Low stack seat-post?

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UpWrong
Posts: 2401
Joined: 31 May 2009, 12:16pm
Location: Portsmouth, Hampshire

Low stack seat-post?

Post by UpWrong »

I'm looking to lower a seat as much as possible on an eBike in the hope the Mrs can ride it. Was wondering if there are any low stack seat-posts which lower a saddle by providing lower saddle rail holders. Any suggestions or ideas? I may need to cut the seat tube if not.
Barrowman
Posts: 441
Joined: 8 Jan 2022, 6:35pm

Re: Low stack seat-post?

Post by Barrowman »

What is seat tube diameter? My wife's bike is 27.2mm (Reynolds 531) and we have an SR Seatpin which is a cradle style but puts the saddle rails alongside the top of the pin rather than on top like most Cradle Seatpins (SR do do 'conventional' cradle pins too)
Barrowman
Posts: 441
Joined: 8 Jan 2022, 6:35pm

Re: Low stack seat-post?

Post by Barrowman »

What is seat tube diameter? My wife's bike is 27.2mm (Reynolds 531) and we have an SR Seatpin which is a cradle style but puts the saddle rails alongside the top of the pin rather than on top like most Cradle Seatpins (SR do do 'conventional' cradle pins too) so have a hunt around. You will need to know your seatpin diameter and there are many different ones , don't make the mistake of thinking they are universal because they are not !.
tatanab
Posts: 5030
Joined: 8 Feb 2007, 12:37pm

Re: Low stack seat-post?

Post by tatanab »

Fit one of these upside down
25446.jpg
thirdcrank
Posts: 36764
Joined: 9 Jan 2007, 2:44pm

Re: Low stack seat-post?

Post by thirdcrank »

tatanab wrote: 7 Dec 2022, 12:37pm Fit one of these upside down 25446.jpg
+1 And back to front, to reduce the reach if necessary. Long ago, I learned how to ride a bike on one with a frame much too big, with the saddle fitted like that. I fancy the main point here is that there's no way to get the saddle lower without alterations to the bike itself. I see SJSC have them in stock at £2-99 but I imagine a traditional LBS might have a drawer ful

https://www.sjscycles.co.uk/seat-posts/ ... dle-clamp/
UpWrong
Posts: 2401
Joined: 31 May 2009, 12:16pm
Location: Portsmouth, Hampshire

Re: Low stack seat-post?

Post by UpWrong »

Thanks for the suggestions. I think the seat-post diameter is 30.9mm, so I'd need to find a suitable seat-pin and seat-clamp. Cheers.
KM2
Posts: 1318
Joined: 23 Oct 2008, 5:38pm

Re: Low stack seat-post?

Post by KM2 »

Is this the type, SR but I believe a 60’s simplex design???
4B3A7DDE-31D0-42B1-B5DB-18EE00923EB5.jpeg
backnotes
Posts: 615
Joined: 16 Jan 2011, 8:36am

Re: Low stack seat-post?

Post by backnotes »

UpWrong wrote: 7 Dec 2022, 2:11pm I think the seat-post diameter is 30.9mm, so I'd need to find a suitable seat-pin and seat-clamp. Cheers.
Plain seat pins of different diameters typically narrow to a standard diameter (22.2mm?) at the top that fits any standard seat clamp like the SJS / Brooks ones suggested upthread. Plain seat pins seem to be easier to find in smaller diameters than 30.9mm. An option would be a £3.99 shim like this https://www.planetx.co.uk/i/q/SPPXSH/jo ... tpost-shim, one version of which reduces from 30.9mm (if that's the diameter you have) to an easier to source 27.2 mm.
Dingdong
Posts: 966
Joined: 22 Apr 2022, 4:59pm

Re: Low stack seat-post?

Post by Dingdong »

KM2 wrote: 9 Dec 2022, 3:39pm Is this the type, SR but I believe a 60’s simplex design???4B3A7DDE-31D0-42B1-B5DB-18EE00923EB5.jpeg
That's the lowest seat stack I've seen, there's an odd one on eBay now and again but they're mostly sized for French frames
KM2
Posts: 1318
Joined: 23 Oct 2008, 5:38pm

Re: Low stack seat-post?

Post by KM2 »

It’s a 27.2 m SR. A Simplex “L Juy” copy.
UpWrong
Posts: 2401
Joined: 31 May 2009, 12:16pm
Location: Portsmouth, Hampshire

Re: Low stack seat-post?

Post by UpWrong »

A quick update. I bought a 30.8mm Ergotec seat pin and Passport saddle clamp from SJS. The next size up was 31.0mm. With some fiddling I was able to fit the clamp upside down to a Charge Spoon saddle which is pretty low profile - just! You need enough of a gap between the rails and the saddle to assemble the clamp in situ. It wouldn't fit an SDG Bel Air. The end result is a success, the saddle is low enough for the Mrs to reach the ground comfortably. I also reversed the clamp to bring the saddle forward. Need to wait for some dry weather and non-icy roads before she can try it out. I can quickly swap the seatposts over when I want to ride the bike with my sprung saddle.
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