HMF

When it comes to clamping a seatpost below the minimum insertion point? I just got a new seatpost that is somewhat shorter than I was expecting. I took it to the bike shop to get some carbon paste and mentioned to the wrench that it's currently clamped below the seatpost, and he seemed fairly certain it would break off. They gave me the paste for free but wouldn't do the work.

The seatpost itself is 27.2mm in diameter and still has 6.5cm in the seat tube, and the bottom of the post extends to just below the junction of the top tube and seat tube. The post is aluminum wrapped in carbon, and the frame is aluminum. I weigh 135lbs.

By all accounts I've found both here and elsewhere, I'm just barely within what most people are willing to risk/recommend. So what do you think? I'm I going to end up with a new *******?

iam7head

is the piece worth a potential butt puncture?

probably not.

good luck

mwandaw

This is the absolute minimum engagement that some have recommended in the past, and you are relatively light weight, so you might get away with it. However, the fact that you're asking shows that you have some doubts. For the cost of a longer seat post, do you really want to ride around worrying about whether you will soon have a new hole in your backside?

eippo1

Having broken off a a seatpost that was well within the minimum, I wouldn't risk injury for something as easy as getting a new one and selling the one you just got. That's just plain dumb.

HMF

I think this is a sign. Maybe this is really just an excuse for me to get a new lighter frame with standard geometry and keep the seatpost. Yes, that must be what the gods are telling me to do.

HMF

So you broke one eh? What happened to you? It seems to be that having a seatpost break is less dire than having the fork break, for example. There are always pedals to stand on when one loses their saddle, right?

Andy Somnifac 

When it breaks, it probably doesn't break slowly, giving you tons of time to react.

eippo1

Not too much. Just went back beyond and skimmed my rear on the rear wheel. Left a mark, but wasn't bad. I've also lost a seat off the seatpost when all the screws decided to come undone all at once. Nothing happened then either besides some laughing at my expense. The former I attribute to riding a small frame with lots of setback and the latter I attribute to using too much grease on the screw threads.

HMF

Plan B: lower the saddle and see if I can live with it. I'm close to the insertion line now and I got a 72 mile ride coming up tomorrow. That should give me the answer.

chado445510

I have a kid's mtb and I had it so that 2.5cm was in the ST until I learned it was about 2 inches below where it should have been. I wasn't too worried, still not too worried.

55/Rad

Lowering it changes your fit and now you will be using your muscles differently. In other words, potential for pain is high.

Change the seatpost.

HMF

Yea, I know. I'll deal with that if my knees start to hurt. So far, I've come to find that there's a range for everything. I'll find out tomorrow if I'm still in that range.

SnowTown

I inserted "just the tip" and wrapped it with duct tape and everything seems to be working out fine so far.

































I haven't sit on the saddle just yet though.

EDIT: Wait, on second look, the seatpost seems a bit crooked... no worries, plenty of duct tape left.

Tunnelrat81

Seatposts can be had for reasonable $ if you keep your eye open. I've had my eye on the Thomson Elite post for a while, and randomly searched my area CL yesterday and found a seller 20 min. up the road selling one for $30. Picked it up same day and couldn't be happier. I bet if you asked nicely at the LBS you could get a take-off stock post for cheap also, or just keep an eye out CL. To me, It's not worth either the risk of injury, pain, frame damage, being stranded 20 mi. from home without a saddle etc. by making other sacrifices.

-Jeremy

djb

+1 on that, I dont know about yoiu guys but I find that even a small diff in seat being too low makes a big diff in my knees not being happy, feeling slow, etc etc.

not worth it , both having seat too low and playing with insertion depth....

but hey, its your body.

HMF

So what I ended up doing was dropping the seatpost so that it's clamped only about 1cm below min insertion, then slid my cleats back about a half centimeter to get more leg extension and keep the knee bend at about 30deg. The funny thing about positioing cleats so that the spindle is under the ball of the foot is that it seems based mostly on tradition. Here's a blog post from Friel on the subject: https://www.trainingbible.com/joesblo...-position.html.

I just finished that long ride (70ish miles) with the new set up and everything felt good. Actually, I felt I was putting more power to the pedals with the new cleat position, and this pain I had in my left ankle that sort of felt like early onset of tendinitis wasn't there at all today. Plus the seatpost didn't break off! I'll update in a month or so.

55/Rad

You didn't think it would break off on the first ride did you? Nah....it'll happen when you're convinced it won't. Murphy says so.

djb

you mean Murphy, that guy with two holes in his butt? (geez, scary even making a joke about it....)

tuxbailey

There is a saying in Chinese that applies to this scenario:

Cutting your toes to fit the shoes.


Just sell the seat post and get a longer one.

HMF

Update:

Well, after about 150 miles or so I decided to just buy a new one. I was all set on just riding with the one from eBay, but then I remembered that sometime soon I'll be getting a new saddle, and there's no telling what necessary changes that will require, but there'd be a good chance I'd have to raise the seatpost to counter the effect of reduced saddle padding. Anyway, the point is, I just got a seatpost that's longer and actually 20grams lighter than the eBay Bontrager post. Case closed.

urbanknight

I wish I still had it as an example, but a friend of mine had inserted a seatpost too little in his mountain bike and ended up bending it right where it entered, making it almost look like those Thomson setback posts. He luckily came out ok, but it was a heck of a challenge getting it out of the frame and hoping the seat tube wasn't damaged in the process.

mmmdonuts

^^^ Yes. Two potential problems the OP had here.

1. Too much leverage on the seatpost, setting up for a bent or broken post.
2. Not enough post in the seat tube butt, setting up for a bent or broken frame.