Hello,
Short question: if you calculate the speed for a given gear ratio at a given cadence, does this also tell you anything about the point at which you will have to spin really fast to gain any more speed ('Spin Factor')? I.e. if you're doing a descent at 30km/h in a given ratio, at what point will your cadence have to become ridiculously fast to gain speed?
A bit more detail:
I've been thinking about different single speed ratios, and found this handy tool for calculating different speeds for various gear ratios at different cadences:
http://www.machars.net/bikecalc.htm
One of the things I'm interested in is whether it's possible to calculate (at least roughly) a 'spin factor' for different gear ratios. For example, the speed for a 46x19 gear at 120 rpm is 36.4 km/h (according to the calculator). So presumably that means that to go any faster than 36.4 km/h you'd have to spin at above 120rpm. So if you're already going that fast (e.g. in a descent), you'd need to spin at a ridiculous cadence to go any faster.
I suppose most of this is obvious, but it's nice to have some numbers for the different speeds and cadences. In general, when riding single speed I'm not that bothered about going fast in descents - I'd prefer to have a slightly lower gear for in the climbs.
However, it seems that the lowest gears have a higher gap between the speeds at higher cadences than the speeds at lower cadences. For example,
46x19 gives a speed of 15.2 km/h @ 50 rpm, whereas 46x21 gives you 13.7 km/h at the same cadence. However, at the higher cadences the gap is bigger: 36.4 mh/h vs. 32.9km/h @120rpm for the same gears. In other words, it's slightly more efficient to use a bit higher gear because you can maintain a higher speed for the same cadence in the descents. You have more to gain in the descents than the climbs.
I have no idea if any of this makes any sense, but I thought it might be interesting.
Short question: if you calculate the speed for a given gear ratio at a given cadence, does this also tell you anything about the point at which you will have to spin really fast to gain any more speed ('Spin Factor')? I.e. if you're doing a descent at 30km/h in a given ratio, at what point will your cadence have to become ridiculously fast to gain speed?
A bit more detail:
I've been thinking about different single speed ratios, and found this handy tool for calculating different speeds for various gear ratios at different cadences:
http://www.machars.net/bikecalc.htm
One of the things I'm interested in is whether it's possible to calculate (at least roughly) a 'spin factor' for different gear ratios. For example, the speed for a 46x19 gear at 120 rpm is 36.4 km/h (according to the calculator). So presumably that means that to go any faster than 36.4 km/h you'd have to spin at above 120rpm. So if you're already going that fast (e.g. in a descent), you'd need to spin at a ridiculous cadence to go any faster.
I suppose most of this is obvious, but it's nice to have some numbers for the different speeds and cadences. In general, when riding single speed I'm not that bothered about going fast in descents - I'd prefer to have a slightly lower gear for in the climbs.
However, it seems that the lowest gears have a higher gap between the speeds at higher cadences than the speeds at lower cadences. For example,
46x19 gives a speed of 15.2 km/h @ 50 rpm, whereas 46x21 gives you 13.7 km/h at the same cadence. However, at the higher cadences the gap is bigger: 36.4 mh/h vs. 32.9km/h @120rpm for the same gears. In other words, it's slightly more efficient to use a bit higher gear because you can maintain a higher speed for the same cadence in the descents. You have more to gain in the descents than the climbs.
I have no idea if any of this makes any sense, but I thought it might be interesting.
