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Belt drive conversion

ep8-rs

Member
Jul 18, 2024
48
27
US
Hey Guys,

So I got an incredible deal on a complete new wheel set for my Orbea Rise. Only thing the rear wheel doesn't have is a cassette ( new is micro spline ). Looking around I had a crazy idea of trying a belt drive with a hub gearing system like a Shimano Alfine. Now please know I'm not looking for opinions on should or should I not do this. I am seeking knowledge here from anyone with experience , and or know how on first , if it is even possible and then if it is , the way of performing the task.
I have started researching and see possibilities , but no firm THIS is what you buy and how you pull it off. Rob's Nicolai Saturn 16 really got my attention with the belt drive , but rather than dropping the $$ , I'd like to find out if I could use my spare wheelset as a test bed for if I'd like a belt or not?

Thanks in advance for sharing of knowledge here as it has always been helpful.

Ride on
 

whitymon

Active member
Nov 29, 2023
290
151
Europe
I saw in the past some rear wheel with a gearbox, but with a chain, now it exists some with belt I guess too (Specialized has some on non mtb). At the very least with a chain you will be able to do some test easier without having to buy too much other things. That said it is not very performant and does not work fine with sport mtb.

But, even if you clearly said you do not want advice, you will never be able to compare a gearbox motor with a very light rear wheel versus a motor + rear heavy gearbox (clunky and not sport oriented).

On purpose of the gearbox motor is to have a light rear wheel, this changes everything when you ride, you will only be able to have a little taste but without a different flavor.

Seems like an expensive conversion if try to match close to an MGU, still if you go that road, please share the conversion and what you get from it!
 

WalterP

New Member
Oct 5, 2024
19
8
Finland
You'll need a rear hub with (boost) trough axle. AFAIK there is no shimano hub available. What comes to mind is rohloff hubs but thats quite expensive.

Also your New rear wheel would need complete rebuilt.

Fitting a best would require you to take rear triangle apart. Possible.

And some heavy duty spring loaded belt tensioner. Although this will affect your suspension because that frame probably has some squat/anti-squat characteristics. Or if tensioner is too weak to the belt will skip when suspension articulates.

This would not turn out cheap nor practical solution. Easier to look for a frame with belt drive possibility to begin with.
 

ep8-rs

Member
Jul 18, 2024
48
27
US
Thank you whityman and WalterP for your responses. I should clarify when I said I wasn't looking for opinions , I was really asking for refrain from the ones hating on belts drives. Opinions on viability ARE welcome and needed. I realized after I posted it that the teardown of the rear hub was unrealistic in keeping it simple as the spare set is tubeless to boot so , yah , not really practical... my bad.
Now with all that in mind , I'm still gonna be out there and ask , well , what about just a single speed belt setup then? Again , just theoretical at this point as I know it wouldn't be practical , but is it POSSIBLE? Is there a actually an existing belt setup compatible with full suspension , micro-spline , roughly equivalent to a 32 chainring and 12 sprocket? Crazy , yes , possible??? :unsure:

Thanks again guys


Ride on
 

WalterP

New Member
Oct 5, 2024
19
8
Finland
Thank you whityman and WalterP for your responses. I should clarify when I said I wasn't looking for opinions , I was really asking for refrain from the ones hating on belts drives. Opinions on viability ARE welcome and needed. I realized after I posted it that the teardown of the rear hub was unrealistic in keeping it simple as the spare set is tubeless to boot so , yah , not really practical... my bad.
Now with all that in mind , I'm still gonna be out there and ask , well , what about just a single speed belt setup then? Again , just theoretical at this point as I know it wouldn't be practical , but is it POSSIBLE? Is there a actually an existing belt setup compatible with full suspension , micro-spline , roughly equivalent to a 32 chainring and 12 sprocket? Crazy , yes , possible??? :unsure:

Thanks again guys


Ride on
I don't know if any exists.

Also no hating for belt drives. Just opinions on is it possible for your bike.
 

whitymon

Active member
Nov 29, 2023
290
151
Europe
Fwiw, some Nicolai bike powered by Bosch are using a Rohloff Hub with Belt.

So if they build such bike you could in theory do the same but to what price, imagine in the end you do not like it?

I really dislike the Rohloff idea but having a belt is really great, pinion gearbox is awesome but too noisy at the moment for me.
 

Shorty4

Member
Nov 7, 2022
34
19
Australia
Can't help with the belt side of things but did fit an 8 speed Alfine gear hub to a Kona Dawg 26" full suspension mtb about 12 years ago. It's also fitted with a Bafang 750w bottom bracket drive and a 48v 14ah battery fitted in the triangle.
It has stood up to the test of time and is still going strong but hasn't had much single track use since I bought a Focus Jam2 a few years ago. I'm 100kg plus the motor, battery and the rear hub all add weight to end up with weight around 25kg for the bike and it still works well. You do have to pause for a split second on the shifts to allow it to change gears but otherwise it has been faultless. Of course it did need to have a chain tensioner as well.
 

ep8-rs

Member
Jul 18, 2024
48
27
US
Hey guys,

So just an update and info for those of the same curiosity as I. It would appear that my venture into belt drive conversion hit a hard wall and is not currently viable on my Orbea Rise. But , as I did receive interest and curiosity from others about the subject , I am posting links to the info I did track down.
For my Rise , the challenge was the mounting and lack of micro spline availability , as in none. Now if money was no object , sure , changing over mounting and completely changing the drivetrain to suit a belt is possible. But as pointed out by others , at a certain point it would be more viable to just buy a bike with and designed specifically for a belt drive.
That all being said , here are the links I found of currently available belt drive systems :

Belt & Pulley:






Rear Hub Gearing:




Pinion and other drivetrains:




Info and YouTube vids:








Just a few of sites I found , but I'm sure there's more to come. Hopefully one day Gates or some other company will decide to make economical conversion kits for riders like myself. But until then , looks like Nicolai is the way to go , although pricey , pretty cool in my opinion.

So if anyone out there has anything to add , edit or help for those of us curious , it would be appreciated.



Ride on
 

slickrock

Active member
Aug 7, 2022
161
160
SF Bay Area
I have this discussion going on in the Pole Forum regarding doing a belt drive conversion for Voima and Sonni that could be of some use to the OP. Belt-driving a Rise you have no choice but to go with an IGH, specifically ones that support Boost 148 thru axles, such as: Rohloff (not an actual thru-axle), 3X3 Nine, Classified, Enviolo, etc.

Next, and this is important, you will need a belt tensioner because the Rise has chain growth throughout its travel so the belt needs to be larger and this length needs to be taken up spring-loaded tensioner. The problem is that there is no standard for this and has been more bike OEM-specific or at least one that can bolt onto the motor (in this case Shimano, and at the moment I'm not aware of any that exist). Pinion and Gen 4 Bosch have some paths to take via Nicolai but Nicolai doesn't do Shimano.

One thing going for the Rise at least is that's it a four-bar Horst-Link design that allow belt routing through the rear triangle by disconnecting the link. VPP and classic DW-Link bikes are not so lucky.
 

ep8-rs

Member
Jul 18, 2024
48
27
US
Wow slickrock , what a great link! Now THAT"S the kind of helpful info I'm looking for!
Really like the specifics of the tensioner. I know that is a major part in the full suspension issues , and I have to say I feel the pulley and belt world has a lot more to offer that simply isn't seen in the bike world just yet.
Thank you for your input. REALLY appreciated!


Ride on
 

ep8-rs

Member
Jul 18, 2024
48
27
US
I do have to add this link in on this thread as well as I've seen it , found it very intriguing , but alas , it is not yet available or proven viable for that matter. Still...:unsure:

 

slickrock

Active member
Aug 7, 2022
161
160
SF Bay Area
It's only 2
I do have to add this link in on this thread as well as I've seen it , found it very intriguing , but alas , it is not yet available or proven viable for that matter. Still...:unsure:

I've seen this but only provides 2 gears and doesn't use Gates CDX belts. Classified has 2 gear setup that is fully wireless and has been out there for a while. I gave this hub some consideration, but really more gear range and steps are needed for EMTB, let alone and SL-EMTB like the Rise.
 

Alfmeister

New Member
Subscriber
Nov 11, 2024
18
16
Uk
Hi, new to the forum, find this conversation very interesting, as this is exactly what I’d love to do to my Orbea Wild some day. Hope the aftermarket manufacturers can come up with some kind of kits in the future.
 

slickrock

Active member
Aug 7, 2022
161
160
SF Bay Area
Hi, new to the forum, find this conversation very interesting, as this is exactly what I’d love to do to my Orbea Wild some day. Hope the aftermarket manufacturers can come up with some kind of kits in the future.
Things in your favor for the Wild that can't be said for some other bikes:
  1. The wild is a 4 bar design that would allow belt drive, even though it does not have an elevated chainstay.
  2. Has the Bosch Perf CX so you can get electronic shifting with Roloff or 3X3. Need permission from Orbea to get software configuration change to support electronic transmission.
  3. Nicolai Belt Tensioner can more readily mount to Bosh motor, but the frame could get in the way. As such you may or may not need to fabricate your own flange attachments for the tensioner, but its not all that out of band if you have some ingenuity.
 

Alfmeister

New Member
Subscriber
Nov 11, 2024
18
16
Uk
Thanks for the reply slickrock, I’ll be eagerly awaiting future developments and as said previously, hope aftermarket bring some type of kit to market. I’m certain this is the future for emtb’s, unless it’s ultimate performance and light weight for racing.
 

DieBoy

Active member
Jul 14, 2023
144
218
EU
This idea has also gone through my head in the past, due to my traditional hate relationship with dérailleurs and positive experience of geared hubs.

The standard hubs like the Nexus or Alphine have a low max torque rating and aren't suitable for ebikes.

That leaves something like the Rohloff E14 ‐ expensive, involves special measurements, and they don't sell to end users. Or one from Enviolo rated for the torque though requires an adaptor to fit in boost axle, and has not overly positive reviews.

In the end I dropped the idea, though I really really like the pinion MGU idea - hopefully when I'm looking to buy a new bike, there'll be something within my budget.
 

slickrock

Active member
Aug 7, 2022
161
160
SF Bay Area
Thanks for the reply slickrock, I’ll be eagerly awaiting future developments and as said previously, hope aftermarket bring some type of kit to market. I’m certain this is the future for emtb’s, unless it’s ultimate performance and light weight for racing.

I really don't ever see aftermarket kits every coming out in the MTB/EMTB space. Bike companies themselves have to believe in the technology to support it. Very few do and when they don't you have to DIY it. IGHs and gearboxes have been around for a very long time and the problem for these bikes is chain and belt tensioners have always been and issue because suspension designers are rarely concerned about chain/belt growth with rear wheel travel. This is because chain growth is inherently subsumed with staid derailleur tech with all the different sprocket sizes in the cassette. IOW, the derailleur IS the tensioner - so what if company's specific suspension design introduces chain growth because the derailleur will fix it? Well the same can't be said of an IGH - you need some tensioner to do this and some of them look just like derailleurs, hanging of the rear axle where they still add unsprung weight and get banged by rocks just the same as the tech its intended to replace. Nicolai has done a good job making one that's out of harm's way, but it's heavy and they aren't licensing it to other companies.

Now, if companies design rear suspension with concentric rear wheel axle paths, then you don't need a tensioner at all. Some downhill bikes have this kind of suspension, they are very active and with EMTB, who cares now if your suspension is very active. I see this foresee this happening with MGU bikes in the future as they become more mainstream
 
Last edited:

slickrock

Active member
Aug 7, 2022
161
160
SF Bay Area
This idea has also gone through my head in the past, due to my traditional hate relationship with dérailleurs and positive experience of geared hubs.

The standard hubs like the Nexus or Alphine have a low max torque rating and aren't suitable for ebikes.

That leaves something like the Rohloff E14 ‐ expensive, involves special measurements, and they don't sell to end users. Or one from Enviolo rated for the torque though requires an adaptor to fit in boost axle, and has not overly positive reviews.

In the end I dropped the idea, though I really really like the pinion MGU idea - hopefully when I'm looking to buy a new bike, there'll be something within my budget.
You may want to look at the 3x3 Nine hub, then:
  1. It supports 250NM of torque so OK with full power EMTB motors
  2. Inherent Boost 148 12mm thru-axle design so doesn't require compliance fittings from Rohloff
  3. Allows for a small front chainring compared to Rohloff: leverage ratio allows 32T rear sprocket and 39T front, whereas Rohloff is 22T max rear with a big 50T front chainring, which looks odd like roadie-sezed chainring on an EMTB.
  4. Bigger gear range than Rohloff
  5. 9 instead of 14 gears - this can be seen as a plus for emtb folks
  6. Costs less than Rohloff
  7. Electronic shifting support for Bosch motors (similar to Rohloff E12)
I intend to go this route with my bike.
 

slickrock

Active member
Aug 7, 2022
161
160
SF Bay Area
So I made some good progress outfitting my EMTB with belt drive. One thing to add is that after all the work that ended up being done to adapt the tensioner to the bike, what motor you have on your EMTB is not really a concern. I thought it would be much easier with the Bosch motor since mounting flanges that came with the tensioner were meant to attach to the Bosch motor, but problems with bike frame intruding on the location where the tensioner needed to go obviated their purpose. So really, the biggest thing to take into consideration boils down to: Is there room for tensioner on you particular bike frame? If so, then its just takes the patience to prototype and fab the flanges to make it work. Luckily with my bike frame having an elevated chainstay and with mixed wheels, there was plenty of room to proceed.
 

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