Seatpost to replace an SR Laprade
 

I’ve got a nice old SR laparade post, however with more than one type of saddle the rails slip all the way backward. It looks as though the rail seats have splayed outward over time and the adjustment bottoms out before sufficient clamping.

What’s a decent vintage or vintage-appropriate 27.0mm seatpost? The Nitto S65 looks ok although it shares the single bolt mechanism as the SR. Should I worry about that or is the design essentially solid?

Cheers!

To me, it sort of depends on the bike and what else is on it.

If'n it were me, it'd be Suntour Superbe Pro or XC Pro, or maybe Dura Ace or XTR.

(My 1985 Trek 720 came with an SR SP-KC seat post- it was a pretty high end unit for the time. I replaced it with an XC Pro- that thing seems to weigh half of what the SP-KC weighs, and I have much better control of the saddle nose angle. )

The Nitto seatposts are excellent. I have two of them and they work flawlessly, no complaints

Hi,

Thanks both, good info. Perhaps I'll look for a Nitto S65 since they come in 27.0 mm. Can't find the S83 in that size. I'm a bit jumpy about going for another single-bolt seatpost, but reading around I hear people talking about using long-handle 6mm Allen keys to get the required torque... I thought I was giving it easily enough already. Maybe my first investment should be a bigger Allen key!

Thanks again!

SR Laprade Versions
 

I assume you have the Laprade version with the steel clamps (Model CT-P5E). They also made one with cast aluminum clamps which should not have the issue your talking about (Model CT-P5). These come up on eBay all the time. I have many bikes using the later version without issue. Good luck no matter what post you choose. Sugino does make some really nice units.


http://www.radiolabworks.com/bikes/p...20Versions.jpg

Yeah my favorite rider came stock with the steel clamped CT-P5E version. I never had any real problems with it, but the aluminum clamp seemed to be a much better design in my opinion. I retained the original post, but swapped out the steel clamp for an aluminum one from another post I had in my parts bin. Much better!

https://i.imgur.com/WaEyc6b.jpg

https://i.imgur.com/SuvvDvm.jpg

That’s interesting because I actually seem to have the aluminum clamp. The shapes are totally different so it would be hard to be mistaken I guess. Perhaps I am missing something else. I do see that when it feels tight, the upper and lower clamp parts don’t have much separation at all, which made me think it is bottoming out somewhere due to distortion. How big of an Allen key and how much force (roughly) do you use with your P5?

Hmm that's odd. Can you post a pic of your clamp? I normally tighten mine with a standard 6mm "L" shaped Allen key that's maybe 5 or 6 inches long. I do tend to really crank it down tight though. I'm kinda finicky about my seat position, so once I get it just where I want it I really try to make sure it won't be easily moved.

FWIW, I've never had a problem with the saddle slipping either forward or backward on any seatpost, let alone a Laprade. Could it be that your saddle rails are undersized, perhaps from wear? Does a different saddle have the same issue? You have nothing to fear with the single-bolt type per se.

https://www.dropbox.com/s/333zgmj1gn..._6071.JPG?dl=0

Here is an image link, but note that here I've shimmed the rails with a few layers of electrical tape (holding so far, see below). So, the gap at full tightness is bigger than it was, but perhaps you can see a small depression in the middle of the upper clamp? Think I can.

Jim, yes this happened with a Cambium too and now this reissue Turbo. Good to know that you don't feel single-bolt designs as such are anything to worry about. Both saddles I got used, though in good condition, but maybe thin rails are a common denominator.

Austin, thanks. I'm weary to overtighten anything on a bike, and like you I currently have a normal 6mm key (perhaps not quite as long). But I'm a 6 foot guy and this time I've tightened as hard as I possibly can. I tried that without the shimming and it still didn't work. Maybe the shim will help but I haven't been on a long ride with it, and I doubt electrical tape is ideal.

In any case, it looks tricky to find those Nitto two-bolt in 27.0mm without importing from Japan.

Thanks all.

Haha yeah I'm a pretty small guy at 5'10" and 125 lbs. so really cranking down for me is probably little more than finger tight for a bigger guy :lol: Looking at that pic though it almost does seem as if the top part of the clamp is kind of bowed out looking. You might find making some shims out of an aluminum can works pretty well. I've used cans to shim all kinds of stuff over the years.

Thanks, that's helpful. I would also guess that the very centre of the clamp, where the bolt pulls, is probably further bowed than is apparent from the back. If the tape-shim continues to hold then perhaps that is the explanation.

Maybe you could replace just the clamping parts, swapping in from a cheap $10 (edit: $20!) Kalloy. I just looked at one I had in my parts bin, and it looks like it would probably work. The bottom of my Kalloy has notches, not sure about your post. Perhaps you could use only the top part. It would also have to fit the part that it slides on, which measures 23.0 mm. There are gajillions of these around, and the clamp from any size should be the same, I think.

The top part of the clamp seems quite a bit beefier than your post, actually.

I've been on the lookout for an older 27.0 post for an old MTB, and haven't had much luck, so I feel your pain.

If you can find one, I can enthusiastically recommend the JPR seatpost. It's vintage, it came in your size, and it's one of the best seatposts I've ever come across - light years better than an SR Laprade.

http://www.classicrendezvous.com/Fra...ice_list_1.JPG
https://c1.staticflickr.com/5/4118/5...4384978a_b.jpg

That JPR stuff is nice!

Nice idea. If you have a pic of your top part I’d love to see it. Indeed I have notches on the bottom part.

I looked over my bikes with the Laprade installed on them and the gap is rather narrow, but no less than 1/16". I have two Sugino 2-bolt models that you talk about and those have a much larger spacing, like 1/8". Off hand I forget the models on the Sugino's as they are both the rebranded Suntour Superbe versions.

If you have a big piece of sand paper you might be able to remove the top half and rub the inner side to bring it down a wee bit. It's just weird as I can't imagine those aluminum clamps wearing down or bending in any way. Being cast aluminum they would break before they bent. Perhaps the seat rails have gotten smaller??

Being extra cautious of over tightening is a good thing. You can always go back and tighten more, but stripping a thread or breaking a screw/bolt is killer! I think SR made the spacing really small so that someone couldn't over tighten and crack the clamp blocks.

You should be able to mill/file/Dremel one half of the clamping section to give you more clearance for tightening. A millimeter or two is all you need.

+1 - the electrical tape won't hold for very long if the reason you have slippage is the clamp bottoming out. Beer can shims are easy and cheap.

Edit: also replacement Laprade posts are fairly common. I have several and none have caused problems yet.

It would be unusual that the aluminum clamping parts would "bend" or "bow"... aluminum doesn't really do that. Unlike steel, which is a pretty ductile metal, aluminum is not. May want to take a look at all the threads of the parts in the clamping stackup... it's possible that the small portion of the threads that are mostly highly used when you clamp things down.. those threads have been wallowed out due to the rocking back and forth of the seat when things weren't synched up tight enough. Usually, the first few threads take about 80% of so of the load, so if they are gone, things wouldn't stay where they need to be.

Not a problem.

Attachment 594616

Attachment 594617

Attachment 594618

Attachment 594619

I measured the top part's apparent thickness in the center, if looking from the front or rear of the bike, and I get about 9.0 mm. I just squeezed this region between the full blade length of my calipers. Of course the thing is highly sculpted on the underside, so it may be tough to make direct comparisons.

It seemed in looking at the 'bottom' part, that the sculpting allows the top to interface with the bottom piece, the special radiused top nut, and still do its job clamping the saddle rails. Unless Kalloy didn't innovate at all in the design, I suspect you'd need to use all three pieces together.

I became a bit curious after my first post, and was wondering if the radiused part of the post-attached aluminum that the bottom part slides on, with the notches, has the same radius. but when I took it apart, I found that it's not really an arc at all... I figure it makes 2 'line' contacts wherever you chose to position it, so it will probably interface with your 'bottom part' okay, even if they have different geometries.

FWIW I don't think you have to worry about an S65 slipping. The quality is very high, better than old Laprades really. Rivendell puts the cutoff at 220 lbs, and that sounds reasonable to me. If you are heavier than that, or tend to sit hard on the seat, look for a dual bolt. I've got a Nitto S65 and have never had the slightest problem. The fixing bolt doesn't need to be tightened especially hard, FWIW. You should use a 'long' arm allen wrench to tighten it regardless. A set of Bondhus ball end combo allens is well worth it.


It does sound like you have the stamped top version of the laprade. If you could find the cast pieces for the top in a coop or something, that would also fix your issue most likely.

Thanks all...
 

Some great info here, thanks. I took it all apart and inspected, and for sure the clamp is a little bowed. Seems odd for aluminum (I checked, nonmagnetic) but remember we do sometimes cold set our aluminum Racer calipers, so I guess it can bend a little bit.

I spotted a little damage on the inside of the upper clamp (on a ‘non-mating’ part) which it seems unlikely could have got there without something bottoming out.

Anyway, for now a coke can shim is in place, and I will watch it carefully. Thanks! :cheers:

..and btw this is very interesting. Looks like an identical design but as you say the numbers could differ. Thanks for doing that.