Saddle slippage
 

Back story: The stock saddle failed on my Yuba Mundo. The saddle clamp had got loose without me noticing, the saddle worked its way all the way back, and eventually the rails bent until they popped out of the saddle body.

I replaced the saddle with an old Selle Royal salvaged from my disused hybrid bike. I am having problems now with the saddle slipping backwards in the clamp. I can start it all the way forward, and by the end of a 5 mile commute it will have slipped all the way back until stopped by the bend in the rails. I don't know if this is the same problem that broke the original saddle, or if I'm having this problem because riding the first saddle loose damaged the saddle clamp.

I am tightening the bolt as much as I can (I have the 4/5/6mm Park Tool hex wrench). Is it just a question of needing more torque? I have a ratcheting wrench with a 6mm hex bit I could try; that would give me a longer handle.

But I'm wondering if the saddle clamp is deformed and no longer is able to pinch the saddle rails perfectly. Does that seem plausible?

My questions are:

1. I don't see any indication on the saddle clamp regarding how it goes together. It looks more or less symmetrical, but is it supposed to face a certain way? Likewise, the rectangular nut that secures the bolt could align either parallel or perpendicular to the long side of the clamp. Does it matter which way?

2. Can a replacement saddle clamp be purchased separately from the seatpost body? (It's the two piece / one bolt kind with a grooved bottom that sits in the concave grooved surface of the seatpost and allows angle adjustment that way.) The seatpost is an unusual 31.8mm diameter, 500mm long seatpost that Yuba sells for $40. Would be nice not to have to replace the whole thing.

3. Am I wrong in assuming I could just swap the saddles over? Could the Selle Royal saddle rails be slightly narrower than the clamp is designed for, and thus won't stay put?

Thanks.

I had this problem as well; after doing a search it turns out it's not that uncommon.

I fixed it by roughing up the parts of the seat rails that contact the clamp.

I used a medium file and just did a mild criss-crossing; nothing too deep since you don't want to create a stress riser that could cause a rail to break.

FWIW, I don't think a "Y" tool provides enough leverage to properly tighten a seatpost clamp.


To answer your questions:

1. Cheapo seat posts usually have clamps that can go either way. Pictures of yours would help.

2. Odds are good that the seatpost was sourced from China so replacement parts might be hard to come by. 31.8 mm is not uncommon; replacements are available for well under $40.

3. While there are some variations in saddle rail width yours is most likely standard so yes, you could swap them over. Occasionally you have to coerce the rails to go into the clamp grooves but since the rails of most saddles are mounted in a flexible shell this is not an issue. Again, photos might help.

:beer:

replace the seat post with one with a 2 bolt mechanism controlling the tilt by balancing the turns on those 2 bolts

those low end 'laprade'1 bolt toothy friction face heads tightening till the rail clamp pieces stretch is irreversible ..

That kind does have better competitors..

For roughening a steel rail a vibrating hand engraver is useful .

BTW 31.8 is = 1.25" some folding bikes use that size seatpost , its not that weird, my brompton uses that

I got a used standard length one I can sell off Having gotten a Longer one in the Bike.

Brompton's saddle clips are excellent , well worth the $30 they sell for . works with any post stepped down to 7/8" at the top [22.2mm]