freeranger

Anyone have experience using a dropper post with a shimmed seat post. Don't feel like getting a new bike, as I'm not the youngest out there, not sure how many more years (hopefully lots!) I'll still be riding trails. My ancient mtn.bike has a very odd seatpost diam, the only way I could use a dropper would be with a shim. Anyone have first hand experience with this?

trailangel

What MTB do you have?
What is the diameter of your seatpost?
What is the diameter of the dropper post you want to use?

freeranger

The current seatpost diam is 29.6-had a hard time finding a post even when the bike wasn't that old. So guess I'd have to go with a 27.2, seeing that 27.2 and 30.9 are the current standards for dropper posts. Some time ago, when I researched, I did find a shim for 27.2 to 29.6. Just wondering if shimming works well with a dropper?

trailangel

Could possibly be 29.4?
Just to be sure I would have someone else measure the post as well as the inside diameter of your frame seat tube.
What is the bike? look up the specs for it.
I don't see why a dropper would not work with a shim.

Happy Feet

I've done that with my fatbike. 31.8 to 27.2. I bought the smaller diameter so I could use the dropper on my gravel bike if I wanted. Its been about a year now with no issues.

HerrKaLeun

Your seatpost should have the nominal size stamped on. that excludes measurement errors.

shim is not ideal, but should be the same like with a non-dropper.

Note 27.2 droppers are limited in travel. this would be a good time to think about a new frame. Not sure how much you like that bike.....

freeranger

Thanks, all. The seatpost/seatube diam is def. 29.6--stamped on the orig.post, one I replaced it with, and as spec'd for my old GT. I've replaced nearly every part on the bike (after GT replaced the orig.frame and I built it back up)., And as stated, I'm not the youngest. Hard to tell how much longer I'll be riding trails where a dropper post would be handy. Already finding I enjoy the less challenging trails more enjoyable than the crazy stuff I used to ride. Still like rock, roots, stream crossings, and the like, just nothing too "extreme". And I really like the bike, it has served me well, stays in perfect tune, and has never let me down. I'll be riding it until I physically can't any longer-hopefully many, many years from now!! Guess I may try a shim.

Happy Feet

I wouldn't discount the dropper if you ride changing elevation a lot. It's an amazing feature to have IMO.

Should add,

Originally I bought my first dropper as a "proof of concept" to see what they were like. I figured if I liked them I would put the original cheap model on my gravel bike where it would see only modest use and invest in a better one for my fat bike. Hence the smaller size and shim. I also chose an externally routed lever so I could do that same idea.
That is still the plan.
If anything, I don't worry about the shim as much as the post itself, as it is narrow and might(?) snap if abused too much. So far, so good. On a bike that sees a high degree of abuse that might be more of an issue. The post and shim are pretty secure in the seat tube though, it's the section outside the tube that might fail in my mind. With a wider dropper you have a wider diameter exposed seat post that should (theoretically) be stronger.

freeranger

Good point, Happy Feet, and one I hadn't thought of. Maybe I"ll pass on a dropper-at least on my current (and probably forever) bike. There was only a few times where I was riding yesterday that got me to thinking about a dropper. They were some steep, rooty, descents (or ascents) to a stream crossing. Not a whole lot of them, so not like I'd be dismounting all that often. And you just saved me some money from spending it on something that probably wouldn't be ideal or absolutely necessary, so thanks!

Kapusta

I’ve used a dropper with a shim on many bikes over the years. Not an issue. Just get a shim with some length to it.

Dropper posts are the best development for trail riding since suspension, IMO. Heck, even my rigid fat bike has one. Total game changer, IMO.

Get a 27.2mm post and shim it.

Fwiw, In have a 27.2mm Gravity Dropper that is 15 years old. Bought it in 2005. Shaft broke a year later, and they replaced with the redesigned post, it has been in constant use for 14 years since with no issues.

PNW makes a 27.2” post that I would take a look at. I have two of their posts and they are pretty good.