Vex U commercial belts legal?

I am wondering if pulley belts are legal on Vex U as I see that SJTU apparently used commercial belts and I don’t see specifically if it is legal or not
This is the video: SJTU VEX-U 2020-2021 Change Up Robot Winter Reveal - YouTube

They’re probably using the VexPro belts and pulleys.

Any parts in the VexPro section are legal to use in VexU. No other commercial parts can be used unless they’re identical to the ones found on the website.


can they be found on another website under the same name “HTB” and would it still be legal?


This is not the case this year unfortunately. Identical parts are no longer legal due to the removal of what was R6d from the game manual. The GDC has confirmed this in a Q&A. I’m honestly not sure what the GDC was thinking doing this because:

  1. How am I as an inspector supposed to tell that a part is identical to a vex part but not sold by vex? Am I supposed to demand receipts for any and all parts that can be purchased from non-vex sources?

  2. VEXPro parts (such as the above) are not sold or shipped to all countries. Are VEXU teams in those countries just out of luck, and at a severe disadvantage now? Previously, they were able to purchase identical replacements from local sellers, but this is no longer possible.

@Jon_Jack Could you provide some insight into the rationale for removing R6d?


Thanks for all the information, I really feel a bit disappointed since we had planned to use our own pulleys made of resin-metal but here in Mexico the only distributor (Reeduca) They cannot get those belts, hopefully the CDC can make an exception in these cases where we do not have access to all the components


Only VEXpro belts are legal. The removal of the clause which allowed identical non-VEX parts finally made this clear. However, no one knows how to inspect VEXU robots, so nearly any event will allow any belts that look similar to VEXpro belts.

I inspected robots at a large VEXU event for Change Up and told a team they would need to remove the XL pitch (standard 0.200") belts they had used on their drivetrain. They said they had been allowed to use them at previous tournaments, so the event partner elevated the question to the REC, who told us we should allow them to compete as-is. They ended up doing very well at the tournament. I can understand the concerns from both this team for being able to compete with a robot and then being told it is illegal at the next, as well as teams who were beat by this team. Other teams interpreted the manual as saying only VEXpro (metric 3mm) belts were legal, while this team gained a significant advantage by using standard pitch belts which lined up with the 1/2" pitch of VEX metal.

VEX and the REC Foundation need to make sure that inspectors are properly trained for VEXU. The robot construction rules are needlessly restrictive, and currently only punish teams who try to follow them. I’ve seen anything from non-VEX belts to non-VEX aluminum and steel extrusion which have given significant advantages to teams be ruled legal at both worlds-qualifying events and the world championship itself. It’s very disheartening to see rulings which are so inconsistent with the official game manual.

The alternative is to allow any mechanical components that a team wants to use. I think this is a much better approach for VEXU since it allows university teams a design space appropriate to the engineering skills they are supposed to be developing.


See below…

There’s a longer back story behind this…

The intent of the current generation (2018-present) of the VEX U robot rules has always been, among other things, to give teams the freedom to explore advanced manufacturing techniques not available in VRC or the old VEX U robot rules.

Prior to Tipping Point, the VEX U construction rules had a problem that the GDC struggled to solve in an elegant way. The problem was making somethings (ex: springs) legal, while making other things (ex: a wire form a team had made at an outside shop) illegal, was difficult. This resulted in a number of Q&As where the internal discussion was essentially “yes, they should be allowed to use this, but can’t under the current rules.”

  • We were okay with teams buying springs to use on a robot, we did not want teams to go and pay to have custom parts fabricated.
  • We were okay with teams using aluminum angle to make a gusset or bracket, but were not okay with teams going to purchasing parts that were designed and manufactured outside of their team.
  • We wanted this to be an opportunity to explore advanced manufacturing techniques, advanced sensors, and custom electronics. We did not want this to turn into who can buy the best robot.

What we didn’t want to do to was turn the VEX U appendix into a never ending list of exceptions. In Tipping Point, we introduced a revised version of these rules that we think better communicates our intent:


Going back to my quote of @Dan2344’s post:

Ant XL timing belt is explicitly illegal since VEX/VEXpro doesn’t sell it. However, it can be difficult to tell specific belt profiles apart, let alone if something is purchased from VEX.

Except that many of the V5 / VEXpro components have some kind of branding on them. This branding helps make it easier to know what is a VEX part and what is a part that might need additional scrutiny under the current VEX U/VAIC robot rules. For example, all VEXpro belts have green printing on them, with a VEXpro logo:


So now the profile doesn’t matter. Is the belt VEX branded? Yes, then it’s legal. No, then the team should provide documentation that they made it.

So by getting rid of R6d it should now be easier for inspectors to tell which parts should have been fabricated by the team and which parts should be purchased from VEX.

Developing rule sets is a multi-dimensional balancing act. You’re trying to balance the interests of the teams, event staff (referees, inspectors, EPs, etc), and spectators. Sometimes you have to take something from one group to make things work for another.

I checked with our sales team and Reeduca is able to purchase these belts.


@Jon_Jack It may be time for an inspector certification to be added to the existing one for referees. I am fortunate to have one of the best crews in the world, but that is not the case at the great majority of events. This would greatly help teams make sure they understand the inspection process and that their robot is legal before going to an event.


It seems to me somewhat inefficient and incoherent that they mention that if it is not a VEX brand belt, then we have to literally manufacture it, it is a gigantic disadvantage that the shipments of these components are from 3 to 4 weeks. The problem is not that you can provide those belts to Reeduca, the problem is how long it will take to get here for a simple belt.