Rubber band starts

[oldguy]

I am working with the owner of a new track in Wisconsin and the first race is July 4th. He is building the back drop gate but we decided to have a backup start using a rubber band just in case the gate would break during the day.
My questions
I looked up surgical tubing and they list neoprene, latex, silicone, pvc, and pure gum as products- which would give the best stretch and durability and be most cost effective as a backup?

Anyone have any idea what the stretch ratio is? the gate is split into 2 65 ft sections would we need 30 ft or???

What diameter would work best?

 

[ellandoh]

dont know a anything about it but the description sounds good? worse comes to worst you could make one heck of a water balloon launcher :laugh: or you have a good excuse to tell the wife you need another pistola :nod:
2nd hit down http://www.google.com/products?q=su...esult_group&ct=title&resnum=1&ved=0CDkQrQQwAA


Sullivan
Sullivan - Fuel Line Tubing 3/32" x 7/32" Latex Surgical Tubing 50ft.
Primarily used as an elastic tubing to launch sail planes. Packaged in fifty foot (15 m) rolls.
Add to Shopping List$45.98 new

 

[FruDaddy]

Two tracks in my are use this type of start, and I hate it. The bands appear to be the fabric bungee cords. Unfortunately I have seen several kids (including my own) removed from their bike to to another jumping the start and the cord wrapping around a leg or catching a wheel . If you do use this type of start, dig a shallow trench for the front tire to rest in. I have seen this mentioned in the AMA rulebook, and while their specs seem a bit large, keeping the bikes back until the release may prevent a lot of unnecessary danger.
I apologize for straying from the original post, but I hope this is helpful. The link below goes to one of these tracks, his contact info is there:
http://sandridgemx.web.officelive.com/default.aspx

 

[BadgerMan]

Do you draw straws or flip a coin to see which of the fellars holding the rubber band gets to let go?

:rotfl:

 

[whenfoxforks-ruled]

What about a flag start? Jump before the flag, turn your bike around? Nothing can help a rubber band start. Sooner or later it will get someone. Vintage Bob

 

[oldguy]

We only want to have it as a backup in case someting went wrong with the steel gate that couldn't be fixed fast. I have been to a couple tracks that used them around here and you sure do not want to be on the outside gates. There is a release mechanism where at the center of the start you pull a pin and the bands snap to the outside where they are attached to posts.
I did see a guy hook one in his back wheel one time and by the end of the start straight he was loosing power fast

 

[Jeff Gilbert]

I raced a new track a while back and my buddy was running the "rubber band" start. It was very funny for me to watch him squat down and stretch the band tight when it came loose on the other end. I've never seen anyone jump up that fast then reassume the squatted position.