Belt Drives vs. Chain for Electric Bikes, Pros & Cons

[Admin]

Hi guys, Brent shot this little video about belt drives vs. chain drives when he was reviewing the Pure Cycles Volta Single Speed and Volta 8-Speed and I thought it deserved a little guide to go along. I ended up adding a few points to his original video because I've tested the Gates CDX belt drive and some others on many more bikes which utilized the NuVinci continuously variable transmission (CVT), Shimano Nexus internally geared hubs, and Rohloff Speed Hub system. You can definitely use gears with belt drives... but they have to be internal vs. a traditional cassette+derailleur setup. Here's the video we created and I've listed some pros and cons below that. Feel free to chime in with your own thoughts on benefits and trade-offs.

Pros of belt drives for electric bicycles:

• Clean and quiet, they won't rust like chains sometimes do and they don't require lubricant that makes a mess when touched
• Extremely durable, a high-quality belt drive from a company like Gates won't wear out as quickly as most chains
• They don't fall off as easily, since belt-drive systems don't use a cassette and derailleur, there isn't any extra slack for changing gears so they won't bounce around and fall off as easily

Considerations of belt drives vs. chains on electric bicycles:

• They almost always cost more because the bike frame has to be design so that the belt can pass through the rear triangle of the frame. Some frames have been designed to work around this design challenge by passing both portions of the belt below the chain stay vs. around it (both above and below)
• Without a derailleur and cassette, you are left with a single speed or internally geared hub or continuously variable transmission... and these two later options tend to weigh more and cost more
• Trail maintenance isn't as easy because you cannot simply replace a link or rely on a tensioner to keep the belt taught, you actually have to adjust the horizontal tension... and this can limit how much power the drivetrain can handle from a mid-motor

As always, it's fun to hear your thoughts and feedback on this. We welcome corrections, additions, tips and other insights

 

[Over50]

More important to me than the chain vs the belt is the IGH that goes with the belt (assuming it isn't a single speed). I love the belt + Alfine 8 combo on my Spot (non electric) city bike but I didn't like the Nuvinci on my R&M thus making the belt somewhat irrelevant. I was disappointed that there wasn't another IGH option out there to pair with a belt along the lines of an Alfine 11. I'm referring to a year ago when I was looking at options to switch out my Nuvinci. I guess now there are Rohloff + belt combinations which should eliminate the gear range limitations that would occur with the Nuvinci N380 or the Alfine 8 (I was advised on the forum that the Alfine 11 isn't robust or reliable enough for a mid-drive e-bike application). I love the belts to reduce maintenance and noise but would still like to see some more robust IGH options along the lines of 10-14 speeds and certainly more than the 380 degrees of the Nuvinci. Probably R&M is the only manufacturer with a Rohloff + belt combo and it would be nice to see more choices in the US of e-bikes with a decent gear range/ratio paired with a belt.

 

[Diarmuid]

Supplemental link:

https://www.rodbikes.com/articles/gates-belt-drive.html

 

[Alaskan]

Is there an efficiency difference between belt and chain?

 

[Mr. Coffee]

Is there an efficiency difference between belt and chain?

https://www.bikeradar.com/us/road/news/article/chain-or-belt-drive-which-is-faster-36074/

The executive summary: A chain drive is very slightly more efficient, but that advantage decreases as more power is passed through the drive and beyond about 200 watts a belt drive is more efficient.

The major point is the efficiency difference is very slight, on the order of 1 watt, between a chain and a belt.

 

[Mikk]

but I didn't like the Nuvinci on my R&M thus making the belt somewhat irrelevant.

Hey Over50!
I was wondering why you didn't like the nuvinci? Im in Seattle and I've always dreamed about building or buying my ultimate commuter and a belt driven n380 is usually near the top of my list. I also recently bought a 2016 Cannondale Mavaro which is a hoot (my first ebike) and I ride it almost every day to work which equals about 4-5k miles/year. I just wish I didn't have to replace chains and cassettes multiple times per year (so much wear from the middrive as I ride in turbo mode mostly) and so I was thinking of looking for a used belt drive ebike with the nuvinci or rohloff too

And then the other question I have for this thread is really: Am I just idolizing the belt drive? How much longer do the belt and cogs last? I oil my chain every week or two but almost never clean it because it just takes too long to make a difference to me... I wish I could get myself to switch to parrafin for my chains but I don't want to use all the degreasers to clean the chain in the first place.

 

[Alaskan]

@Mikk I live just north of you in Bellingham. I ride 700 - 1000 miles a month so I am a good test study. I had a R&M Nevo with the Nuvinci and a belt. I loved the smooth intuitive shifting experience of the Nuvinci 380 but ultimately found the narrower gear range and significantly lower efficiency (wattage loss) to be frustrating. I think it is a nearly ideal drive train for someone living in a relatively flat city where the efficiency is not such an issue and there is continual start & stop riding with constant ration changes needed. Riding out in Whatcom and Skagit Counties it was just not what I wanted.

I went to the 2018 Homage Rohloff HS that came with a chain (no belt option). The chain is the equivalent of an 8 speed so it has good wear characteristics but still needs cleaning and lube regularly. I did miss the belt that came on the Nevo Nuvinci GH as the chain is just dirty, fussy and needs attention. My wife now rides that bike once a week or so so the chain will last a long time and only needs cleaning and lube every few months.
Now I am riding a 2019 Homage Rohloff HS with the Gates belt. It is as close to a perfect drive train as I could imagine, The belt has over 3000 miles on it now and looks brand new. It is quiet, efficient and maintenance free. The Rohloff needs and oil change once a year. That's it. The gear range is amazing. I can climb the 14% hill my house is on without an issue and ride down a long slope at 35mph without spinning out. In 12th gear I can rip down a flat road at 24 mph spinning at 85 rpm for miles. I can't imaging a better setup.

 

[Mikk]

@Alaskan
Ohhh I love this info!! 3000 miles on a belt looking brand new is awesome! Especially when you think about how much power is being transferred through it. My coworker has a rohloff and I used to have an alfine so I'm a-ok with the annual oil change. And I'd think swapping the oil is more environmentally friendly than buying new cassettes twice a year!
Guess I'll be needing a 2019 Homage to fulfill my dreams. If you ever sell yours drop me a line!!

I didn't think I could ever sell our second car but this ebike is shaving enough time off my bike commute to make it close to my drive time. And if there's an accident or bad traffic the bike is usually a tiny bit faster (and way less stressful)!

 

[Mikk]

And good to know you can really feel the system drag in the Nuvinci! My current cassette is 11x36 so the range is only 330%. The nuvinci 380 would be an upgrade for gear range but the drag would probably annoy me too.

 

[Alaskan]

I don't think I will be selling the 2019 anytime soon. I just returned from our farmers market with this weeks greens and goodies. Nancy and I are heading out on a 45 mile ride shortly.

 

[Over50]

Hey Over50!
I was wondering why you didn't like the nuvinci? ...

Mine might have been defective. I think the person I sold it to was able to file a warranty claim or had it replaced at his own expense. For me, it wasn't providing the gear range I needed to comfortably ride around 25 mph. At about 23 mph, I'd be spinning like a hamster. I could ride at 25 mph but it was taxing because of the cadence I had to maintain. I didn't have another Nuvinci bike to compare it to so I thought at the time that it must be the limited gear range (and also my LBS checked it out and said it was ok). The difference with the Rohloff is that I can cruise at 25 mph and I am only in 13th gear (1 gear remaining) and pedaling at a comfortable cadence. My Rohloff however is a noisy beast. I feel like my traditional drive train commuter (Haibike) is giving me slightly better battery range (I suspect the traditional setup is more efficient but I don't know this for fact).

I have a belt drive on my non-electric bike that is paired with an Alfine 8. I really like that combo for a lower speed bike. I don't have much in the way of hills so even the Alfine 8 is more than I need for gear range on a non-electric.

 

[smorgasbord]

@Over50, note that the front ring size (in teeth) as well as the wheel diameter also play a role in effective gear range. True, the wider range of the Rohloff makes that less critical, but the Nuvinci is wide enough that top gear at 28mph should still leave you plenty of low gear for climbing most hills.

BTW, Rohloff is more efficient than Nuvinci. External gears are most efficient, but the Rohloff is a close second while the Nuvinci is a more distant third.

 

[Alaskan]

What’s The Difference In Speed Between Gearbox Systems? Rohloff, Pinion, Shimano

https://www.cyclingabout.com/speed-difference-testing-gearbox-systems/
https://www.cyclingabout.com/speed-difference-testing-gearbox-systems/

 

[WilliamT]

Chains are so easy to work with and cheap to replace (~$10) that I've never even considered a belt drive. My hardtails, full-suspensions, cargos, folding, race bikes all use chains.

 

[Alaskan]

Chains are so easy to work with and cheap to replace (~$10) that I've never even considered a belt drive. My hardtails, full-suspensions, cargos, folding, race bikes all use chains.

If you use sub $10 chains on a mid drive ebike, with its added power, you will be changing them out continually, unless you don't ride very often or don't care about chain stretch.

I am kind of a nut about having everything clean, well lubed, dialed in a functioning at its best. I often ride more than 1,000 miles per month, use Shimano Dura Ace chains at $43. If kept clean and well lubed they last far longer than cheap chains.

That said, I have one bike with a belt. It stays free of oil, grease and accumulated gunk. If it get dirt on it, rinse it off and let it dry...done. There is no stretch and they can last 10,000 miles or more. However they only work with internally geared rear hubs not derailleurs.

 

[Green Destiny 2.0]

I just learned one drawback about my otherwise flawless Gates belt drive. During an early, sticky snowfall, the white stuff stuck to everything, packed between the belt and cog and untracked it.

 

[Feliz]

More important to me than the chain vs the belt is the IGH that goes with the belt (assuming it isn't a single speed). I love the belt + Alfine 8 combo on my Spot (non electric) city bike but I didn't like the Nuvinci on my R&M thus making the belt somewhat irrelevant. I was disappointed that there wasn't another IGH option out there to pair with a belt along the lines of an Alfine 11. I'm referring to a year ago when I was looking at options to switch out my Nuvinci. I guess now there are Rohloff + belt combinations which should eliminate the gear range limitations that would occur with the Nuvinci N380 or the Alfine 8 (I was advised on the forum that the Alfine 11 isn't robust or reliable enough for a mid-drive e-bike application). I love the belts to reduce maintenance and noise but would still like to see some more robust IGH options along the lines of 10-14 speeds and certainly more than the 380 degrees of the Nuvinci. Probably R&M is the only manufacturer with a Rohloff + belt combo and it would be nice to see more choices in the US of e-bikes with a decent gear range/ratio paired with a belt.

I use a Alfine 8 with a belt on one of my mid drives and I haven't had any issues. A lot of the people who have issues with IGH don't know how to shift.

 

[tomjasz]

If you use sub $10 chains on a mid drive ebike, with its added power, you will be changing them out continually, unless you don't ride very often or don't care about chain stretch.

I am kind of a nut about having everything clean, well lubed, dialed in a functioning at its best. I often ride more than 1,000 miles per month, use Shimano Dura Ace chains at $43. If kept clean and well lubed they last far longer than cheap chains.

That said, I have one bike with a belt. It stays free of oil, grease and accumulated gunk. If it get dirt on it, rinse it off and let it dry...done. There is no stretch and they can last 10,000 miles or more. However they only work with internally geared rear hubs not derailleurs.

Belt drives are sweet, but out of range price wise for most buyers. You have a great bike. And valuable input, but the cost is on the high end of the spectrum. I beat the beejeebus out of chains on my 1500W mid drives. But 132 link cheap chains easily run over 1000 miles. All of $12 to replace. Look I get that belt drives are great, but they’re out of range price wise for most.

 

[Feliz]

I would never go out of my way to buy/build a bike with a belt drive. My favourite setup is a chain, derailleur, sprocket, and it's also the most efficient. Rear hub drive or mid drive are good although for mountain biking I prefer mid drive.

 

[Feliz]

Belt drives are sweet, but out of range price wise for most buyers. You have a great bike. And valuable input, but the cost is on the high end of the spectrum. I beat the beejeebus out of chains on my 1500W mid drives. But 132 link cheap chains easily run over 1000 miles. All of $12 to replace. Look I get that belt drives are great, but they’re out of range price wise for most.

How many gears do you run Tom? I like 10/11 speed 11-46.
I have a Rohloff on my Ultra Watt Wagon and I don't think I've used more than 5 or 6 gears. Not the fault of the bike I just always ride it on level pavement, usually the highway.