Automated Starting Gate Ideas.....?

4 replies to this topic
  • Chaindrive

Posted September 14, 2002 - 08:31 PM


I'm pretty handy with a welder and have a buddy with a real nice MX track. I want to build a 4 bike starting gate for him. That part is fairly easy.

I want it to be automated so you don't have to get off your bike to reset it. I think I can handle the mechanics of that with an electric-over-hydraulic long-ram jack that is collecting dust in the corner of my shop. A foot or wheel activated reset switch should not be beyond me either. :)

I come before this distinguished brain-trust today to seek advice on some sort of electronically actived (random delay even?) triggering device that I can integrate into a mechanical release. Due to my limited knowledge of electronics, my daydreaming and doodling on bar napkins ends abruptly at using an electric eye of the type used on overhead garage doors to sense obstructions to initiate the (random?) timer for the release mechanism.

I'm even considering using the entire actual garage door opener (instead of the long-ram jack) to reset the gates.Resetting AND Triggering would then be a simple matter of one rider pushing a bar-mounted remote. Trouble is, that guy would have a definite advantage. How do I incorporate some kind of random delay?

Lets hear some ideas!! :D

  • tk421

Posted September 14, 2002 - 09:32 PM


Hey Chainy, there’s probably 100 different ways to do this.
Your application would be ideal for a Programmable Logic Controller PLC . You could have an input from a photo eye to start things off, you could cascade the timers in the controller for random starts. A relay output from the controller would be wired to a solenoid or some device to drop the gate. Another timer would reset the gate.
It’s not cheap though. You would be looking at $100 for the PLC and another $100 for the programming software.
Just a thought.

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  • yamaha.dude

Posted September 14, 2002 - 09:41 PM


One way that pops to mind... a noise meter... once they revved up beyond a certain limit for a certain period, the noise meter would trip and set the circuit off...

You may do well to go over to the McMasterCarr website and look or post in one of their forums... plenty of mechanical/electrical/hydraulic/pneumatic engineers over that way...

I think you could consider having a flashing light that all the riders could see, then no one would have the advantage... The light would start flashing and then they would have 15 or 30 seconds... just like a real race with a 15 sec board held up... then they can practice their anticipation of the gate dropping and get a sense for that sort of delay...

Just a thought...


  • HaremScarem

Posted September 15, 2002 - 03:15 PM


I sketched a simple electrical control circuit for your gate. The cost of the Start contactor, ice cube relays and Spring top Micro-Switch should add up to less than 60 bucks. If you like the idea, I can draw you a wiring diagram.
The system uses a micro switch with a 5" spring actuator mounted at the bottom of a gate. Extend the Spring length by placing a Bike flag or other plastic pole, upwards to the level of your handlebars. When you are ready to launch, swat the plastic pipe with your hand to start the timing sequence. A red light will illuminate, showing the sequence has started. 45 seconds later, a green light will illuminate acting as the 15 second warning, followed by....your back
flip. :D just kidding...

good Luck :)

Start Gate

I also found a website called

  • Chaindrive

Posted September 16, 2002 - 07:08 AM


You guys are great!! :) Not to mention smart! Love the ideas, it seems very do-able.

HaremScarem, I printed off a copy of your schematic. You mentioned being able to do wiring diagram?

I'm starting on the gate itself, if you could do a wiring diagram and/or a list of parts that I can take to my local Radio Shack(?) I'll get going on that, too.

tk421, that PLC gizmo looks pretty cool (and I only understand @ a tenth of it!) I'll run it all by Dewayne and see what he thinks. Good option if I can't build a HaremScarem device.

yamaha.dude's noise meter idea is ingenious! I don't know if I could make it work, but I can definitely picture a few loop-outs if I did! :D I will check out that McMasterCarr site, too.

Thanks Guys!! :D

It will take me awhile, depending on how much repair and maintenence my boys' bikes require over the next few weeks... :D Doggone high-strung 50s anyway. Gotta go replace a stator now (they just can't take the heat & $130 a pop!)


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