tomtomtom123

The setback problem got me thinking again about my brooks saddle with it's very short rails. It's still too far forward with it pushed all the way back. I measured my Thudbuster ST and it has around 12-13mm of setback. The specs says 11mm. I decided to try 3D printing a TPU insert for my Thudbuster ST with a different shape to increase the static unloaded setback. With the new shape, I measured an additional 10-11mm of setback, and a 3-4mm drop. Here is a GIF of the mockup in ABS plastic. I'll have the finished TPU part in a few weeks and will give it try.

Sy Reene

Have you looked at the IRD "Wayback" seatpost?

Wayback Seatpost ? Interloc Racing Design / IRD

tomtomtom123

I have a folding bike with 33.9mm diameter seatpost, so the Wayback seatpost won't work, unless I get a telescoping seatpost and replace the top part with this. It's also got a single bolt, which might slip and is more difficult to fine tune, unless it's got serrated teeth? I also would lose my elastomer suspension.

Drew Eckhardt 

It depends on design.

Campagnolo single bolt seatposts don't move given a firm tug on a standard 6mm hex key, although 1978-1997 they don't use serrations.

Campagnolo titanium and carbon fiber posts which followed used serrations - 1 degree at first which could be a bit low or high, then 1/2 degree which were presumably fine. Unfortunately, the cradles broke with time.

My Nitto S65 took a significant 16 NM to hold its adjustment. "Tight" with a standard length hex key didn't work, "tight" with a long one didn't work, and I bumped it up with a torque wrench until it held.

Drew Eckhardt 

1. Put some assembly paste on the mating surfaces.

2. Make it _tight_. Many single bolt seatposts stay parked with a firm tug on a standard 6mm hex key. Some don't - I had to crank a Nitto S65 up to 16 NM to get it to hold. Usually a 6mm head goes with an 8mm bolt with a 30 NM recommended torque for class 8.8. A 6mm bolt (I didn't check threads) should get 16 NM for class 10.9 and 12 NM 8.8.

rumrunn6

got the grand cru on. time will tell





Velo Orange Grand Cru Long Setback Seatpost MKII: 30.2mm Setback, 27.2mm

rumrunn6

ridges are rounded. into recycling it goes

rumrunn6

meanwhile, cpl months later, took it for a ride. held firm & was glad the angle I chose was good. no mid-ride adjustments required

Wilfred Laurier

My experience with inexpensive single-bolt posts is that both the clamping force and the weight of the rider might deform (bend) the bottom part of the clamp, which allows the top part of the clamp to bottom out on the bottom part before the seat rails are firmly clamped. This could be why you were tightening it so much that the bolts were breaking. The worn down ridges on the bottom part of the clamp and the head of the post would also require additional bolt torque.

rumrunn6

the single bolt never broke. or were you were referring to Drew Eckhardt?

Wilfred Laurier

I think so