Cassette durability! Convert to SRAM EX1? Try Rohloff E14, Nuvinci n360?

dadoftwinsfml

New Member
Hey all,

I ride a bafang ultra based ebike. I keep going through cassettes, at a rate of about 1 cassette every 200-300 miles. I really only have problems with the bottom 11T ring, as I often do stretches at 35-40MPH with the motor cranking at 1500W. The small number of teeth (I think) get ground down quicker and the chain starts to slip.

I've tried finding the hardest steel cassettes I can (which helps!) but still, this motor eats through them pretty quick.

I'm considering a few things:

1) Replace the drive train with SRAM EX1. It has a 400$ (!?) hardened steel cassette. Only thing is I've been reading reviews and there are a lot of complaints that the derailleur is crap and has a manufacturers defect that SRAM isn't fixing. I'm leary of switching when I read a lot of people saying their switching back after 400 miles and what not. Anyone have more experience with EX1 and can speak directly to durability of the lower range gears after thousands of miles?

I love the idea of being able to shift under load! But I'd hate to switch and a) the problem isn't solved or b) the setup has other annoying issues?

2) Buy cassettes and chains in bulk and just keep going through em. It's a possibility! I mean, I would have to go through 10 regular steel cassettes in order to make up for one single SRAM EX1 cassette.

3) Go internal gears. I've heard good things about the Rohloff E14, but obviously this is both a big investment and not the easiest task to perform myself. I'm not sure I trust myself to build my own wheel, and I have no idea how to go about getting a wheel built for my bike. Has anyone done this?

Any thoughts from others with high output e-bikes? Are others experiencing this? Anyone found a good solution?

Thanks!
 

Dmitri

Active Member
Okay, well let me prefix this by saying that the Bafang Ultra is, ahem, a pretty bad motor. It's made infinitely worse by the default programming that it originally comes with. Its startup behavior is very abrupt, which puts unreasonable strain on the chain, leading to premature chain wear. Some companies such as Biktrix manage to tune the motor prior to selling it to perform better, but still, in the end you end up with something that's far too powerful given the load. As far as the 11T ring goes, it's not really surprising due to the huge gear ratio involved when going at high speeds. Also, unlike Bosch, Bafang has no shift detection so when you shift under power you wear out your drive train even more.

The idea of stocking up on EX1 cassettes is a bit silly because all you get is a slightly thicker chain. In my experience, thicker chains do not translate to longevity gains and in fact you sometimes get the reverse situation. Besides, as you yourself describe, this really will not help the situation if you're primarily wearing out your smallest cog. If you really want to buy into a wide-range 8x system, you probably want SunRace — that's where you can actually stock up on the cassettes (since they're much cheaper) but I doubt it will help.

The idea of shifting under load is a bad idea and you should quit it. Did you know... we Rohloff users cannot shift under any load. That's right, it's impossible. Yet we somehow live with it.

Regarding Rohloff. First, you probably won't manage to retrofit it onto a Thru Axle system. So if you've got a Biktrix or something like that, it's impossible. If you've got a Frey — yep, that can be done. Now I'm saying probably because if you've got the special Rohloff measurement kit ($400), you can measure your rear Thru Axle droupouts and custom-order a hub, but... most people won't manage that, it's too complicated. Building a custom wheel isn't actually complicated, so if your bike supports QR, all you need is a Rohloff hub (there's like 80 variations, so be sure to get the right one) and a rim (most likely 36-hole), take it to your LBS and there you have it!

Second, while Rohloff theoretically claims to be able to handle this sort of strain, there are hubs which are cheaper and can handle it better. This includes the 8- and especially the 3-speed Shimano hub. Again, these are only compatible with QR dropouts, so if you have TR, forget it. Also, the idea that you actually need >3 gears on an Ultra-equipped bike is a silly one anyway because whatever you do, literally as soon as you're turning the pedals, you're straining the system an insane amount just due to the terrible way the whole PAS/torque system in the Ultra is designed (it can only marginally be mitigated with good programming). Ultra doesn't do gradual assist like other motors, it does 'all or nothing' so all those gears, well, they don't make that much sense.

The real problem though is one you cannot solve: the very abrupt spin-up of the motor. Which is why I love Yamaha: they understand that start-up needs to be gradual. Bosch get it too, but Yamaha does it better.
 

jim6b

Active Member
Back in the day, the smallest cassette rings were independently replaceable. That is the 11 T itself could be removed from the cassette and replaced while keeping the other rings.

You might look around to see if there is a cassette with a 11 T ring that could be replaced individually.
 

dadoftwinsfml

New Member
Okay, well let me prefix this by saying that the Bafang Ultra is, ahem, a pretty bad motor. It's made infinitely worse by the default programming that it originally comes with. Its startup behavior is very abrupt, which puts unreasonable strain on the chain, leading to premature chain wear. Some companies such as Biktrix manage to tune the motor prior to selling it to perform better, but still, in the end you end up with something that's far too powerful given the load. As far as the 11T ring goes, it's not really surprising due to the huge gear ratio involved when going at high speeds. Also, unlike Bosch, Bafang has no shift detection so when you shift under power you wear out your drive train even more.

The idea of stocking up on EX1 cassettes is a bit silly because all you get is a slightly thicker chain. In my experience, thicker chains do not translate to longevity gains and in fact you sometimes get the reverse situation. Besides, as you yourself describe, this really will not help the situation if you're primarily wearing out your smallest cog. If you really want to buy into a wide-range 8x system, you probably want SunRace — that's where you can actually stock up on the cassettes (since they're much cheaper) but I doubt it will help.

The idea of shifting under load is a bad idea and you should quit it. Did you know... we Rohloff users cannot shift under any load. That's right, it's impossible. Yet we somehow live with it.

Regarding Rohloff. First, you probably won't manage to retrofit it onto a Thru Axle system. So if you've got a Biktrix or something like that, it's impossible. If you've got a Frey — yep, that can be done. Now I'm saying probably because if you've got the special Rohloff measurement kit ($400), you can measure your rear Thru Axle droupouts and custom-order a hub, but... most people won't manage that, it's too complicated. Building a custom wheel isn't actually complicated, so if your bike supports QR, all you need is a Rohloff hub (there's like 80 variations, so be sure to get the right one) and a rim (most likely 36-hole), take it to your LBS and there you have it!

Second, while Rohloff theoretically claims to be able to handle this sort of strain, there are hubs which are cheaper and can handle it better. This includes the 8- and especially the 3-speed Shimano hub. Again, these are only compatible with QR dropouts, so if you have TR, forget it. Also, the idea that you actually need >3 gears on an Ultra-equipped bike is a silly one anyway because whatever you do, literally as soon as you're turning the pedals, you're straining the system an insane amount just due to the terrible way the whole PAS/torque system in the Ultra is designed (it can only marginally be mitigated with good programming). Ultra doesn't do gradual assist like other motors, it does 'all or nothing' so all those gears, well, they don't make that much sense.

The real problem though is one you cannot solve: the very abrupt spin-up of the motor. Which is why I love Yamaha: they understand that start-up needs to be gradual. Bosch get it too, but Yamaha does it better.
Thanks for the thoughts!

If you watch the videos for the SRAM EX1 (e-bike specific groupset), the designer of the cassette says it's designed to shift under load: https://www.mtb-mag.com/en/interview-srams-ex1-cassette-engineer-henrik-braedt/ (see the video in the article)

I wasn't saying I would stock up on EX1 cassettes (they're 400$ a piece!), I was wondering if 1 EX1 cassette would stop me from having to change regular steel cassettes frequently. The other option I am mulling over is simply to stock up on regular steel cassettes and just keep replacing them. An EX1 cassette is worth 10 regular cassettes!

I'm not having a problem with abrupt spin up of the Bafang motor. I never have problems with my starting gears (ie 36T all the way down to whatever is right before 11 are fine now that I've found some semi-decent steel cassettes).

I think, being used to Yamaha and Bosch -- those motors are lower power compared to the Bafang. You're not able to dump 1500 watts continuously with those motors, so the comparison isn't exactly fair. Calling the Bafang motor bad is a bit subjective; I like the torque it provides, and I could stick to say 1000W when cruising at high speed and stop destroying cassettes but I'm here asking if anyone has found a solution that can handle it.

Again, the issue isn't abrupt start up or high torque, and I don't shift under load (yes the bafang has a shift sensor), and yes it does gradual assist. In some settings it's barely noticeable. The issue is prolonged dumping of 1500W into the smallest 11T cog while maintaining 40 MPH for stretches. Any motor that can do this is going to destroy cassettes.

I appreciate the info on Rohloff, very helpful!
 

dadoftwinsfml

New Member
Back in the day, the smallest cassette rings were independently replaceable. That is the 11 T itself could be removed from the cassette and replaced while keeping the other rings.

You might look around to see if there is a cassette with a 11 T ring that could be replaced individually.
I think you might be thinking of freewheels (the technology that came before cassettes) -- they used the last cog to tighten the whole thing together and so it was easily replaceable? Not exactly and option these days, but it's a great idea!

A lot of cassettes have independent cogs that aren't attached to each other and you could technically replace individual ones, but in practice I can't find a way to buy them separately. Also it seems, from experience, that the longer lasting cassettes are the ones where they're pinned together so the load from one cog is distributed to the others.

I'd be okay going to the 400$ EX1 hardened steel cassette if I knew for sure the 11T would hold up under the load of 1500W, but I'm not 100% convinced -- would love to hear from someone who has an EX1 based bike with a high output motor!
 

Ravi Kempaiah

Well-Known Member
3) Go internal gears. I've heard good things about the Rohloff E14, but obviously this is both a big investment and not the easiest task to perform myself. I'm not sure I trust myself to build my own wheel, and I have no idea how to go about getting a wheel built for my bike. Has anyone done this?
This bike was built with Bafang ultra motor + Rohloff Speedhub + Gates drive.
It is quite durable and very low maintenance.

Reach out to @pushkar and he can ship you a wheel (depending on your bike dropout size) equipped with Rohloff. You could just use a chain instead of the belt and it will hold up for 4000 miles before you may need to replace anything.
 

mbouck

Member
Okay, well let me prefix this by saying that the Bafang Ultra is, ahem, a pretty bad motor. It's made infinitely worse by the default programming that it originally comes with. Its startup behavior is very abrupt, which puts unreasonable strain on the chain, leading to premature chain wear. Some companies such as Biktrix manage to tune the motor prior to selling it to perform better, but still, in the end you end up with something that's far too powerful given the load. As far as the 11T ring goes, it's not really surprising due to the huge gear ratio involved when going at high speeds. Also, unlike Bosch, Bafang has no shift detection so when you shift under power you wear out your drive train even more.

The idea of stocking up on EX1 cassettes is a bit silly because all you get is a slightly thicker chain. In my experience, thicker chains do not translate to longevity gains and in fact you sometimes get the reverse situation. Besides, as you yourself describe, this really will not help the situation if you're primarily wearing out your smallest cog. If you really want to buy into a wide-range 8x system, you probably want SunRace — that's where you can actually stock up on the cassettes (since they're much cheaper) but I doubt it will help.

The idea of shifting under load is a bad idea and you should quit it. Did you know... we Rohloff users cannot shift under any load. That's right, it's impossible. Yet we somehow live with it.

Regarding Rohloff. First, you probably won't manage to retrofit it onto a Thru Axle system. So if you've got a Biktrix or something like that, it's impossible. If you've got a Frey — yep, that can be done. Now I'm saying probably because if you've got the special Rohloff measurement kit ($400), you can measure your rear Thru Axle droupouts and custom-order a hub, but... most people won't manage that, it's too complicated. Building a custom wheel isn't actually complicated, so if your bike supports QR, all you need is a Rohloff hub (there's like 80 variations, so be sure to get the right one) and a rim (most likely 36-hole), take it to your LBS and there you have it!

Second, while Rohloff theoretically claims to be able to handle this sort of strain, there are hubs which are cheaper and can handle it better. This includes the 8- and especially the 3-speed Shimano hub. Again, these are only compatible with QR dropouts, so if you have TR, forget it. Also, the idea that you actually need >3 gears on an Ultra-equipped bike is a silly one anyway because whatever you do, literally as soon as you're turning the pedals, you're straining the system an insane amount just due to the terrible way the whole PAS/torque system in the Ultra is designed (it can only marginally be mitigated with good programming). Ultra doesn't do gradual assist like other motors, it does 'all or nothing' so all those gears, well, they don't make that much sense.

The real problem though is one you cannot solve: the very abrupt spin-up of the motor. Which is why I love Yamaha: they understand that start-up needs to be gradual. Bosch get it too, but Yamaha does it better.
I have a Biktrix Ultra 1000 (with the Bafang MM 510.1000 Ultra motor) and I will say I have zero issues with my cassettes (Shimano 10 speed as shipped) getting chewed-up. First of all, yes, Biktrix tunes the programming so it's much smoother than the stock configuration. Second of all my bike came with a Bafang shift sensor installed so it's partially incorrect to state the Ultra does not drop power during shifts - only if the shift sensor is not installed. Mechanically, the Ultra motor is a solid design - if there is a "flaw" it is with the default controller programming which can be fixed. As far as the motor being "too powerful" - that's entirely subjective. Too powerful by what metric? Local laws? Engineering constraints? Finally, it all comes down to how you use the motor and making sensible choices. For my use I dumped the crappy (but beautiful) DPC-18 display and got myself an EggRider. I then changed the PAS levels to 10 (was 5 on the DPC-18) with the current limits going up ~10% for each PAS level. I spend most of my time in PAS 2 or 3 so the Ultra is being current-limited to about 30% of max output. The throttle I set to have max current available so the power is there when I need it to zoom through intersections, etc. Works for me.
 

dadoftwinsfml

New Member
This bike was built with Bafang ultra motor + Rohloff Speedhub + Gates drive.
It is quite durable and very low maintenance.

Reach out to @pushkar and he can ship you a wheel (depending on your bike dropout size) equipped with Rohloff. You could just use a chain instead of the belt and it will hold up for 4000 miles before you may need to replace anything.
Awesome thanks!!! This is exactly the info I was hoping for. I'll drop @pushkar a message. There's lots of options with Rohloff, so before dropping that much money on a wheel I want to make sure it's going to work :). Ideally looking for an expert to build the wheel too. I'm not sure I trust some rando who's never done it before at the LBS.

I'll be looking to use a chain because of my frame. It does have a split in it to allow for belt drive, but it's full suspension and I'm not sure it'll handle the tension properly. I'm okay changing a chain out every 4k miles.
 

jim6b

Active Member
I think you might be thinking of freewheels (the technology that came before cassettes) -- they used the last cog to tighten the whole thing together and so it was easily replaceable? Not exactly and option these days, but it's a great idea!

A lot of cassettes have independent cogs that aren't attached to each other and you could technically replace individual ones, but in practice I can't find a way to buy them separately. Also it seems, from experience, that the longer lasting cassettes are the ones where they're pinned together so the load from one cog is distributed to the others.

I'd be okay going to the 400$ EX1 hardened steel cassette if I knew for sure the 11T would hold up under the load of 1500W, but I'm not 100% convinced -- would love to hear from someone who has an EX1 based bike with a high output motor!
Regretfully, my "back in the day" is way back.

Thanks for the clarification.

gl
 

dadoftwinsfml

New Member
I have a Biktrix Ultra 1000 (with the Bafang MM 510.1000 Ultra motor) and I will say I have zero issues with my cassettes (Shimano 10 speed as shipped) getting chewed-up. First of all, yes, Biktrix tunes the programming so it's much smoother than the stock configuration. Second of all my bike came with a Bafang shift sensor installed so it's partially incorrect to state the Ultra does not drop power during shifts - only if the shift sensor is not installed. Mechanically, the Ultra motor is a solid design - if there is a "flaw" it is with the default controller programming which can be fixed. As far as the motor being "too powerful" - that's entirely subjective. Too powerful by what metric? Local laws? Engineering constraints? Finally, it all comes down to how you use the motor and making sensible choices. For my use I dumped the crappy (but beautiful) DPC-18 display and got myself an EggRider. I then changed the PAS levels to 10 (was 5 on the DPC-18) with the current limits going up ~10% for each PAS level. I spend most of my time in PAS 2 or 3 so the Ultra is being current-limited to about 30% of max output. The throttle I set to have max current available so the power is there when I need it to zoom through intersections, etc. Works for me.
I have a Biktrix Juggernaut FS Ultra 1000! Love Biktrix and the bike... can't say enough good things. I will say I am very hard on the cassettes (on purpose). I like to do multi-mile stretches in PAS5 sport mode (1500W continuous) with me also cranking as hard as I can (+250-300W) to the 11T cog. I have experimented with not riding like an idiot, and sure enough -- the cassette is perfectly fine :p.

The question I'm here to answer is: can I ride like an idiot AND also not go through cassettes so quickly?

Also just to be clear, I'm only doing this on totally clear stretches, away from cars and people (actually on a horse trail -- and never when horses are present!).
 

mbouck

Member
"I keep blowing my head gasket when I continuously stay on the red line" = "hey doc - why does my arm hurt when I do this (*insert crazy contortion*)?"

I hear SpaceX uses iconel and exotic alloys for their turbine impellers - worth a shot!
 

dadoftwinsfml

New Member
"I keep blowing my head gasket when I continuously stay on the red line" = "hey doc - why does my arm hurt when I do this (*insert crazy contortion*)?"

I hear SpaceX uses iconel and exotic alloys for their turbine impellers - worth a shot!
Lol fair point 😂... seriously though it shouldn't be too hard to sort this problem out. Maybe 3 gears and a motorcycle chain? 😋

I do like the idea of going rohloff anyway, and their e14 is specifically made with this application in mind. Might have to give it a go.
 

TForan

Well-Known Member
I have a Biktrix Ultra and they do have a shift sensor that works well. I just changed my cassette , chain and chainring after well past a 1000 miles. The chain didn't measure any stretch and the chainring was fine. I also ride in 3-5 boost and never baby it. It must have something to do with Biktrix's programming. "A pretty bad motor" ? I'll take it all day long to gutless euro spec motors.
 

Dmitri

Active Member
Thanks for the thoughts!

If you watch the videos for the SRAM EX1 (e-bike specific groupset), the designer of the cassette says it's designed to shift under load: https://www.mtb-mag.com/en/interview-srams-ex1-cassette-engineer-henrik-braedt/ (see the video in the article)

I wasn't saying I would stock up on EX1 cassettes (they're 400$ a piece!), I was wondering if 1 EX1 cassette would stop me from having to change regular steel cassettes frequently. The other option I am mulling over is simply to stock up on regular steel cassettes and just keep replacing them. An EX1 cassette is worth 10 regular cassettes!

I'm not having a problem with abrupt spin up of the Bafang motor. I never have problems with my starting gears (ie 36T all the way down to whatever is right before 11 are fine now that I've found some semi-decent steel cassettes).

I think, being used to Yamaha and Bosch -- those motors are lower power compared to the Bafang. You're not able to dump 1500 watts continuously with those motors, so the comparison isn't exactly fair. Calling the Bafang motor bad is a bit subjective; I like the torque it provides, and I could stick to say 1000W when cruising at high speed and stop destroying cassettes but I'm here asking if anyone has found a solution that can handle it.

Again, the issue isn't abrupt start up or high torque, and I don't shift under load (yes the bafang has a shift sensor), and yes it does gradual assist. In some settings it's barely noticeable. The issue is prolonged dumping of 1500W into the smallest 11T cog while maintaining 40 MPH for stretches. Any motor that can do this is going to destroy cassettes.

I appreciate the info on Rohloff, very helpful!
Here's an idea: what if you simply stock up on 11t cogs? They are cheap.