FarHorizon

The clamp on my Brooks B135 saddle has repeatedly slipped while riding. The clamp is securely fastened to the seat post, but the plates that control the saddle angle will slip. Usually, when weight is placed on the back of the saddle, the nose will tilt upward while riding. This is a safety hazard.

I've written Brooks about it, and they merely posted my text in their "negative comments" section of the B135 web page. This doesn't make the problem any better.

To try and put more torque on the Brooks clamp, I've doubled the washers that retain the rails to the inner clamp and I've replaced the stock through-bolt with a larger diameter one from the hardware store. Alas - still slipping.

So my questions are:

1. Does anyone make an after-market clamp for the double-rail Brooks saddles that will stay any better?

2. If not, is it feasible to add inner washers on the through-bolt to limit the flex of the side rails when clamping? I realize that some slack would be needed for the clamp to tighten on the seat post sufficiently, but once that slack was taken up, the washers would allow more torque between the clamp body and the inner side-plates.

3. Is there any way to adapt the double-rail Brooks saddles to use a standard single-rail micro adjust seat post? That would solve the flex problem by transferring the tilt adjustment to the seat-post mechanism, not the post clamp.

I really like the saddle, but don't feel safe using it with the factory seat post clamp.

Thanks - FH

PS: I just found the SA-003 double-rail clamp. Does it work?

skycomag

have you check the rail for at the clamping area?
maybe the rail diameter is slightly smaller.
since the washer only push against the side of the mount but doesn't clamp on the rails. or try to bend the part of the mount that supports the rail to make the diameter smaller
I would try wrap the rail with grippy hockey tape to increase the rail diameter.

dsbrantjr

How about trying some coarse valve grinding compound or carbon assembly paste between the working surfaces of the clamp, to increase the friction and "lock" the parts together? Or perhaps "washers" cut from emery cloth or similar to accomplish the same effect. Or find an angle adjustment you like and drill and pin (or tack weld) the thing.

FarHorizon

Hi @skycomag & @dsbrantjr -

The rails are not undersized. The problem is that when additional torque is placed on the binding bolt, the clamp ears (that are also the inside of the angle adjuster) are pinched out of parallel with the rail halves of the angle adjuster. Therefore, more binding-bolt torque = less surface area being in contact on the angle adjuster plates.

The "pin or weld the plates" is an excellent suggestion and would work. The SA-003 rail-spacer plate, though, seems the better solution. With the bottom rail-supports of the micro-adjust seat-post supporting the bottom rail of the saddle, and the top plate of the seat-post supporting the upper rail, any torque applied to the seat-post binding-bolt will be applied directly to the saddle rails. This should prevent the saddle from shifting angle while riding. I now have one on order from Harris Cyclery. Should the plate fail to be efficacious, I'll probably try the "drill & pin" option since I don't have a welding machine.

Thank you kindly for the feedback!

FarHorizon

dsbrantjr

Another solution might be to replace the thru bolt and 2 nuts with a piece of all-thread and 4 nuts, 2 inside and 2 outside of the clamp pieces. In this way the clamping of the seat post and the clamping of the rail angles can be separated. Set the inner nuts to control the post clamping force, then jam the outer nuts against the inner ones to clamp the rail angle. Sort of like adjusting your front axle cones.

I think the spacer plate will work, though.

Mr IGH

Yes, very well, thank you:

FarHorizon

Thank you also, @dsbrantjr and @Mr IGH -

Yes, the 4-bolt on all-thread would work better than a spacer pack - thanks for the idea. But if the SA-003 adapter works as well as Mr IGH says, then this problem is solved.

FH

Mr IGH

Mine is the gold anodized version, I bought it from an advert in the back of a bike magazine sometime in the 80's and have been using it since then. This is my second B72 that I've used it on, I wore out the first one after 30 years. It works.

I did grind down the weird shaped rectangular "nut" that the Laprade's bolt threads into (on top of the clamp, right under the saddle). My B72 sags under my load, the leather touches the "nut" on bumps and such. I never noticed it whist riding, just saw the leather dents and addressed the situation the prevent any issues.

FarHorizon

My post will have a rounded top with threads that are internal, so no worries there. I may just go ahead and order two of the SA-003 spacers - I plan to buy a B190 in the future.

SJX426 

Is the Brooks clamp ID matched to the seat post OD? Part of the mechanics of clamping is dependent on the "ears" contacting the post and no longer moving (slack). If the OD is too small, the clamp ears will not "bottom" out causing the rail clamp not to reach required clamping force to prevent rotation. The other issue is that if the saddle has moved often enough, the "teeth" of the mating surfaces are now round allowing for rotational slip. Adding a gritty surface between the two might help but would be marginal IMHO.

WRT 2. A sleeve would work too, but now you need to use trial and error to determine the correct length that will allow for sufficient clamping to the post before allowing for increased clamping to the rail.

Maybe you just need a replacement post or Brooks clamp.

Is this what you are working with?
[IMG]OLYMPUS DIGITAL CAMERA by superissimo_83, on Flickr[/IMG]

fietsbob

4 rail saddles have different needs than 2 rail types the SA -003 (formerly Breezer seat sandwich) is a workaround to use a 4 rail saddle in a seat post designed,

as Most Are, for 2 rail saddles ..

the straight seat posts are 7/8" (22.2mm) on top, as a standard..

as I read before, there .. is a lot of rider mass being placed on the saddle

but that standard saddle clip , has been used, as has the saddle it self, for 100 years ...