Setback saddle mount post?

Where can I find something similar to this:

My post diameter is 36 MM, I think  I don't know what the inner diameter of the tube is.

Moving the saddle back by sliding back on the mounts has resulted in a recent break so I'm looking for a way to mount the saddle further back.

If anyone know of a local shop that has, or can get, something like this let me know.  I's prefer to shop local that search online.

Thanks.

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Permalink Reply by Doug Haynes on October 18, 2014 at 11:41am

That post is probably for fit purposes and would not be suitable for actual riding.

I also doubt your seat post diameter is 36mm.

The bigger question is why do you want that much setback on the seatpost?

Moving that far back is going to get you WAY behind the bottom bracket and that is not really a desirable place to be when it comes to your knees and general fit.

Permalink Reply by Bob Kastigar on October 19, 2014 at 6:57am

I took it out and all I found were the maximum length measurement marks.  I had a second tube and didn't see the diameter.  I used a caliper and it measured 3.6 CM.  I seemed to remember when I wanted to get a second tube that the diameter was a little unusual.

Why? With age my waist has gotten too big!  My only alternative would be to buy a bike with a larger frame size.

I don't need the variable as shown in the picture.  I'd just like to get a post that's got about an inch or two setback.

Permalink Reply by Kevin Mulcky on October 19, 2014 at 7:44am
I have a post like the one you've pictured. I think it's a 26.8 post. Let me know if that works for you.

They often show up on eBay and are from the old school mtb era.
Permalink Reply by Doug Haynes on October 19, 2014 at 12:19pm

How does your waist size require you to be farther back on the bike?

Permalink Reply by Martin Hazard on October 20, 2014 at 3:13am

Thompson makes a setback seat post in a good variety of sizes, though the 36? is probably not one of them. They are pricey, but will give your bike theft appeal.

Permalink Reply by Kevin Mulcky on October 20, 2014 at 4:32am
Thompson posts only have 15mm of setback. And they ugg.
Permalink Reply by Bob Kastigar on October 20, 2014 at 2:43pm

I'm an older rider and it's easier to stop and stand astride the bike rather than doing a leg-over to get off.  I have a drop-frame bike which makes this easier.  Standing, with a big waste, makes this uncomfortable. I'm more interested in comfort than speed or efficiency.

I did stop by a couple of bike today to measure seatposts.  (I hope I didn't look like I was casing bikes for a theft!) I measure two at 3.1 and one at 3.2 so my seatpost at 3.6 is larger in diameter than most.

KevinM: I would be interested in buying your seatpost, even with the 26.8 diameter.  I know I'd have to get a shim or two but it looks like shims for seatposts are fairly common.

Permalink Reply by Doug Haynes on October 20, 2014 at 6:08pm

You have got to be trolling with this, right?

What do you mean by stand astride?  You mean you just get off the saddle and stand over the bike when you stop?  If you need a step through frame to do that you have a serious fit issue with your bike.  It sounds like you are basically saying you are to fat to currently fit between your bars and saddle which seems unlikely...

You do realize that by moving your seat farther back that unless you move the bars back as well you are going to have extend the reach on the bike which is going to have an effect on your overall position. right?  You will have a choice between being more stretched out (a position the less flexible or larger rider usually does not prefer) or having the same bar to saddle reach just farther back.  You are also moving yourself back over the bottom bracket which may effect comfort as well.

How are you measuring the seat posts?

You do not want to shim from 26.8 all the way up to 30.6...


Bob Kastigar said:

I'm an older rider and it's easier to stop and stand astride the bike rather than doing a leg-over to get off.  I have a drop-frame bike which makes this easier.  Standing, with a big waste, makes this uncomfortable. I'm more interested in comfort than speed or efficiency.

I did stop by a couple of bike today to measure seatposts.  (I hope I didn't look like I was casing bikes for a theft!) I measure two at 3.1 and one at 3.2 so my seatpost at 3.6 is larger in diameter than most.

KevinM: I would be interested in buying your seatpost, even with the 26.8 diameter.  I know I'd have to get a shim or two but it looks like shims for seatposts are fairly common.

Permalink Reply by Bob Kastigar on October 21, 2014 at 3:56am


notoriousDUG said:

You have got to be trolling with this, right?


I didn't realize there was a rigid standard on how to ride a bike.  To ask about alternatives is to be a troll?

What do you mean by stand astride?  You mean you just get off the saddle and stand over the bike when you stop?  If you need a step through frame to do that you have a serious fit issue with your bike.  It sounds like you are basically saying you are to fat to currently fit between your bars and saddle which seems unlikely...

I have a step-through from, Trek calls is a WSD or Woman's Specific Design, or something like that.

Yes, essentially I am to fat for my existing frame.  A better alternative would be to lose 50-pounds.  I wish I could.

You do realize that by moving your seat farther back that unless you move the bars back as well you are going to have extend the reach on the bike which is going to have an effect on your overall position. right?  You will have a choice between being more stretched out (a position the less flexible or larger rider usually does not prefer) or having the same bar to saddle reach just farther back.  You are also moving yourself back over the bottom bracket which may effect comfort as well.

All of the above is true. 

How are you measuring the seat posts?

With a caliper, something similar to this:

You do not want to shim from 26.8 all the way up to 30.6...

The seat tube already has a deep cut that allows it to expand or contract under pressure so I don't see the shim as a problem.

Permalink Reply by Doug Haynes on October 21, 2014 at 4:27am

See, now I am REALLY confused...

There is no 'right' way to ride a bike but there some pretty solid fit 'rules' that apply to being comfortable on the bike.  Moving yourself back over the BB is going to change your fit, in what are probably negative ways, to solve an issue I don't understand.  I have fit and set up people WAY larger than you look in your picture and have never really had an issue like you describe.

Where are you contacting the bike that is the issue?  

Why do you need a step-through frame to stand 'astride' your bike at a stop?  

If you have a properly sized bike you should be able to stand over the top tube with your feet flat on the ground.  

Your frame is not meant to move that much to tighten on a seat post and I would not recommend a shim that large but hey, do what you want there but don't come back whining when you have a chronic slipping seat post or cracks around the binder.


Bob Kastigar said:


notoriousDUG said:

You have got to be trolling with this, right?


I didn't realize there was a rigid standard on how to ride a bike.  To ask about alternatives is to be a troll?

What do you mean by stand astride?  You mean you just get off the saddle and stand over the bike when you stop?  If you need a step through frame to do that you have a serious fit issue with your bike.  It sounds like you are basically saying you are to fat to currently fit between your bars and saddle which seems unlikely...

I have a step-through from, Trek calls is a WSD or Woman's Specific Design, or something like that.

Yes, essentially I am to fat for my existing frame.  A better alternative would be to lose 50-pounds.  I wish I could.

You do realize that by moving your seat farther back that unless you move the bars back as well you are going to have extend the reach on the bike which is going to have an effect on your overall position. right?  You will have a choice between being more stretched out (a position the less flexible or larger rider usually does not prefer) or having the same bar to saddle reach just farther back.  You are also moving yourself back over the bottom bracket which may effect comfort as well.

All of the above is true. 

How are you measuring the seat posts?

With a caliper, something similar to this:

You do not want to shim from 26.8 all the way up to 30.6...

The seat tube already has a deep cut that allows it to expand or contract under pressure so I don't see the shim as a problem.

Permalink Reply by Kevin Mulcky on October 21, 2014 at 4:48am


Or you could raise the bars. 
Cameron 7.5 mi said:

If the issue is that your seat and handlebars are too close together a longer stem might be a better option. This will increase the space between the seat and handlebars without changing the relative position of the seat and pedals. Moving the seat back further behind the bottom bracket will result in an awkward pedal motion.

Permalink Reply by Tom A.K. on October 21, 2014 at 5:16am
I think DUG does not fully understand the sometimes special needs and conditions of age and type specific cyclists. Bob Kastigar is asking for help and assistance from this community so he can continue to ride in comfort. Yes, this issue seems to be a fit issue and Bob is dealing with a bike setup with alternative standards. A bike mechanic should recognize this situation, then advise the cyclist of his best/safest options and risks and then let them decide on how their bike will be setup.

Bob, your setback saddle mount post will be under more stress than usual and have a higher propensity to break once again. I would always try to have access to a stand-by replacement mount post in the future. Keep riding ! Good luck !

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