track width

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Hi folks,

Just a quick question if anyone would be good enough to help. Just looking at the various spec for the carts and was wondering what minimum track width is. Is it the minimum allowed distance between opposing wheels. I know its a bit of a basic question but i want a general purpose cart that can do a number of different cousres. An with that in mind is there an optimum dimension for carts.....or is that too much of a "trade" question.

Cheers

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scottishcarties's picture

Cartie dimensions

Track is the distance between two wheels on the same axle. It is usually measured between the centreline of two wheels where they touch the ground.

As far as I know, only Cadwell, Cairngorm and Border Bogies specify a minimum track, and they all use 700mm. I did a summary of the various dimensions in use at the main events (click here), with a derived set of dimensions that would work for all of them. Of course, you can change the figures slightly if there are any races you don't intend to enter.

As for optimum dimensions - dunno yet... still working on it... my guess is that track v. wheelbase will probably be closed to the golden ratio.

scottishcarties | September 24, 2010 - 00:16
scottishcarties's picture

A bit more about track

The reason minimum track is specified is for safety reasons, to make the carties wider and hence less likely to tip over. However, track width on its own won't do that, and carties also need to have a low centre of gravity. There is no great advantage to having a narrow track anyway, so I'd suggest making it as wide and low as possible. I don't know which events you have in mind, but in order to make one size that will fit all you're stuck with a maximum width of 3'8" (1118mm), which, if you assume a typical hub width of 100mm plus 2cm for the retaining nuts, gives you a track of 998mm. Using the "golden ratio" theory, that would imply a wheelbase of 1615mm.

Next problem is length. If you use 20" BMX wheels, a 1615mm wheelbase would imply a minimum length of 2123mm, which would be too long for the Cancerwise Soapbox Derby at Goodwood, but OK everywhere else. If you want to keep it down to 2000mm length, a slightly narrower track of 922mm might be appropriate. Alternatively, you could try smaller wheels instead.

scottishcarties | September 24, 2010 - 07:45

Bloomin heck! Thanks very

Bloomin heck! Thanks very much for the excellent response. thought i had it all sussed out until you mentioned the golden ratio that bit of info has passed me by. Thanks again and cheers for the help.
Shutz | September 24, 2010 - 15:59

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