seatpost very tight fit
03-03-17, 08:01 PM
#1
Senior Member
Thread Starter
Join Date: Dec 2016
Posts: 169
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 118 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
seatpost very tight fit
Hey so I found a seatpost and put it into a bike. But it was very hard to get it in.
The frane takes a 27.2 mm and im not sure what size the seatpost is. If it was to big would I be able to slide it in very stiff or would it just not go in at all.
Its so stiff I was only able to get it about 1/3 to 1/2 down.
Does this sound like ita the wrong size or just very stiff?
The frane takes a 27.2 mm and im not sure what size the seatpost is. If it was to big would I be able to slide it in very stiff or would it just not go in at all.
Its so stiff I was only able to get it about 1/3 to 1/2 down.
Does this sound like ita the wrong size or just very stiff?
03-03-17, 08:16 PM
#2
Calamari Marionette Ph.D
All seat posts are "stiff". Some fit tightly and some fit loosely, but they are all "Stiff".
Did you grease it?
Did you grease it?
03-03-17, 08:28 PM
#3
Senior Member
Does the seatpost have any inscribed numbers that might be the diameter?
If not, best bet would be to take some calipers and measure both so you know both seatpost diameter and seat tube inner diameter.
If there's any gunk or corrosion on the inside of the seat tube, that can prevent the seatpost from being fully seated. A bike shop can use a seat tube reamer and clean it out for you.
If not, best bet would be to take some calipers and measure both so you know both seatpost diameter and seat tube inner diameter.
If there's any gunk or corrosion on the inside of the seat tube, that can prevent the seatpost from being fully seated. A bike shop can use a seat tube reamer and clean it out for you.
03-03-17, 08:37 PM
#4
Senior Member
Join Date: Feb 2004
Location: St Peters, Missouri
Posts: 30,225
Bikes: Catrike 559 I own some others but they don't get ridden very much.
Mentioned: 16 Post(s)
Tagged: 0 Thread(s)
Quoted: 1572 Post(s)
Liked 643 Times
in
364 Posts
I'd check to see if either the seat post or the bike frame's seat tube were bent. I'd also check the inside of the seat tube for obstructions. If you can get it in 1/3 of the way I'd have to think that the seatpost was the right size.
__________________
My greatest fear is all of my kids standing around my coffin and talking about "how sensible" dad was.
My greatest fear is all of my kids standing around my coffin and talking about "how sensible" dad was.
03-03-17, 09:18 PM
#5
Senior Member
Join Date: Aug 2005
Location: Pittsburgh, PA
Posts: 33,656
Bikes: '96 Litespeed Catalyst, '05 Litespeed Firenze, '06 Litespeed Tuscany, '20 Surly Midnight Special, All are 3x10. It is hilly around here!
Mentioned: 39 Post(s)
Tagged: 0 Thread(s)
Quoted: 2026 Post(s)
Likes: 0
Liked 1,096 Times
in
742 Posts
As bargainguy noted, if the seat tube is rusty or dirty inside or distorted, the fit could be very tight even with the right size seat post.
03-03-17, 11:43 PM
#7
Full Member
Join Date: Jul 2010
Location: San Antonio, Texas
Posts: 467
Bikes: 84 Coppi - 94 Hujsak - 82 Colnago Superissimo - 78 Ciöcc - 70's Galmozzi - 73 Lambert - 78 Motobecane Grand Record - 87 Peugeot Triathlon - 66 Peugeot H-40 - 78 Peugeot U08 - 85 Raleigh C-40 - 82 miyata 310 - 82 Univega - 85 Sterling SIS Mixte
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 39 Post(s)
Liked 42 Times
in
14 Posts
03-04-17, 02:49 AM
#8
Senior Member
03-04-17, 08:25 AM
#9
Senior Member
Thread Starter
Join Date: Dec 2016
Posts: 169
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 118 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
03-04-17, 08:51 AM
#10
The Infractionator
Join Date: Mar 2016
Location: Rochester, NY
Posts: 2,201
Bikes: Classic road bikes: 1986 Cannondale, 1978 Trek
Mentioned: 9 Post(s)
Tagged: 1 Thread(s)
Quoted: 875 Post(s)
Likes: 0
Liked 3 Times
in
3 Posts
Could the post just be too long? My Cannondale seat tube narrows after a certain distance. I had to shorten a post so that my saddle could sit a bit lower.
03-04-17, 11:09 AM
#11
Banned
A perfect fit was attained in the process of taking my 27.0 RB1 seat tube , to 27.2, by having the seat post in hand,and using an adjustable reamer
to shave out just enough, ID until the post fit , and quitting..
a shop I worked in, used to get out a ball burnisher ( It looks like a grape cluster ), chucked up in a Drill-motor. and running it into the seat tube
of every new bike as we were assembling it. for a second. de burring the factory ream job.
...
to shave out just enough, ID until the post fit , and quitting..
a shop I worked in, used to get out a ball burnisher ( It looks like a grape cluster ), chucked up in a Drill-motor. and running it into the seat tube
of every new bike as we were assembling it. for a second. de burring the factory ream job.
...
03-04-17, 03:18 PM
#12
Senior Member
Join Date: Feb 2012
Location: Rochester, NY
Posts: 18,095
Bikes: Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Mongoose Tomac ATB, GT Bravado ATB, JCP Folder, Stewart 650B ATB
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4210 Post(s)
Liked 3,875 Times
in
2,315 Posts
Seat post fit is based on both the ID of the seat tube below the lug/joint area and the fit at the clamp. Note I didn't say "the ID at the clamp" The clamp insides are often not very round, distortion from heat being a common cause although other after manufacturing causes can also be present. The seat tube ID below the joint (and therefore away from any heat distortion) is usually the max post diameter that will work. Smaller post diameters might be needed to fit within the clamping portion. I suggest a lot of care and consideration before taking a reamer to a seat tube, once metal comes off it usually is gone forever and where that metal is removed is not always where it seems that it should be from. I have heard of seat tube wall being tragically thinned to a point of failure. The tool operator was watching the post fit in the clamped portion and not what was going on below. Honing with the common flex hones won't remove hardly any metal but will reduce down any burrs. I would work a tight clamp area first with mechanical methods then metal removing ones. Andy
