USE Shims

[Imlach]

Hi

I have been having a hell of a time finding a 30.4 seatpost so I've been looking at these shims from USE. If I want to use a 27.2mm seatpost in my frame which takes a 30.4mm seatpost, am I correct that I'd have to buy the following: https://www.sjscycles.co.uk/seat-posts/ ... 272-mm-id/ and choose 30.4 as the outer diameter?

Also, I have my seatpost in quite deep and I was wondering if I should be worried about frame stress from using a shim? I am a 290-300lbs rider so I like things to be snug with no play at all. From what I can tell the shim goes down about 10cm, if my seatpost were to go further than that wouldn't it cause some kind of play?

Chris

 

[CassidyAce]

Re:

Yes, choose 30.4 in the dropdown menu and then it will be the right shim for 27.2-->30.4. I doubt if you will be putting undue strain on the seat tube: the USE shims are 10cm long, which is about the minimum insertion length for most seatposts, so it should be fine, and especially if the post is a long way into the seat tube because there will be less leverage being applied than there would be if there were 25-30cm of seatpost poking out of the top of the seat tube. There shouldn't be any play either: 10cm of snug fit should be enough to hold the post steady.

Choices are relatively limited for 30.4. Cheap Chinese carbon fibre, some old Specialized seatposts or, one I bought not so long ago, the BBB Skyscraper, which is functional but nowt special: 27.2 with a shim is a good way to go.

 

[Yogi bear]

Personally I wouldn't do it. At 290lbs you are no tinkerbell! I dont know how much seat post you have out of the frame, but with a shim all the leverage will be on the top 10cm of the seat tube and welds. Shimmed posts are known to crack seatposts.
However, you might have a super sturdy strong frame and be a very gentle trail rider, in which case you should be fine.

 

[Imlach]

Personally I wouldn't do it. At 290lbs you are no tinkerbell! I dont know how much seat post you have out of the frame, but with a shim all the leverage will be on the top 10cm of the seat post and welds. Shimmed posts are known to crack seatposts.
However, you might have a super sturdy strong frame and be a very gentle trail rider, in which case you should be fine.

Tinkerbell with bulimia more like

I've got about 18 to 20cm seatpost sticking out

I'm starting to think that the bbb skyscraper is the way to go until I can find a replacement.

 

[Yogi bear]

Personally I wouldn't do it. At 290lbs you are no tinkerbell! I dont know how much seat post you have out of the frame, but with a shim all the leverage will be on the top 10cm of the seat post and welds. Shimmed posts are known to crack seatposts.
However, you might have a super sturdy strong frame and be a very gentle trail rider, in which case you should be fine.

Tinkerbell with bulimia more like

I've got about 18 to 20cm seatpost sticking out

I'm starting to think that the bbb skyscraper is the way to go until I can find a replacement.

Not a massive amount sticking out then, but twice the amount that would be supporting it in the seat tube.

(I meant crack seat tubes in my previous post not seat posts)

 

[mk one]

Some people dont like to shim a post if they can help it, personally i have used shimmed posts on a lot of my bikes, usually USE posts and never had any trouble. To be fair if i had the right diameter post and it was what i wanted then i would use that instead, just happens i have a few USE posts and also like them.

 

[Imlach]

Some people dont like to shim a post if they can help it, personally i have used shimmed posts on a lot of my bikes, usually USE posts and never had any trouble. To be fair if i had the right diameter post and it was what i wanted then i would use that instead, just happens i have a few USE posts and also like them.

I'd prefer not to shim. I reckon I'll get myself a fairly long, cheap seatpost for now and then fingers crossed I'll come across a syncros or similar sometime.

Thanks to you all for the input.

 

[Trialsmeister]

Re: 30.4

Here's one on ebay if useful, though maybe shorter than you wanted...

https://www.ebay.co.uk/itm/MTB-Seatpost ... 1438.l2649

No connection, just sharing.

Cheers,

M

 

[Imlach]

Re: 30.4

Here's one on ebay if useful, though maybe shorter than you wanted...

https://www.ebay.co.uk/itm/MTB-Seatpost ... 1438.l2649

No connection, just sharing.

Cheers,

M

Thanks for sharing. Unfortunately it's a fair bit too short for me.

 

[FluffyChicken]

Re:

If you don't mind black and a Ritchey/Kalloy old school look and can get past some modern logo.
30.4 400mm
https://www.tredz.co.uk/.System-EX-Seat ... ?sku=25657

or the
Inline Kalloy design
https://winstanleysbikes.co.uk/bbb-bsp- ... r-seatpost?

I'll post some more up if I find any.
shame the silver isn't available.