The Lowly Seatpost

1920’s CCS clamp

Seatposts are an often ignored and misunderstood component. If you’ve ever replaced a saddle or a seatpost, or adjusted your saddle to fit your riding style, you’ll know what I mean.  A well designed seatpost is critical to riding comfort, yet rarely do cyclists give much thought to the component, simply tolerating whatever seatpost they are currently using.

The world of seatposts is surprisingly varied and complex, with many features to be considered, including seatpost diameter, clamp style, saddle rail style, angle adjustment, and fore/aft positioning.  The seatpost conundrum is part of the saddle mystery, and when working together properly they can solve part of the puzzle of rider discomfort.

Late 1800’s seatpost

Late 1800’s seatpost for bamboo frame

Historically, seatposts were first designed to allow fore and aft adjustment via a sliding clamp on a horizontal tube.  Saddle height was usually adjusted via a binder bolt on the frame’s seat tube. The bamboo bike shown above, however doesn’t have a height adjustable seatpost because it is incorporated into the ornate lugs binding the frame together. (Photo credit:  The American Bicycle (c) 1995 Jay Pridmore & Jim Hurd).

Lever actuated design

Later, mid-Century component makers focused on fore/aft adjustment, with some designs allowing for adjustment while pedaling!  As shown above, the Grimpex and the Alpina allowed the rider to reach under the saddle and loosen the clamp in order to move the saddle back and forth while riding.  There was even a lever actuated model, although I can’t quite figure out how this worked. Cycling lore of the time held that it was critical to sit in a different position relative to the handlebars while ascending and descending steep hills.  Fortunately, this “innovation” died out as most cyclists would have no need to make such onboard adjustments.  These seatposts would also have been heavy in comparison to standard designs.  And most importantly: yikes!  (Text credit:  Rebour (c) 2013 Rob Van Der Plas).

The ubiquitous steel clamp

For the masses, cyclists were offered those funky steel clamps that fit over a straight seatpost (also often steel). Straight seatposts are found on vintage British bikes, French bikes, and some early mountain bikes.  A narrower section at the top allows you to mount the clamp, to which the saddle is affixed. These clamps typically came with different numbers of serrations ranging from 24 to 54.  The more serrations on your clamp, the better chance you have of getting the most suitable angle on the saddle.  However, according to Fred Delong, even the high serration count produced an angle difference of about 7 degrees which is still a big jump in the saddle angle.  That’s why seatposts with true micro-adjusting clamps are better.

These clamps also require a LOT of tightening so that you don’t find yourself in a new position after hitting bump, but I’ve also stripped the threads on these clamps trying to get them to hold.  You can find higher quality clamps made for straight seatposts which also offer true micro adjustment, such as the clamp on my Brompton.

Campagnolo’s double bolt design, a true micro adjusting seatpost, was also introduced mid-Century and was definitely an innovation.  The downside was doing the actual adjustment which required patience as well as a special 10mm wrench.  This is an elegant seatpost, but maddening to use in practice due to the adjustment and tightening difficulty.

Photo Credit: Delong’s Guide to Bicycles & Bicycling (c) 1974 Fred Delong

Credit: Bicycle Design by Tony Hadland & Hans-Erhard Lessing (c) 2014

As time progressed, a lot of different ideas emerged, especially in regard to micro-adjustment.  The above scans show designs by Nitor, Ideale, and Simplex.  There’s also a lightened seatpost from France-Loire and a ratcheting model by Vincar.

A special problem for vintage bicycle restorers is the flat rail saddle carriage (often made from “Dural” or “Duralumin”) featured on the higher end saddles of the time. The above scans show offerings from Dumont, Mansfield and Ideale. These saddles require a special clamp.

I have such a saddle on my 1947 Camille Daudon.  It features a custom seatpost handmade by Daudon.  But, one of the clamp brackets had failed.  Daudon used an alloy clamp, which was unusual for 1947. Not being able to find a replacement, I modified a double rail steel clamp and got it to work by straightening the brackets in my vice to match the shape of the original brackets.  Not the best solution, but a decent hack for now.

J.P. Routens seatpost with angled clamp

Vintage Titan seatpost

Simplex single rail

Seatpost diameter indicator

25.0 American Classic for ALAN bicycles

While modern seatposts are mostly utilitarian (with the exception of Nitto), vintage seatposts were often elegant as well as innovative.  And, higher end vintage seatposts offer the same micro adjustment that’s available on current models.  If you are working with a straight seatpost and clamp, you may be able to upgrade the clamp to a model with more micro adjustment, but still preserve the original seatpost.  Or, you can simply decide to replace your vintage seatpost with a higher end vintage offering such as a Simplex, Nitor, or Campagnolo model.  For seatpost and saddle adjustment tips, I recommend visiting the Sheldon Brown site, for this article authored by bike guru John Allen. If you are experiencing discomfort while riding, it may take a while to figure out what’s wrong.  One thing I’ve learned when making adjustments:  resist the urge to make more than one adjustment at a time.  Don’t adjust saddle height and the fore/aft position simultaneously.  Don’t change saddle angle and bar height.  Do each of these separately and take long enough test rides to feel the effects of each change.  It can take time to get to the perfect solution for cycling comfort, and if your seatpost is part of the problem, consider replacing it.  There are many fine vintage seatposts available to solve the seatpost conundrum.