4 ms·

With these, you could store energy by pedaling, even when going downhill. If you pedal downhill with a chain, that's just wasted energy.

samstave 4y ago
Unless you downshift and peddle hard to gain a lot of speed :-)
- a4isms 4y ago
  You're joking, but to answer the question seriously, the problem with slamming it into your biggest gear and pedalling downhill is that wind resistance increases with the square of your velocity. When going downhill, you are going faster thanks to gravity. A small increase in speed requires a disproportionally large increase in effort. Hand-waving over the inefficiencies involved in an electric power train, you are far better off pedalling and storing the energy on the downhill, then "spending" that stored energy on the flats or even saving it for the next uphill. With respect to going downhill faster with this system, I doubt it can do anything useful in a straight line descent, but in a long, switchback descent of the type seen in the big Grand Tour races on mountain stages, cyclists need to brake into the switchbacks and accelerate out of them. Regenerative braking followed by assisted pedalling out of the corners would be a huge win.
  - a4isms 4y ago
    > Regenerative braking followed by assisted pedalling out of the corners would be a huge win. ...Until the next ascent, where you have to haul the weight of the battery and what amounts to two electric motors uphill... Although it seems sacrilegious to imagine energy-recovery units in UCI bicycle racing, innovation is strongly influenced by the big manufacturers who are trying to sell bikes. It's unlikely there will be a UCI-sanctioned ERU any time soon, but if there was, the key to adoption would probably be the UCI minimum weight regulations. We are now at the point where high-end bikes often need weights added to meet the minimum, and if the rest of the bike ever gets light enough, it could be possible to add an ERU without compromising the total weight for climbing. But that would require breakthroughs in the culture of bicycle racing and multiple technologies.
  - samstave 4y ago
    >"...The problem with slamming it into your biggest gear and pedalling downhill is that wind resistance increases with the square of your velocity." -- Are you much of a biker? (I put on around ~1,000 miles a month on a 29" mtn bike. Knobby tires and all. At no point ever have I worried about wind resistance - and im not a "shave my legs tour de france" (my brother is, but hes an ultra athelete-type-A Doctor) type that worries about my grams per component, corporate spandex or $12,000 week-end ride. So, while you may be "technically correct" you're commenting as "functionally illiterate"
    - Steltek 4y ago
      Mountain bike descents and road bike descents are dramatically different things.
      - samstave 4y ago
        Find me a road bike with an electric motor.
        a4isms 4y ago
        They exist, and that's why UCI scan bikes at the race start line for electric motors, it's a serious enough problem that it has a name, "Motor doping." Famously, Femke van den Driessche received a six-year ban after being caught motor-doping in cyclocross. https://www.bbc.com/sport/cycling/36142963 https://www.bbc.com/sport/cycling/36142963 If you don't want to cheat with a motor, bicycle stores sell all kinds of road bikes with pedal assist for non-competitive riding. Trek, for example, make several e-assist versions of their Domane road bikes: https://www.trekbikes.com/us/en_US/ebike_collection/ https://www.trekbikes.com/us/en_US/ebike_collection/
        samstave 4y ago
        Where newsletter and how subscibe
    - a4isms 4y ago

samstave 4y ago

Unless you downshift and peddle hard to gain a lot of speed :-)

a4isms 4y ago
You're joking, but to answer the question seriously, the problem with slamming it into your biggest gear and pedalling downhill is that wind resistance increases with the square of your velocity. When going downhill, you are going faster thanks to gravity. A small increase in speed requires a disproportionally large increase in effort. Hand-waving over the inefficiencies involved in an electric power train, you are far better off pedalling and storing the energy on the downhill, then "spending" that stored energy on the flats or even saving it for the next uphill. With respect to going downhill faster with this system, I doubt it can do anything useful in a straight line descent, but in a long, switchback descent of the type seen in the big Grand Tour races on mountain stages, cyclists need to brake into the switchbacks and accelerate out of them. Regenerative braking followed by assisted pedalling out of the corners would be a huge win.
- a4isms 4y ago
  > Regenerative braking followed by assisted pedalling out of the corners would be a huge win. ...Until the next ascent, where you have to haul the weight of the battery and what amounts to two electric motors uphill... Although it seems sacrilegious to imagine energy-recovery units in UCI bicycle racing, innovation is strongly influenced by the big manufacturers who are trying to sell bikes. It's unlikely there will be a UCI-sanctioned ERU any time soon, but if there was, the key to adoption would probably be the UCI minimum weight regulations. We are now at the point where high-end bikes often need weights added to meet the minimum, and if the rest of the bike ever gets light enough, it could be possible to add an ERU without compromising the total weight for climbing. But that would require breakthroughs in the culture of bicycle racing and multiple technologies.
- samstave 4y ago
  >"...The problem with slamming it into your biggest gear and pedalling downhill is that wind resistance increases with the square of your velocity." -- Are you much of a biker? (I put on around ~1,000 miles a month on a 29" mtn bike. Knobby tires and all. At no point ever have I worried about wind resistance - and im not a "shave my legs tour de france" (my brother is, but hes an ultra athelete-type-A Doctor) type that worries about my grams per component, corporate spandex or $12,000 week-end ride. So, while you may be "technically correct" you're commenting as "functionally illiterate"
  - Steltek 4y ago
    Mountain bike descents and road bike descents are dramatically different things.
    - samstave 4y ago
      Find me a road bike with an electric motor.
      - a4isms 4y ago
        They exist, and that's why UCI scan bikes at the race start line for electric motors, it's a serious enough problem that it has a name, "Motor doping." Famously, Femke van den Driessche received a six-year ban after being caught motor-doping in cyclocross. https://www.bbc.com/sport/cycling/36142963 https://www.bbc.com/sport/cycling/36142963 If you don't want to cheat with a motor, bicycle stores sell all kinds of road bikes with pedal assist for non-competitive riding. Trek, for example, make several e-assist versions of their Domane road bikes: https://www.trekbikes.com/us/en_US/ebike_collection/ https://www.trekbikes.com/us/en_US/ebike_collection/
        samstave 4y ago
        Where newsletter and how subscibe
  - a4isms 4y ago