ECVT/MGU: The Great Belt vs. Chain Debate

slickrock

slickrock

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Starting a separate thread on the chain vs. belt debate, as the topic has been cropping up a lot on other threads now.

Now that ECVT's have have been the talk of the town and we are clearly starting to envision a future without derailleurs, a significant Y in the trail is to embrace the new ebikes with either belt drivetrains or chain drivetrains. Before MGUs and ECVTs the choice was like the Ford Motor company slogan "you can choose any color you want so long as it's black"; no choice - it has to be a chain.

This choice between belt vs. chain has always existed, but stake were a limited market in which this choice has up till recently been quite small or has simply not applied to our EMTB space: bikes with IGH hubs (e.g. city bikes), downhill gearbox MTBs, esoteric bikes (e.g. Cavalerie), and those few Pinion MGU converts happily riding their new breed of EMTBs.

But now we must chose as the derailleur-less EMTB market will soon explode . We must influence the product managers as to what system we prefer or think what we prefer. Let the debate begin.

Edit: Areas of discussion:
  • Aesthetics
  • Exclusivity
  • Reliability
  • Maintenance
  • Efficiency
  • Noise
  • Weight
  • Performance
  • Implications for bike rear suspension design
  • Chain tensioner consequences
  • Cost
  • Choice driven by Locales/Weather/Terrain
 
Last edited:
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Chain all the way for me. With a chain driven ECVT you will still save a decent amount of maintenance over a conventional drive train. Cleaning and re lubing essentially a single speed chain drive will be very little hassle.
 
DylanJM said:
Chain all the way for me. With a chain driven ECVT you will still save a decent amount of maintenance over a conventional drive train. Cleaning and re lubing essentially a single speed chain drive will be very little hassle.
Click to expand...
In a way, chains have been getting a bad rap because of what they have evolved into: thin, finicky, and fragile versions of their prior selves. Namely, because the industry has pushed rear cassettes to 12 cogs to take on what a front chainring used to do - provide the extra gear steps and range for MTB riders. Already this is overkill for EMTB. A good, old-fashion, single-speed chain, is really all that is needed for MGU/ECVT will be more durable and reliable like the Schwinn chains of yesteryear, except with a tensioner.
 
I’m on the mgu train, but for sure gonna wait for the issues to show when they first drop and the hype dies a little. I think time will just tell which is better. I’m not one to freak out if my bike breaks and I can’t ride a week or two.

So imo I’ll just go with whatever bike is attached that I think is better (hopefully crestline). I also trust troydon would make the right call on what is best on his frame. We know belts have had failures and so have chains. Unless we find belts to be failing at a much greater rate when they drop then I’m fine with it.
 
irie said:
Loving opinion stated as fact. :LOL:
Click to expand...
To be facts, they must have already occurred. Rather, this is prediction with high precision (based on my Bayesian model, which of course could be wrong). Also, what I meant by "explode" is reference to where it is now, at probably less than 0.2% of all EMTBs out there.
Brawwp said:
I’m on the mgu train, but for sure gonna wait for the issues to show when they first drop and the hype dies a little. I think time will just tell which is better. I’m not one to freak out if my bike breaks and I can’t ride a week or two.

So imo I’ll just go with whatever bike is attached that I think is better (hopefully crestline). I also trust troydon would make the right call on what is best on his frame. We know belts have had failures and so have chains. Unless we find belts to be failing at a much greater rate when they drop then I’m fine with it.
Click to expand...
Agreed, that the bike design has a much bigger influence on chain vs. belt debate. It's doubtful that a bike brand would offer an option to choose belt or chain for a particular model of bike, like in an Orbea bike configurator. Either the bike design will force this decision or the other way around. Bike companies and their designers will probably take sides on this debate, and that could factor into the choice more than anything.
 
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slickrock said:
To be facts, they must have already occurred. Rather, this is prediction with high precision (based on my Bayesian model, which of course could be wrong). Also, what I meant by "explode" is reference to where it is now, at probably less than 0.2% of all EMTBs out there.

Agreed, that the bike design has a much bigger influence on chain vs. belt debate. It's doubtful that a bike brand would offer an option to choose belt or chain for a particular model of bike, like in an Orbea bike configurator. Either the bike design will force this decision or the other way around. Bike companies and their designers will probably take sides on this debat, and that could factor into the choice more than anything.
Click to expand...
Impressive prescience. :LOL:
 
This is what a do not like. The bottom of the tensioner is below the line of the motor bash guard. The whole point of the MGU for me is to remove exposed bits where there is sometimes contact with obstacles. Just have that a bit higher, and the arm slightly longer if needed.

A belt, tensioner and snubber like below. I would try. Because I just don't see the belt getting damaged in that configuration on the terrain I mostly ride. Also it would be very straight forward to replace all the belt cogs with chain sprockets, and remove the snubber, if I was experiencing issues with the belt, and I could replace with a chain.

1783899587580.webp
 
Onetime said:
I’ll take the belt. Reese Wilson and several others have proven them to be durable enough on the World Cup DH series for the last few years.
Click to expand...
The only thing with those guys, is how often are they checking and changing the belt ? Any nicks in the belt, would be picked up by the mechanic, and they would change them. So the chances of a nick becoming a broken belt, would be slim. Same with any stripped teeth not being picked up.

My gates belt drive E-motorcycle belt had stripped teeth. I did notice the slightly odd sound before belt failure. So replaced it before getting stranded.

Chain failures are far less an issue, if you carry a spare link, which I do. Hence my reluctance to run a belt on an EMTB.
 
Astro66 said:
... Also it would be very straight forward to replace all the belt cogs with chain sprockets, and remove the snubber, if I was experiencing issues with the belt, and I could replace with a chain.
...
Click to expand...
My sense is the moving to a chain from an EMTB delivered with a belt will be much easier than the reverse. There are additional constraints with a belt that chains can easily negotiate:
  1. Chains can handle longer chain growth suspensions by using double pulleys (ugly yes, but is a hack designers can fall back on, such as Rotwild). This basically puts constraints on belted bike designs as to how much chain growth they can accommodate (which actually may be a good thing IMO)
  2. Easier to route chains through VPP and DW4 unified rear triangles.
  3. Belts have fixed sizes whereas chains have link-length adjustability. A specified chain-based loop size for the bike model may not have the corresponding length in belt size, where as you could easily create a chain loop to match a belt size.
  4. HP idlers can be smaller and tighter with chains, so may be difficult to swap with belt equivalent
In short, if you buy chained MGU/ECVT, don't expect it can run on a belt.
 
slickrock said:
My sense is the moving to a chain from an EMTB delivered with a belt will be much easier than the reverse. There are additional constraints with a belt that chains can easily negotiate:
  1. Chains can handle longer chain growth suspensions by using double pulleys (ugly yes, but is a hack designers can fall back on, such as Rotwild). This basically puts constraints on belted bike designs as to how much chain growth they can accommodate (which actually may be a good thing IMO)
  2. Easier to route chains through VPP and DW4 unified rear triangles.
  3. Belts have fixed sizes whereas chains have link-length adjustability. A specified chain-based loop size for the bike model may not have the corresponding length in belt size, where as you could easily create a chain loop to match a belt size.
  4. HP idlers can be smaller and tighter with chains, so may be difficult to swap with belt equivalent
In short, if you buy chained MGU/ECVT, don't expect it can run on a belt.
Click to expand...
Agreed. As someone who has played with belt drives and fitting motors to them. That configuration on the Radiate with the belt drive looks simple enough and protected enough, to not cause issues, and retro-fit a chain, if you do hate it.

So it will come down to frame and transmission design, whether I consider getting a belt.

Can I add. The most important point you missed with converting from a chain to a belt, is the chainline must be exactly lined up for a belt. Unlike a chain. A belt will not tolerate any misalignment of front and rear sprocket, or the idler either in a HP.
 
Can I add. Because of the alignment between the front and rear sprockets, must remain perfectly aligned with a belt. The rear triangle on my belt drive is much stiffer. So this will also adds to the issues you may have if converting from chain to belt. The flex in your rear triangle, could cause the belt to drop when cornering.

Also. This may be a reason to stick with a chain, as you may want some flex. And also. The belt is not going to tolerate any sideways movement of your pivot joints. So you will need to keep them in perfect order. That said. You should anyway.
 
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Astro66 said:
Can I add. Because of the alignment between the front and rear sprockets, must remain perfectly aligned with a belt. The rear triangle on my belt drive is much stiffer. So this will also adds to the issues you may have if converting from chain to belt. The flex in your rear triangle, could cause the belt to drop when cornering.

Also. This may be a reason to stick with a chain, as you may want some flex. And also. The belt is not going to tolerate any sideways movement of your pivot joints. So you will need to keep them in perfect order. That said. You should anyway.
Click to expand...
Gates belts aren't that sensitive, after all that's why Gates invented CDX centertrack. I've used my belt drive dual-suspension MTB with alloy frame for a decade without issue, albeit only 120mm travel.
 
slickrock said:
Gates belts aren't that sensitive, after all that's why Gates invented CDX centertrack. I've used my belt drive dual-suspension MTB with alloy frame for a decade without issue, albeit only 120mm travel.
Click to expand...
I disagree. I had an alignment issue with my E-Motorcycle, and it wore the belt teeth out quickly. I fitted the new belt myself and got the alignment perfect. The new belt now has twice the km of the old one, and still in great shape.

The belt is not designed to be rubbing continuously to centre itself. It will eat teeth and the belt. There is significantly more tension required for the belt. So any rubbing is bad. And the belt will drop off the rear sprocket if not aligned properly or the rear triangle twists.

And the stiffer the frame. The less tension you need on the belt. Lower tension helps in so many ways, both wear and efficiency.

1783917097587.webp

www.cyclingabout.com

Gates Carbon Belt Drive: Everything You Ever Need to Know - CYCLINGABOUT.com

Belt drive systems are valued for their low maintenance requirements and typically offer 3-4× the service life of a traditional chain.
www.cyclingabout.com www.cyclingabout.com
 
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Astro66 said:
I disagree. I had an alignment issue with my E-Motorcycle, and it wore the belt teeth out quickly. I fitted the new belt myself and got the alignment perfect. The new belt now has twice the km of the old one, and still in great shape.

The belt is not designed to be rubbing continuously to centre itself. It will eat teeth and the belt. There is significantly more tension required for the belt. So any rubbing is bad. And the belt will drop off the rear sprocket if not aligned properly or the rear triangle twists.

And the stiffer the frame. The less tension you need on the belt. Lower tension helps in so many ways, both wear and efficiency.

View attachment 188569
www.cyclingabout.com

Gates Carbon Belt Drive: Everything You Ever Need to Know - CYCLINGABOUT.com

Belt drive systems are valued for their low maintenance requirements and typically offer 3-4× the service life of a traditional chain.
www.cyclingabout.com www.cyclingabout.com
Click to expand...
Is it CDX belt? Does it have a centerline notch? Tolerances, construction, size, pitch, and width for Gates Poly Chain GT Carbon or Gates Moto X9 are quite different.

Agree in general that belt line is more critical than chain line. I also agree that belts require more tension than chains, so bike designers do need to keep that in the back of their minds, but nowadays most frames, especially these enduro style EMTBS are not noodly enough to exceed belt tolerances and affect performance. I would be more concerned with the bikes if they were that noodly.
 
slickrock said:
View attachment 188559View attachment 188560

Starting a separate thread on the chain vs. belt debate, as the topic has been cropping up a lot on other threads now.

Now that ECVT's have have been the talk of the town and we are clearly starting to envision a future without derailleurs, a significant Y in the trail is to embrace the new ebikes with either belt drivetrains or chain drivetrains. Before MGUs and ECVTs the choice was like the Ford Motor company slogan "you can choose any color you want so long as it's black"; no choice - it has to be a chain.

This choice between belt vs. chain has always existed, but stake were a limited market in which this choice has up till recently been quite small or has simply not applied to our EMTB space: bikes with IGH hubs (e.g. city bikes), downhill gearbox MTBs, esoteric bikes (e.g. Cavalerie), and those few Pinion MGU converts happily riding their new breed of EMTBs.

But now we must chose as the derailleur-less EMTB market will soon explode . We must influence the product managers as to what system we prefer or think what we prefer. Let the debate begin.

Edit: Areas of discussion:
  • Aesthetics
  • Exclusivity
  • Reliability
  • Maintenance
  • Efficiency
  • Noise
  • Weight
  • Performance
  • Implications for bike rear suspension design
  • Chain tensioner consequences
  • Cost
  • Choice driven by Locales/Weather/Terrain
Click to expand...

I don't know. Let someone build a gearbox and belt drive, install it on a bike I'd want to ride, and then I'll tell you. Of course all the things you mentioned are a consideration. These newfangled belts have to be MORE reliable than chains, and not so expensive as to make the purchase prohibitive. Let the manufacturers do their best. If it's good, we'll buy it. If it's not, we won't.
 
Onetime said:
I’ll take the belt. Reese Wilson and several others have proven them to be durable enough on the World Cup DH series for the last few years.
Click to expand...
Well, true but they change wheels often so maybe it’s a new belt every run, WCDH doesn’t prove durability over time it certainly proves its tough tho. Mind you, not much pedalling going on.
 
Brawwp said:
I’m on the mgu train, but for sure gonna wait for the issues to show when they first drop and the hype dies a little. I think time will just tell which is better. I’m not one to freak out if my bike breaks and I can’t ride a week or two.

So imo I’ll just go with whatever bike is attached that I think is better (hopefully crestline). I also trust troydon would make the right call on what is best on his frame. We know belts have had failures and so have chains. Unless we find belts to be failing at a much greater rate when they drop then I’m fine with it.
Click to expand...
The Nicoali with MGU is a fabulous, powerful beast but for me too much weight and too much power. Amazing on super steep climbs of course. An SL version would certainly interest me, I LOVED the gearbox element of the setup - I'd choose chain though
 
I've a belt driven hardtail, non-ebike though and I must confess I replaced the belt with a chain. Fine dust causes the chain to "squeak" and hosing it "clean" does not help, you have to brush it clean. And it's waaaayyy more picky when it comes to tensioning the belt/chain. And if you f*ck up your belt, good luck with the spare parts...

I'll choose chain.
 
slickrock said:
View attachment 188559View attachment 188560

Starting a separate thread on the chain vs. belt debate, as the topic has been cropping up a lot on other threads now.

Now that ECVT's have have been the talk of the town and we are clearly starting to envision a future without derailleurs, a significant Y in the trail is to embrace the new ebikes with either belt drivetrains or chain drivetrains. Before MGUs and ECVTs the choice was like the Ford Motor company slogan "you can choose any color you want so long as it's black"; no choice - it has to be a chain.

This choice between belt vs. chain has always existed, but stake were a limited market in which this choice has up till recently been quite small or has simply not applied to our EMTB space: bikes with IGH hubs (e.g. city bikes), downhill gearbox MTBs, esoteric bikes (e.g. Cavalerie), and those few Pinion MGU converts happily riding their new breed of EMTBs.

But now we must chose as the derailleur-less EMTB market will soon explode . We must influence the product managers as to what system we prefer or think what we prefer. Let the debate begin.

Edit: Areas of discussion:
  • Aesthetics
  • Exclusivity
  • Reliability
  • Maintenance
  • Efficiency
  • Noise
  • Weight
  • Performance
  • Implications for bike rear suspension design
  • Chain tensioner consequences
  • Cost
  • Choice driven by Locales/Weather/Terrain
Click to expand...
High Rock Ruti

Chains are so good that I carry spare master links and a complete new chain in my backpack, I'll tolerate two breaks with master link repairs, before installing a new chain. Chains can't handle the stress of 600 watts never mind 1300 watts. Next bike; motor gear box and belt. I mean just look at Harley Davidson belt drive, a brand know for......sorry, oh yes attitude.

Warm Regards Ruti
 
Onetime said:
I’ll take the belt. Reese Wilson and several others have proven them to be durable enough on the World Cup DH series for the last few years.
Click to expand...
As long as you're only riding for about 5 mins or so...
 
If mgu or ecvt is to ever grow in volume I think it is more likely to be in bicycle segments other than emtb. Indeed that is probably the only way mgus would achieve sufficient volumes to enable wider component manufacturer competition and therefore functional development. Mechanical mgus have been around for quite a while without making any real market penetration. I suspect ecvts have the potential to do better but not if the primary focus is full suspension emtb. The emtb market is only a small niche of the bicycle industry and I personally do not believe it will prove functional for emtb use anyway. Direct mechanical connection between rider and rear wheel is more likely to be functional for emtb If the current issues of weight and noise can be resolved. If that happens, both belt and chain options could see further development specific to that application.
 
DylanJM said:
Chain all the way for me. With a chain driven ECVT you will still save a decent amount of maintenance over a conventional drive train. Cleaning and re lubing essentially a single speed chain drive will be very little hassle.
Click to expand...
I hope the belt system can work as we will put this on our eSummit electric fat bike eventually and the idea of just leaving the bike (sans battery of course) outside or in garage to drip-dry without customers having to oil and eBike chain (which is its own special task) is very appealing. We sell the Bulls line of eBikes in the USA, and one of the first belt drive models did have issues as that belt had to be exactly the right tension or it would not work. I think they have solved all these issues now, so my vote is for the belt!
 
Kepa said:
I've a belt driven hardtail, non-ebike though and I must confess I replaced the belt with a chain. Fine dust causes the chain to "squeak" and hosing it "clean" does not help, you have to brush it clean. ...

I'll choose chain.
Click to expand...
This is your savior:
1783966469568.webp


Yep. Belts do start to squeak. Spray this dry lube on the belt and it goes away. But I can see the chain fans saying: Ha! you have to lube that belt just like a chain! Big difference here though is no gunk build up, one application lasts half a season or more, survives rinse downs easily. If you wash our bike with something like Carpro, you may not even need to spray.
 
35 years riding bikes.
Probably close to 10 on ebikes upgrading every 2 years.
Purchased zerode g3 2 years ago for park duties (gates belt drive.)

My latest range cx recently how power upgrade 120nm.
2 weeks ago my first chain failure lead lead to decent crash.

Owning belt drive bike has been amazing!
Zero maintenence, never cleaned that bike drivetrain specifically.
Just the odd silicone spray.

So far the new ebike deurailier and chain have been constant issue.
Totally over it since all this power war started.

For me there is only one answer as tested and proven proven personally.

Back at 85nm my opinion was quite different, the other commenter speaking about surron is really comparing a huge power and rpm difference so not sure how relevant that is..... But Harley havidson still run belts.......
 
slickrock said:
This is your savior:
View attachment 188637

Yep. Belts do start to squeak. Spray this dry lube on the belt and it goes away. But I can see the chain fans saying: Ha! you have to lube that belt just like a chain! Big difference here though is no gunk build up, one application lasts half a season or more, survives rinse downs easily. If you wash our bike with something like Carpro, you may not even need to spray.
Click to expand...
Good tip 👍 I’ll give it a try
 
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