[Closed] dropper post drop dilema.

If the xl frame is taller in the seat tube then you might it have room for more. Stick a normal post in and measure it.

I reckon it just makes sense to squeeze in as much drop as the frame can take- I can't imagine anyone's ever going to wish they had an inch less drop...

I'm confused....if your new frame is larger (which usually means the top of the seat-tube is further from the BB), then you won't be able to extend a dropper post as far as you would on a smaller frame. So why are you concerned that a 125mm won't be long enough ?

Have a look at the chart below. You need to figure out what your 'G' measurement will be, which is what mikewsmith's suggestion will tell you.

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bookmarking for useful chart

I'm confused....if your new frame is larger (which usually means the top of the seat-tube is further from the BB), then you won't be able to extend a dropper post as far as you would on a smaller frame. So why are you concerned that a 125mm won't be long enough ?

I think its more of the case of the saddle being out of the way enough when dropped.

A day the answer isn't posting a inside leg measurement it's measuring the seat post in the frame. That method gets you an accurate answer.

I think its more of the case of the saddle being out of the way enough when dropped.

Right, but the 'high' position of the saddle will be the same distance from the BB as it was on the previous frame (unless the old frame was miles too small). The thing that will cause you problems will be having a "G" figure that is too big, so you can't get the seatpost far enough into the frame. Meaning at full extension it's too high for you to sit on and still reach the pedals.

Short answer: Bigger frame=shorter seatpost.

Long answer:
You need to know the distance from BB to saddle rails that you want. (lets call it X)

And then you need to know how tall the seat tube is (let's call that Y).

Then X-Y = Z, so Z is the distance between the top of the seatpost clamp and the saddle rails.

You want to look at the G figure from the chart above when choosing a dropper. You need X to be bigger than G but X also needs to be smaller than the length of the post when measured from saddle rails to the minimum insertion point.

Let's say you need 700mm from BB to saddle rails.
Your new bike has a seat tube of 495mm
So you need your dropper to be 205mm long at max extension. If 700mm is right then the 150mm dropper would be too long, with a G of 220mm.

Your old bike had a seat tube of 457mm.
So you needed a seat post of 243mm to get you to the right position.

So with a bigger frame you need [s]a smaller post[/s] less exposed seatpost to get you in the same position. A 150mm drop may be fine, it depends on what BB-saddle distance you want.

With a 150mm drop, the lowest your saddle can be is 495mm + 220mm(G from above) = 715mm. If 715mm is less than your optimal BB-saddle distance then go for a 150mm. If you went for a 125mm in that scenario then you'd end up with the same 'high' position, but not be able to drop the saddle as much. But if 715mm was higher than you want your saddle to be above the BB then don't get a 150mm post as your saddle will be too high.

I think 150mm will be fine. I have a 125mm in my large Patrol frame and it fits well with my 33.5" legs. Not at the limit mark and not slammed in the frame either. If you have short legs a 125 might fit better.

Personally, I would go to a shop and try it. One of the times when buying local could save a bit of hassle for a little more cash.

beer247, you said "I think its more of the case of the saddle being out of the way enough when dropped."

If I'm understanding you rightly, you want to make sure you can get the saddle as low as possible ? If so, the only things that would prevent you getting it as low as you'd like are:

1) Curved seat-tube or suspension pivot bolt in seat-tube preventing the dropper outer sleeve from being fully inserted (Reverb), or obstruction to the adjustable shaft (mechanical type, e.g. Gravity Dropper or RaseBike)
2) The top of your seat-tube is high, i.e. your frame is too large
3) The 'D' dimension of your dropper post is quite long (this varies by up to 30mm depending on the model of dropper).

Assuming we're just talking about one particular model, e.g. Reverb, then it doesn't matter whether it's a 100mm, 125mm or 150mm version as this won't affect any of the above 3 points. As Bails points out, your main problem will be the 'G' length being too long when the dropper is fully extended, and this is where the version of dropper is crucial. If your new frame is larger, you might actually need a shorter dropper, i.e. a 100mm version. Obviously with something like a Reverb, you don't have to ride with it fully extended, but you don't want to be using your backside to set the correct saddle height every time you extent the post after a downhill.

I've got a stealth 150 reverb on my large smuggler and it's fine with 32 inside leg. having said that its just gone back having problems so if I was going to change I would go for a 9point8 or the new Easton/race face dropper as they sound more reliable and can be serviced at home. they have a cable remote rather than hydraulic which is far easier to manage and thread through frame

ive just gone from 125-150mm drop on my medium Process, Im only 5'8 but the extra inch has given me loads more pleasure