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[smithy]

Hi All,

I'm toying with the idea of converting my Experia to belt drive, not a necessity, I'm doing it more as an experimental challenge. I know the swingarm needs to be removed to fit a belt and there's not a lot of room for a wide-ish belt....The Zero SR/F uses a 20mm wide belt and they produce similar torque to the Experia and they seem to run ok. The Experia will probably be restricted to a 20mm wide belt also due to the limited space currently between the chain and frame. The stock 520 chain is close to 19-20mm wide.

I'm in the process of trying to source appropriate sized "blank pulleys" and belt. I need to keep as close as possible to the 3.25:1 ratio so the speedo will read relatively close to correct. The 8mm pitch belt will need to be 2000mm long and 250 teeth due to the long swingarm and size of the pulleys required. The pulley's I'm thinking of are 34t front and 112 rear using 8mm pitch to keep as close as I can to the 3.25:1 ratio, it turns out to be 3.29:1 so pretty close. The correct rear pulley would be 110 teeth but blanks with that tooth count aren't readily available...so 112 it is. Attaching the pulleys to the bike will also be a challenge...I have thought about it and have a few ideas rattling around in my head....will be interesting to see what I come up with after sourcing the parts.

The pulley OD's will be very close to the stock sprocket sizes within a couple of mm's so hopefully it won't look too out of place. Continental do a "Contitech" carbon reinforced drive belt of the right dimentions, so I'll see if I can get hold of one to test my theory.

I may be restricted to an 8mm pitch belt & pulleys due to the ratios required, if I went to the more common 14mm pitch, the smallest front pully I can get is 27t and would be too big in diameter to fit in the space provided, the rear would need to be 88 teeth and would also be huge and probably wouldn't fit in the swingarm space. 11mm pitch pulleys and belts seem to be near impossible to source in the right sizes and 20mm width. The Zero uses an 11mm pitch drive belt system but the rear pulleys are huge.

I'm thinking of going with an 8mm pitch belt setup, which I though may not be strong enough...but my research seems to prove otherwise. Many Harley's use an aftermarket 8mm pitch belt for their primary drive, albeit a lot shorter & wider and they can handle plenty of torque between the crank and clutch basket in those big cubic inch engines. I'll also need to think about a possible tensioner similar to the one used by the old Buell bikes as the swingarm pivot and front pulley aren't on the same pivot centre like the Zero's. Although the belt drive Harley's don't seem to bother with a tensioner. Lots to think about and lots of potential machining work to do.

I will also try to make the system retrofittable/swapable back to chain drive easily if things don't work out as I'd hoped. Time will tell.

It won't be a cheap modification....but I'll certainly enjoy the challenge.

Thoughts for or against.??

Smithy.

[jotjotde]

I am not too sure that the belt drive used for the Zeros are really OK.
Having owned an SR/F for half a year I liked the nearly totally noiseless propulsion, but I also heard a lot about sudden failures. My dealer sold Zeros besides Energicas and he had to organise a transport back from Norway because a Zero rider was stranded there with no chance to get a replacement for the broken belt.

Personally I like chains better even if the maintenance might appear to be a hassle. But you can easily measure the chain wear, you can also see and hear it. Even a totally messed chain will bring you home. What's going on inside a belt you never know until it's too late. And if you are regularly riding in wet & dirty conditions, a belt is also wearing down even faster than a chain.

Last point is, but this is only an asthetic aspect, I never liked the huge chain wheel on my Zero, destroys the good look IMO.

But in any case I wish you good luck with you undertaking!

[Grauteufel]

I'm all for belt drives as the noise reduction and cleanliness would be appreciated. I believe a tensioner would be required as the changing length under suspension movement would cause the belt to jump, I suspect the harleys get away with it as they have negligable suspension travel on the rear.

From experience with cycle gates carbon drive belts, they always reccomend going with the largest front sprocket that fits (in our case largest combination that maintains the correct ratio) as the belts aren't fond of tight radii

[princec]

I had 3 belts fail suddenly and without warning on my SR/F within 20,000 miles. Massive annoyance. I have upgraded to the 25mm belt from the DSR/X, and already feel vastly more confident that it's not going to snap.

Cas

[Demoni]

IMO it's not going to work, not enough room between the wheel and swingarm to fit a belt wide enough to have the strength required. But if your just looking for an engineering project and don't mine if the end result is non functional I'm all for it!

I suspect you have already been searching on McMaster for pulleys? You can buy blanks for the front and then machine them to accept the center part of a Energica sprocket and weld them together.



The rear is just about matching the sprocket carriers bolt pattern and spacing it to align the front and rear. You might be able to find dished pulleys for the rear if you need to manage a large offset. Worse case you could redesign the carrier that fits into the cush drive of the rear wheel.

There is no way a 8mm belt would not snap like a shoelace when attached to the Experia, you really need to aim to at a minimum match what Zero is doing and they are already notorious for snapping belts.

[Specter]

 my unqualified opinion,  i think the experia is going to make a bit more torque and probably pop the thing a bit faster.  That's one thing that bike can give you is stubborn pull.

Aaron

[smithy]

All good thoughts guys....and you've all given me plenty of food for thought....Looks like i'll be doing a lot of thinking.

@Demoni, the welding of the Experia sprocket centre, (which is also the same as the Aprilia Tuono), to a matching pulley to get the required offset sounds like a good idea. I did the measurement of the rear pulley and although it will be very close, it should fit in the swingarm space if I get the offset correct, it's essentially the same overall diameter as the stock 52 tooth sprocket, which has ~10mm clearance.

I'd love to run an 11mm pitch 20mm wide belt like the Zero's but I cannot easily find one in the correct length and width...I'll need ~2000mm length and 182 teeth to mate up with the pulley ratio I'm thinking of and the front pulley will likely be too large in diameter to fit anyway...more thinking required. The BMW F800GT runs an 11mm pitch 182 tooth belt but it's 34mm wide. The BMW F800 also runs an 80tooth rear pulley which might work if I could find a 25 tooth front pulley...but their front pulley is 40teeth...much too big unfortunately....and only a 2.0:1 ratio, belt is 34mm wide anyway and would probably be too wide to fit. 

I can however easily get a 2000mm long, 8mm pitch, 20mm wide, 250 tooth belt which in theory, will mate up with my desired pulley sizes. Whether the 8mm pitch Contitech "Carbon" belt will be strong enough is the issue I suspect. If it works, great...if not, I can easily revert back to the normal 520 chain & sprockets.

Thanks again gents, you've given me plenty to think about.

Smithy.

[Grauteufel]

It'd be nice if anyone had the cad files for our bikes, that would make it easy to do test fits for just about anything.

Looking at those conti synchrochain belts I notice a conspicuous lack of speificiations regarding torque and speeds

[smithy]

It'd be nice if anyone had the cad files for our bikes, that would make it easy to do test fits for just about anything.

Looking at those conti synchrochain belts I notice a conspicuous lack of speificiations regarding torque and speeds

This is the 8mm pitch belt I was able to source:

https://simplybearings.co.uk/shop/p2099766/ContiTech-SCC8M2000X21-Synchrochain-Carbon-Timing-Belt-21mm-Width-2000mm-Length-250-Teeth/product_info.html

It mentions 4150N of "peripheral force" whatever that means..??

Smithy.

[ESokoloff]

……. The BMW F800GT runs an 11mm pitch 182 tooth belt but it's 34mm wide.....

Smithy.

I wonder how hard it would be to successfully cut 14mm off the width?

[smithy]

……. The BMW F800GT runs an 11mm pitch 182 tooth belt but it's 34mm wide.....

Smithy.

I wonder how hard it would be to successfully cut 14mm off the width?

Not easy I'd imagine...but then getting 20mm wide 11mm pitch pulleys in the right tooth count would be the issue I suspect.

Smithy.

[Grauteufel]

It mentions 4150N of "peripheral force" whatever that means..??

Smithy.

I assume thats either the lateral force on the "tooth" or the tension on the outer face of the belt. Either way, I would be a little wary of the value, as thats only 420 odd kgf. While 0-100km/h in 3.5s is only 0.8g, the arse dyno says that there is more force in that 70-100 range, which with 260kg bike plus rider doesn't leave much headspace.

[ESokoloff]

……. The BMW F800GT runs an 11mm pitch 182 tooth belt but it's 34mm wide.....

Smithy.

I wonder how hard it would be to successfully cut 14mm off the width?

Contact Gates & ask?
https://www.gatesaustralia.com.au/


Not easy I'd imagine...but then getting 20mm wide 11mm pitch pulleys in the right tooth count would be the issue I suspect.

Smithy.

[Specter]

id think cutting anything off the belt would severely compromise it's integrity.  Leaving a ragged side, might be opening yourself up for a damage area for tearing and other disassembly to get to work at.

Aaron

[Demoni]

All good thoughts guys....and you've all given me plenty of food for thought....Looks like i'll be doing a lot of thinking.

@Demoni, the welding of the Experia sprocket centre, (which is also the same as the Aprilia Tuono), to a matching pulley to get the required offset sounds like a good idea. I did the measurement of the rear pulley and although it will be very close, it should fit in the swingarm space if I get the offset correct, it's essentially the same overall diameter as the stock 52 tooth sprocket, which has ~10mm clearance.

Did a little field work for ya. Looks if you lined everything up perfectly there is 24mm between face of the motor and the inner face of the swingarm. Meaning you should be able to squeeze a 20mm bolt and pulleys in there.

Also you can download 3d files of every part Mcmaster sells. If you have a 3d printer you can import that into a slicer and print prototype parts.