Are rollers accurate for distance?
12-06-05, 11:34 PM
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Are rollers accurate for distance?
When using rollers with the belt that spins the front drum, does the belt on typical rollers keep pace with the rear drum, or does it slip?
I'm wondering if a computer magnet and sensor mounted on the front wheel would read differently if moved to the rear wheel. Not that distance means anything with no resistance, but you might be able to mentally calculate something like:
35km on rollers = 23km of actual flat road ride in terms of calories expended.
I'm wondering if a computer magnet and sensor mounted on the front wheel would read differently if moved to the rear wheel. Not that distance means anything with no resistance, but you might be able to mentally calculate something like:
35km on rollers = 23km of actual flat road ride in terms of calories expended.
12-06-05, 11:43 PM
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I use a resistance unit on mine, and I can get it dialed in to feel pretty comparable.
Another way to get a good comparison is to go by time, and heart rate. Go for a ride outside for a given amount of time, check your heart rate with either an HRM or manually. Pretty easy.
Then, get on your rollers, and hit those for the same amount of time. My usual target is about 5bpm higher inside than outside. Simply for the fact that the heart will work harder to 1) cool you and 2) move fluids due to dehydration.
Never actually bother looking at the odometer function when on the rollers.
Another way to get a good comparison is to go by time, and heart rate. Go for a ride outside for a given amount of time, check your heart rate with either an HRM or manually. Pretty easy.
Then, get on your rollers, and hit those for the same amount of time. My usual target is about 5bpm higher inside than outside. Simply for the fact that the heart will work harder to 1) cool you and 2) move fluids due to dehydration.
Never actually bother looking at the odometer function when on the rollers.
12-07-05, 01:00 AM
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Put a mark (a piece of reflective tape is probably ideal) on each roller, either on the top edge or on the end.
Get a strobe light with a variable strobe rate and get a helper to adjust it.
Get on the rollers and have the helper adjust the strobe until the rear mark appears to be stationary (assuming you don't throw up or fall off).
If the front mark is also stationary they are spinning at the same rate (assuming they're the same diameter), but if the front mark is slowly wandering the belt is slipping.
Get a strobe light with a variable strobe rate and get a helper to adjust it.
Get on the rollers and have the helper adjust the strobe until the rear mark appears to be stationary (assuming you don't throw up or fall off).
If the front mark is also stationary they are spinning at the same rate (assuming they're the same diameter), but if the front mark is slowly wandering the belt is slipping.
12-07-05, 03:41 AM
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If you use a strobe light while riding on rollers, make sure to film it. I think that would be great for the Darwin awards. Your speed would be a little different front to back but not detectable on a bike computer. As you said do to slippage and difference in tire pressures.
