250mm is about 9 3/4" in length. Imo, you should have about 3-4" (at a minimum) left in the seattube when your seat is fully extended so you don't put too much stress on your frame. That leaves you with ~ 6" of post remaining to get your full height. That's not a lot of post, but if you've got shor legst, it could be enough. Ideally, at full extension, the seatpost should go down just past where the TT meets the seattube.
Look at how much seatpost you have on your bike now when you're at full height and make the call accordingly. A good deal on a Thomson won't be that great if you can't use it.
A forum community dedicated to Mountain Bike owners and enthusiasts. Come join the discussion about bike parts, components, deals, performance, modifications, classifieds, trails, troubleshooting, maintenance, and more!