my belts last forever (>1000km), but i mostly ride at constant speed a lot. never lost a belt just like this - has always been due to debris working itself into the belt and then weakening it at this point.
running 99% in the dry no real hills 15mm 15/33T with 190kv and 90mm wheels
my belts are very loose too, just at the edge of skipping!
Might be the water also.
@whitepony that distance would be a dream, no hills really take easy on the belt
@Titoxd10001 to test I will not let the current belt get wet, my classes resume this week, so just on commute if the weather helps should be 100km, plus night rides and the weekend
i think a loose belt is the key. a belt actually gets hot when its too tense, so it really cant be very good for its life.
coasting is so much better with a loose belt and that energy loss with a tight belt gotta end up somewhere (and it hast to be taken in by the belt for the most part).
I think saul hit it on the head. The 12T pulley doesn’t engage enough teeth and i bet it shreds the belts. My evolve started to shred belts, I found it was due to the teeth wearing down on the drive gear. Do you use aluminum drive pulleys?
The belt breaks on the tight side which is the side being pulled by the motor, if the tensile strength is overcome by the tensile force it will shear. This is combination of the smaller pulley (12t) creates a small radius of curvature around the pulley so the belt basically is stretched a lot on its outer edge while the teeth side is probably not stretched. In addition the small curvature has less teeth in mesh unless the pitch is also very small and the belt is thin. Basically the only way to fix this if you stay with that 12t, to get a thinner belt wider belt. If you increase the pulley radius it allows for a bigger curvature meaning less bending stress on the belt and on the outer side of the belt. Plus it allows more teeth in mesh. Making the belt wider allows for more tension dispersion along the width of the belt.
@whitepony exactly, my best experience was with a 3M belt, there was almost no drag, but it skipped like crazy even with a lot of pre load
@Fiori no, hardened steel, what’s the teeth count on the evolve?
@wmj259 I just done some calculations, I’m well below the breaking strengt, my 15mm belt should be good for 4785 N, but my setup loads the belt with a theoretical max force of 267 N, that’s a lot of headroom
I think is safe to assume that my problem really is bending fatigue of the fibers, since apparently I’m the only one that has this problem and only one that uses 12T pulley
I just bought a new belt and put it on my board and it is making a weird poping/snapping noise towards the back of the board by the back wheel, any ideas what it is.
Evolve uses 15T pulley. Iv’e read somewhere on here before that anything less than a 14T drive pulley caused some belt traction issues.
What is your plan with the data? Engineers have gone through this issue in designing power transmission with belts.
It’s also good to add in a safety factor as well as design factor. Those two are separately used but used sequentially.
@chuttney1 if enough people answer we can identify what are the major causes of belt failure and avoid them
@Fiori thanks, it really depends on the load and the diameters relation to determine how many teeth in mesh
@wmj259 yeah, on the gates design manual, even considering all the factors still has a huge margin
Pulley ordered, since it’s custom made it should take 2 weeks or more
New belts arrived, now i’m with 12/36 without idler, let’s see what happens
The belt may be too tight but i’m afraid of it skipping, early tomorrow i will test on the way to uni
From my experience a big hit (gap in road or pothole) or very heavy vibrations can cause belts to break. I’m not exactly sure what is going on there. I don’t think the belt is scraping pavement either since I run larger wheels. Not sure if anyone else has had the same experience.
I will post a chart provided by Gates of the most common types of belt failure showed for timing and v-belts if anyone needs a reference.
Most likely the the wheel loses contact to the ground and spin up rapidly, and when the contact is back all the motor inertia is transferred to the ground via belt, this put a huge stress on it
most of mine ruptured in a particular patch o very bad pavement that to make it worse is the steepest part of my commute
I also lost one rubber belt. I think it was because tension was too high and i hit many simultaneous gaps on the road in row…
now im using poliurethane belt with steel wires running inside, should.help with durability.
Where did you find this?
An update, i hit the 100km mark and the belt is looking great, no superficial damage