blake711

Ok some basic Seat post questions. My trek 7.2 hybrid has a no name shock seat post on it. I want to change it out to a solid post. Which part of the post do you measure to find the tube size and length? From where to where is my question in simple terms. I see their are multiples sizes available and don't want to get the wrong one.

Thanks,
Blake

well biked 

Take the old post out, wipe off any grease, and look closely for any markings indicating the diameter of the post on the bottom portion of the post. Something like 27.2, 29.4, etc. As for length, you can measure the old post for length to make sure you get a post with plenty of extension. Common lengths are usually in the neighborhood of 350mm long.........If you can't find markings indicating the diameter of the old post, take the bike to a bike shop and they can measure with calipers-

Nermal

Just by the way, I got a Salsa post, which is available up to 400mm long. Turned out to be more than needed, but how much can the extra 50mm weigh.

mlts22 

If you need to find the tube size, check Trek's website -- they even have back to 2000 models. I found my Gary Fisher's seatpost size this way, to replace it.

blake711

I looked on their site and wasn't able to locate it. I sent them an email and they replied with the size. Thanks all

Allen

You can always take a hacksaw to what you don't need, like trimming a fork to length.

blake711

one other question. Is there a minimum amount of post that has to be in the tube below the clamp to be safe? Thanks, Blake

well biked 

Yes, look for a short line on the lower portion of the post, that's the minimum insertion mark, usually labeled as such. On some frames where the seat tube extends well above the top tube, the mark might not be enough insertion, though, because you need to make sure the post is inserted beyond the seat tube/top tube joint-

atomship47

you can adjust the preload on some of the stock, trek seatposts (i can on my 7300). pull the post and turn the allen head set screw (on the end that goes into the seat tube) to stiffen the preload. mine has almost no give in it at all now.

kokomo61

My Trek's suspension seatpost pretty much disintegrated on its own. I swapped it out for a solid one.