cross-posted from: https://lemmy.ca/post/49655095
This is an Ultegra 11s chain after 1000km of wear from a 1500W mid-drive. Used to ride a Tangent back in 2016. T’was shredding till it went *clunk*.
cross-posted from: https://lemmy.ca/post/49655095
This is an Ultegra 11s chain after 1000km of wear from a 1500W mid-drive. Used to ride a Tangent back in 2016. T’was shredding till it went *clunk*.
I feel like 1500 Watts is crazy for anything categorized as a “bicycle.” That’s like having four elite road racers towing you along. I’m impressed that a chain designed for human power levels lasted 1000km.
The peak torque was similar to pushing standing on the pedals, a torque a chain must sustain, but not necessarily for extended periods. This motor could sustain that torque for as long as the battery lasts. Production motors these days can do similar peak torque during start from a stop but don’t sustain it indefinitely. I think the Tangent was geared to do about 120Nm. The new DJI does 120Nm for half a minute. Bosch has a few models that do 100. After trashing that chain, I switched to ebike-specific model from KMC. Never had an issue with it and lasted thousands of km on that monster. I now ride all my bikes with X11e EPT / e11 EPT even though I don’t use mid-drives anymore. It lasts a lot and it handles a lot of abuse and neglect.
Care to educate me about drive types and why mid drive is not your preference anymore. Am looking into ebikes.
Both mid-drives and hubs are great. The main differences come down to weight distribution and climbing ability. Climbing ability is significantly better with mid-drives because they can use the bike’s drivetrain to achieve higher speed reduction and therefore higher torque. This allows a mid-drive to exchange bike speed for torque which makes it able to climb steep inclines. Hubs generally come with a fixed gearing or no gearing at all. The highest reduction hubs come with 13:1 gearing which is much smaller than the effective gearing a mid-drive and drivetrain can achieve. The lower the gearing ratio, the larger and heavier the motor has to be to achieve equivalent torque. Which brings me to weight distribution. Mid-drives sit low, in the middle of the bike which doesn’t significantly affect handling. Hubs add 1.8kg at a minimum to one end of the bike. 1.8-2.5kg on the lower end is noticeable but it isn’t horrible. Larger hubs are more noticeable. Many hubs are in the 3-5kg range. On flat ground or low inclines, there’s no significant differences in the behaviour of a small hub compared to a mid-drive. Both feel great.
Another important difference is the ability to shed heat. Most hubs shed heat poorly and overheat if pushed hard at low speed over many minutes. Some are better than others. Mid-drives are better at that and typically have internal temp monitoring and control.
Both hubs and mid-drives have special requirements around frame mounting. Most mid-drives need special frames. Hubs require strong dropouts, and/or torque arms. Installing a hub on an aluminum frame is only safe without atorque arm in the rear. And even then you may start mangling the material when cycling the nuts at 40-50Nm as required.
Hubs generally require less maintenance as tbey don’t wear your drivetrain. Direct-drive hubs should be almost indestructible as they have no internal gears to melt.
Factory mid-drives like Bosch, etc. require authorized service to repair so DIY is no-go as far as I’m awarr. Hubs don’t. This is the main reason I’m riding small hubs (Bafang G310). I can repair any part of the system myself. If the hub goes, I can replace it with another, even different hub and get the rest of the system to play nice with it.
In the end, if I were not into bike DIY, I’d probably buy a factory bike with a mid-drive. And if I wetr into DIY, then it depends on the application.
The thing is, you don’t need 1500w for climbing. I have a mid drive I limit to 450w and it’s perfectly fine. I’ve legitimately never once felt like it needed more power as long as I’m pedaling. I feel like the only reason to have these big mid drive motors is if you are allergic to pedaling.
Oh yeah, you don’t need more than 500W for climbing if you pedal. That said, if you ran a small hub of the 2-2.5kg range at 400-500W at low speed, like when climbing, you’d overheat it and melt its gears in minutes. Ebikes.ca have a nice motor simulator that can pretty accurately estimates how long it takes for many different motors to overheat.
You’re doing something seriously wrong if you’re melting gears.
Not quite. Just ran a couple of simulations with the motor I use. If you run a Bafang G310 at its nominal power of 250W at 5% incline, it would reach 150°C in 25 minutes. Its gears are nylon which soften and lose a lot of their strength well before that - in the 65-85 range. Their teeth would strip under power well before the motor reaches 150°C. At 10% incline it overheats in 5 minutes, gears would strip in less. If you run it at 500W on 5% incline and many controllers would give it that much, it would overheat in 12 minutes. Even on flat ground, I can get mine to 85°C by riding hard at high speed with the motor at ~450W in under 45 minutes. If then started climbing a steep incline with the same power and low speed, I’d very likely strip the softened gears. A friend stripped his this way. This is what they looked like:
You can see how the stripped teeth are at the motor rotor shaft end, which is one of the hottest parts of the motor.
A beefier motor like the GMAC can withstand 5% grade at 500-700W of power without overheating. Perhaps without losing teeth too since its gears are significantly stronger even if still nylon. 10% at ~650W would kill it under 13 minutes.
So it depends on a few variables but especially small motors aren’t difficult to “melt their gears of” by which I mean soften enough to strip under load.
Oh wow. I didn’t assume nylon gears!
You need a better polymer with a higher glass transition temp.
The relevance here is that mid-drive uses the chain since the motor is near the pedals, hub drive powers the wheel directly. So in this context, they no longer need to worry about the durability of the chain versus powerful motors.
Sure, if you’re Tadej Pogačar + 250 watts!
I can see that. I bought a new (non e)bike for work commute, and my riding style was always accelerating at max, or working hard to keep the speed max. When I went back for their complimentary tune up a few months later, they said they’d never seen a cassette and chain worn so much for a new bike. What can I say? 200lb guy getting to work as fast as possible, every day. Chain and cassette no designs for 200lb guy giving it the most.
Hahaha. What chain and cassette?
Well, I was told by my local shop that with the heavy riding I do with wet lube (most common oil type) that a 1000 was when the chain was worn, I had several last 3000. Now I had to do replace other parts at that time as well.
Waxing (if done correctly) is supposed to allow the chain to last longer before it’s stretched out, or breaks in a couple possible ways.
There is also dry oil, but I haven’t used or looked into that as I went from wet lube to wax because of some coworkers.
1500 Watts (2 horsepower) is still pushing the limit of the “bicycle” category as a whole. That’s at the low end of what 50cc gas scooters output. In some jurisdictions it’s enough power to require a drivers license. I guess I’m just impressed with what the ebike world is getting away with calling a bicycle.
The ebike world isn’t getting away with calling this a bicycle. This was a custom designed mid-drive made by a crazy guy that wanted to shred offroad. This contraption would never pass any legal certification for an ebike. I don’t think he made more than a few hundred of these before he stopped making them. In fact that was part of the reason I switched to a small hub. It was lots of fun but both illegal and unsafe. Going over 55kph at the push of a button is not something you want long-term. Accidents happen and the energy the body has to absorb coming to a stop grows exponentially with speed so…
E: The most powerful version was 6KW. Here’s a guy riding it, limited to 4KW.
Motorized bicycle kits (the cheap ones, 1.5 to 2 HP) come with 410 chain for the drive sprocket, and people often upgrade that to 415 chain, because the 410 is just “okay” for that. (Or is it 415 and 420? Been a while, I forget, but the point is they come with beefier chains than bicycles, and even those are insufficient for 1.5HP.)
Even on a full and proper chain-driven motorcycle, the chain and sprockets need to be replaced kind of regularly, and that’s with cleaning and oiling often.
This on a bicycle chain driven by 1500W is no surprise whatsoever.
Fair.