“This model has three settings,” he explained. “It produces between 50 to 75 watts for about an hour and a half, does 150 watts for an hour and in its highest setting, produces 250 watts for up to 30 minutes."
It can provide a substantial advantage at the high levels of competition.
for sure ... average power on a stage might be in the high 300 Ws for a tough mountain time trial, lower over the whole race when you're in the peleton, an extra > 50W or 0.5 W/kg would turn a nobody into a champion.
Look at some of the brushless motors used in RC cars and planes ("drones" as the terminology seems to be today...) --- the power densities are absolutely amazing.
Here's a 4kW (more than 5HP!) motor that's less than 5cm in diameter and 10cm long:
One problem with fitting these into a bike is that they require plenty of active cooling to not overheat, but it shows that such power densities are definitely possible. Especially if for intermittent use with long periods of cooling. 4kW is also extreme overkill if all you're after is a small competitive advantage. As for batteries, 250W for 30 minutes is 125Wh, around the same energy as a typical 9-cell laptop battery.
Problem with those motors is you have to get from 10krpm down to 60-110rpm at the crank. This carries a surprisingly huge penalty in weight and efficiency, up to a point where it's a good idea to just choose a different motor.
My first thought was that it should be impossible, too, but the answer is that the battery isn't in the frame. It's either in the saddlebag or (in the fancier version) disguised as a water bottle.
There's plenty of room in a frame for a battery. You don't need to run the motor 100% of the time - 1 minute bursts at critical times is more than enough.
Shimano, Campagnolo and SRAM all make batteries designed to fit in the seat tube for electronic gear shifting.
> Shimano, Campagnolo and SRAM all make batteries designed to fit in the seat tube for electronic gear shifting.
Electronic shifting uses almost no power; the derailleur just has to periodically move a few millimeters. There's absolutely no comparison.
In total, there is "plenty of room in a frame" and so it's probably theoretically doable, it would just require much more work to pack it with cells and wire everything up. The companies currently making these motor kits are probably using off-the-shelf battery packs.
Maybe you're right, though, that a smaller battery providing "bursts of power" would be enough to make a difference though.
Absolutely - in a climbing stage of le Tour, a racer would just need a few bursts to match the acceleration of the other tops riders as they try to drop the peloton on the steepest sections. 20-30s bursts, 100-200W, would be more than enough to stay in the race.
In something like cyclocross, the difference from a frame motor would probably be even bigger. The races are shorter (60 minutes vs 4-6 hours) and the power bursts are short and intense - power through a mud pit, stay on bike instead of running a super steep hill, etc.
“This model has three settings,” he explained. “It produces between 50 to 75 watts for about an hour and a half, does 150 watts for an hour and in its highest setting, produces 250 watts for up to 30 minutes."
It can provide a substantial advantage at the high levels of competition.