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[Specter]

that frame slider, i could see maybe an occasional rub but distorting the drive path that much, that would be a problem, being it's not a normally rolling element, like a pulley.  The friction would definitely be bad.  how much is the bend when the bike flexes?  You might want to keep that off there.

Aaron

[smithy]

that frame slider, i could see maybe an occasional rub but distorting the drive path that much, that would be a problem, being it's not a normally rolling element, like a pulley.  The friction would definitely be bad.  how much is the bend when the bike flexes?  You might want to keep that off there.

Aaron

The "lower" plastic frame slider in mainly there for chain slap under power I suspect....it hasn't been touched by the chain though and is in new condition even though the bike has done 40k km. It isn't there anymore and will only be refitted if/when I refit the chain/sprocket system.

The belt should not go near the lower frame in operation as there is always a considerable amount of tension on the belt. I'm still thinking of running a tensioner like the one I showed previously....just need to make up a mounting bracket...a little engineering is required there methinks.

I'll eleaborate more when the whole system is up and running and bugs ironed out.

Smithy.

[ESokoloff]

The belt is a Continental CT1208...182 tooth, 11mm pitch, 2000mm long & 34mm wide, (~1 3/8"), and is the same belt as used on the BMW F800GT. I could'nt find a slightly narrower belt with the same tooth count which would have been nice...but not to be. Clearance to the frame just above the swingarm pivot is minimal..

Smithy.

At the factory, belts are made in continuous wide batches & then cut to exact width for multiple individual belts so you should be able to accurately trim your belt as needed (just need to figure out how).

[smithy]

At the factory, belts are made in continuous wide batches & then cut to exact width for multiple individual belts so you should be able to accurately trim your belt as needed (just need to figure out how).

There was a chap on one of the Harley groups who did "slice" his belt to a narrower width to accommodate a wider rear tyre...he made up a belt holding fixture which allowed it to be "pulled" through the fixture which had a sharp blade fixed in it to get the required width...as you mentioned...that's all they do at the factory when making belts.

I'd like to avoid making the belt narrower if I can due to the torque the electric bikes make from zero rpm, I might be being a little paranoid though, some 300kg+ Harleys run a 1" belt without issue and they put out a decent amount of torque.

Smithy.

[smithy]

Hi All,

Just to follow up on this project...

I went for a ~100km run today, to test the belt setup.....no tensioner fitted as the parts I ordered for it haven't arrived yet. All seemed to go well, it's exceptionally smooth...although electric bikes tend to be smooth anyway.....gone are the chain & sprocket noise and vibrations, I wasn't even aware the sprockets and chain had any vibration....I stand corrected.

As you may all be aware, the belt and rear pulley are taken from a BMW F800GT whilst the front pulley is a modified BMW F650 CS  "Scarver" item. Neither of these bikes use a tensioner either so I was fairly confident it would work ok. I didn't do any full throttle pulls as I still don't know the capacity of the belt, I'll creep up on it slowly, I suspect it will probably be ok though.

So far so good..! I won't call it a success until a decent amount of miles/kms have been travelled without issue. I am also looking at a front pulley with a tooth count which will be a lot closer to optimal...this will take time to organise and setup though. For the ideal pulley ratio, a 16/52 sprocket setup has the speedo reading near perfect which is 3.25:1....to get a belt pulley of the same ratio I need a 24.6 tooth front pulley...so I'll go for a 25/80 toothcount, or a ratio of 3.20.... currently it's 28/80 which is 2.86:1...this throws the speedo out fair way unfortunately.

I'll report back when I have all the required parts and the machining and assembly has been completed.

Smithy

[Specter]

smithy most people have their phones on their bikes when they ride anyways right? do you?  just open up waze or an app called gps essentials and you can get real time speed right there.  i have my phone to run the dragy app when im riding spirited and it does a decent job, ill have to look but i got the ribelle dialed in so the mph is dead snot on from basically 0 to 150+ even double checked with my airbag suit and it's right on the money now.

Just a friendly reminder, tire size will set you off too.  if i throw some 205s on because im going to be dragging on a saturday, the speed is off a bit.
in theory your rimsize could too somewhat... if were looking for needle accuracy

Aaron

[smithy]

smithy most people have their phones on their bikes when they ride anyways right? do you?  just open up waze or an app called gps essentials and you can get real time speed right there.  i have my phone to run the dragy app when im riding spirited and it does a decent job, ill have to look but i got the ribelle dialed in so the mph is dead snot on from basically 0 to 150+ even double checked with my airbag suit and it's right on the money now.

Just a friendly reminder, tire size will set you off too.  if i throw some 205s on because im going to be dragging on a saturday, the speed is off a bit.
in theory your rimsize could too somewhat... if were looking for needle accuracy

Aaron

Yeah...I had my phone "speedo app" running....@100kmh on the GPS it was showing ~90kmh on the bike speedo...so ~10% under reading. Once I get the front pulley size sorted, I'll go for a 25 tooth item, it's 28 tooth currently, that should get it back to very close.

Smithy.

[smithy]

Hi All,

Another small update...I've covered ~1400km on the belt drive since fitting thus far. No issues to speak of and there's no strange wear or noises that I can detect.

I'm still on the search for a 25T front pulley, I have found one or two but they'll require a significant amount of "modification" to fit the Experia.

I rode the bike into work this morning, this trip is 50km each way and has 90% 100kmh motorway running....so nothing real strenuous for the belt/pulleys. I still have not fitted a tensioner, I do have all the parts required...but I'm still undecided....still trying to figure out if it is really necessary....as mentioned previously, the bikes the original parts come from don't use a tensioner of any sort. Both of these being the BMW F800GT and F650CS, as can be seen in the pic...no tensioner.

So far, so good.

Smithy.

[Specter]

if it's not giving you any grief then really no need for extra parts and complexity id think.
if you don't plan on really stomping on it or something that is going to wildly torque the belt to the point it might jump, you really shouldn't have to worry if it's lasting this long so far.

aaron

[SilentPea]

awesome setup!
you mentioned the process for adapting the rear sprocket to bolt on the pulley, but not the front.
Did you end up doing the chop&weld approach or were the bmw splines able to be massaged to fit?

edit: Do you have to pull the swingarm pivot bolt to mount up? That was mildly annoying on the zero belts. 

[ESokoloff]

…………I still have not fitted a tensioner, I do have all the parts required...but I'm still undecided....still trying to figure out if it is really necessary....as mentioned previously, the bikes the original parts come from don't use a tensioner of any sort. Both of these being the BMW F800GT and F650CS, as can be seen in the pic...no tensioner.

So far, so good.

Smithy.

How much belt “slop” on your install vs the BMW during suspension travel?

The way I see it, an auto tensioner is only needed if the “slop” is excessive without it.

[smithy]

…………I still have not fitted a tensioner, I do have all the parts required...but I'm still undecided....still trying to figure out if it is really necessary....as mentioned previously, the bikes the original parts come from don't use a tensioner of any sort. Both of these being the BMW F800GT and F650CS, as can be seen in the pic...no tensioner.

So far, so good.

Smithy.

How much belt “slop” on your install vs the BMW during suspension travel?

The way I see it, an auto tensioner is only needed if the “slop” is excessive without it.

There's is no slop at all, I use the 50hz tension requirement that many belt drive bikes use.

Smithy.

[ESokoloff]

To be clear I ment belt tension on full swingarm travel of both the BMW set up(s) & your’s.
If you’re setup yields constant tension (but not excessive) at every point in the swingarm travel then I can’t see how/why an auto tensioner is needed.

I’m thinking you could use a ratchet strap to compress the rear shock so the belt tension can be checked full travel of swingarm.

[Specter]

@smithy - but if you are south of the equator, don't you need a left handed sinewave on your hertz-o-meter?  Don't want your coriolis swirling your boreallis backwards on that wheel now !  You might want to flush the toilet to see which way the water spins just to be sure   

Aaron

ps did you try sprocketcenter.com for your front pulley?  they have all kinds of interesting and sometimes off the wall stuff for bikes.   if this setup is working nicely for you, what are you expecting / hoping to do with the different size up front?

[smithy]

To be clear I ment belt tension on full swingarm travel of both the BMW set up(s) & your’s.
If you’re setup yields constant tension (but not excessive) at every point in the swingarm travel then I can’t see how/why an auto tensioner is needed.

I’m thinking you could use a ratchet strap to compress the rear shock so the belt tension can be checked full travel of swingarm.

The swingarm is at it's longest with rider aboard, the tension is obviously not constant through the entire travel, it is less at full travel in either way....the BMW F800GT is the same and they don't seem to suffer any ill effects.
Good idea with the ratchet strap...I might give it a shot and see exactly what happens. The swingarm is very long compared to a lot of other bikes so the arc difference is not too drastic.

I have "mocked up" a constant tension tensioner just in case. Thoughts..??

Smithy.