thomson masterpiece seatpost issues
 

my saddle keeps sliding and tilt keeps changing on my thomson...i have it torqued to thomson specs...i had to stop like 6 times to reset the saddle besides getting chased by a dog the last 1/4 mile it ruined the ride......anyone have issues like this or any suggestions?

Did you grease the seatpost? It's supposed to be done partially to keep it from seizing but it also helps with a snug fit.

Did you try squirting the dog with your water bottle?:D

No grease ever. Use carbon assembly paste. Even if there is no carbon involved. There is no reason for the angle to change.

Why do you say that? Grease on the seatpost has always been done and before widespread use of carbon. Is paste better on non-carbon?

the point of carbon paste is to increase grip so you can decrease torque applied to the fastener. its good to use everywhere you can.

Thompson says to grease only the threads of the bolts on seat rail clamp. They say not to put grease on the washers or under the head of the bolts. They specifically state not to use anti-sieze and are silent on carbon assembly paste. No grease on the post itself for a carbon frame. Torque spec is 6.8Nm for the Elite, 5.1Nm for the Masterpiece.

Reference https://www.bikethomson.com/wp-conte...0/PostInst.pdf

Something is assembled wrong if the saddle is sliding and tilting or the post is broken. I would take it all apart, degrease everything, inspect and reassemble if not damaged. Only a small amount of grease on the threads of the seat rail clamp bolts. Make sure the clamp is not bottomed out on the post because of too great an angle.

Could be the OP has oval rails on his saddle. The clamps on Thomson posts are made for round 7x7mm rails. They sell a special clamp for oval rails up to 7x10mm. https://www.bikethomson.com/product/...pset-7x7-rail/

[MENTION=183557]rpenmanparker[/MENTION], why do you say no grease ever and why do you recommend carbon assembly paste? I'm not trying to challenge but rather to learn. I've never had occasion to work with carbon assembly paste but have read about it and would really like to hear what you have to say.


-Tim-

Kind of off topic to the OP but do you put it on bolt threads in place of a lubricant or do you put it on the parts being clamped together by the bolts? Or both?

Betcha a bag of spiced mango that the OP has oval saddle rails.

parts being clamped, grease on bolts still

carbon paste is basically just grease with tiny balls in it

I have oval carbon rails on my saddle, paired with the "normal" Thomson clamp, never any problem with the saddle slipping. I don't use any sort of product on the clamp, rails, or fasteners. All assembled dry.

So my guess is some sort of contaminants on the clamp and/or rails.

Grease is appropriate for the fasteners but not for the surfaces you want not to slip. The reason should be obvious. Have you ever tried to climb a greased pole? Carbon paste creates grip.

If it makes everyone feel better, use assembly compound. Park tools has one that's not "carbon" specific.

Thanks for the clarification.

You said "no grease ever" and I thought you were talking about fasteners as well.


-Tim-

I think it's pretty impossible for the saddle tilt angle to change unless the bolts are loose! The Thomson is pretty rock solid in the tilt department!