saddle sliding backwards

javidr

Hi

I have noticed that my saddle is constantly sliding back when I ride the bike. I don’t notice it moving, but, I move it forward before I ride the bike, and when I arrive home, it’s totally moved backwards

I assume the problem is not tight enough but I am worried about breaking the seat post (i believe it’s carbon, it’s a Boardman 9.4) if I screw it too much

I might also think the problem might be related to the washer, it is a bit bent, although I believe it was the original shape (pic attached).



The saddle rails have some scratches, or can be seen in the other pic, caused by the friction when it moves back, so it proves it’s quite tight



What can I do to fix it?

Thanks

daniel_b

Never come across that before - I'd probably look to apply some carbon paste to the rail, and the clamping surfaces - anything that makes contact basically.

If that doesn't work, I'd either up the nm on the bolt, or sand the rails a little bit where you want to clamp, but still apply carbon paste.

Some of them need a lot of nm, my Ritchey wcs ones need 12nm

DeVlaeminck

Assuming the saddle rails fit the clamp ok just tighten it more.

imposter2.0

As above - if the saddle is slipping, then the clamp is not tight enough. The post itself may be carbon, but the fastenings are all likely to be steel, so I suspect your worries about breaking something are probably misplaced.

MidlandsGrimpeur2

Some of them need a lot of nm, my Ritchey wcs ones need 12nm

I have a Zipp sl speed which has a single bolt on the side of the clamp for tightening. That requires 12nm as well. I couldn't bring myself to go above 10nm at first but If you try and use less torque it will creak like mad as you ride. After 3 years of use it hasn't cracked the post or rails so guess it is fine!

javidr

Right, I will try that then. Thanks!

daniel_b

MidlandsGrimpeur2 said:

Some of them need a lot of nm, my Ritchey wcs ones need 12nm

I have a Zipp sl speed which has a single bolt on the side of the clamp for tightening. That requires 12nm as well. I couldn't bring myself to go above 10nm at first but If you try and use less torque it will creak like mad as you ride. After 3 years of use it hasn't cracked the post or rails so guess it is fine!

Yes I'm not convinced it is the optimum design, and I too went for less nm at first, but then the whole saddle pivoted on the first ride, so 12nm it was.

Having said that, when I adjusted the saddle once, and tightened the bolt back up to approaching 12nm, using a decent quality Sealey torque wrench, the bolt snapped - Wiggle to give them their due sent me out a whole new clamp assembly, but it shows how on the limit it may be, or I was unlucky with a defective bolt perhaps.

MidlandsGrimpeur2

Zipp only seem to do this with the carbon post. I have 4 alloy Zipp posts on different bikes and they all have the standard 2 bolts under the seat clamp configuration. No idea why.

trevor.hall12

From the Boardman site