Boardnamics Mounts Issue

Hey guys this is kind of a dumb post and I already have several solutions, but hear me out.

I have 2x boardnamics idler mounts on the precision hangers, 97mm ABEC 11 wheels, and the new Maytech motors from the Fiori group buy. I am trying to set up the mechanics of it and it is not quite working out. I have a 40T wheel pulley and a 14T motor pulley, the belt that I have to use for it is 320mm, which is what was suggested on the website and by several other people, however, I have run into some issues.

I cannot get the idler tight enough without crashing into the wheel. I don’t think I am doing anything wrong but it just doesn’t make sense that 320mm would be suggested as a size when even with the idler completely tightened, the belt is still almost too big. Am I just screwed here, needing to buy a shorter belt? Or should I pursue a different solution?

Couple solutions: Buy new belt - would need return the belts, takes time.
3d print an idler expander (diameter) - really not the prettiest solution.

Flipping the motor pulley around doesn’t make any difference and the shaft of the motor is already too short for the pulley to grip with the allen screws, so I was going to need to loctite it anyway

Pressing the belt to almost the right tension, except the idler hits the wheel

Definitely not tight in this photo either, idler crashing into wheel

Pressing to right tension without the idler on - clear in this shot that the belt seems to be too long

This clearly isn’t the solution either (flipping the pulley so that the allen screws grip the shaft) The overhang between the pulleys is crazy, will be shown further with the idler

Obviously you can’t run the idler like this

Using all the washers from the other idler to put it in the right spot, still crashes into the wheel.

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It really does look like the belt is too long.

One possible solution is to add space between the wheel pulley and wheel using spacers.

And longer screws of course.


Hmmm that is a possibility… I don’t know how that would affect the longevity of the wheel though, having the axial load further away from the bearing support

Yeah that would be probably more annoying to do than getting a different belt

I assume I should just use the belt length calc to figure it out, I just didn’t check it because it was suggested to me that 320 would work with this kind of combo.

Anyone else?

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is the 320 recommended with 15t pulley? or 14t? the belt does look too long

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@Boardnamics trying to place an order but error

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You could always shave the back of the wheel a bit to clear the idler…

The belt only needs to be tight enough to not skip during acceleration/braking - any tighter just increases stress on parts. Have you tried setting the idler as tight as you can and testing it? You might be surprised how loose it can be and not skip.



Shorter belt and spacer between pulley n wheel.


Or get a bigger idler


I had a similar issue previously where the inner wall of the wheel rub against the edge of the idler bearings :sweat_smile:

Have you try adding maybe another 2 or 3 washer on the truck axle and sort of have wheel sit further out thus making the gap between the inner wall of the wheel and the mount bigger?

Hope what I said make sense and hope it helps :+1:

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That is true, I have not, waiting for the board to arrive. I agree that over tightening it is pointless, so I suppose it can’t hurt to try.

Will probably just do this

Good suggestion too, I thought maybe of printing an expansion but I suppose a bigger one would work too.

Unfortunately I am already out on the very end of the shoulder bolt. Even if I were to add space there, the wheel pulley would move with it, and ultimately this is what needs to be aligned with the motor pulley. Thanks though :slight_smile:

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Too long of a belt it seems, maybe my calculator needs updating, sorry :frowning:

I have been gone for 11 days and my business partner dumped me so my support and finances are on fire right now. Once the jet lag wears off, I can normalize again. Also I start college today so yeah it’s a mess lol


320mm is for 16/36 ratio I believe

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I realize that but I have 14/40, essentially the same thing. :man_shrugging:

Don’t beat yourself up about it, I easily could have used a belt length calculator before I got the belts, I just thought that the number listed was right, so I didn’t take the time to do it.

And yeah about the other business matters, hopefully it all evens out but you definitely don’t want to lose your first semester of college to this. Keep your straight A’s first year and it sets you up nicely for the rest of the time. Did for me anyway.


Oh my god lol :rofl:

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@Boardnamics listen…


But the bbman calculator seems to suggest 320mm as the correct one too so I am genuinely confused with it :sweat_smile:

But I did have an experience where my 320mm belt is actually longer than my 325mm belt…no idea how that happened :laughing:

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Technically 320 would work if the wheels were smaller but with them being 97mm obviously they will take up more space

I am going to get a 305 or 300 from … well somewhere I can’t find any nearby yet

Oml hahah


I have a set of 300s, albeit some sort of weird widths
One measures 13mm the other 14mm.
I’d be happy to send em your way for postage cost
In in Ventura so local pickup is an option if you’re dedicated enough.

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