Confused by dropper post specs

SiTW

Hi

Am after some help finding a dropper post for my bike. I'm a bit confused re the specs/options available. I've been looking at the Brand-X Ascend which Wiggle have in sizes as per https://www.wiggle.co.uk/brand-x-ascend-dropper-seatpost-1/

My bike is a GT Pantera Expert, specs here: https://www.rutlandcycling.com/bikes/mountain-bikes/gt-pantera-expert-2017-hardtail-mountain-bike-blue_378749

The seat tube is about 30mm across I'd say, with the seat post obvs slightly narrower. The distance between the cranks and the seat clamp is about 350mm. The length of the seat post from the clamp to the rails when at its highest that I use is about 260mm.

Any advice on what to go for here?

Many thanks

cooldad

You need to know the exact size.

If the seat post is 30mm or less, obviously none of those will fit.

Take the seat post out and check what size it is. It should be marked.

swod1

yes check the size of the seatpost as a lot of dropper posts are 30.9, 31.6 or 34.9mm in size

The Rookie

According to Evans it’s a 30.9

https://www.evanscycles.com/gt-pantera- ... e-EV281695

steve_sordy

This diagram showing all the important dimensions on a dropper and what they are called is very useful. It also has the dimensions for quite a few popular droppers.

https://www.alltricks.fr/surl/choisirsa ... copique_v2

It will open to a diagram in French, but Google should offer an instant translation which you should accept (unless you can speak French of course).

SiTW

Thanks. Cleaned up the post and found the markings. It’s a 30.9. So based on the measurements above, should the longer option (480mm, 150mm travel) work okay? There are measurement on the site but they don’t explain themselves very well at all.

The Rookie

You need the following
1/ How far is it from the top of your seat tube to the saddle rails at optimum pedalling height
2/ How far can the seatpost go down into the frame when pushing it in (top of seat tube to bottom of seatpost)

Then you can work out what will fit, for example as I have short legs I don't have as much seatpost showing (6-7") as most riders will, in most brands then I'm limited to a 125mm drop, HOWEVER as my frame has a kinked seat tube many 125mm droppers need more post in the frame than I can fit, so I'm stuck with a 100mm drop (one or two brands can fit but they are the expensive ones).

Only YOUR measurements can tell you what will fit, a 150mm will achieve your riding height, I'd expect you can get 220mm in the frame but you need to CHECK, even just a bottle cage boss will stop it and you can see them on the seat tube in that Evans link.