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Discussion Starter · #1 ·
Ok so I bought my first road bike a few months ago and i've enjoyed it quite a bit but i've came across a problem.

Aside from the saddle making my ass completely numb there is nothing to keep the seatpost/saddle from sinking down into the tube.

What can I buy or better yet what is the proper name for this a clamp that would prevent this ?




thanks !
 

· Militant commuter
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943 Posts
First...check that the seatpost is the right size for the frame -- you may want to bring the bike to your LBS to get measured.

Is that a used frame? Sometimes on older frames, the seat tube gets a bit "wallowed out" from overtightening and the proper seatpost won't fit correctly. One solution might be to have it reamed a bit oversize and buying a seatpost to match the new diameter, or to shim the existing seatpost with a strip of beer can aluminum to take up extra room. Finally, you could try a bit of carbon assembly paste...that might provide enough friction to keep the post from slipping.

To prevent slipping posts on bikes used in the cobbled classics like Paris-Roubaix, the pros use a simple hose clamp cinched right above the seat tube opening. Worth a try (and it's cheap).
 

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1,846 Posts
Can't tell from the picture, Is the back of the seat lug slotted to allow it to be clamped closed?

If so you tighten the post by tightening the bolt across the seat stays. As I remember those, you'll need 2 5mm keys. In order for that to work, you have to have the right size seatpost which is easy to recognize because it's the largest diameter that will fit and will have zero play even before tightening.

If your current post has any ability to rattle in the frame it's too small, also if the tops of the seat lug slot come closer than 1/16" to each other when clamped the post is too small. Seat posts are sized to 0.2mm, (0.008") in diameter so we're talking about very small differences having a big effect.

If your seat lug is not slotted, your frame requires a seatpost with an internal expander to clamp itself into the seat tube, the same way quill stems are clamped.
 

· duh...
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you can't add a clamp...the binders on those old treks often got mushed together so they didn't really bind well. something to check when buying a used one
 
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