OverandUnder

So, Ive ridden my bike to work for a couple of days worrying mostly about the rear wheel and spokes. The only issue I have come up with so far is that the darned seat post keeps sliding down

This is a trek navigator and it seems that maybe I might be too heavy for the QR thats used on it. Does anybody have ANY suggestions? I dont have any plans on adjusting the seat height at all.

achoo

Quick release? Get rid of that. Use a proper clamp/bolt.

Then make sure it's torqued to spec. Once that's done, and if the seat still slips, do you have a seatpost-mounted taillight? Just put the clamp for the taillight on the seatpost, pressed as far down as it will go against the seat

Black wallnut 

If it were me I'd take it back to the dealer and have them replace the QR with a non QR clamp.

NCbiker

The Quick release should hold if it's adjusted correctly, at least the one on my Navigator does. If you've adjusted it and it still gives you problems, I say take it back to the dealer and have them put a regular clamp on it. You will also reduce the chance of someone stealing your seat and post with with a regular clamp.

gyozadude

Have you tried to tighten the nut a little and re-clamp the seat post QR? That might work and get the post tight enough so it doesn't slip.

ChrisM2097

I've seen people mount QR's backward (compression point toward front of seat post). It may hold, but not very good. Make sure the QR is mounted and adjusted correctly.

OverandUnder

Ive tightened down as far as I feel safe, any more and I am afraid Ill break the clamp or damage the post. I will have the lbs replace it. Ive read a few issues of other people having similar issues with these specific clamps.

Thanks for the help everybody!

goldfinch

My husband has the Navigator and had exactly the same problem. The LBS put on a heavy duty clamp with no quick release. He as had no problems since. This was after a lot of fussing trying to get the original clamps to work.

gyozadude

Be aware also that it can be sometimes that the size of the seat post is too small for the seat tube. I was upgrading an old cheap MTB with 26.0 steel seat post with the nutted collar to an alloy seatpost with single 6mm allen bolt. To my surprise, the old metal seatpost, even though it was stamped 26.0 measured more like 26.10 and and the steel one would occasionally slip when testing it out. The 26.0 alloy post was clearly too small. I managed to have a 26.2 in stock and found it a tight fit. So I borrowed a neighbour's reamer to just clean out the seat tube a tiny bit, and managed to get 26.2 seatpost to slide in nicely. Now it bolts up fine and no slipping. But it may be good to have the shop check also for diameter of the seat tube to validate the size of the seat post is optimal.

Biggziff

I usually wipe all the grease off the seat post and clean most of it out of the seat tube as well. That often will correct the issue.

bdinger

You sir, need a Surly Constrictor. Either that or a Salsa Lip Lock, I've had both and two of me could jump up and down.. ain't no slipping going to happen on one of those!

Push

+1 on the Salsa Lip Lock, I have em on all of my bikes that get ridden regularly.

fietsbob

just be aware of all the stuck alloy posts in steel frames..

a seat post clamp band like Salsa Stainless steel can be tightened more
than one threaded into aluminum.. others, as above, use a steel nut.

OverandUnder

LBS is going to take a look at it and more than likely change out the clamp or look at post sizing and see if they can slip one in just a bit larger. Cant wait to have it not move on my ride to work. Its been making the ride that much less enjoyable.

Biggziff

I know galvanic corrosion can happen, but I've never had it happen on a bicycle ever.

Chesha Neko

+2 on the Salsa Lip Lock. It fixed my seatpost issues too. Now it takes a month of daily riding to slide down a few millimeters.

OverandUnder

LBS tightened the QR down quit a bit and it seems to be holding well. Found out that the guy in the service area is actually really good friends with my family, so thats a plus I suppose. I havent had a chance to do a long ride with the bike to really test it ou,t but I did go for about 20 minutes after the LBS tightened it down more and nothing moved at all. We will see tonight!

Captlink

A short split tube around the seat-post held in place by a screw type hose clamp should prevent any downward movement.The split tube should distribute the pressure across the seat-tube as not to damage it.