Past Minimum Insertion on Seatpost
08-10-11, 04:35 PM
#1
Senior Member
Thread Starter
Join Date: Apr 2011
Posts: 257
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
Past Minimum Insertion on Seatpost
An old mountain bike is past minimum insertion on the seatpost by about an inch when I put the saddle high enough.
The post measures 1.064" (27.0 mm) and extends about 8" out of the frame.
I had no lock searching here or finding a longer seatpost. Or, figuring out what to order anyway.
Could someone please explain how seatpost measurements work?
The post measures 1.064" (27.0 mm) and extends about 8" out of the frame.
I had no lock searching here or finding a longer seatpost. Or, figuring out what to order anyway.
Could someone please explain how seatpost measurements work?
08-10-11, 05:17 PM
#2
Senior Member
Join Date: Jan 2002
Location: Northern Neck Tidewater Va.
Posts: 1,688
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
I don't know how the measurements work, but pulling that much too much out is asking for trouble. Did you look at Nashbar and the other on line sites for a longer seat post?
luck
luck
08-10-11, 05:23 PM
#3
Banned
Join Date: Jun 2009
Posts: 4,788
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 2 Times
in
2 Posts
Check Price Point, too. But before you do that, read the side of the seatpost to find out your size.
8" post? That's about 400mm, good luck finding one appreciably longer...........
8" post? That's about 400mm, good luck finding one appreciably longer...........
08-10-11, 05:38 PM
#4
Senior Member
Thread Starter
Join Date: Apr 2011
Posts: 257
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
I'm not sure how these are measured. The post says 27.2 mm dia.
From the rails to the end of the post is 11-3/4", or 300 mm. The minimum insertion mark to the end is 4". I would have 3", which I agree is asking for trouble.
From the rails to the end of the post is 11-3/4", or 300 mm. The minimum insertion mark to the end is 4". I would have 3", which I agree is asking for trouble.
08-10-11, 06:14 PM
#5
Cycle Year Round
Google or call the LBSs for "27.2 x 400 mm seatpost".
__________________
Land of the Free, Because of the Brave.
Land of the Free, Because of the Brave.
08-10-11, 07:45 PM
#8
rebmeM roineS
Join Date: Jan 2006
Location: Metro Indy, IN
Posts: 16,216
Bikes: Bacchetta Giro A20, RANS V-Rex, RANS Screamer
Mentioned: 15 Post(s)
Tagged: 0 Thread(s)
Quoted: 653 Post(s)
Liked 347 Times
in
226 Posts
You measured 300mm - that's one of the standard sizes. The next size larger from what you have should be just right for you. 350-400, as suggested previously.
Seat post length is measured "from the bottom of the post to centerline of the seat rails." I seen that on the internet.
Seat post length is measured "from the bottom of the post to centerline of the seat rails." I seen that on the internet.
__________________
Bacchetta Giro A20, RANS V-Rex, RANS Screamer
Bacchetta Giro A20, RANS V-Rex, RANS Screamer
08-11-11, 01:37 AM
#10
Senior Member
Just in case it becomes important to the OP or anyone else, 8" is nowhere close to 400mm. 8" is almost exactly 200mm. 400mm is about 15 3/4". I did it the easy way and pulled out the old English/metric tape measure. Makes a really dandy rough calculator.
__________________
Some people are like a Slinky ... not really good for anything, but you still can't help but smile when you shove them down the stairs.
Some people are like a Slinky ... not really good for anything, but you still can't help but smile when you shove them down the stairs.
08-11-11, 04:28 AM
#11
Membership Not Required
Join Date: Jan 2005
Location: On the road-USA
Posts: 16,855
Bikes: Giant Excursion, Raleigh Sports, Raleigh R.S.W. Compact, Motobecane? and about 20 more! OMG
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 70 Post(s)
Likes: 0
Liked 15 Times
in
14 Posts
I might pull a seat post a 1/4"-1/2" past the minimum mark, but no more and I would rather not. Depending on the type of bike, strength/weight of the rider and the frame composition even that small amount could be too much. Get a longer seat post.
Aaron
Aaron
__________________
Webshots is bailing out, if you find any of my posts with corrupt picture files and want to see them corrected please let me know. :(
ISO: A late 1980's Giant Iguana MTB frameset (or complete bike) 23" Red with yellow graphics.
"Cycling should be a way of life, not a hobby.
RIDE, YOU FOOL, RIDE!"_Nicodemus
"Steel: nearly a thousand years of metallurgical development
Aluminum: barely a hundred
Which one would you rather have under your butt at 30mph?"_krazygluon
Webshots is bailing out, if you find any of my posts with corrupt picture files and want to see them corrected please let me know. :(
ISO: A late 1980's Giant Iguana MTB frameset (or complete bike) 23" Red with yellow graphics.
"Cycling should be a way of life, not a hobby.
RIDE, YOU FOOL, RIDE!"_Nicodemus
"Steel: nearly a thousand years of metallurgical development
Aluminum: barely a hundred
Which one would you rather have under your butt at 30mph?"_krazygluon
08-11-11, 11:25 AM
#12
Humvee of bikes =Worksman
Join Date: May 2004
Posts: 5,362
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 10 Post(s)
Likes: 0
Liked 6 Times
in
6 Posts
For safety's sake long seat post should start to lean towards solid bar stock rather than tubing.
I know, I've just been down that road.
Rode out, walked back with a bent seat post.
I know, I've just been down that road.
Rode out, walked back with a bent seat post.
__________________
My preferred bicycle brand is.......WORKSMAN CYCLES
I dislike clipless pedals on any city bike since I feel they are unsafe.
Originally Posted by krazygluon
Steel: nearly a thousand years of metallurgical development
Aluminum: barely a hundred, which one would you rather have under your butt at 30mph?
My preferred bicycle brand is.......WORKSMAN CYCLES
I dislike clipless pedals on any city bike since I feel they are unsafe.
Originally Posted by krazygluon
Steel: nearly a thousand years of metallurgical development
Aluminum: barely a hundred, which one would you rather have under your butt at 30mph?
08-11-11, 11:44 AM
#13
...
Join Date: May 2007
Location: Flagstaff, AZ
Posts: 105
Bikes: 2007 Specialized Globe City 7.1, 2002 Trek 4500 Alpha, 2002 Kona Hahanna
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
I just noticed last week that I've been riding for over two years with my seat post almost an inch beyond the minimum insertion point. Maybe I should think of getting a longer seat tube?
08-11-11, 11:56 AM
#14
Banned
People have broken off the end of the frame's , seat-tube, by riding with the post
up past the max height line..
it needs to extend into the frame past the lower side of the top tube join.
I found a proper diameter 2 bolt Campag seat post,
but it was to be to far extended, when I built my sloping top tube touring frame.
solution was buy a similar OD Kalloy post, have the OD and ID
of the 22.2 end of the post machined , sleeved to fit together,
then welded together, and machined the aluminum bead back down
to the same OD of the rest of the seat post..
2 bolt Campag seat posts and brooks leather 2 rail saddles
are made for each other.
up past the max height line..
it needs to extend into the frame past the lower side of the top tube join.
I found a proper diameter 2 bolt Campag seat post,
but it was to be to far extended, when I built my sloping top tube touring frame.
solution was buy a similar OD Kalloy post, have the OD and ID
of the 22.2 end of the post machined , sleeved to fit together,
then welded together, and machined the aluminum bead back down
to the same OD of the rest of the seat post..
2 bolt Campag seat posts and brooks leather 2 rail saddles
are made for each other.
08-11-11, 12:20 PM
#15
DON'T PANIC!
Join Date: Mar 2010
Location: Capital District, NY
Posts: 497
Bikes: Fuji Absolute 3.0
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Likes: 0
Liked 0 Times
in
0 Posts
A hollow tube will have nearly all of the strength of a solid bar for a fraction of the weight. The fact that you bent one probably has to do with how it was damaged or a manufacturing defect.
08-11-11, 01:05 PM
#16
Banned
The post measures 1.064" (27.0 mm) and extends about 8" out of the frame.
SBS/ Red Line makes them available, 1" OD, a machined shim with the 25.4mm ID
and the proper OD to match the inside diameter of the Frame's seat tube
is available , so the solution to the OP's situation is just a trip to the Bike Shop.
08-11-11, 04:07 PM
#17
Humvee of bikes =Worksman
Join Date: May 2004
Posts: 5,362
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 10 Post(s)
Likes: 0
Liked 6 Times
in
6 Posts
https://physics.stackexchange.com/que...ar-of-same-o-d
A hollow tube will have nearly all of the strength of a solid bar for a fraction of the weight. The fact that you bent one probably has to do with how it was damaged or a manufacturing defect.
A hollow tube will have nearly all of the strength of a solid bar for a fraction of the weight. The fact that you bent one probably has to do with how it was damaged or a manufacturing defect.
That said, tube wall thickness also plays a huge role in tube strength. Most cycle stuff is thin wall tubing so it really isn't all that strong.
I'm a BIG fella so in order to get a safe solid seat post for my Cruiser I went to a solid 7/8" stainless steel bar stock post. It will not bend under my weight.
Sure I know that a bar stock post is sinful heavy but it's a choice....ride safe or ride with a post that might bend or break poking you know where!!
__________________
My preferred bicycle brand is.......WORKSMAN CYCLES
I dislike clipless pedals on any city bike since I feel they are unsafe.
Originally Posted by krazygluon
Steel: nearly a thousand years of metallurgical development
Aluminum: barely a hundred, which one would you rather have under your butt at 30mph?
My preferred bicycle brand is.......WORKSMAN CYCLES
I dislike clipless pedals on any city bike since I feel they are unsafe.
Originally Posted by krazygluon
Steel: nearly a thousand years of metallurgical development
Aluminum: barely a hundred, which one would you rather have under your butt at 30mph?
08-11-11, 08:27 PM
#18
Membership Not Required
Join Date: Jan 2005
Location: On the road-USA
Posts: 16,855
Bikes: Giant Excursion, Raleigh Sports, Raleigh R.S.W. Compact, Motobecane? and about 20 more! OMG
Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 70 Post(s)
Likes: 0
Liked 15 Times
in
14 Posts
I don't worry about the seat post breaking I worry more about the frame on the bike splitting out.
Aaron
Aaron
__________________
Webshots is bailing out, if you find any of my posts with corrupt picture files and want to see them corrected please let me know. :(
ISO: A late 1980's Giant Iguana MTB frameset (or complete bike) 23" Red with yellow graphics.
"Cycling should be a way of life, not a hobby.
RIDE, YOU FOOL, RIDE!"_Nicodemus
"Steel: nearly a thousand years of metallurgical development
Aluminum: barely a hundred
Which one would you rather have under your butt at 30mph?"_krazygluon
Webshots is bailing out, if you find any of my posts with corrupt picture files and want to see them corrected please let me know. :(
ISO: A late 1980's Giant Iguana MTB frameset (or complete bike) 23" Red with yellow graphics.
"Cycling should be a way of life, not a hobby.
RIDE, YOU FOOL, RIDE!"_Nicodemus
"Steel: nearly a thousand years of metallurgical development
Aluminum: barely a hundred
Which one would you rather have under your butt at 30mph?"_krazygluon
