Cycling and bicycle discussion forums. 
   Click here to join our community Log in to access your Control Panel  


Go Back   > >

Classic & Vintage This forum is to discuss the many aspects of classic and vintage bicycles, including musclebikes, lightweights, middleweights, hi-wheelers, bone-shakers, safety bikes and much more.

User Tag List

Reply
 
Thread Tools Search this Thread
Old 11-16-11, 11:22 PM   #1
RoboIsGod
Senior Member
Thread Starter
 
RoboIsGod's Avatar
 
Join Date: Apr 2009
Location: Boston
Bikes: 2013 Fuji Altamira 1.0//2006 CAAD8
Posts: 769
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Can someone explain to me zero set-back seatposts?

When are these appropriate? Isn't set-back necessary to properly fit a bike (as in putting your body in the right position over the cranks)? Would these only be appropriate in instances where the geometry of a bike (or size) necessitates the rider to be farther forward? Or do some people just like being more forward?

You always explain things the best C+V, do your magic!
RoboIsGod is offline   Reply With Quote
Old 11-16-11, 11:28 PM   #2
Velognome 
Get off my lawn!
 
Velognome's Avatar
 
Join Date: Nov 2010
Location: The Garden State
Bikes: 1917 Loomis, 1923 Rudge, 1930 Hercules Renown, 1947 Mclean, 1948 JA Holland, 1955 Hetchins, 1957 Carlton Flyer, 1962 Raleigh Sport, 1978&81 Raleigh Gomp GS', 2010 Raliegh Clubman
Posts: 6,128
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 20 Post(s)
For myself, on a frame with slightly relaxed geometry, a zero set back seems to put me in a more responsive positon.
Velognome is offline   Reply With Quote
Old 11-16-11, 11:47 PM   #3
thirdgenbird
Senior Member
 
Join Date: Nov 2009
Bikes:
Posts: 7,108
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
you can use them to get a more aggressive position when converting a road frame to tri/tt use.

if you want to go more aggressive, profile did, or does, makes a psot they call the "fast forward":
thirdgenbird is offline   Reply With Quote
Old 11-17-11, 12:02 AM   #4
thirdgenbird
Senior Member
 
Join Date: Nov 2009
Bikes:
Posts: 7,108
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
more research shows that profile has updated the looks of the above seatpost. the intention is to effectively change a seat tube from 73 degrees to 78 degrees.

i know it is not what you asked, but it may provide some insight.
thirdgenbird is offline   Reply With Quote
Old 11-17-11, 12:06 AM   #5
DRietz
Senior Member
 
Join Date: Oct 2009
Bikes:
Posts: 2,699
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
For a proper fit.

Seat and head tube angle are the same at 73.5degrees.

Using a setback seatpost of the Moots variety puts you 15degrees back. Using a straight post puts you zero degrees back. In order for my knees to be in their most efficient position, my seat is positioned rather forward on a zero setback post:


Last edited by DRietz; 11-17-11 at 12:18 AM.
DRietz is offline   Reply With Quote
Old 11-17-11, 12:23 AM   #6
rothenfield1
Senior Member
 
rothenfield1's Avatar
 
Join Date: Jun 2009
Location: Montereyish
Bikes:
Posts: 2,330
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
That’s a good question. Where one positions the saddle is completely up to the rider’s preference obviously. I think the optimum riding position puts the rider’s weight equally distributed between the wheels, and this would depend on your riding style. If you have a more upright riding position, then you would have your saddle slightly forward to bring your upper body’s weight more towards the center than someone who rides with their upper body stretched out and leaning forward.

I think that the reason that there are setback seat posts to begin with probably is more of a manufacturing decision that came about when the standard went from a straight seatpost stuck up into the saddle clamp versus the seatpost/clamp style that we are used to today. There had to be a flat place to mount the clamp, so they bent the tube backwards.

The only rationale for a “zero setback” seatpost today IMHO is to use on bikes that are slightly too long in the TT for the rider, or for very aggressive riders who want to get their weight as forward as possible. I ride one on my MTB because I want my weight very forward for aggressive uphill riding. It does seem to make a difference.

Last edited by rothenfield1; 11-17-11 at 12:26 AM.
rothenfield1 is offline   Reply With Quote
Old 11-17-11, 12:27 AM   #7
DRietz
Senior Member
 
Join Date: Oct 2009
Bikes:
Posts: 2,699
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by rothenfield1 View Post
The only rational for a “zero setback” seatpost today is to use on bikes that are slightly too long for the rider or for very aggressive riders who want to get their weight as forward as possible. I ride one on my MTB. It does seem to make a difference.
I kind of adhere to the rule of KOPS (knee over pedal spindle), which some may disagree with, etc. But, since I have a shorter femur and torso, in order to obtain this KOPS, I need to be a bit further forward.

Fit isn't set in stone - I just go with the advice of those I trust.
DRietz is offline   Reply With Quote
Old 11-17-11, 01:52 AM   #8
pat5319
Senior Member
 
pat5319's Avatar
 
Join Date: Sep 2000
Location: Spokane WA
Bikes: Seven Axiom Ti, Trek 620, Masi cylocross (steel). Masi Souleville 8spd, Fat Chance Mtn (steel), Scwinn Triple Bar cruiser, Mazi Speciale Fix/single, Scwinn Typhonn
Posts: 1,141
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
ZERO IS FOR PEOPLE WITH SHORT THIGHS AND TRI-ath....
pat5319 is offline   Reply With Quote
Old 11-17-11, 02:16 AM   #9
THEJAPINO
Noob
 
Join Date: Nov 2009
Location: Bay Area
Bikes: 80's Vitus 979, '86 Schwinn Paramount
Posts: 355
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
While looking at a bunch of saddles, both older and modern, I noticed that the rail's range of adjustment isn't always in the same place. An example would be a couple of Selle Italia's I recovered. The older Turbo had it's rails towards the back of the saddle whereas the SLR had it's rails directly in the middle of the saddle. I'm not saying that saddles were the reason for today's trend of zero setback post, it's just something I've noticed.

So what came first, the mid-railed saddle or the zero setback seatpost?
THEJAPINO is offline   Reply With Quote
Old 11-17-11, 04:56 AM   #10
Henry III 
is just a real cool dude
 
Henry III's Avatar
 
Join Date: Aug 2010
Location: The Thumb, MI
Bikes:
Posts: 3,093
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 10 Post(s)
Depends on the how the fitting goes on the given frame I thought. If you can't get enough setback or have too much then that would deem a laidback or zero offset required. You could also use that use it in design. Say if you had a seatpost already chosen then the seattube angle would be adjusted to suit the amount of setback given. It all depends on the KOPS method of sizing(if you believe in that method). Plus if your building a frame or working with a given frame and working off of those angles trying to make work for you. I already had the post(zero setback) and saddle when designing the my frame(plus it's what Doug Fattic asked to bring to frame building class).
Henry III is offline   Reply With Quote
Old 11-17-11, 08:54 AM   #11
T-Mar
Senior Member
 
Join Date: Nov 2004
Bikes:
Posts: 12,127
Mentioned: 44 Post(s)
Tagged: 0 Thread(s)
Quoted: 236 Post(s)
I've always been of the impression that zero-setback seatposts were created by the ATB fraternity for two reasons. First, it allowed for a much lighter post without sacrificing strength and reliability. Secondly, ATB geometry was usually more relaxed than the road and used longer cranks, making it difficult to duplicate a road position, which many ATB riders wanted.

After that, it got adopted by the triathlon/TT crowd as it allowed the forward saddle position necessary to maintain the angle between the torso and thigh when in an extreme aero position.

Of course, lighter components to a roadie are like diamonds to a wife, so they started using them and saddle manufacturers started evolving saddle rail dimensions to accommodate the new designs.
T-Mar is offline   Reply With Quote
Old 11-17-11, 09:03 AM   #12
Italuminium
Cisalpinist
 
Italuminium's Avatar
 
Join Date: Jan 2011
Location: Holland
Bikes: blue ones.
Posts: 5,557
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by T-Mar View Post
Of course, lighter components to a roadie are like diamonds to a wife, so they started using them and saddle manufacturers started evolving saddle rail dimensions to accommodate the new designs.
true, true, true. I run a 150 gram post on my modern roadie, and it turns out it is way more comfortable than the old setback one (while being a full 100 g heavier!)
Italuminium is offline   Reply With Quote
Old 11-17-11, 09:03 AM   #13
repechage
Senior Member
 
Join Date: Jun 2006
Bikes:
Posts: 10,957
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 100 Post(s)
Quote:
Originally Posted by THEJAPINO View Post
...

So what came first, the mid-railed saddle or the zero setback seatpost?
Saddles changed first.
repechage is offline   Reply With Quote
Old 11-17-11, 09:49 AM   #14
norskagent
car dodger
 
norskagent's Avatar
 
Join Date: Aug 2005
Location: garner/raleigh nc
Bikes:
Posts: 3,365
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
On longer rides on my paramount (55cm) I noticed I was occasionally shifting my weight back slightly, so I adjusted my saddle forward. Eventually my saddle ended up all the way forward, and the weight shifting issue was solved. Then I switched to a non setback seatpost and set the saddle in the "mid" position, which was the same as the former "forward" position. My other bikes are ~53 or 54cm and I use setback seatposts on those.
__________________
1989 Schwinn Paramount OS
1980 Mclean/Silk Hope Sport Touring
1983 Bianchi pista
1976 Fuji Feather track
1979 raleigh track
"I've consulted my sources and I'm pretty sure your derailleur does not exist"
norskagent is offline   Reply With Quote
Old 11-17-11, 10:33 AM   #15
Mr IGH
afraid of whales
 
Mr IGH's Avatar
 
Join Date: Apr 2009
Location: Front Range, CO
Bikes:
Posts: 3,707
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 76 Post(s)
seat tube angle is important to note

For the same rider on frames with different seat tube angles the placement of a given saddle on a given seatpost (with fixed seatback) will be different. Each degree change of seat tube angle effects the correct seat position by ~1cm.

A frame with 72* seat tube and 600mm top tube will have ~1cm more seat forward in the seatpost vs a frame with 73* seat tube and 590cm top tube. (If the rider wants to have the same position on both bikes.)

Do the trig and you'll see what I mean. This is why "stack" and "reach" are important measurements, they take seat tube angle into account, not just top tube length.
Mr IGH is offline   Reply With Quote
Old 11-17-11, 10:50 AM   #16
eippo1 
I like beans
 
eippo1's Avatar
 
Join Date: Feb 2007
Location: Meffa, MA
Bikes: Tarmac Pro, Bianchi Zurigo, Raleigh Gran Sport, Fuji Del Rey, Ironman Centurion
Posts: 3,353
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
I usually need a zero setback seatpost due to the fact that I like bikes with a 56.5 top tube, a 100 mm stem and a huge amount of saddle to bar drop. If I didn't have the ability to slide myself forward with that amount of drop, then I'd be putting a lot of stress on my knees because the angle would be all wrong. Here's a pic of my drop.
__________________
You got it buddy: the large print giveth, and the small print taketh away

2009 Dean El Diente Superlite
2011 Bianchi Zurigo CX
2005 Specialized Sworks E5 "Calamity"
2007 Fuji Thrill LT1.0
199? Tommasini ? (pending build)
2001 Della Santa
eippo1 is offline   Reply With Quote
Old 11-17-11, 11:04 AM   #17
clubman 
Youngman Grande
 
clubman's Avatar
 
Join Date: Jan 2010
Location: Nova Scotia
Bikes: roadsters, club bikes, fixed and classic
Posts: 3,107
Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 61 Post(s)
Quote:
Originally Posted by pat5319 View Post
ZERO IS FOR PEOPLE WITH SHORT THIGHS AND TRI-ath....
truth.
clubman is offline   Reply With Quote
Old 11-17-11, 11:04 AM   #18
Mr IGH
afraid of whales
 
Mr IGH's Avatar
 
Join Date: Apr 2009
Location: Front Range, CO
Bikes:
Posts: 3,707
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 76 Post(s)
Quote:
Originally Posted by eippo1 View Post
I usually need a zero setback seatpost due to the fact that I like bikes with a 56.5 top tube, a 100 mm stem and a huge amount of saddle to bar drop. If I didn't have the ability to slide myself forward with that amount of drop, then I'd be putting a lot of stress on my knees because the angle would be all wrong.
Yes, but if that frame had everything the same except the seat angle was shifted from 73* to 74*, then the top tube would be ~1cm shorter and you'd need to slide the seat back by ~1cm for the same position relative to the pedals.

Last edited by Mr IGH; 11-17-11 at 11:13 AM.
Mr IGH is offline   Reply With Quote
Old 11-17-11, 11:13 AM   #19
753proguy
Senior Member
 
Join Date: Feb 2008
Bikes:
Posts: 1,092
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by THEJAPINO View Post
While looking at a bunch of saddles, both older and modern, I noticed that the rail's range of adjustment isn't always in the same place. An example would be a couple of Selle Italia's I recovered. The older Turbo had it's rails towards the back of the saddle whereas the SLR had it's rails directly in the middle of the saddle. I'm not saying that saddles were the reason for today's trend of zero setback post, it's just something I've noticed.

So what came first, the mid-railed saddle or the zero setback seatpost?
It's a factor. A lot of people look for a high-setback post to use with a Brooks saddle, for example.

I just used a zero-setback post for the first time ever, recently, on a bike for my wife. I used it get the cockpit more equivalent to what she likes. The STA on this (road, we don't do the ATB thing) frame was about 72 degrees, whereas she usually rides more like a 74, so the no-setback post moved the saddle's adjustment range to where I could better replicate her desired cockpit dimensions....
753proguy is offline   Reply With Quote
Old 11-17-11, 11:14 AM   #20
753proguy
Senior Member
 
Join Date: Feb 2008
Bikes:
Posts: 1,092
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by T-Mar View Post
I've always been of the impression that zero-setback seatposts were created by the ATB fraternity for two reasons. First, it allowed for a much lighter post without sacrificing strength and reliability. Secondly, ATB geometry was usually more relaxed than the road and used longer cranks, making it difficult to duplicate a road position, which many ATB riders wanted.

After that, it got adopted by the triathlon/TT crowd as it allowed the forward saddle position necessary to maintain the angle between the torso and thigh when in an extreme aero position.

Of course, lighter components to a roadie are like diamonds to a wife, so they started using them and saddle manufacturers started evolving saddle rail dimensions to accommodate the new designs.
I would vote for this scenario.....
753proguy is offline   Reply With Quote
Old 11-17-11, 11:45 AM   #21
eippo1 
I like beans
 
eippo1's Avatar
 
Join Date: Feb 2007
Location: Meffa, MA
Bikes: Tarmac Pro, Bianchi Zurigo, Raleigh Gran Sport, Fuji Del Rey, Ironman Centurion
Posts: 3,353
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Quote:
Originally Posted by Mr IGH View Post
Yes, but if that frame had everything the same except the seat angle was shifted from 73* to 74*, then the top tube would be ~1cm shorter and you'd need to slide the seat back by ~1cm for the same position relative to the pedals.
True, I never needed a zero setback post on my Bianchi because the seat tube angle was different, exactly as you mention. Plus I didn't ride such an aggressive position when I was younger.
__________________
You got it buddy: the large print giveth, and the small print taketh away

2009 Dean El Diente Superlite
2011 Bianchi Zurigo CX
2005 Specialized Sworks E5 "Calamity"
2007 Fuji Thrill LT1.0
199? Tommasini ? (pending build)
2001 Della Santa
eippo1 is offline   Reply With Quote
Old 05-03-13, 10:05 PM   #22
rykebider
Newbie
 
Join Date: May 2013
Bikes:
Posts: 3
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
One situation that calls for zero offset would be Townie Electra. It's an elongated frame sold as "patented flat foot technology." Well, any moron with a tape measure and 12 month subscription to a popular bicycling magazine can figure out you can't move the cranks forward 7 inches, put the seat low enough to place heals flat on the road and still have full extension of the legs. Take that tape measure from the spindle to the seat of a properly adjusted bike, start drawing an arch backwards and you'll see just how far back the seat needs to be to place the feet flat on the ground without reducing seat-to-pedal distance. And one need not know big words like patellofemoral pain or chondromalacia patellea to know a seat set too low can cause chronic knee pain and potentially permanent injury -- especially for an old guy like me.

So why would anyone buy a Townie Electra in the first place? Never mind that. I have other bikes. The long wheel base is way cool, but the seat on Townie's stock geometry is too far back. Not only did Electra ignore the impact of seat-to-pedal distance, they set up some of their bikes with low-rise handlebars even though the top tube is a full seven inches longer than a comparable cruiser bike. No problem. They make several sizes of handlebars, including 8-inch and 10-inch risers. With those, the seat-to-handlebar length can be corrected for a decent upright posture, albeit not so low one can stay in the seat and put feet flat on the ground. Once I tried some "monkey bars" and 8 inch-rise cruiser bars that let me reach the handlebars with the seat further back, I moved the seat back, and lower. It felt comfy to ride -- especially on paved downhill switchbacks -- but let's just say I'm hoping my knees recover.

Problem was, it's nearly impossible to stay positioned back in the seat like that during a long ride. Some hotshot on a road bike is going to try to pass and I'll move forward to sprint and keep up. I'll try to climb a hill and slip forward into a more aggressive posture. So I moved the seat forward to where I'd started -- all the way forward in a typical offset seat post -- but there's still that crazy "crank forward" stuff. It's not far enough forward to make it a recumbent, or even a Rans-style semi-recumbent real flat foot bike - no matter what their U.S. patent or threatening enforcement letters to Giant and Raliegh -- who toyed with long-wheel base bikes until suddenly Electra was the only one still the game -- might have said.

And a little "Crank forward" ain't such a bad thing. Just like a no-offset seatpost can provide a more aggressive posture on a typical diamond frame, a longer wheelbase and more relaxed seat-to-bottom-bracket angle can provide a more casual posture. But not that much - not 7 inches back like the Townie out of the box. So to reduce that extreme rearward position resulting from an extra 7 inches between the BB and the seat-tube/chain-stay joint -- you guessed it -- a no offset seatpost closes the distance. Of course, I could use a steel tube seat post and an ugly three-peice clamp turned backwards, but get real - the idea is to have a comfy bike and a good looking ride. The no offset post lets a rider move the weight forward, for a more realistic front-back weight distribution, have a long wheel base for cruising, and look way cool (*Kids along the trail say, "His bike is like a motorcycle, mommy")
rykebider is offline   Reply With Quote
Old 05-04-13, 02:04 AM   #23
Tulok
Senior Member
 
Tulok's Avatar
 
Join Date: May 2009
Location: Logan, UT
Bikes:
Posts: 288
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
In ohter words, For each rider's individual comfort.
now i'm going to have to look up an electra townie...
Tulok is offline   Reply With Quote
Old 05-04-13, 03:03 AM   #24
bradtx
Senior Member
 
Join Date: Jun 2010
Location: Pearland, Texas
Bikes: Cannondale, Trek, Raleigh, Santana
Posts: 6,698
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 58 Post(s)
Same saddle, different bikes

Quote:
Originally Posted by RoboIsGod View Post
When are these appropriate? Isn't set-back necessary to properly fit a bike (as in putting your body in the right position over the cranks)? Would these only be appropriate in instances where the geometry of a bike (or size) necessitates the rider to be farther forward? Or do some people just like being more forward?
If the seat rails were any shorter than what they are I'd have had to go zero setback when the saddle was moved from my crit bike to my touring bike due to the tourer's more relaxed seat tube geometry. For the recreational cyclist the major reason is fitment. For the competitive time trial/tri cyclist it provides the ability to be more 'on top' of their pedals without having to sit primarily on the saddle's nose.

Brad

Last edited by bradtx; 05-04-13 at 03:04 AM. Reason: corr
bradtx is offline   Reply With Quote
Old 05-04-13, 08:21 AM   #25
easyupbug 
Senior Member
 
Join Date: Jan 2013
Bikes: too many sparkly Italians, some sweet Americans and a couple interesting Japanese
Posts: 518
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 13 Post(s)
Quote:
Originally Posted by Mr IGH View Post

Do the trig and you'll see what I mean. This is why "stack" and "reach" are important measurements, they take seat tube angle into account, not just top tube length.
Please can someone explain how ST angle plays into stack and reach. Seems to me one could, if they wanted, vary the seat tube angle without the location of the top center of the head tube relative to the BB changing an at all.
easyupbug is offline   Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off



All times are GMT -6. The time now is 05:16 PM.