New order, new colors!! Redesign Rocky Mountain tilted seat clamp.

[novocaine]

I don't agree. There is abigger cylindrical area effectively working in the perpendicular plane. But ill refine and ill do a finite element analysis.

But the clamping pressure is still radial and there is no material on the other side of the clamping bolt to take said force. This means the forces are not balanced and you end up with a torsional force at 120 and 240 degrees. Look at you original and where it snapped. You've added more material yes but the stress riser is still in the same place.

Move your bolt down to below the lowest point on the angle of the seat tube. It becomes a ring and the forces become balanced.

Your FEA will show two stressed areas as indicated above. These will work hardener whilst the remainder stays ductile and it will fail at which ever of those points reaches yield first. Fatigue is a bitch.

It's still an arse to machine as well.

But as I have no horse in this race I'll bow out now, I hope it works.

 

[Fatboy1974]

Thank you for your feedback. In this design we have a 7-8 mm area of complete cilinder, against 0 of the original. It should improve a lot. I'll try to obtain a compromise betwen aestetics ( this ******* angle), and the biggest radial area possible. Maybe I will increase the rradial width to 10, but I don't want to destroy the stilism ( the only good thing) of this concept. But they abandoned it in 96, it's clear why.
Bolt can be moved downwards, abut again affecting the good looking.

 

[RockiMtn]

A fast checking:

93: Tibolt (Ti) 27,2 mm seatpost
Altitude (Cr) 27,2 mm seatpost
94: Tibolt (Ti) 26.8 mm seatpost
Altitude (Cr) 27,2 mm seatpost
Vertex (AL) 26.8 mm
The Edge (AL) 26.8 mm
Blizzard (Cr) 27.2 mm
95: Suzi Q (Al) 26,8mm?
Altitude and Altitude TO (Cr) 27,2 mm seatpost
Vertex and Vertex TO(AL) 26.8 mm
The Edge (AL) 26.8 mm
Blizzard (Cr) 27.2 mm

Seems that all Seatclamps should be same dimension. I see that alu bikes has 26.8mm, usually because Alu tubes are thicker, so external id should be similar to their Steel sisters. Anybody can check the external ID of their bikes in that models (93 to 95)?

From 96 in advance they understood that it was a bad idea so all Seatclamps are straight.

there was at least two sizes of those clamps that i'm aware of. one for steel frames and a larger one for alum. i have a 93 Altitude and i have a couple spare seat clamps but not sure which size.

 

[Fatboy1974]

there was at least two sizes of those clamps that i'm aware of. one for steel frames and a larger one for alum. i have a 93 Altitude and i have a couple spare seat clamps but not sure which size.

Could you check them? I need a 27,2mm seatpost one. If I can't find one, I would need to manufacture some batch to get a "reasonable price per unit". I think it could be interesting if I'm able to improve its durability, making it beautiful enough at same time.
I saw that the alu frames used also think seatposts, so maybe they can share seatclamps.

I see mostly 27,2mm for steel and 26,8 mm for alu. But yes, seems than 0,2 mm of wall for alu is not an option. If you can check it both, I can plan to do a batch of both dimensions. I heard something about 29.8mm in steel ( 1.3 mm thickness). For alu should be near the 2 mm range at least.

 

[klunkrider]

For those with steel frames, a barrel binder brazed directly to the frame would be an easy fix, I am not a mechanical engineer though so may or may not be a good ide to put these stresses right into the frame. Would arguably look nicer then the clamp though...

 

[Fatboy1974]

Yes, nice idea. But I don'tknow a good welder, and my frame is new, so I want to maintain the original painting. I will consider it seriously in an used frame!

 

[Fatboy1974]

there was at least two sizes of those clamps that i'm aware of. one for steel frames and a larger one for alum. i have a 93 Altitude and i have a couple spare seat clamps but not sure which size.

If you plan to sell any of them, let me know! Thank you

 

[FluffyChicken]

View attachment 764984This ******* 30° seat collar got broken today!! Not specially tighten, but its an abnormal engineering item
Which solutions do i have? For sure it happened before......

The 1993 one is a nicer machined job.

 

[RockiMtn]

so besides the one on my 93 RM Altitude, and the two spare ones i mentioned, i forgot i had another one on a cracked 95 Vertex frame.

the steel and aluminum clamps appear to have the exact same outer dimensions, and the only difference is the inner bore diameters to fit over the seat tube and the corresponding lip. note the thinner wall for the black aluminum one versus the red steel one.

The 1993 one is a nicer machined job.

what difference are you referring to? i'm not seeing much difference between the clamps i have.

 

[Fatboy1974]

I would need internal Id to produce both sizes if needed . Are you planning to sell any for steel frame? Thsnk you