Belt Stength, is 15mm really worth it?

So I started out the riding a Dual 9mm belt set up and for the most part it worked okay it but did occasionally skip teeth under hard braking.

Ive used 12mm belts in all my other builds and I always wondered if I really needed a 15mm belt like everyone else. Ive never broken a 12mm belt or even have it skip on a dual set up so it made me wonder why people go 15mm on dual set ups.

Recently on my 4wd build I fell bad because my motor got loose and the belt got caught in the idler and locked up the wheel.

You would think with the grip of a pnumatic wheel and the weight of a 300lb rider the belt should had easily snapped but instead it did not it bent my motor mount and twisted all 4 truck screws to the left and sent me flying.

After my last incident I just can’t see any advantages of a wider than 12mm belt only disadvantages.

What are your opinions on this topic?



Logic bomb incoming, heed this advice


I recommend them and I’m thinking about moving up to 20mm on some boards. Only problem is pulleys are only available in 20mm (and 23mm) in 36T – and only for ABEC11 (but I’ve modified some to be kegel)

With wider belts you can run them looser too reducing idle drag which increases range slightly as well


I see that point but my current mounts with idlers has has the best free roll compared to any board I’ve ridden including 15mm set ups.

I’ve been asked how i got such good free roll, it’s my mount set up.

1 Like

But yeah I can see how it’s better for free roll with no idlers.

1 Like

I went from breaking 9mm belts daily. Switched to 12mm a year ago. I run them loose. Haven’t broken one since. I’m all for wider belts. Just don’t know if I’ll even need any wider for my application I guess.

1 Like

I would keep what you have then and post detailed information to help others :smiley:


It’s a TB prototype mount. It never went on sale but it’s essentially a TB reverse mount with 2 fixed idlers and belt tension is adjusted by sliding the motor. I tell Dexter that this mount is gold and he should sell it lol

1 Like

wide belts are great for ride quality, run them loose with no idlers…

the issue with wide belts is they’re open and not enclosed and eat debris. solve the debris and 15-20mm would be some of the smoothest quietest riding you can get.


Maybe I haven’t tried a good set up yet then. I’ll let you ride mine if I can try yours haha


I’d like to point out another variable that makes or breaks the belt skipping or not situation, regardless of belt size: core play… That is, how much play does your wheel have when you torque it down with properly aligned spacers and speed rings?

My Abec 107s, and flywheels in general to a lesser extent, have always had some small amount of play. Using wheel pulleys that don’t integrate their own bearing to center the pulley itself magnifies this small bit of play, and plagued me for months with tons of belt skipping, although to a lesser extent with idlers and/or very tight belts- skipping was still very much present under heavy breaking.

On the same exact setup, dual 15mm, since adding in a wheel pulley bearing (and small 3D printed adapter to make it fit), I’ve been running loose belts with no idlers and I havent had a single skip on my belts, period.

Belt width no doubt can help, but I’m sure there are 9mm and 12mm belt setups out there that outperform 15mm or 20mm belts just based on the play in a core magnifying overall pulley play by lack of wheel pulley bearing alone.

TLDR: belt width matters, but don’t get hung up on that solving all your skipping problems or thinking that narrower belts perform inherently worse… Other factors in your belt drive setup make a huge difference as much (or maybe more) than width alone.

To answer the question in the title? It depends. Lots more factors to consider besides belt skipping at that point. Your boards max torque and the rated load your belts can handle might drive some people to wider belts.


Also looser belts deal with snow better without snapping – and wide facilitates loose


on my street set up i used old stock enertion slip on pulleys they have a center bearing and it is much much better than a bolt on solution but that alone wasnt enough i had much more resistance using enertion mounts and i cant run enertion mounts loose at all maybe this case would be perfect for a 15mm belt set up.

1 Like

That, maybe. I’ve never used slip on pulleys so I can’t speak from experience… But,

I can envision that they may in some cases have a bit of play of their own, just around their own bearing, wiggling a tad about the core. Maybe not though, maybe it’s sufficiently tight enough of a press fit into the core. If not, bolting on and locking it to your wheel, giving you 3 bearings + spacers worth of width would resist any sort of wobble/play in the pulley, and maybe that’s the best case. I don’t know though. Sad to hear you still had belt skipping on that setup though. I guess all advice is good taken with a grain or two of salt :wink::sunglasses:

the pulley may not be bolted to the wheel but when i tighten my wheels is all the way down i dont leave any play in there. If there is any play there in the pulley its very little cause the pullies fit snuggly into the wheel.

1 Like

I run 25mm belts on my Bludgeon. It never skips, smooth as silk and mad torque. I’ve never had debris issues but it’s terrible on watt hours per mile, about 30% more than 15mm belts.

1 Like

think the debris is more so a concern on street wheels and the low ride distance of pulley to ground :slight_smile:

1 Like

I need no help. lol.

1 Like