Originally Posted by
Bob Ross
It was simply impossible to get the saddle into a position where I could fully engage the larger leg muscles (quads & glutes) during the power portion of the pedalstroke. I was too "on top of" the cranks. Getting a seatpost with ~25mm of offset resolved the issue nicely, allowing me to feel more comfortable during hard efforts and generate more perceived power (though I don't have any objective data to back up that last assertion).
fwiw nowadays all my bikes are set up with about 8cm of saddle setback [nose of saddle behind center of bottom bracket] but back then with a Thomson straight 0-offset seatpost, a Selle Italia SLR saddle, and this old (circa 1986) Bridgestone frame, I simply could not achieve that much setback.
Hi, Bob, I sympathize! I have the same desire, to have more saddle setback for better comfort and to better use the meager “old guy” strength that I have. I found a small collection of saddles which help me a lot to get a good setback position. The saddles are Specialized Toupe Gel, Selle AnAtomica with rails that have 10 cm of straight saddle (on the newest family of models, the long rail is defunct
), a Ideale 92 which offers 2 cm more than a Brooks B17. I also have a Rivet Independence with 8 or 9 cm (Rivet says 9 cm but I'm not sure yet! But right now i like it!
For any saddle the limit of setback is when the position of the forward end of the straight saddle rail is up against the front edge of the saddle rail clamp on the seatpost. The saddle cannot be slid back any farther than that point. So getting setback is also about moving the seat post’s saddle clamp back. For this I use the Nitto S-84 seatpost, to get about 20 mm more setback than a Campy two bolt Microadjust offers. Additionally using an older Toupe saddle or a steel-rail Selle AnAtomica can place your butt significantly behind the seatpost, on frames with a 75 degree or steeper seat tube. One of my bikes with that steep angle is my classic 1980 Masi, and I worry that the extra bending moment may stress the frame. For me a 70 degree seatpost seems very suitable.These two measures result in a weird-looking bike.
To have a less weird looking bike you just need a frame which has i highly laid back seat tube, such as the mentioned 70 degree. This is why I’m experimenting with a 1952 Redge 27” Clubman-style bike. This one and the Raleigh Super Lenton were the top “racer-boy” (translation: aspiring long-distance time trialers, such as Lands' End to John O'Groats or London to Edinburgh. The way amateur cyclists now think they may be able to show the talent to go to TdF, amateurs tried to work up their skills to conceive of running such great and classic time trials.
In any case I’m building up my Rudge to thrust it into service for another aspirational (I guess there's a fine line between aspiration and fantasy ... ) TT rider, me. But it has a 70 mm seat tube angle! In any event it should make a suitable perch for local rides, 10 to 40 miles reasonable this year!
As a measurement I look at setback as the distance from a plumb line to the BB axis to the widest point of my saddle. This number lets me set up any saddle to satisfy my setback criteria, choosing a seatpost which will allow it, if I can find such a seatpost.
A few take-always: use a saddle with a long straight rail, use a seat post where the saddle clamp is “pretty-far back” from the seat tube axis, and use a frame with a shallow seat tube angle, maybe 72 or less as a target range. Between those three I can find a 28 to 29 cm setback from my contact point and the BB plumb line for quite a few frames. It lets me see if the particular solution looks reasonable and safe for the frame. This measuring works for odd saddles like
Selle AnAtomica, Rivet, and others with long rails, and more conventional racy saddles like Specialized Toupe, and classics like Brooks and Ideale, and Selle Italia.
I can also set reach practically by measuring from the widest point of my saddle to a line connecting the front of the hoods. I can see if I need a different top tube, stem extension, or handlebar reach, and match the riding properties across my collection of frames.
If folks want I can work up some pictures.