I’m using the seat post supplied with my bike, but to get it to fit right the min. insertion line is exposed approx. 3cm and I have about 5cm in the seat tube. Is this a bad idea or is that line just another “cya” thing created by laywers? If it matters it is an FSA K force light post. It is the 250mm one and I know they make a 350mm. Is it worth dropping $170 or whatever for a new one that is the same thing only 100mm longer?
It’s not a good idea. You could get a new, longer post of equivalent quality and weight for a lot less than $170 if you shop around.
The specs are put on each piece of equipment for real safety reasons - just think how much your hospital bills would be if the seat post snaps because you have put too much torque on the non-exposed portion. Just my 2c worth…
If you decide that you don’t care about the minimum insertion, be sure that you also don’t care if/when it fails under load and you get hurt.
Sure, it might not happen…
Ah - bad idea.
May I suggest this though instead of that FSA post for $170? Are you sure?
Thank you for your insight. I’m was trying to get some help deciding if I should care. Thought I’d tap into this vast pool of knowledge. So far, sounds like a new seatpost would be good insurance and peace of mind.
I actually looked at that post yesterday. I’ve heard good things. Here’s what I don’t know about the Thompson: I need a little setback and a 32.4 (or 31.6 and a shim). Can I get the one with setback in a 32.4 (ideal) or 31.6? Also, any disadvantage to using a shim?
Yes, they make a set back version (the post itself will appear “bent”). This is one of those unique pieces of bike equipment that you can safely buy and keep forever and recommend to anyone. There is nothing better overall for weight, quality, cost, etc. Highly recommended.
I’ve got 3 different Thomson posts. This is one place where the carbon fad is just plain stupid, when you can get a bombproof Alu post that’s just as light and far more secure for half the cost. If you simply have excess $$ to burn on a carbon post, get the Thomson instead and donate the balance to a good cause.
heh heh heh… he said insertion… now if it breaks you really could have insertion
It’s not just about the seat post failing.
The post needs to be inserted far enough in the seat tube to extend past the top tube and seat stays. Otherwise, the top few inches of the seat tube is the only thing supporting the post and could fail. Then you need a new frame.
heh heh heh… he said insertion… now if it breaks you really could have insertion
Yes that was also a concern of mine. I’m not really sure I’d be into that kind of thing. I think broken carbon fiber could have some nasty splinters.
I frequently ignore manufacturers instructions. Seatposts are important and while it wouldn’t bother me to exceed the minimum a bit, your case is alot. Keep in mind some seatposts are beefed up in the clamping zone that can be an issue. Some light frames are assuming a certain amount of post in the frame, so the post may not break but the frame may. Given the risk, sell your post onebay and buy an equivalent longer one on ebay. You will likely be out $10 and have piece of mind.
Styrrell
Yeah, the cost would probably be money well spent. I guess it bums me out a little because I bought a new frameset that fits me great with this one exception. Seems like the manf. spec’d the wrong length because I’m certainly not “leggy”. I know this particular FSA post comes in either 250mm or 350mm. Of course they give you the 250 on a semi-compact geometry frame.