bombadero
Active Member
Kind of funny to see you debating class I vs. class II because I just built the bike below with a combined total of 1100W (although still many thousands less than the crazy bikes you can buy from the likes of Stealth, HPC or other companies). I've actually had to start rebuilding some things on the bike after a few test rides and some "knees on" learning which is how I ended up here.
I was on a thread a while back about getting a full face helmet to wear on certain rides, and was debating if it was overkill. After riding this new bike as essentially a moped for a few rides while I wait for my BB torque sensor, all doubt has been dispelled. Throttle only, it only tops out around 29 MPH, so it's just barely illegal in terms of speed. However, having ridden a class I for the past 3 years as a car replacement, I can report that while it seems small on paper, the difference between 20 and 29 MPH is nothing short of remarkable. 20 MPH feels completely safe, as do faster speeds when going downhill on the class I. 29 MPH on flat ground on this bike feels like a motorcycle even though you aren't going much faster arithmetically speaking. Part of the reason for this is that the amount of road wind increases substantially, which you don't expect on flats. Whereas 20 MPH can feel casual, at 29 MPH my eyes start to water requiring more eye protection. This is probably because aerodynamic efficiency reduces exponentially over 20 MPH on a two-wheeled vehicle.
I also learned that I have the wrong front tire for my intended use. This bike is built as a hill-climbing beast, and my two Grin Tech motors, a GMAC and a Grin All Axle, have very high torque. When I finish the human transmission, to that will be added an 11-50T 11-speed high range cassette and a 3-speed crank (don't remember the teeth) that will give it a >4:1 gear ratio. Even with throttle only, the torque is such that with a 26"x4.8" fat bike tire, you can lose control off the line if you give it too much torque, which is exactly what caused my spill. These tires apparently are also no good on any amount of water over asphalt; the road was lightly spritzed with water from a median sprinkler and it was like I was riding on an iced-over lake. So I've ordered an Origin8 Supercell 26"x4.0", which riders have reported performs well on roads, including in wet conditions, because it is a little narrower and has decent siping. From research, I've learned that apparently the big knobby tires are good at just about every other kind of surface, including wet off-road conditions, besides wet roads. Dry roads are so-so, but they have increased rolling resistance and are quite loud. That didn't seem to hinder this bike, but again as soon as it hits a tiny bit of water it breaks tread. It also self-steers a lot off the line on dry roads. I've seen reviews of dual motor factory e-bikes with knobby fat tires riding on roads, for instance on Electrek, and now know these bikes are death traps. You should change the tires from stock as soon as you buy one if you intend on road riding, or only ride them in off-road conditions.
I also don't plan to use the throttle off the line in the future. I've noticed in a number of videos that people will either apply very light throttle or pedal to start and then gently ease into the throttle while underway. It's hard to modulate my thumb throttle too finely though. It's probably more useful for passing traffic, an additional brief boost on a hill, or if you are very tired. The top speed can only be achieved by pedaling, however, which will probably be somewhere a little over 30. I don't plan to do that very often, but having test ridden a class III I can tell you that it is very confidence inspiring to be able to pass cars going 25 MPH or less. It sounds like a small thing, but often on a class I, class II or unassisted bike you are sort of trapped near befuddled drivers sometimes who are lost or looking for parking, limited by your own top speed of 20 MPH or so, because they are going fast enough you can't pass them, but also braking erratically and making sudden movements. It feels really great to overtake them and leave them behind, not just because it's annoying being trapped like that, but also because it's kind of unsafe, as they are often completely unaware of you in these situations. I also find, when towing a lot of cargo, that I am often put in a similar situation by slower bicycle traffic during rush hour traffic in a bike lane. Because I am towing a lot of stuff, my acceleration is much slower than the mostly unassisted bikes around me, so they take off, sometimes annoyed by me and overtaking from behind. But then I overtake them back as a I gather speed, usually well before the middle of the block. I often have to take the lane in this leap-frogging game, which is again both annoying and somewhat risky. It will be nice to be able to leave these riders behind and simply, and literally, put the problem behind me along with car traffic in these situations in the future. The only thing it doesn't solve is motorcyclists lane splitting, passing or sharing the bike lane, but that doesn't happen very often.
All of that said, I think more protective gear is in order even with safer riding technique and safer tires; I believe I will be getting some elbow and knee guards at a minimum, and possibly a shirt as well. If anyone can recommend a shirt, I would appreciate it. Seems like Leatt makes a good one, but I don't really know what to look for never having raced and all of this generally tending to be racing gear.
I should mention as a post script that a nice thing about a DIY bike build like mine based on a Cycle Analyst computer is that you can change it to being fully road legal with a couple of quick button presses. I have 3 presets programmed in: Eco (class I/II), Speed (class III), and Unlimited. It should be noted Speed can be made illegal instantly by using the throttle while going faster than 20 MPH, then becomes legal again as soon as you release the throttle. I also have a potentiometer wired to the maximum power output; if I dial it down to the minimum of 1.5 kW, which makes the effective nominal power 750W, it is magically road legal along with the Eco or Speed presets being selected. I probably won't have to worry about it too much though, because enforcement in my jurisdiction is basically nonexistent. People ride Stealths and 6000W push scooters in the bike lane worry free here, even though it's entirely illegal. The cops really don't seem to care at all. I don't think they are even aware of the California e-bike laws.
I was on a thread a while back about getting a full face helmet to wear on certain rides, and was debating if it was overkill. After riding this new bike as essentially a moped for a few rides while I wait for my BB torque sensor, all doubt has been dispelled. Throttle only, it only tops out around 29 MPH, so it's just barely illegal in terms of speed. However, having ridden a class I for the past 3 years as a car replacement, I can report that while it seems small on paper, the difference between 20 and 29 MPH is nothing short of remarkable. 20 MPH feels completely safe, as do faster speeds when going downhill on the class I. 29 MPH on flat ground on this bike feels like a motorcycle even though you aren't going much faster arithmetically speaking. Part of the reason for this is that the amount of road wind increases substantially, which you don't expect on flats. Whereas 20 MPH can feel casual, at 29 MPH my eyes start to water requiring more eye protection. This is probably because aerodynamic efficiency reduces exponentially over 20 MPH on a two-wheeled vehicle.
I also learned that I have the wrong front tire for my intended use. This bike is built as a hill-climbing beast, and my two Grin Tech motors, a GMAC and a Grin All Axle, have very high torque. When I finish the human transmission, to that will be added an 11-50T 11-speed high range cassette and a 3-speed crank (don't remember the teeth) that will give it a >4:1 gear ratio. Even with throttle only, the torque is such that with a 26"x4.8" fat bike tire, you can lose control off the line if you give it too much torque, which is exactly what caused my spill. These tires apparently are also no good on any amount of water over asphalt; the road was lightly spritzed with water from a median sprinkler and it was like I was riding on an iced-over lake. So I've ordered an Origin8 Supercell 26"x4.0", which riders have reported performs well on roads, including in wet conditions, because it is a little narrower and has decent siping. From research, I've learned that apparently the big knobby tires are good at just about every other kind of surface, including wet off-road conditions, besides wet roads. Dry roads are so-so, but they have increased rolling resistance and are quite loud. That didn't seem to hinder this bike, but again as soon as it hits a tiny bit of water it breaks tread. It also self-steers a lot off the line on dry roads. I've seen reviews of dual motor factory e-bikes with knobby fat tires riding on roads, for instance on Electrek, and now know these bikes are death traps. You should change the tires from stock as soon as you buy one if you intend on road riding, or only ride them in off-road conditions.
I also don't plan to use the throttle off the line in the future. I've noticed in a number of videos that people will either apply very light throttle or pedal to start and then gently ease into the throttle while underway. It's hard to modulate my thumb throttle too finely though. It's probably more useful for passing traffic, an additional brief boost on a hill, or if you are very tired. The top speed can only be achieved by pedaling, however, which will probably be somewhere a little over 30. I don't plan to do that very often, but having test ridden a class III I can tell you that it is very confidence inspiring to be able to pass cars going 25 MPH or less. It sounds like a small thing, but often on a class I, class II or unassisted bike you are sort of trapped near befuddled drivers sometimes who are lost or looking for parking, limited by your own top speed of 20 MPH or so, because they are going fast enough you can't pass them, but also braking erratically and making sudden movements. It feels really great to overtake them and leave them behind, not just because it's annoying being trapped like that, but also because it's kind of unsafe, as they are often completely unaware of you in these situations. I also find, when towing a lot of cargo, that I am often put in a similar situation by slower bicycle traffic during rush hour traffic in a bike lane. Because I am towing a lot of stuff, my acceleration is much slower than the mostly unassisted bikes around me, so they take off, sometimes annoyed by me and overtaking from behind. But then I overtake them back as a I gather speed, usually well before the middle of the block. I often have to take the lane in this leap-frogging game, which is again both annoying and somewhat risky. It will be nice to be able to leave these riders behind and simply, and literally, put the problem behind me along with car traffic in these situations in the future. The only thing it doesn't solve is motorcyclists lane splitting, passing or sharing the bike lane, but that doesn't happen very often.
All of that said, I think more protective gear is in order even with safer riding technique and safer tires; I believe I will be getting some elbow and knee guards at a minimum, and possibly a shirt as well. If anyone can recommend a shirt, I would appreciate it. Seems like Leatt makes a good one, but I don't really know what to look for never having raced and all of this generally tending to be racing gear.
I should mention as a post script that a nice thing about a DIY bike build like mine based on a Cycle Analyst computer is that you can change it to being fully road legal with a couple of quick button presses. I have 3 presets programmed in: Eco (class I/II), Speed (class III), and Unlimited. It should be noted Speed can be made illegal instantly by using the throttle while going faster than 20 MPH, then becomes legal again as soon as you release the throttle. I also have a potentiometer wired to the maximum power output; if I dial it down to the minimum of 1.5 kW, which makes the effective nominal power 750W, it is magically road legal along with the Eco or Speed presets being selected. I probably won't have to worry about it too much though, because enforcement in my jurisdiction is basically nonexistent. People ride Stealths and 6000W push scooters in the bike lane worry free here, even though it's entirely illegal. The cops really don't seem to care at all. I don't think they are even aware of the California e-bike laws.
. Although I have to admit that after the first test ride in the Unlimited preset, I did say to myself, "I've been a baaaaad boy!" I guess in addition to the Bat Bike I could call it the Bratt Bike.
