4 ms·

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 increase

by 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
  I really don't want this to devolve into chest-pounding, but I have worked in the bike industry, and have raced on-and-off as an amateur in road, cyclocross, MTB, and duathlon dating back to the late 80s. I remember when the Ritchey P23 was the state-of-the-art in lightweight mountain biking, something I chuckled at when riding a 17 pound carbon Ibis a couple of decades later. Wind resistance absolutely matters in every discipline of cycling, and you don't need to have been fooling around with bikes for forty years to know that. If it didn't matter, what are all those triathletes and time trialists doing with aero bars, flat backs, and disc wheels? It matters in MTB as well. The optimal position for efficiently generating power on a bicycle is actually quite upright, you can see this if you look at pictures of people riding "roller races," they usually flipped their handlebars up so they could be much more upright than when riding on a track. XC MTBs have much lower bars than would be most efficient on rollers without wind resistance, and that's because the lower position generates less drag, knobby tires and all. Even if you aren't riding a time trial or racing XC on an MTB, knowing where to expend your energy and where to save it matters greatly. If your daily commute involves hills, you will work less and arrive sooner if you don't try to crank your max while descending, and save your efforts for climbing. That's just math and physics. --- Also, please, I'm not upset at any random internet person using insulting language, but it is not constructive for our community to go around suggesting other users are "functionally illiterate."

by a4isms 4y ago

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
I really don't want this to devolve into chest-pounding, but I have worked in the bike industry, and have raced on-and-off as an amateur in road, cyclocross, MTB, and duathlon dating back to the late 80s. I remember when the Ritchey P23 was the state-of-the-art in lightweight mountain biking, something I chuckled at when riding a 17 pound carbon Ibis a couple of decades later. Wind resistance absolutely matters in every discipline of cycling, and you don't need to have been fooling around with bikes for forty years to know that. If it didn't matter, what are all those triathletes and time trialists doing with aero bars, flat backs, and disc wheels? It matters in MTB as well. The optimal position for efficiently generating power on a bicycle is actually quite upright, you can see this if you look at pictures of people riding "roller races," they usually flipped their handlebars up so they could be much more upright than when riding on a track. XC MTBs have much lower bars than would be most efficient on rollers without wind resistance, and that's because the lower position generates less drag, knobby tires and all. Even if you aren't riding a time trial or racing XC on an MTB, knowing where to expend your energy and where to save it matters greatly. If your daily commute involves hills, you will work less and arrive sooner if you don't try to crank your max while descending, and save your efforts for climbing. That's just math and physics. --- Also, please, I'm not upset at any random internet person using insulting language, but it is not constructive for our community to go around suggesting other users are "functionally illiterate."