Seat will not stay at set height

[okobojicat]

I've always had this issue, but I'm trying to bike a lot more this summer than last year as the wife got her own REI ebike. I cannot get the seat to stay at the height I want.
It has always slipped in. Basically, if I have any sort of sideways tension on the set, like, you know, pedaling, then the seat slips sideways and down.
I only weigh 215 lbs so its not like I'm overweight for the bike.
I have both of the seat clamps as tight as I can. I tighten them to the point where I can't actually close the clamp, then let off a half turn, and then close the clamp. The bike seat still slips down once I start riding.
Any advice or ideas?

[handlebar]

I've always had this issue, but I'm trying to bike a lot more this summer than last year as the wife got her own REI ebike. I cannot get the seat to stay at the height I want.
It has always slipped in. Basically, if I have any sort of sideways tension on the set, like, you know, pedaling, then the seat slips sideways and down.
I only weigh 215 lbs so its not like I'm overweight for the bike.
I have both of the seat clamps as tight as I can. I tighten them to the point where I can't actually close the clamp, then let off a half turn, and then close the clamp. The bike seat still slips down once I start riding.
Any advice or ideas?

I'd use a solvent like contact cleaner to wipe any trace of lubricant from the post and tube.

[Antti L]

I am having the same issues with my RadWagon4. I weigh about 85 kg (185 lbs). I also have to tighten the clamp as much as physically possible, but still the seat slips and after about 30-45 min of riding it has slipped enough to be noticeable. This is a big PITA. I share the RadWagon with my spouse, who is much shorter than me, so she needs to adjust the seat, but she can't undo the clamp as it is too tight, so she basically can't use the bike. I have cleaned the extra grease off of the seat tube, but it doesn't help, and to avoid galvanic corrosion the seat tube should be lightly greased anyway. This is just one of many problems and issues that I've had with my RadWagon. If I could go back in time I would fork out the extra cash for a Tern GSD. If you ride sometimes on the weekends, then sure, the RadWagon is fine for that, but I live without a car, and for such heavy duty daily use, the quality just isn't there with the RadWagon.

Please post if you find a working solution!

[handlebar]

Please post if you find a working solution!

https://ebikepursuits.com/slipping-seat-post/

I solved the problem on my Radrunner a couple of years ago. That was a different model. As I recall, I cleaned the post and tube, greased the QR cam to be sure it would tighten smoothly, and rotated the lever to an angle where the tube or post wouldn't keep it from closing all the way. This article says that a bike may ship with a kind of grease that causes slipping, so you should remove it and use a suitable grease to prevent seizing.

This article says to use a caliper to check diameters. Another article says out-of-round is the most common cause of slipping. Besides checking size, a caliper could be used to check for roundness.

[klurejr]

Make sure the clamp is set so the opening and closing side of the clamp matches up to the notch on the back of the post. You need all the squeezing pressure to actually move the metal of the post, if you are clamping on the solid side it will not clamp as well.

[klurejr]

Klurejr, What is slid side? Do you you mean solid side?

yes, sorry. I updated my post to fix the spelling error.