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SR LaPrade Seatpost Seat Slippage

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SR LaPrade Seatpost Seat Slippage

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Old 07-05-12, 10:42 AM
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Coophawk
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SR LaPrade Seatpost Seat Slippage

So lately, my saddle has been shifting a few degrees quite fast when I'm riding- from a nice horizontal or just below horizontal angle, to a nose-up angle that's quite uncomfortable.

The bike is an 83 Voyageur with the stock SR LaPrade 26.6 Seatpost (single bolt). I've got it cranked down as much as I can, but it doesn't really seem to help.

I've had a couple of friends recommend that I swap to a double-bolt seatpost, but I thought I'd as for suggestions here first.

But failing repair/rework suggestions, I'm open to suggestions for a replacement seatpost. I do rather like the Alloy post, but those don't seem commonly available.
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Old 07-05-12, 10:49 AM
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Plenty of new, inexpensive seatposts available in 26.6mm size.

I've used plenty of LaPrades without issue. Disassemble it and post pics if possible. Make sure you have the top nut seated properly and in the right orientation (there is a top and bottom). Also inspect the ridged surfaces of the clamp and use a file to give them more bite if necessary.
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Old 07-05-12, 10:54 AM
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I might suggest taking the seat post clamp apart completely, clean all of the pieces including the serrations on the seat post, and grease the
mounting bolt. Check the small bolt on the top of the clamp for bad threads, and inspect the rectangular clamp pieces; place them on the seat
rails (one on top, one underneath) and see if the clamp looks distorted (the clamp looks 'bent' slightly or the outer edges look as if they're
curling up just a tad). If it looks like that the clamp has distorted and you'll need a new clamp, or a new seat post.

Most any single or double bolt post will work; with a double you have more nose up/nose down adjustment.

Most times with a Laprade just cleaning all the parts and lubricating the bolt will do the trick.

EDIT: The COL beat me to it!!
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Old 07-05-12, 11:17 AM
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Thanks guys.

I disassembled and cleaned it when I put on the new seat, but I'll give it another workover this evening and see if I can't get it to work.

The clamp may be a bit distorted- I know it seemed like the rails on the Brooks didn't fit it quite as exactly as the old Avocet that was on there, and that might be the problem. If I can't get it fixed, I'll post pictures after I'm done and see if there's something I'm missing.
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Old 07-05-12, 11:22 AM
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There are only four parts to a Laprade seat post clamp, two of which are the nut and bolt. I doubt you're missing anything.

Brooks seat rails might be a slightly different diameter than other seat rails; if they're smaller that might be the culprit.

Just let us know, and I'm sure someone will pipe in with some more insights.
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Old 07-05-12, 11:35 AM
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Haha, I meant missing something as to why it's not working, not literally missing something.

Actually, it seems like the Brooks rails are a slightly larger diameter- they won't slide forward and back in the clamp, I have to completely open it, place the rails, and then close it.
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Old 07-05-12, 11:41 AM
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French maker, JPR made a double bolt seatpost that never slips and is easy to micro adjust.
They made a variety os sizes mostly catering to French bikes, but they do have more common sized ones like 27.2. There's a good chance that they made one in your size. Prices for them are just like all other French stuff these days = all over the place. But I've seen them for low prices too at eBay once in a while in good used condition. A NOS 27.2 size was recently for sale at something like $19.00, so ignore the goofy sellers selling them for over $100.

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Old 07-05-12, 12:55 PM
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I have one of those JPRs on my Peugeot. It's pretty nice and the particular two-bolt setup it has is different than other seat posts I've seen.

http://www.flickr.com/photos/speedpl...n/photostream/
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Old 07-05-12, 01:56 PM
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What would seat rail diameter have to do with a slipping tilt adjustment?
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Old 07-05-12, 01:59 PM
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Originally Posted by Grand Bois View Post
What would seat rail diameter have to do with a slipping tilt adjustment?
With a LaPrade, nothing. I believe the LaPrade will tighten down on itself and not slip.
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Old 07-05-12, 02:01 PM
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Originally Posted by Grand Bois View Post
What would seat rail diameter have to do with a slipping tilt adjustment?
If the seat rails are slightly smaller the seat clamp doesn't tighten all the way down. Even if the bolt feels tight through
the wrench, it might have bottomed out at the end of its thread cut.

Ergo... if the clamp is even slightly loose on the serrations, butt pressure will cause the seat to go nose up, especially if
the seat is clamped all the way forward on the rails.
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Old 07-07-12, 06:43 PM
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So I took it apart- the notches are pretty worn down, and since they're enclosed in the clamp, it will be rather hard to get to them to do any sort of decent filing. The post itself I can file new notches in easily.

However, I think part of the problem was that the last time I adjusted it, the seat got shifted back in the clamp- it was making a nice torque angle for the seat when I put much weight on the back.

Putting it back together and moving the seat forward seems to have (for now) stopped the problem.

I noticed Loosescrews has a KAlloy replacement clamp and bolt set- anyone have any experience with how decent it is? Then I could file new notches in the post, and just replace the clamp.
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Old 07-07-12, 08:10 PM
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You can always get one of these.

http://www.amazon.com/Origin8-Sport-.../dp/B000AO9NBI
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Old 07-08-12, 12:29 PM
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Hey, I had this happen a long time ago, i.e., brooks slipping in Laprade. I replaced the the SR nut and pillow with steel parts from another seat post and somehow fixed it. Not sure why it worked, but you may not want to add the extra weight or aesthetic.
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Old 07-08-12, 12:34 PM
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If the angle adjustment teeth strip out, , it's scrap.
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Old 07-08-12, 03:55 PM
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edit: duh. i just actually read the post. sorry. buy a new seatpost.

i have an SR laprade that slips. fortunately for me, i want the saddle all the way back so it isn't an issue.

you can wrap some old tube around your post and clamp it down. it should hold a little better. otherwise the kalloy 2-bolt posts are pretty good for less than $20.

Last edited by illwafer; 07-08-12 at 04:11 PM.
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