Seat Post sliding down

[David1]

Can't seem to solve this issue. I've snapped the bolt on my St2 from repeated tightening. I use a Thudbuster and Brooks B-17. I weigh 203 lbs. I have recently ordered a backup clamp for post . As having this bolt snap while adjusting back up while 20 miles from home , well would be a major riding challenge without a seat. I've tried roughing up post and seat collar with 40 grit sandpaper without any success. I can already see the bolt starting to bend . I carry some pieces of gorilla tape , like super strong duct tape in my kit to rap around post on the road if bolt snaps again, possibly wedging in collar and and allowing me putting some weight on seat to get home. Any ideas would be greatly appreciated .I have also heard of another clamp called a Surley Constrictor that uses a larger bolt for allowing greater torque.
David

 

[ProfSharona]

Is it possible you have the wrong diameter thud buster? It comes in many sizes. If it is too small you can get a shim to step up to the right size.

 

[David1]

Thanks Prof I was not aware of different sizes. I should have thought of contacting Thudbuster. Thanks again.

 

[Llcjay]

Do u have a pic of the broken bolt? Can't be too tough to replace.

And try using your original seat post

 

[David1]

Thudbuster uses a special machined post for their design. And the bolt shot who knows where when it snapped , Ill make sure I'm wearing some kind of eyewear when adjusting seat post height in the future.

 

[opimax]

all of my seats move on both Stromers, 2 Thudbusters and 1 Body float. It has been recommended to to wrap w/Aluminum foil to add a little thickness, i have not tried it yet

 

[PowerMe]

Thudbuster LT & ST sizes
25.4 / 26.8 / 27.0 / 27.2 / 30.9 / 31.6 / 33.9

I purchased the 31.6mm size. You have to get the size that is closest to your seat post size (look at the original post to see what is stamped on it). You might need a shim for any differences.

 

[opimax]

Stromers are 31/6 I believe

 

[Llcjay]

I would use a soda can for shimming. My old road bike has that in the headset. Works fine

 

[David1]

Called Thudbuster and they said try friction paste used for carbon seat posts on Carbon bikes. I will get some and Let you know what happens. Thanks Prof for the help. Great idea on soda can , Try that if paste fails.
David

 

[BTB]

See if removing the seat tube's plastic shim (or collar), degreasing it, and reinstalling it "dry" helps, after you degrease the shaft of the thudbuster, body float or seat, of course. With a plastic shim (collar), the bike shouldn't need grease in this location. Beyond that, you may need to add material between the seat tube at the plastic shim, in effect shimming the shim.

 

[J.R.]

Use a torque wrench and follow the specs for the clamp. Applying so much torque to shear the bolt will damage the seat tube and is a sure sign something else is wrong. You don't want a catastrophic failure at speed.

 

[David1]

Friction paste used on carbon bikes was the solution to stopping my seat post slippage. Thanks for all the suggestions. Thudbuster knew what I needed. Were very helpful over the phone. Mellow Johneys here in Austin had some. Really cool stuff has some kind of silica grit which allows you to use 30 percent less torque. Found a great new route today and no slippage when back from ride . Problem solved !

 

[Jed Charlesworth]

Friction paste used on carbon bikes was the solution to stopping my seat post slippage. Thanks for all the suggestions. Thudbuster knew what I needed. Were very helpful over the phone. Mellow Johneys here in Austin had some. Really cool stuff has some kind of silica grit which allows you to use 30 percent less torque. Found a great new route today and no slippage when back from ride . Problem solved !

I had sliping used ParkTool Carbon Past it works great.