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[DonTom]

I once did a poll here (but was before the SR/F was available) about how many Zero belts have snapped. It was surprisingly very  low. Most Zero owners NEVER had a belt snap.  Many bikes had a lot of miles on the original belt.


In fact, the extra small belt on the 2016 DSR, Shadow,  the moderator here, wore his belt teeth down to nothing when he changed his belt. Never snapped.


I have wondered what makes some of these belts snap so soon. One reason could be Zero sometimes has them way too tight from the factory! I was just looking at a NEW Zero SR/S here in Reno, at Eurocycles. The belt was obviously way too tight, just like all the bolts on my Zeros. All way too tight. To the point that tools break trying to loosen some of them. 


I would be afraid to ride it a block with the belt that tight. No slack at all.


I don't believe for a second that Zero follows their own torque specs on new bikes, from what I have seem with mine. And the same goes with their belts, at least in some cases. See here.


-Don-  Reno, NV

[princec]

Mine was running at 55kg as I recall last time I measured it.

Cas

[umrath]

In a parallel discussion on a discord channel regarding the same topic, sudden load changes appear to be a relevant factor for belts snapping.

So, if you ride nicely paved roads, you are probably less likely to encounter issues compared to someone on a bumpy road or riding in the wild, as you will have situations when the wheel is suddenly spinning free (and thus spinning up quickly) and then ever more suddenly stopping, when some solid surfaces is getting in contact with the tire and quickly decelerating it.

[princec]

Definitely. Though this time, the road was smooth, and AFAICT, grit-free... it was just ordinary in every way. I think what it comes down to is that the belt Zero have specified is just not strong enough for the job.

Cas

[NetPro]

In my case, the area was repaved just a few months back and the surface was as smooth as they come. And totally flat too.

One factor that doesn’t help the longevity of these belts is the lack of a tight tolerance for the rear sprocket’s machining.

As mentioned by me in another thread on this forum, if you measure the roundness of the sprocket with a good caliper, you would find terrible highs and lows areas, as you turn the sprocket under the caliper.
Maybe mine was worse than most but I think the machining of this part is just poor.

I took my sprocket to an advanced machine shop to have two solid chain sprockets I had purchased to convert my bike to chain (to cut the big hole in the center and the 5 holes for the bolts to attach it to the wheel) and the machinist told me that when he “scanned” it with his machine —CAD— it showed to be quite off.

As an off-centric sprocket turns, the tension on the belt has to fluctuate and perhaps, on the bikes where this is more severe, the belt is more likely to snap.
This is pure speculation but something to think about specially if you keep the tension as recommended by Zero, on the high side.
I keep mine on the lower end of the range.

[Richard230]

When I bought my 2018 S its belt was very tight as set at the factory (as was the belt on my 2014 S). Right at the upper limit of tension, 75Kg as I recall. When I took it in for the 600-mile servicing I asked the technician to check the tension and he verified that it was set properly. When I changed my rear tire at 6K miles, I reduced the tension to around 50Kg. So far at 10K miles the original belt is holding up and doesn't show any unusual wear.

For some reason the factory assemblers set the belt tension very high. But I have always seen the same thing when buying a new chain-drive ICE Japanese motorcycle. The chain slack would be undetectable and as soon as I returned home with the new bike I would loosen the chain to achieve the correct slack. The only reason that I can think why this is done is that maybe the factory believes that the owner will never check the chain after purchase and they somehow feel that setting it very tight will allow it to loosen up after a few thousand miles.  And of course any damage due to a tight chain would not be covered by the bike's warranty, since chains and bearings are considered "wear items" and are exempted from most motorcycle warranties.   

[alby62]

la  mia cintura  ha 45000km , e la cambierò quando sostituirò il pneumatico posteriore.  quella di dotazione l'ho cambiata  a  14000 km perchè l'ho spezzata  atterrando  da  un salto  con gas  aperto , appena  la  ruota  a toccato il terreno si è spezzata.
 cambiarla non è semplice  occorre togliere il forcellone .

[DonTom]

la  mia cintura  ha 45000km , e la cambierò quando sostituirò il pneumatico posteriore.  quella di dotazione l'ho cambiata  a  14000 km perchè l'ho spezzata  atterrando  da  un salto  con gas  aperto , appena  la  ruota  a toccato il terreno si è spezzata.
 cambiarla non è semplice  occorre togliere il forcellone .

Treanslates to:


"My belt has 45000km, and I will change it when I replace the rear tire. I changed the supplied one to 14000 km because I broke it landing from a jump with open gas, as soon as the wheel hit the ground and broke.
  changing it is not easy, it is necessary to remove the swingarm."

[Skidz]

On my DSR '16 the first belt broke at 4000km, there was a fault at the rear sprocket that slowly chewed away the belt. The sprocket was replaced under warranty, the belt wasn't. Second broke after 16kkm, lost traction off-road and when regaining traction suddenly (Stones under the sandy road) i heard a "Twang!" sound of the belt skipping a tooth. Tooth snapped right off and made it home but didn't make it to the dealer 40km's away because of the belt skipping more and more teeth, eventually snapping. Third belt at around 30kkm, just snapped on the highway at 100km/h. Luckily I was on the right lane. The fourth belt is still under, going strong at 46kkm.
To avoid being without a belt I ordered a spare one, so if it snaps it can be replaced directly whilst a new one can be ordered.

Anyway, switching to  chain soon. Will save a bit of stress when driving highways with an 'old' belt