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The problem with fast eBikes is safety -- there's a huge difference in injury (and survivability) between a 15mph collision and a 30mph collision. If a collisi

The problem with fast eBikes is safety -- there's a huge difference in injury (and survivability) between a 15mph collision and a 30mph collision. If a collision between an unprotected bicyclist and a stationary object is similar to that between a car and a pedestrian, the chance of death in a 15mph (25kph) collision is around 5% and the chance of non-minor injury is 10%. In a 50kph collision, that jumps up to a 50% chance of death and 95% chance of non-minor injury. http://www.safespeed.org.uk/killspeed.html http://www.safespeed.org.uk/killspeed.html So sure, build your 30mph bike if you want to, but understand that it's no longer a bike, it's a motor vehicle, and should be restricted to licensed adults and should not be used on bike paths and the rider should probably be wearing a motorcycle-style helmet. I know there's some debate on the effectiveness of bicycle helmets at preventing injury in the low-speed accidents cyclists are usually in, but for motorcyclists, the benefits are more clear -- a 37% reduction in deaths and 67% reduction in brain injuries. http://www.iihs.org/iihs/topics/t/motorcycles/fatalityfacts/motorcycles http://www.iihs.org/iihs/topics/t/motorcycles/fatalityfacts/... Oh, and make sure that your brakes are able to stop your 1000W+ motor if the throttle gets stuck wide open.

throwaway7767 10y ago
> Oh, and make sure that your brakes are able to stop your 1000W+ motor if the throttle gets stuck wide open. This cannot be stressed enough. The amount of new builds on ebike forums where people are building essentially electric motorcycles on bicycle frames with no upgrades to non-drivetrain components is scary. Even with my 500W motor (illegal here, but would be legal in the states, and puny compared to the stuff the article's author is talking about), I found myself wishing the brakes were more responsive. I upgraded the brake pads which made the ratio of stopping power to acceleration acceptable. Then after a year of using that, the aluminum stirrup that the brake noodle slides into bent enough for the noodle to pop out, putting my front brake out of service. This happened while I was applying braking power during a steep downhill descent going 35-40km/h, I lost control and fell off the bike. The stirrup wasn't designed to handle the braking forces I was applying to it with the new brake pads, so over time it bent outwards and eventually gave way. Don't neglect your brakes! After this I upgraded to mechanical disc brakes. EDIT: Regarding "if the throttle gets stuck wide open" - if you don't have motor safety cutoffs installed on your brakes, you should do so now. I've had my PAS controller get into a state where it decided to just apply power even with no movement on the pedals. Always have a cutoff switch! If you dislike the chinese ebrakes (and they do suck), there are inline wire sensors you can install to keep your existing brake handles, and it's also fairly simple to modify your existing handles with a reed switch.
- phkahler 10y ago
  Don't you guys have regenerative braking via the electric motor? From the sound of it, the motor controllers out there are rather primitive in this market. Thoughts?
  - Neliquat 10y ago
    I expect it is a cost/benefit thing, where an ebike is already quite pricey, and equipped with a very reliable fallback.
  - maxerickson 10y ago
    Towards the bicycle end of the spectrum you probably want it to be able to freewheel.
  - Johnny555 10y ago
    There's not a whole lot of energy to recover -- most of the eBike's energy is spent fighting wind resistance, so there's not much left to recover when you're slowing to a stop at a stop sign. Long descents where there is significant energy to recover are not that common for most riders.
    - petre 10y ago
      Well you could just use the drive as an electromagnetic brake w/o necessarily recovering all power by diverting all or just a part of it to a load. Train engines do this.
      - Johnny555 10y ago
        Well you could, but it comes at a cost (in dollars, complexity and weight), and is likely not worth it since the bike still needs friction brakes. It's a different story with a 50 ton train where a 20 KW resistor bank is not a significant amount of weight, but adding a 500W resistor bank to a bike (since you need somewhere for energy to go when the battery is fully charged) is probably not going to be worth the weight and expense. Plus you need some sort of blending between regenerative and friction braking, so it's yet another thing that needs adjusted and maintained.
barrkel 10y ago
Spot on. If you want moped speed, get a moped. You can't safely upgrade one component; you need to upgrade them all. And it's not just your safety, it's the safety of the public, and they have a right to legislate that you don't drive a dangerous vehicle on the public highway.
- cmdrfred 10y ago
  I agree. I personally don't care if this guy cracks his own head open but I believe "my freedom ends where yours begins" and if he's going fast enough to seriously injure or kill someone on the sidewalk he needs to carry some form of insurance to cover the liability. "Here take my iPhone brah” isn't enough for someone who will never walk again. Also if he wants to play around and weave in and out of cars at 30 mph+ and he ends up as a road waffle too bad, so sad.
  - WD-42 10y ago
    What makes you think he's riding on the sidewalk? Riding on the sidewalk is a rookie move and anyone that rides more than once a year knows it. Author has been riding seriously for 40 years. I've been riding nearly daily for 15 years and not once have I ever come in physical contact with a pedestrian. I've been hit by 2 cars though, both times by drivers not paying attention.
    - deleted 10y ago
      [deleted]
    - cmdrfred 10y ago
      Or bike lane, or cross walk. It doesn't matter where he hits the person. He is describing a literal motor vehicle it should be treated as such.
      - petre 10y ago
        I'd say Californian law is spot on.
    - 10y ago
jcoffland 10y ago
> In a 50kph collision, that jumps up to a 50% chance of death and 95% chance of non-minor injury. Oh come on. Exactly how was that statistic collected? When people have non-fatal accidents they usually don't report it. In fact, the link you posted above is to a guy complaining that the stats you quoted don't stand up to reason. http://www.safespeed.org.uk/killspeed.html http://www.safespeed.org.uk/killspeed.html
- Johnny555 10y ago
  Admittedly I just picked the first speed versus fatality chart I could find with references (and they do link to the government site where the data came from). Here's another study: https://www.aaafoundation.org/sites/default/files/2011PedestrianRiskVsSpeed.pdf https://www.aaafoundation.org/sites/default/files/2011Pedest... This one shows a fatality rate of 2.3% for speeds from 10.0 – 19.9 mph, and 35% for speeds from 30.0 – 39.9mph. Even though the rate is different, it's still showing over a 10X difference in fatality rates at the higher speeds. Consider this, at 30mph a cyclists body has to dissipate 4 times more energy than a 15mph cyclist. There's not much in a bike to absorb energy like in a car.
gammaray 10y ago
> Oh, and make sure that your brakes are able to stop your 1000W+ motor if the throttle gets stuck wide open. Fortunately, a lot of custom sinusoidal controllers have a voltage gap between 0-1V and 4-5V (or whatever full throttle is for a build) to prevent full throttle or full braking with any electrical component in the case of wiring failure.
faster 10y ago
Speed is one factor, difference in speed is a more useful measure of the risk of harm. If you're going 15mph on a road marked 35, you are in danger BECAUSE you are slower than the rest of the traffic on that road. Other vehicles expect traffic to go at or near the posted limit, if conditions allow it. Hitting a wall at 15mph is one hazard; getting hit by a car going 20mph faster than you is a bigger hazard. In Hawaii, because some people tend to drive too slowly and doing so causes crashes, they post the minimum speed below the limit on a lot of roads. Across the US, it is illegal to go more than 15 below the limit in clear conditions. Once a cyclist has a motor, it seems they are more likely to 'claim' a lane and then they need to keep up or risk being a roadblock. It's less safe either way, and I'm not sure there is a viable solution. Part of the thrill of cycling in traffic, I guess.
- gertef 10y ago
  Momentum matters as much as speed. Suppose you are doing 35mph on a bike the road and you get sideswiped by a car doing 35mph. The direct impact is negligible, but now you've got angular momentum that is going to send you into another car or the ground at high speed. And even if you are doing 35mph, and claiming a lane, you'll still be passed (often unsafely) by cars doing 40, 50mph. (Source: motorcyclist who can't go fast up hills)

throwaway7767 10y ago

> Oh, and make sure that your brakes are able to stop your 1000W+ motor if the throttle gets stuck wide open. This cannot be stressed enough. The amount of new builds on ebike forums where people are building essentially electric motorcycles on bicycle frames with no upgrades to non-drivetrain components is scary. Even with my 500W motor (illegal here, but would be legal in the states, and puny compared to the stuff the article's author is talking about), I found myself wishing the brakes were more responsive. I upgraded the brake pads which made the ratio of stopping power to acceleration acceptable. Then after a year of using that, the aluminum stirrup that the brake noodle slides into bent enough for the noodle to pop out, putting my front brake out of service. This happened while I was applying braking power during a steep downhill descent going 35-40km/h, I lost control and fell off the bike. The stirrup wasn't designed to handle the braking forces I was applying to it with the new brake pads, so over time it bent outwards and eventually gave way. Don't neglect your brakes! After this I upgraded to mechanical disc brakes. EDIT: Regarding "if the throttle gets stuck wide open" - if you don't have motor safety cutoffs installed on your brakes, you should do so now. I've had my PAS controller get into a state where it decided to just apply power even with no movement on the pedals. Always have a cutoff switch! If you dislike the chinese ebrakes (and they do suck), there are inline wire sensors you can install to keep your existing brake handles, and it's also fairly simple to modify your existing handles with a reed switch.

phkahler 10y ago
Don't you guys have regenerative braking via the electric motor? From the sound of it, the motor controllers out there are rather primitive in this market. Thoughts?
- Neliquat 10y ago
  I expect it is a cost/benefit thing, where an ebike is already quite pricey, and equipped with a very reliable fallback.
- maxerickson 10y ago
  Towards the bicycle end of the spectrum you probably want it to be able to freewheel.
- Johnny555 10y ago
  There's not a whole lot of energy to recover -- most of the eBike's energy is spent fighting wind resistance, so there's not much left to recover when you're slowing to a stop at a stop sign. Long descents where there is significant energy to recover are not that common for most riders.
  - petre 10y ago
    Well you could just use the drive as an electromagnetic brake w/o necessarily recovering all power by diverting all or just a part of it to a load. Train engines do this.
    - Johnny555 10y ago
      Well you could, but it comes at a cost (in dollars, complexity and weight), and is likely not worth it since the bike still needs friction brakes. It's a different story with a 50 ton train where a 20 KW resistor bank is not a significant amount of weight, but adding a 500W resistor bank to a bike (since you need somewhere for energy to go when the battery is fully charged) is probably not going to be worth the weight and expense. Plus you need some sort of blending between regenerative and friction braking, so it's yet another thing that needs adjusted and maintained.

barrkel 10y ago

Spot on. If you want moped speed, get a moped. You can't safely upgrade one component; you need to upgrade them all. And it's not just your safety, it's the safety of the public, and they have a right to legislate that you don't drive a dangerous vehicle on the public highway.

cmdrfred 10y ago
I agree. I personally don't care if this guy cracks his own head open but I believe "my freedom ends where yours begins" and if he's going fast enough to seriously injure or kill someone on the sidewalk he needs to carry some form of insurance to cover the liability. "Here take my iPhone brah” isn't enough for someone who will never walk again. Also if he wants to play around and weave in and out of cars at 30 mph+ and he ends up as a road waffle too bad, so sad.
- WD-42 10y ago
  What makes you think he's riding on the sidewalk? Riding on the sidewalk is a rookie move and anyone that rides more than once a year knows it. Author has been riding seriously for 40 years. I've been riding nearly daily for 15 years and not once have I ever come in physical contact with a pedestrian. I've been hit by 2 cars though, both times by drivers not paying attention.
  - deleted 10y ago
    [deleted]
  - cmdrfred 10y ago
    Or bike lane, or cross walk. It doesn't matter where he hits the person. He is describing a literal motor vehicle it should be treated as such.
    - petre 10y ago
      I'd say Californian law is spot on.
  - 10y ago

jcoffland 10y ago

> In a 50kph collision, that jumps up to a 50% chance of death and 95% chance of non-minor injury. Oh come on. Exactly how was that statistic collected? When people have non-fatal accidents they usually don't report it. In fact, the link you posted above is to a guy complaining that the stats you quoted don't stand up to reason. http://www.safespeed.org.uk/killspeed.html http://www.safespeed.org.uk/killspeed.html

Johnny555 10y ago
Admittedly I just picked the first speed versus fatality chart I could find with references (and they do link to the government site where the data came from). Here's another study: https://www.aaafoundation.org/sites/default/files/2011PedestrianRiskVsSpeed.pdf https://www.aaafoundation.org/sites/default/files/2011Pedest... This one shows a fatality rate of 2.3% for speeds from 10.0 – 19.9 mph, and 35% for speeds from 30.0 – 39.9mph. Even though the rate is different, it's still showing over a 10X difference in fatality rates at the higher speeds. Consider this, at 30mph a cyclists body has to dissipate 4 times more energy than a 15mph cyclist. There's not much in a bike to absorb energy like in a car.

gammaray 10y ago

> Oh, and make sure that your brakes are able to stop your 1000W+ motor if the throttle gets stuck wide open. Fortunately, a lot of custom sinusoidal controllers have a voltage gap between 0-1V and 4-5V (or whatever full throttle is for a build) to prevent full throttle or full braking with any electrical component in the case of wiring failure.

faster 10y ago

Speed is one factor, difference in speed is a more useful measure of the risk of harm. If you're going 15mph on a road marked 35, you are in danger BECAUSE you are slower than the rest of the traffic on that road. Other vehicles expect traffic to go at or near the posted limit, if conditions allow it. Hitting a wall at 15mph is one hazard; getting hit by a car going 20mph faster than you is a bigger hazard. In Hawaii, because some people tend to drive too slowly and doing so causes crashes, they post the minimum speed below the limit on a lot of roads. Across the US, it is illegal to go more than 15 below the limit in clear conditions. Once a cyclist has a motor, it seems they are more likely to 'claim' a lane and then they need to keep up or risk being a roadblock. It's less safe either way, and I'm not sure there is a viable solution. Part of the thrill of cycling in traffic, I guess.

gertef 10y ago
Momentum matters as much as speed. Suppose you are doing 35mph on a bike the road and you get sideswiped by a car doing 35mph. The direct impact is negligible, but now you've got angular momentum that is going to send you into another car or the ground at high speed. And even if you are doing 35mph, and claiming a lane, you'll still be passed (often unsafely) by cars doing 40, 50mph. (Source: motorcyclist who can't go fast up hills)