Changing to a suspension seat post

[Highkicker79]

I'm quite a tall guy at 6' 2" and have a 20" frame bike. The seat post is just about right when it's at it's max height but I wish to change the seatpost for one that has some suspension built in. I was looking at the ULTIMATE USE Vybe Suspension Seat Post as it seems to have good reviews. My main concern is comfort and good build quality. I don't really care for aerodynamics, lightweight or any other performance related thing.

Do all seatposts have the same length stem? Will I be able to get the same height adjustment as my existing seat post? The above seatpost doesn't have any stats on it's length so I'm guessing they are all the same length.

[mjr]

Seatpost lengths vary, as do minimum insertion lengths. Ask the retailer questions, buy from a retailer who lists more measurements, or try to find another user of that model to ask.

[NATURAL ANKLING]

Hi,
Mmmmmmmmmm retail of £120 and vague specs.
Chain reaction are saying 400 mm.
I Suggest that you will need a 400 mm at your height.
Allowing for a 75 mm min insertion to frame, frame 500 crank 150 seat post 325 = 975 rail to pedal ?
Check your frame top to rail dimension and add 80 mm.
Not sure but I am assuming rail clamp to bottom is a max of stated post length?

You need to confirm the seat post length you are going to buy yourself so its not to short for your needs?

[iandriver]

If you're reasonably tall, check the layback you need also.

[mercalia]

you dont indicate how much you weigh. I wonder if heavy people can really use them?

[The utility cyclist]

you dont indicate how much you weigh. I wonder if heavy people can really use them?

I'm 102kg wet through, no problems when I've had them in the past and they were cheapo ones.
If you're going to spend that sort of cash then Cane creek thudbuster might be suitable

[pwa]

Some Brooks style saddles (the leather ones) are a bit more springy that other saddles and actually give a little bit of suspension over bumpy ground. And as they are a bit taller than other saddles they can end up with you having to lower the seat post a bit. Just an alternative tack.

[Brucey]

I'm quite a tall guy at 6' 2" and have a 20" frame bike. The seat post is just about right when it's at it's max height but I wish to change the seatpost for one that has some suspension built in. I was looking at the ULTIMATE USE Vybe Suspension Seat Post as it seems to have good reviews. My main concern is comfort and good build quality. I don't really care for aerodynamics, lightweight or any other performance related thing.

Do all seatposts have the same length stem? Will I be able to get the same height adjustment as my existing seat post? The above seatpost doesn't have any stats on it's length so I'm guessing they are all the same length.

Seat posts vary in length; check the specs carefully. When calculating whether one is really long enough, you should allow for any sag in the setup.

What does 'sag' mean? Well suspension in usually has a small amount (~25% typically) of travel used when the working load (you) is sat on the bike. However suspension seat posts can be different to that; they may be set up with lots of preload so that there is no sag and the suspension only moves when you hit a bump over a certain size. This apparent anomaly is preferred by many for two reasons

- it helps to prevent 'bobbing' as you pedal and
- suspension movement affects the saddle to pedal distance, which is bad for pedalling

In simple suspension seat posts the preload on the suspension is adjustable and this (together with a choice of springs /elastomers inside) can adjust the threshold at which the suspension starts to move. So basically it often boils down to a choice of having active travel vs keeping a consistent pedal to saddle distance more of the time.

Another approach to this is taken by the 'thudbuster' seat post. This has two clever features;

1. The mechanical advantage over the spring element varies through the stroke (which helps to inhibit bobbing)
2. the suspension linkage moves the saddle in an arc, which means that (for any amount of vertical movement) the pedal to saddle distance is more consistent than it would be with a telescopic post.

But the post is wide between your legs, heavy, and there are lots of bushings which wear out unless protected from mud (for which purpose a boot is available). So it doesn't suit everyone.

cheers

[pete75]

Hi,
Mmmmmmmmmm retail of £120 and vague specs.
Chain reaction are saying 400 mm.
I Suggest that you will need a 400 mm at your height.
Allowing for a 75 mm min insertion to frame, frame 500 crank 150 seat post 325 = 975 rail to pedal ?
Check your frame top to rail dimension and add 80 mm.
Not sure but I am assuming rail clamp to bottom is a max of stated post length?

You need to confirm the seat post length you are going to buy yourself so its not to short for your needs?

Eh? They have fairly full and precise specs on their website. The first thing a google search comes up with is this https://ultimateuse.com/use-components/seatposts/vybe which gives the below info al;ong with details of diameters available.

Technical Specs

Weight
455g
Length
400mm
Diameter
27.2mm
Material
Aluminium
Setback
10mm
Finish
Anodised
SHOCKPOST SPRING OPTIONS

Spring Rate Spring Colour Rider Weight - Lbs Rider Weight - Kgs
Soft Green 85 - 120 38 - 55
Medium Yellow 120 - 174 55 - 80
hard Purple 174 - 225 80 - 100

[NATURAL ANKLING]

Hi,
You obviously looked harder than I wanted to

Edited- You can but a suspension post for £ 20 to try out.

[Gattonero]

I'm quite a tall guy at 6' 2" and have a 20" frame bike. The seat post is just about right when it's at it's max height but I wish to change the seatpost for one that has some suspension built in. I was looking at the ULTIMATE USE Vybe Suspension Seat Post as it seems to have good reviews. My main concern is comfort and good build quality. I don't really care for aerodynamics, lightweight or any other performance related thing.

Do all seatposts have the same length stem? Will I be able to get the same height adjustment as my existing seat post? The above seatpost doesn't have any stats on it's length so I'm guessing they are all the same length.

May I ask what bike are you riding?
6ft 2" on a 20" frame seems too small, unless is an Mtb.

The problem you may have, it that with a suspension seatpost you won't realize is a two-edges sword: on a rough road you don't feel the bumps but your wheels are likely to be under more stress. Think about it.

[NATURAL ANKLING]

Hi,
Un-sprung weight.......................

[BigG]

The problem you may have, it that with a suspension seatpost you won't realize is a two-edges sword: on a rough road you don't feel the bumps but your wheels are likely to be under more stress. Think about it.

The stress on the wheels is actually less with a suspension seatpost. The suspension transfers your body weight (or at least that part of it supported by the saddle) from unsprung weight to sprung weight. When hitting a bump the rear wheel has basically only to bear the additional force needed to accelerate the rear of the bike upwards. It doesn't need to accelerate you by nearly as much.

[Gattonero]

The problem you may have, it that with a suspension seatpost you won't realize is a two-edges sword: on a rough road you don't feel the bumps but your wheels are likely to be under more stress. Think about it.

The stress on the wheels is actually less with a suspension seatpost. The suspension transfers your body weight (or at least that part of it supported by the saddle) from unsprung weight to sprung weight. When hitting a bump the rear wheel has basically only to bear the additional force needed to accelerate the rear of the bike upwards. It doesn't need to accelerate you by nearly as much.

That's only part of it. In reality the rider does not understand what's going on with the road, everything feels smooth so it's unlikely that he/she will end up balancing the weight of the body on the bicycle, to absorb the bumps.
This is the very reason why hardtail Mtb's, when used properly, almost never use a suspension seatpost: you feel what's going on with the terrain and work out accordingly.

If willing to stay seated 100% of the time you need a proper full-suspended frame, though even with dual suspension on technical terrain it demands to balance the weight anyway.
There is a big difference in having the wheels suspended on their own, and to have them rigid with the frame. The latter means that the rider's weight becomes a relevant mass that is proportional to weight, speed and shape/height of the obstacle (like a pothole)

[Highkicker79]

Just to report back, I ended up doing a lot more research and then I delayed for a bit as I thought I could manage without. In the end, I finally bit the bullet and went for a Cane Creek Thudbuster LT as it had excellent reviews. I also think the slightly rotational movement will be more comfortable than the up and down suspension type. It's an expensive item but if it softens all those jarring pothole bumps then I'll be happy.