I’m looking to buy a reverb and want to know how to choose between them.

I get the diameter, that’s sorted 30.9, but drop why would you choose 100mm over 125mm

Also length, if choosing 100mm drop there are 3 lengths, why would you go for the shortest or the longest?

I’ve take measurements of my existing post and there is about 190mm above the seat clamp at normal riding height and the frame needs a minimum of 100mm inserted into the seat tube.

So any advice, please?

Length inside the frame depends if you are thinking of changing frames to something smaller or with an interrupted tube. Your call on how much to have inside. Weight weenies say least flexibility generally(unless interrupted frames etc are coming) says more.

For drop you need to get the measurements of the exposed nut at the top + the seat mounting bit and see if you have 125mm left over.
You are probably right on the edge. Assume your buying online so very cheeky to go to a shop and measure one.

The most important part is that it’s natural up position is where you want it for pedalling.

Mike could you explain the bit about drop I don’t quite follow you.

Anyone got photos with measurements next to one?

Basically of your 190mm you need to fit in the silver nut (may be different colour) and the bit at the top you mount your seat to. When you have taken those lengths off then you have the max drop.

No measurements here as the last one we got was last years.

Ask where you are buying it for the exact measurements.

http://singletrackworld.com/forum/topic/100mm-or-125mm-drop

I chose 100mm drop as my old post is 100mm and I feel its more than enough for 95% of the riding I do. There will be the odd time I would want to slam the whole thing right down but very rarely. The next biggest reason is that at full extension I’m a bit wary of the slim upper shaft at full extension on a 125. I just have this idea that the 100mm extension might hold up better in it’s lifetime over a 125mm. It just looks a bit dodgy when you see 125’s at full length. It’s only a small amount but,well..you never know ;O)

Just a thought!

125mm drop needs 195mm from centre of rails to top of seat tube clamp… You might struggle.

I wonder if I can gain a few mm as the seat clamp is this one,

Maybe a clamp with a very small overlap would give me more room.

Seems a shame to loose an inch of drop due to a few mm