so that I can compare my workouts.
I've been told that you can calibrate the turbo by:
1. pumping the rear tyre to 100psi
2. riding at 25 mph at usual cadence (100) then stopping and measuring time taken for rear wheel to stop spinning
3. adjusting the resistance (by either the resistance setting or by adjusting the roller)so that the time taken for wheel to stop spinning is 10 seconds.
On my usual (uncalibrated) setting the wheel stopped turning after only about 3-4 seconds. I found that to keep the wheel turning for 10 seconds required the resistance to be very very light so much so that I was having to ease off to bring the speed to 25mph. This clearly can't be right. Has anybody tried calibrating their turbo in this way?
I'm tempted to get a table of gears and speed and adjust the resistance based on say 52/17 - although I've no idea if this will give me the right readings in other gears. Anyone any thoughts?
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Turbo is not the same as the road, so it won't be the same.
Clearly if you're having to ease up to get down to 25mph, then its not hard enough though, so add some resistance until it feels pretty sensible. Then keep it like that.
A cadence of 100 is pretty rapid.
the number of brain cells (in millions) that voluntarily kill themselves per second rather than endure any more of the mind numbing boredom
I bought some Krispy Kreme doughnuts in London last week - they're nice, but nothing special ?
Re the other tips: I've never ridden for more than 70 minutes on the turbo. Most are 30-60 min sessions and pretty hard. I find that boredom is not really the main issue above 85%HRR.
Also just in case you thought I was a total anorak, I do 100+pw outside.
I know there is an army of protestors waiting to leap into action on this forum if anybody mentions those two dirty words: turbo & treadmill.
I've heard about the spin-down method of calibrating, and from respectable sources too (er, well, respectable *forum* sources), though I can't remember the details. But the cadence you ride with and the gear you do it in have no relevance whatsoever once your wheel is spinning freely.
How about putting on your HRM and trying maybe 20 minutes steady on the road (on the flat, on a still day), then trying the same nominal speed on the turbo - if your heart rate isn't the same, the resistance isn't right.
Yes I have computer.
Altering the resistance will have a direct bearing on what speed I can do for a given effort. If the resistance is light I could hold 25mph+ without breaking sweat. If the resistance is high I might struggle to hold 18mph in the same gear and cadence.
The gear ratio speed tables work outside really well (on a calm day), for example I can ride at 24.0 mph in 52/17 at a 100 cadence which is what the tables say. My idea was to adjust the resistance on the turbo so that I reproduce these figures.
The HR method sounds like a sensible idea.
LOL :-)
Top of my Santa list is one of those towelling thingies that catch the sweat :-)
By the way, speed = gear ratio x cadence x 2 x Pi x wheel radius. Not dependent on effort, wind, slope or anything else.
I think we are in agreement but as it is a fairly complicated point I've set out how I understand it and what I am trying to do.
If you cycle in a particular gear at a particular cadence then the wheel will turn at a given speed which will be equal to the speed the bike moves forward. This is true whether you are cycling indoors or outdoors providing you are not going downhill.
Wind resistance and cycling uphill won't make the speed any less if you can maintain the cadence at the given gear. The only effect will be the difference in effort required to maintaining the speed. Similarly on the turbo, increasing the resistance will not affect the speed if you can maintain the gear and cadence.
So what I am trying to do on my turbo is (as a starting point) match the effort required to turn a gear at a particular cadence with that required to turn the same gear at the same cadence on a flat road outside without any wind resistance (this is my reason for using the gear/speed tables). Then maybe I can tweak the resistance a little bit higher to factor in the wind resistance on a still day.