samesist

I've turned the nut clockwise countless times but the seat is still slipping, no idea why. The nut still turns but the seat does not stay in place. How do I fix this?

kunsunoke 

Is there another nut on the opposite side of the seat clamp? Does that nut turn when you wrench on the other nut? If so, you're not tightening anything. The seat is going to keep slipping.

Above assumes you're working with a band clamp and a standard, non micro-adjust seat-post. A better description of the actual seat clamp assembly you're working with would help. There are a lot of different kinds used on bikes throughout the world.

samesist

unfortunately, i cannot add a photo yet as I am very new to the forum, but yes, there is another nut on the other end — what should i do? I'm quite lost, my apologies for that.

smontanaro 

You should be able to add a photo to the gallery. Click the "Gallery" link right below the Bike Forums icon in the upper left-hand corner.

samesist

Right, I've uploaded a photo

smontanaro 

I see. It looks to me like you are using a carbon seat post, yes? Besides double (and triple) checking that the post is the correct size for your bike, you might need to add some carbon paste to keep it from slipping. I'm not a carbon seat post user though. In my experience, the dominant cause of a slipping seat post is that it's too small for the seat tube.

samesist

i believe it is either aluminum/steel painted black. The nut seems to be twisting but it does not get off when I turn it counter clockwise, or move anywhere closer for that matter. On the other end, the bolt seems to be completely stationary and does not move at all. The seat was actually fine earlier, until I attempted to raise it, is it possible that i've busted the whole component?

FBOATSB

Is that a carbon seat post? You might want to take the whole assembly apart and inspect the hardware to make sure that bolt is not stripped and bent from over tightening. And make sure the seat post is the right size and undamaged. Welcome to bikeforumssamesist

samesist

Yes, but the nut does not move at all, besides rotate, so I cannot take it apart

FBOATSB

That pretty much verifies that the bolt is stripped.

randyjawa 

That was my first thought the moment I saw the picture. An easy fix, to say the least,

Were it me, I would take a hacksaw blade (fine tooth) and cut diagonally the nut. Be careful to not damage the frame = go slow and exercise patience. Sooner or later, the nut will loosed or be cut half through. It will then be easy to remove.

Next, you need to find a replacement. I cannot help but believe that there are many seat post bolts available here, through Bike Forum members. Probably have what is needed myself.

Road Fan

I would check by taking two wrenches that fit the nut and the bolthead well, and turn to verify that they only turn together. If the bolt and nut are locked together (usually by rust or grit caught in the threads), you can try to unlock them.

Try a drop of oil where the nut and washer touch the frame. Hold the nut and the bolthead securely with wrenches that fit well and twist in the direction that should loosen. You may need to crank on it like you mean it. If the bolt snaps, that's ok, just take the parts to a good hardware store and buy replacements. Get a stainless steel bolt and nut. They would be immune from locking due to rust, but not due to grit. Once the bolt is out, check the slot in the back of the seat lug to see if it is tapered, i.e. smaller at the top. If so, the seat post is not thick enough and you need either a fatter one or a to put a shim between the frame and the seatpost. Put some grease on the inner surface of the seatpost.

BTW, I think your frame is steel and the post is painted or anodized aluminum. I don't expect the carbon non-slip stuff would work even it it is carbon, if the post is too skinny for the seat tube hole.

jdawginsc 

The pinch space looks awfully small, as if it had to be over pinched to hold a smaller seatpost...looks like too small a post, maybe threads ran out on bolt? If it had an unthreaded portion?

Juan Foote

Lol, I went into a local bike store, now closed, and asked them for some assembly paste. The mechanic on duty was one of their young fellows and he stood there and argued in the face of Google results SHOWING him it existed. I later went in and talked with the old dude, long time mech. who worked there. They didn't carry any but he suggested to me to use the plain old white toothpaste. Been working great.

dddd

I believe that's a knurled steel seatpost with some kind of black coating on it. Everything should be fine once the stripped bolt/nut is corrected.

Not sure what kind of tools that the OP has access to, but a cut-off wheel might be fastest/cleanest(?).

Luckily this is a heavily-constructed frame, so that only the bolt suffered from likely previous over-tightening of the nut.

Drilling a progressively larger hole into the center of one of the flats on the nut might make it possible to go straight through the bolt until it breaks off.
This would be my approach if I perhaps had only a drill and good sharp bits handy.

Road Fan

I may be missing something, but it seems to me bolt and nut free-turning together indicates the bolt is stripped only if the hole in the frame is threaded, and either the bolt or the frame hole is stripped. With that kind of seat lug I suspect that is not the case, at least it's my assumption. At the very least the bolt and the nut are locked inside the nut. I've never tried the diagonal nut-cut technique, but it would allow the elasticity of the nut's steel to be exploited, and open a free path for Liquid Wrench to flow into the joint.

randyjawa 

Could be but I am pretty sure that the bike frame hole is not threaded. Equally sure that the nut will come off with the angle cut and a bit of effort. As for penetrating oil - not sure that will help with a striped fastener. Of course, i could be wrong.

kunsunoke 

Looks like this had nothing to do with the seat, but is instead related to the seat-post bolt.

Some observations:

1. The seat-post looks undersized. It's likely a previous owner decided to use what they had vs. what was appropriate. Look here for information on what size seat-post diameter may be appropriate for this frame. https://sheldonbrown.com/seatpost-sizes.html
2. The cable hanger is pinched, due to item 1. It will need to be straightened or replaced.
3. OP appears to be turning on the bolt-head instead of on the nut. Proper technique is to secure the bolt head with a wrench, then loosen the nut with a socket or box-end wrench until it is removed from the bolt. After removal of the nut, the bolt can be tapped out with a punch of the appropriate size.
4. If the bolt is stripped it will need to be replaced. Same holds for the nut.
5. Stripped nut/bolt combinations can be removed by cutting the nut diagonally. This can be done using a hacksaw (per Randy's recommendation) or by using a Dremel rotary tool and a cutting wheel. If the former is used, cutting lubricant will be required for the hacksaw blade. The latter can also be used to cut the bolt in half through the gap in the clamp (after removal of the cable).
6. The seat post clamp is pinched and needs to be expanded to the proper size.