Going down just a 5% grade any rider can easily hit 40mph. Going down a 10% grade you don't even have to pedal to hit 50mph. There is so much that is ignore in the ebike debate. Below 20mph the NHTSA doesn't even car about max power which explains why the federal ebike definition only establishes a power limit above 20mph at the level that would sustain a 170lb at 20mph on a level surface (which is around 300-350W depending on bike type). I know most technical ignorant people think the federal definition established a 750W limit but that is NOT TRUE - it's a rating which engineers can explain or you can go to Grin's website and read more on this.
Keeping it Legal for the Common Good, Staying Within the Legal Classes
- Thread starter Djangodog
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jabberwocky
Well-Known Member
The good news is we don't really have to speculate about power outputs for elite/pro cyclists, many of them post training and race numbers. The top guys can sustain ~5w/kg for an hour, and in the 4-4.5w/kg for 3-4 hours. Rider weights vary (dedicated climbers tend to be super thin, time trialists and sprinters are heavier and generalists are somewhere in the middle) but that translates to a few hundred watts average over multi-hour rides.
During the 2023 tour de frances last time trial, Jonas Vingegaard (eventual tour winner) pushed 465w average over 32min, winning the stage. It should be noted this was considered an absolutely massive effort on his part.
Dedicated time trialists generally put out the biggest numbers (since time trials don't allow tactics like drafting and are usually pretty flat so power to weight is less important than raw power). Elite cyclists doing stuff like the hour record average in the 400-450w range for the full hour.
Sprinters can put out absolutely bonkers numbers (in the thousands of watts) when sprinting at the end of a stage, but they can only sustain it for a few seconds.
Neither of these are true statements. On your average normie road bike riding on the hoods down a 10% grade you'll probably get into the low 30s without pedaling. If you have a very aero bike with low rolling resistance and are riding in the drops to reduce frontal area you can maybe get to 45mph coasting. Wind resistance force is an exponent in that equation so it fights you very fast. If you're riding something more upright (basically anything that isn't a road bike) those numbers decrease quite a bit. If you're very heavy those numbers do go up.
Down a 5% grade on an average bike (like a hardtail MTB), a 200lb rider would need to be putting in ~1000w to hit 40mph. Even on a nice road bike riding in the drops you'd need to input 400+watts to hit 40mph. Definitely not numbers that "any rider" can put up.
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