Fiberglass REarset mounts?

[Rein]

Still toying around with making a mount for my rearsets and just had a though pop into my head: What about a fiberglassed plate?

It would be easy to form, easy to drill and tap with a nutsert or something similar. Also lightweight, strong, and free, if you already have some fiberglass supplies.

I think the mounts would be far enough away from the exhaust so that they won't be damaged.

Is there any flaw in my idea?

[Tarbash 27]

i think aluminum plate would be better, I would not trust fiberglass.

[Rein]

i think aluminum plate would be better, I would not trust fiberglass.

Why specifically? Is it heat issues? Fiberglass is plenty strong, my 200 lb, 6"4' brother could standon my fiberglass seat no problem. The seat was suspended in between two cinder blocks.

Demonstrated by Rocket Scientist Burt Rutan:

http://www.youtube.com/watch?v=7eUt0YnNF3o

[Zooks]

Fibreglass would break. Not because it's not strong but because of the angle that the force would be applied and the constant vibrations hammering through it. It would need to be an inch thick and even then I wouldn't trust it. Imagine your rearset breaking and your foot hitting the ground at 100+ km/h.

[Rein]

Fibreglass would break. Not because it's not strong but because of the angle that the force would be applied and the constant vibrations hammering through it. It would need to be an inch thick and even then I wouldn't trust it. Imagine your rearset breaking and your foot hitting the ground at 100+ km/h.

Hmm, jut realized that. Force would be going downward, opposite of the way the mats are oriented. I do have a jar of flox though, not sure if that would help the strength

[drhach]

I'm sure that you could make it work. However, I'm not sure you'd like the way it would look in order to design it properly. The biggest mistake people make is expecting a composite (Fiberglass kevlar, carbon fiber) part to take te same shape as a metal part and have it be just as strong. Look at carbon fiber bicycles. They are shaped that way in order to play to the strengths of carbon fiber. If you just made a bunch of tubes, you'd have the same issues. Think about the shifting loads that you apply to your foot pegs. This creates a twisting stress (moment) around several axes. If your foot was always in the same place it might be a little easier, but your foot moves depending on how you ride. So, it complicates things. Hence Zook's point about making the plate so thick. You would either have to make a horribly thick fiberglass plate, or make one that is really large and funky looking. It's not that fiberglass won't work. It's just that making it work in this case may not be the best choice given that there are size constraints. Cut a 1/8" inch piece of aluminum and call it a day. Otherwise, you'll need to do a great deal of math.

[Rein]

I'm sure that you could make it work. However, I'm not sure you'd like the way it would look in order to design it properly. The biggest mistake people make is expecting a composite (Fiberglass kevlar, carbon fiber) part to take te same shape as a metal part and have it be just as strong. Look at carbon fiber bicycles. They are shaped that way in order to play to the strengths of carbon fiber. If you just made a bunch of tubes, you'd have the same issues. Think about the shifting loads that you apply to your foot pegs. This creates a twisting stress (moment) around several axes. If your foot was always in the same place it might be a little easier, but your foot moves depending on how you ride. So, it complicates things. Hence Zook's point about making the plate so thick. You would either have to make a horribly thick fiberglass plate, or make one that is really large and funky looking. It's not that fiberglass won't work. It's just that making it work in this case may not be the best choice given that there are size constraints. Cut a 1/8" inch piece of aluminum and call it a day. Otherwise, you'll need to do a great deal of math.

1/8" is thick enough to prevent warping?

[drhach]

1/8" is thick enough to prevent warping?

I don't know. I guess it depends on what type of aluminum you are using and the size of the part. I said it more to make a point than to suggest a design spec. My point was that you could take a piece of flat metal (thickness and type to be chosen by you) and it would likely be more compact given a comparable design made from composites.

[hp1000s]

Made of the correct fiberglass laminates(heavy woven roving core), and west-system epoxy, it would work just fine(and a neat idea as well). It would probably end-up in the 3/8ths to 1/2 inch thickness, though. Probably, the biggest advantage would be visual; to have a sculpted look against the frame.

[Agemax]

i would not trust fibreglass for footrest mounts ever, carbon fibre maybe. ali is your best bet, at least 10mm thick.
you are putting your whole body weight and your life on those footrests

[LeeGS550E]

FWIW, I've got 1/4" aluminum for my plates. Works just fine, flexes a bit though. My guess is that much fiberglass won't handle the shear.

[Rein]

FWIW, I've got 1/4" aluminum for my plates. Works just fine, flexes a bit though. My guess is that much fiberglass won't handle the shear.

Hmm, I lack the resources and the funds to cut out 1/2" of aluminum, so at this point I'm considering 2 pieces of 1/4".