[Help] Belt tension | Sector 9 | Enertion R Spec & Mount | 6s |

I have an issue with my belts going bad so quickly. I remember reading somewhere here that someone had a belt go for over a year without malfunctioning.

I’ve already gone through 3 belts and it’s only been 2 months since I got my board running. I feel like it’s the tension of the belt.

I don’t what kind of tension is suitable for it to not break. My motor mount is Enertion’s mount.

I would post a photo, but I’m not home at the moment. Anyone have suggestions?

enertion has a video on his youtube channel about setting up his motor mount, and it includes belt tension.

I ran one of enertion’s belts for over a year before it broke, so it’s definitely not the quality of the belt.

You can use a cheap belt and they would even last. It’s the angle or alignment of your setup. Your belts being too loose that the teeth get pulled off and/or similar.

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all of my belt breaks have been due to misalignment or bad tensioning as well.

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Having the belt too tight will create friction and heat and ruin the belt as well. I made all 3 mistakes…too loose, too tight, not aligned.

Is there a rule of thumb when putting the belt on? I just put a new belt on last night and it’s pretty tight. If I try to loosen it, it’ll just get too loose.

Also, Enertion’s video didn’t really help.

Also, check to make sure you don’t have any anything stuck in the pulleys. I once had a tiny rock that wedged itself in there and broke two belts because I didn’t notice it.

  1. Pull the belt as tight as possible so that you can feel the resistance increase in the wheel when you try to rotate it… (rotating the motor should also feel more restricted)

  2. Now… Loosen the belt fully so that there is zero resistance felt when rotating the wheel. Now you have experienced both extremes, too tight & too loose.

  3. NOW… Slowly increase the tension until you start to feel the rotation of the wheel become very- slightly-restricted by the tension… STOP.

The aim is to get the belt tight, but not put unnessecary force into the bearings.

With the correct belt tension the wheel will feel loose and free and the belt will feel firm without slack.


I just broke my first belt the other day. It had done just over 400km and had 3 holes in it from small rocks.

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Check out how Metroboard uses a guitar string app to measure belt tension. https://www.youtube.com/watch?v=on_L6wAo5yA


What are peoples thoughts on idler pulleys to tension belts? I have always left it because its more effort than just moving the motor.

But I can see benefits in meshing more teeth…

i think idler belts will be a huge benefit… i just haven’t spent much time working out exactly how to integrate that into my mounts.

More teeth in mesh is always better… can use much smaller motor pulleys and achieve greater reduction… this could help with efficiency as you could have the motor spinning at higher RPM - around the 8500 mark.

Read this build thread. I made one for a couple of builds. I called it a tensioner, but it’s doing the idler job as well. And works amazingly. https://endless-sphere.com/forums/viewtopic.php?f=35&t=59259

Can anyone show a visual representation, if possible, of how much tension you have? This is what my board looks like. Just before I took the photos, I loosened the belt a bit from what it was at previously. Not sure if this helps.

I also have a video of me turning the wheel with the same amount of tension. Not sure if you can hear the noise.

Apart from the obvious “mechanical” reasons of belts wearing out due to bad alignment OR being too tight/loose.

There can also be “electro-mechanical” reasons for the belt to wear out prematurely that are related to the ESC? What ESC are you using?

There are two ways the belt can be damaged by the ESC.

  1. Acceleration Curve, If the ESC tries to accelerate the motor faster than what the torque load rating of the belt can handle the belt will skip. Load on the belt decreases as momentum increases. If you try to spin up too fast, before load has the chance to decrease you could exceed the torque rating of the belt. You will know because the belt will be skipping teeth during starting.

  2. Brake force progressiveness, If the ESC brake is very abrupt and comes on really strong & early the same problem happens. The momentum load is too great for the belt to slow you down without skipping…

both these things will damage a belt quickly.

If you are a heavy guy 90+kg you might need two motors! this will double the torque load rating of your drive train. You can also modify your throttle control technique to try and become smoother.

You may also consider upgrading to a wider belt, ill have a 12mm wide belt system available soon that is designed for single drive boards that need to have better performance.

Also, you might consider going a larger motor pulley to increase the “teeth in-mesh” the more teeth in mesh the greater the torque load transfer.

I weigh roughly 180lb. (~81kg) and I’m using the Hobbywing EZ Run 150amp ESC. I also use the Wiiceiver by Austin David.

I also noticed the acceleration curve, so I usually kick off pretty good, then gradually increase speed. It takes me a bit of time to get up to speed, but I don’t really mind it.

With the brakes, I know the Wiiceiver abruptly breaks at whatever position I put it in, but whenever I need to stop I plan ahead and just coast, then use the brakes when needed by going down on the joystick very slowly so that it doesn’t stutter.

That 12mm wide belt system sounds very promising, though since I just got my board finished, I don’t have money to spend on upgrades in the near future.

What amount of teeth in the pulley is enough? My pulley has 40 teeth on it.

What pulley has 40 teeth? i assume you mean the wheel pulley?

@csn I really like metroboard’s mount design; a single screw to tension the belt would take a lot of the guesswork out of it!

if you read their feedback you’ll see some complaints. People still have the same issue with the addition of bending braking the tool

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Oh shoot, I didn’t read correctly. That was the wheel pulley I was referring to. I have a 14 tooth motor pulley.