Frame clamps

cowboysculptor

cowboysculptor

Been Around the Block
Anybody out there use 3-piece frame clamps like these to mount rearsets?

http://www.phatperformanceparts.com/PhotoDetails.asp?ShowDesc=N&PhotoURL=/photos/2404-0362.jpg

I just picked up a pair of Pro-Tek rearsets from a cbr 600 off craigslist ($75!) and I'm looking at mounting options. My concern is that the clamps won't hold steady when I'm pressing down hard on that brake lever (when I really really need them not to move). I can always fabricate aluminum mounting blocks that use existing bolts on the bike, but these little clamps are just so nice and tidy.
 
cowboysculptor said:
Anybody out there use 3-piece frame clamps like these to mount rearsets?

http://www.phatperformanceparts.com/PhotoDetails.asp?ShowDesc=N&PhotoURL=/photos/2404-0362.jpg

I just picked up a pair of Pro-Tek rearsets from a cbr 600 off craigslist ($75!) and I'm looking at mounting options. My concern is that the clamps won't hold steady when I'm pressing down hard on that brake lever (when I really really need them not to move). I can always fabricate aluminum mounting blocks that use existing bolts on the bike, but these little clamps are just so nice and tidy.
Click to expand...
I wouldn't. The clamping force required to NOT slip would be in the tube crushing category, never mind that the screws that hold the clamps together are in sheer and even if you could get them to clamp tight enough I think the screws would break.
 
You wouldn't generate enough force to shear the screws (provided they're bigger than an M5), but those are some pretty flimsy looking clamps. If you want to go the clamp route you need something like a machined split clamp.

Two_Piece_Shaft_Collar_Steel.jpg


I'd also pin it to the frame to prevent any chance of rotation.
 
M5 -10/32 are about as big as those could possibly be and I'd still be that if clamped enough to not shift they'll sheer, especially with the added loading and shock force that a rearset would put on them. Wouldn't trust my safety to any fastener that small, even on that split clamp.
 
Something like this could be made to work but as mentioned above should be pinned, which if done correctly so as not to compromise the integrity of the frame would require a tube being welded into the frame spar or at least a bung. If you're going that far just weld in somet threaded bungs and bolt on your choice or rearset. Clamp on setups unless massively overbuilt (read as: uselessly heavy) wouldn't be my first or 50th choice, no offense to anyone who comes up with the idea. Any critical, stress bearing chassis interface should be mechanically joined in such a way as to not allow shifting or misalignment that could potentially cause harm. Having your rearset shift a couple degrees in a tight corner at speed could potentially be deadly.

Or don't...someone smarter will likely buy the wreck at an estate sale or parts yard and wonder who the knob clamped his peg on was.
Hell...use some vicegrips for a truly industrial look!
 
Great input all around. Arsey, thanks for the pics, now that I can see it, I don't like it. If I ever wanted to get the frame clamps to slip I think I would attach a long lever and stand on it with all my weight, which is exactly what I'd be doing at every sudden stop.

Squadra, that's a great setup, but a bit too bulky for me I think. I'll probably just weld the mounting plates on and be done with it, I was just hoping for something with a maximum of adjustment options with a minimum of material.
 
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