Another creeky seat-post thread
#1
my nice bike is at home
Thread Starter
Another creeky seat-post thread
I have a good looking, very fast aluminum track bike, I quite like, a Leader. It's the early iteration: 2014. w/ a traditional (round )seat-post.
It does what it was designed for very well and has real get up an go. Only thing is, it creeks... a lot.
mostly because the seat post clamp seems to have a design -flaw, in that there are thin layers of metal which are part of the inside seat clamp.
This is how it comes from the factory:
(photo is with seat clamp itself removed to show the situation better)
Seat post is fine, frame is solid.
One way I can make it go away is by really OVERLY greasing the clamp-area.. but as the grease dissipates, the creek creeps back the next day or so.
Another easy fix : stand on the pedals and mash! No sitting at all ..
Seriously : has anyone come up w/ a fix for this?
It is, otherwise, a hydro-formed masterpiece and a good application of the material.
Aluminum is very stiff which is a good thing for a track frame.
It does what it was designed for very well and has real get up an go. Only thing is, it creeks... a lot.
mostly because the seat post clamp seems to have a design -flaw, in that there are thin layers of metal which are part of the inside seat clamp.
This is how it comes from the factory:
(photo is with seat clamp itself removed to show the situation better)
Seat post is fine, frame is solid.
One way I can make it go away is by really OVERLY greasing the clamp-area.. but as the grease dissipates, the creek creeps back the next day or so.
Another easy fix : stand on the pedals and mash! No sitting at all ..
Seriously : has anyone come up w/ a fix for this?
It is, otherwise, a hydro-formed masterpiece and a good application of the material.
Aluminum is very stiff which is a good thing for a track frame.
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Last edited by kraftwerk; 09-16-20 at 03:39 PM.
#2
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Try some carbon assembly paste instead of grease. Or some valve grinding paste.
#3
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Is the thin layers of metal maybe a shim that someone wrapped around a seat post that was too small and now time, grease, goo, or something is just making you think it's part of the clamp area in the seat tube?
If your seat post that goes down below the clamp area is too small a diameter with respect to the seat tube down at that point, then it will rock back and forth using the clamp area as it's pivot point.
If your seat post that goes down below the clamp area is too small a diameter with respect to the seat tube down at that point, then it will rock back and forth using the clamp area as it's pivot point.
#4
my nice bike is at home
Thread Starter
"Is the thin layers of metal maybe a shim that someone wrapped around a seat post that was too small and now time, grease, goo, or something is just making you think it's part of the clamp area in the seat tube?"
No. This is how the factory made the frame. It does look like a (removable) shim but it is actually part of the frame.
"Try some carbon assembly paste instead of grease. Or some valve grinding paste."
Will do. Been meaning to buy some assembly paste anyhow, for my BMC.
No. This is how the factory made the frame. It does look like a (removable) shim but it is actually part of the frame.
"Try some carbon assembly paste instead of grease. Or some valve grinding paste."
Will do. Been meaning to buy some assembly paste anyhow, for my BMC.
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#5
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Did you buy this new?
The picture shows up now, where it didn't before.
Just the couple bikes I looked at when I googled Leader bikes, showed a seat post that matched the profile of the upper part of the seat tube. I want to think that if you bought this used, that someone got a frame and didn't want to shell out for the profiled seat post and came up with their own solution.
Creaking might be more in the round tube and how it's mounted in the profiled tube and your other efforts that seem to temporarily work are just coincidental.
The picture shows up now, where it didn't before.
Just the couple bikes I looked at when I googled Leader bikes, showed a seat post that matched the profile of the upper part of the seat tube. I want to think that if you bought this used, that someone got a frame and didn't want to shell out for the profiled seat post and came up with their own solution.
Creaking might be more in the round tube and how it's mounted in the profiled tube and your other efforts that seem to temporarily work are just coincidental.
#6
my nice bike is at home
Thread Starter
I bought the frame lightly used, I am the second owner. The early frames, from 2014, as this one is, only have round seat-tubes. Latter on, the frame was redesigned
( and the factory changed probably ) those frames were built to have a tapered seat post, it's a totally different design in every way.
( and the factory changed probably ) those frames were built to have a tapered seat post, it's a totally different design in every way.
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I'm still stuck on the layers of thin material you mention.
I assumed at first you just meant inside the seat tube in the clamp area. Or are you talking about the clamp itself which is not in the picture?
Still, I'd think it's a shim that someone put in there and it was maybe a soft aluminum or other material that has gotten smashed into the post from the clamp forces and maybe a smaller diameter post rocking back and forth over time. I've seen many a shim in other industrial mechanical uses that were so stuck they had to be machined out with a reamer.
Shims are only a thin piece of whatever material you want them to be. Aluminum, brass, paper or whatever someone had handy when they found out they bought too small a seat post and wanted to make it work. Might have been cut from their beer can.
And if the clamp area of the seat post has been made smaller by any reason to fit an undersized seat post then the post will rock. Whether it makes noise or is felt is going to be a case by case basis.
because the seat post clamp seems to have a design -flaw, in that there are thin layers of metal which are part of the inside seat clamp.
Still, I'd think it's a shim that someone put in there and it was maybe a soft aluminum or other material that has gotten smashed into the post from the clamp forces and maybe a smaller diameter post rocking back and forth over time. I've seen many a shim in other industrial mechanical uses that were so stuck they had to be machined out with a reamer.
Shims are only a thin piece of whatever material you want them to be. Aluminum, brass, paper or whatever someone had handy when they found out they bought too small a seat post and wanted to make it work. Might have been cut from their beer can.
And if the clamp area of the seat post has been made smaller by any reason to fit an undersized seat post then the post will rock. Whether it makes noise or is felt is going to be a case by case basis.
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Is the thin metal sleeve that accepts the round seatpost aluminum or steel? Have you tried to get an actual measurement of the internal diameter using a metric dial caliper?
What size seatpost are you using? You say it is OK but could it be 0.1 mm (or less) undersized? Is it a 27.2mm?
If the sleeve is aluminum, and your seatpost is 27.2 you could use an adjustable reamer hone with cutting oil and ream a small amount of metal shavings from the interior of the sleeve until you can fit the next size of seatpost into that sleeve. This would be a 27.4 mm. Thomson makes them or if you don’t need as long of a post and want more retro there are Dura Ace 7400 posts that came in 27.4.
Could you post a photo of your seatpost and seatclamp?
What size seatpost are you using? You say it is OK but could it be 0.1 mm (or less) undersized? Is it a 27.2mm?
If the sleeve is aluminum, and your seatpost is 27.2 you could use an adjustable reamer hone with cutting oil and ream a small amount of metal shavings from the interior of the sleeve until you can fit the next size of seatpost into that sleeve. This would be a 27.4 mm. Thomson makes them or if you don’t need as long of a post and want more retro there are Dura Ace 7400 posts that came in 27.4.
Could you post a photo of your seatpost and seatclamp?
#9
my nice bike is at home
Thread Starter
Yes and yes, fixed this today.
The gaps, apparent in the first photo, look really suspicious and guilty.
At the very least they were confusing everyone, including myself.
Iride01 said it looks like a shim or shims may be present but the problem is there needs to be shims.
Whenever shims are considered I recall that bit of Robert Pirsig's famous book....
remember I found it kind of boring at 15, but the shim thing really stuck with me, the beer-can shim is the answer!
So: those gaps you see in front of the 'sleeve' got filled with three shims, all varying sizes, to fill the space , 'just -so'
The seat-post hole is not quite round either, so two shims went in there. The seat post 27.2.
All clamped it down well with plenty of grease, I took the bike out for a ride,
carrying a 10lbs. tool-filled knapsack (-had other things to repair elesewhere..)
So far the seat post was quiet (!) lovely. Will test-ride again tomorrow, but so far I like what I hear: nothing!
Masi61 is absolutely correct that the tube should be reamed or at least rounded somehow.
Might be a good long-term solution to go up to 27.4. For now it's shims.
I remember when I built the frame up, with new headset and forks,
I had to actually shim the head tube somewhere as well, that was a first for me.
'Chinese precision' calls for lots of shims.
I think the sleeve is made of steel.
Will post more pictures tomorrow when the light is good and do a magnet-test on the sleeve.
Thanks all.
The gaps, apparent in the first photo, look really suspicious and guilty.
At the very least they were confusing everyone, including myself.
Iride01 said it looks like a shim or shims may be present but the problem is there needs to be shims.
Whenever shims are considered I recall that bit of Robert Pirsig's famous book....
remember I found it kind of boring at 15, but the shim thing really stuck with me, the beer-can shim is the answer!
So: those gaps you see in front of the 'sleeve' got filled with three shims, all varying sizes, to fill the space , 'just -so'
The seat-post hole is not quite round either, so two shims went in there. The seat post 27.2.
All clamped it down well with plenty of grease, I took the bike out for a ride,
carrying a 10lbs. tool-filled knapsack (-had other things to repair elesewhere..)
So far the seat post was quiet (!) lovely. Will test-ride again tomorrow, but so far I like what I hear: nothing!
Masi61 is absolutely correct that the tube should be reamed or at least rounded somehow.
Might be a good long-term solution to go up to 27.4. For now it's shims.
I remember when I built the frame up, with new headset and forks,
I had to actually shim the head tube somewhere as well, that was a first for me.
'Chinese precision' calls for lots of shims.
I think the sleeve is made of steel.
Will post more pictures tomorrow when the light is good and do a magnet-test on the sleeve.
Thanks all.
__________________
BMC Race Machine / BMC Team Machine / Rossin Record / 80's Pinarello Traviso / Merlin MTB / Raleigh "Folding 20" / Ti-Swift (!)
Erikson w/C&C couplers / Trek's: 2300, 1200, 990 / Jamis 'Sputnik'
BMC Race Machine / BMC Team Machine / Rossin Record / 80's Pinarello Traviso / Merlin MTB / Raleigh "Folding 20" / Ti-Swift (!)
Erikson w/C&C couplers / Trek's: 2300, 1200, 990 / Jamis 'Sputnik'
Last edited by kraftwerk; 09-25-20 at 07:38 AM.
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