Settling seat post???

[CharPatton]

re: Platinum Interceptor with mag wheels

I LOVE my Pedego. Have not driven my car to work in 4 months!

But have noticed that the seat post “settles”, ie it gradually sinks down over the course of 1-2 weeks of daily commuting (5 miles each way). I then have to loosen the clamp and pull the seat back up higher on a regular basis. The clamp is really, really tight, so tight that I’m afraid I’m going to break it (I have strong hands and often overtighten and break things). Thus, I don’t think that simply tightening the clamp any further is a good solution.

Any one else with this problem? Any suggestions?

Could this be due to a size mismatch of the seat post (too skinny relative to frame)? A buddy who is an engineer suggested this as a possibility.

Any ides for fixes? Specifically, I’m thinking of another clamp that will go tightly on the seat post, just before it sinks into the frame. Does anyone have any ideas where I would get this part if you recommend this?

Thank you!

 

[Nova Haibike]

It could be a size mismatch. The seatpost needs to be the exact size; sometimes the difference between sizes is only 0.2mm. Does it use a quick release clamp? Sometimes those are poor quality, and do not tighten well or smoothly. Is the clamp facing the correct direction? There is a spit in the seat tube itself; the clamp's opening should be facing the split in the tube.

 

[PDoz]

Specifically, I’m thinking of another clamp that will go tightly on the seat post, just before it sinks into the frame. Does anyone have any ideas where I would get this part if you recommend this?

Thank you!

If you're willing to accept a dodgy fix, just buy a cheap radiator hose clamp and fit it as you describe ( that way you're not paying the 3000% bicycle indistry premium )

But perhaps, first, try to increase friction between the seat post and frame - eg scratch the seatpost a bit ( nb do NOT do this if your frame / post are dissimilar metals and you ride in a high corrosion area - seaside / salt on icy roads etc)

 

[ebikemom]

My local bike tech put some kind of sauce on the seatpost that is a bit sandy to keep it from slipping. I've also found on some bikes that after tightening the quick-release clamp, tightening it down even more with an allen wrench takes care of the slippage problem. The only downside to the latter is that the quick-release clamp then won't work because it's all too tight.

 

[slomoshun]

Shops commonly grease the seat post during assembly to prevent corrosion and aluminum-to-aluminum galling. The goop can cause slippage, though. Instead, clean the grease off the post and tube and liberally apply Finish Line 'Dry' chain lube. It isn't as slippery as grease so the post stays put, but it creates an adequate boundary layer against corrosion.

 

[Nova Haibike]

My local bike tech put some kind of sauce on the seatpost that is a bit sandy to keep it from slipping.

The sauce is known as carbon assembly paste or friction paste.

 

[ebikemom]

Thanks, @Nova Haibike ! I'm really learning the lingo now!!!

 

[rich c]

Have you tried a non quick release clamp? Our son came home on the commuter train, and found that his seat was gone. He'll only use the bolt style now.

 

[ymarty]

When I replaced my seat and post, I had to buy a shim. You might need a thin one to tighten around the post

 

[Robie]

Get you some graphite paste at any good bike shop for seatpost slippage they all know about it it's got a slight grit that keeps it from sliding mine did the same thing till I put some of that on

 

[Nova Haibike]

When I replaced my seat and post, I had to buy a shim.

A shim is only required when a seat post diameter is smaller than what is intended for the bike. For example, a Body Float suspension post only comes in four diameters, yet there are well over a dozen different seat tube diameters. Shims are used to make up the difference.

 

[ebikemom]

When I replaced my seat, I used the original seatpost.

 

[chriskmee]

I had a similar issue, here is what I tried:

1. tightening down the seat-post clamp above recommended torque. Not recommended, made problem better but didn't completely fix it.

2. wipe off grease from tube and use recommended clamp torque. This seemed to work, but without any lube it started creaking/clicking.

3. bought some carbon paste (Park Tool Supergrip Carbon and Alloy Assembly Compound). Never actually got around to using this, but I think it would have worked. I have an aluminium frame and post.

4. bought a longer seatpost. As a tall rider my post was a good amount out, but not at the minimum insertion point. I ended up getting a 420mm bofyfloat seatpost, I think my stock post was 350mm. So far I've had no noise and no slippage. I haven't added any paste or lube to the post yet, but if it starts making noise ill add some of that carbon paste

 

[6zfshdb]

I have the same problem with my mag wheel Platinum Interceptor. In my case, I'm using a 350mm Thudbuster seatpost with shim. I solved the slippage problem by getting a Chromag QR seatpost clamp which has bronze bearing surfaces:

https://www.treefortbikes.com/Chrom...WUAzV-YFcIXXLjVX9Oz_5JiqdqHDizQBoCJgYQAvD_BwE

It isn't cheap but the clamp is quite a bit stronger than the OEM unit. As an added measure, I also use a carbon fiber paste:

https://www.amazon.com/Finish-Line-Carbon-Bicycle-Assembly/dp/B018FT9HOW

 

[JohnT]

Great suggestions. I’d also add that it might help to make sure the gap in the seatpost clamp lines up with the slot in the seat tube. Oh, and sometimes I lube the barrel nut that the lever pivots on so it closes more easily. Either of these might allow you to clamp tighter without having to push so hard on the lever.

 

[CharPatton]

Thanks to all for taking the time to weigh in and for all the good advice! I really appreciate it!

The Platinum Interceptor with mag wheels is totally stock (ie, I didn't modify it at all) so I'm hoping all the parts are what they were supposed to be. I just ordered the "Finish Line Fiber Grip Carbon Fiber Bicycle Assembly Gel" that was suggested by 6zfshdb. When that arrives I'll clean the post, apply the grit, and post back with the result.

Again, much appreciated.

 

[Trihonda]

I also like the idea of adding some sand paper grippy area. Take the seatpost, remove any applied grease, then spin the sestpost around inside some sandpaper (cupped in your hands). Do this in the area that is likely to be in contact with the seat tube. This roughens up the area to increase friction and doing so perpendicular to the direction of slippage will help. Be careful to not make deep gouges in the seatpost... if there are significant ridges, this could potentially lower the surface area to be in contact with the inside of the seat tube.

Also use the paste as suggested and ensure your clamp is solid.

 

[CharPatton]

I cleaned post, "lubed" contact area with the "Finish Line Fiber Grip Carbon Fiber Bicycle Assembly Gel", and retightened. Here is how the clamp is set-up relative to seat post (3 pics attached) re comments from John T and Nova Haibike. This is how it came from dealer so hopefully it is correct. Again, thank to all!!!

PS Know that duct tape is ugly, but once (hopefully!) this gets fixed I'll remove it; right now it's a great indicator for slippage

 

[JohnT]

The clamp looks good! Sometimes, opening and closing them makes them shift.

 

[CharPatton]

Awesome; thanks for follow-up! Have two days on it with no settling now so keeping my fingers crossed. Much appreciated.