A Cycling & bikes forum. CycleBanter.com

Go Back   Home » CycleBanter.com forum » rec.bicycles » Techniques
Site Map Home Register Authors List Search Today's Posts Mark Forums Read Web Partners

Thoughts about head tube



 
 
Thread Tools Display Modes
  #1  
Old October 1st 06, 01:26 AM posted to rec.bicycles.tech
William O'Hara
external usenet poster
 
Posts: 89
Default Thoughts about head tube

I'm trying to figure this out. Is a taller head tube going
to produce better handling(combined with less rake on fork)?
I really liked the front end of my former Specialized Allez.
It seems from websites that many bikes have a short headtube.
The Allez went much better than my old motobecane in handling.
Why are so many designs of popular lines running with shortish
head tubes?

I gotta have an answer to this question. I know that a shorter
wheelbase and short chainstays are supposed to help on ascents.
Some bikes practically have the downtube joint right next to the
toptube joint. Plus, not all websites mention actual numbers for
this item. A fuji bike seems rather typical(plus the LBS has
perceived these as a good value on componentry pricing). The
head tube length is 189 mm. My old allez was in the 230 mm area.
I think this quite a different. An inch and half to me is a huge,
but I suppose others would disagree.

The Fujis from the ads appears to have very little angle in the
stem too.

Another question in my ramblings pertains to the length of the
stem. I am assuming that closest to the head tube equals more
control. Isn't this correct?

--
---
William O'Hara
www.N1ey.com - Amateur Radio and Railfan Blog
www.yahoogroups.com/group/illinoiscentral - premier discussion list
ICRR
Ads
  #2  
Old October 1st 06, 04:25 PM posted to rec.bicycles.tech
Mark Hickey
external usenet poster
 
Posts: 1,083
Default Thoughts about head tube

"William O'Hara" wrote:

I'm trying to figure this out. Is a taller head tube going
to produce better handling(combined with less rake on fork)?
I really liked the front end of my former Specialized Allez.
It seems from websites that many bikes have a short headtube.
The Allez went much better than my old motobecane in handling.
Why are so many designs of popular lines running with shortish
head tubes?

I gotta have an answer to this question. I know that a shorter
wheelbase and short chainstays are supposed to help on ascents.
Some bikes practically have the downtube joint right next to the
toptube joint. Plus, not all websites mention actual numbers for
this item. A fuji bike seems rather typical(plus the LBS has
perceived these as a good value on componentry pricing). The
head tube length is 189 mm. My old allez was in the 230 mm area.
I think this quite a different. An inch and half to me is a huge,
but I suppose others would disagree.

The Fujis from the ads appears to have very little angle in the
stem too.

Another question in my ramblings pertains to the length of the
stem. I am assuming that closest to the head tube equals more
control. Isn't this correct?


It's a non-issue. You have to start from the assumption that the bars
have to end up in the same position, no matter what the length of the
head tube.

Say you have two otherwise identical frame, one with a 12cm head tube
and one with a 13cm head tube. You set up the latter with a 12cm stem
and 1cm of spacers for the proper fit. To put the bars in the same
position on the former, you'd simply use another cm of spacers, and
the stem (and bars) would end up in precisely the same position.
Hence, there's no effect on handling one way or the other.

Other than that, the question becomes "does moving the bars up a
couple inches change the handling", and the short answer is "yes".

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame

  #3  
Old October 1st 06, 04:56 PM posted to rec.bicycles.tech
jim beam
external usenet poster
 
Posts: 5,758
Default Thoughts about head tube

William O'Hara wrote:
I'm trying to figure this out. Is a taller head tube going
to produce better handling(combined with less rake on fork)?


if you mean "softer", yes. if you mean immediacy of response, no.
longer tubes, anywhere on the bike, make for a more springy frame.
obviously, you won't notice much between frames that only have a few mm
difference between the top and down tube spacings on the head tube [the
dimension that matters], but that's how the engineering principle works.

I really liked the front end of my former Specialized Allez.
It seems from websites that many bikes have a short headtube.
The Allez went much better than my old motobecane in handling.
Why are so many designs of popular lines running with shortish
head tubes?


see above. for aluminum frames, it makes for better fatigue properties too.


I gotta have an answer to this question. I know that a shorter
wheelbase and short chainstays are supposed to help on ascents.
Some bikes practically have the downtube joint right next to the
toptube joint. Plus, not all websites mention actual numbers for
this item. A fuji bike seems rather typical(plus the LBS has
perceived these as a good value on componentry pricing). The
head tube length is 189 mm. My old allez was in the 230 mm area.
I think this quite a different. An inch and half to me is a huge,
but I suppose others would disagree.

The Fujis from the ads appears to have very little angle in the
stem too.

Another question in my ramblings pertains to the length of the
stem. I am assuming that closest to the head tube equals more
control. Isn't this correct?



  #4  
Old October 1st 06, 09:12 PM posted to rec.bicycles.tech
William O'Hara
external usenet poster
 
Posts: 89
Default Thoughts about head tube

Say you have two otherwise identical frame, one with a 12cm head tube
and one with a 13cm head tube. You set up the latter with a 12cm stem
and 1cm of spacers for the proper fit. To put the bars in the same
position on the former, you'd simply use another cm of spacers, and
the stem (and bars) would end up in precisely the same position.
Hence, there's no effect on handling one way or the other.

Other than that, the question becomes "does moving the bars up a
couple inches change the handling", and the short answer is "yes".


What about ride quality?

--
---
William O'Hara
www.N1ey.com - Amateur Radio and Railfan Blog
www.yahoogroups.com/group/illinoiscentral - premier discussion list
ICRR
  #5  
Old October 1st 06, 09:13 PM posted to rec.bicycles.tech
William O'Hara
external usenet poster
 
Posts: 89
Default Thoughts about head tube

jim beam wrote in
t:

William O'Hara wrote:
I'm trying to figure this out. Is a taller head tube going
to produce better handling(combined with less rake on fork)?


if you mean "softer", yes. if you mean immediacy of response, no.
longer tubes, anywhere on the bike, make for a more springy frame.
obviously, you won't notice much between frames that only have a few
mm difference between the top and down tube spacings on the head tube
[the dimension that matters], but that's how the engineering principle
works.


If this is case, then why don't more bikes go in this direction?
Isn't this desired with the "comfort performance roadbikes?"


--
---
William O'Hara
www.N1ey.com - Amateur Radio and Railfan Blog
www.yahoogroups.com/group/illinoiscentral - premier discussion list ICRR
  #6  
Old October 1st 06, 09:24 PM posted to rec.bicycles.tech
William O'Hara
external usenet poster
 
Posts: 89
Default Thoughts about head tube

Other than that, the question becomes "does moving the bars up a
couple inches change the handling", and the short answer is "yes".

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame


I see there is a difference between your "team frame" and the
regular road frame. You used a different downtube and you have
the musucular chain stays. Why the design differences? The regular
road looks pretty good to me. I'm actually thinking that perhaps
I should get the 62 or 64 for a new bike.

--
---
William O'Hara
www.N1ey.com - Amateur Radio and Railfan Blog
www.yahoogroups.com/group/illinoiscentral - premier discussion list
ICRR
  #7  
Old October 2nd 06, 03:10 AM posted to rec.bicycles.tech
jim beam
external usenet poster
 
Posts: 5,758
Default Thoughts about head tube

William O'Hara wrote:
jim beam wrote in
t:

William O'Hara wrote:
I'm trying to figure this out. Is a taller head tube going
to produce better handling(combined with less rake on fork)?

if you mean "softer", yes. if you mean immediacy of response, no.
longer tubes, anywhere on the bike, make for a more springy frame.
obviously, you won't notice much between frames that only have a few
mm difference between the top and down tube spacings on the head tube
[the dimension that matters], but that's how the engineering principle
works.


If this is case, then why don't more bikes go in this direction?
Isn't this desired with the "comfort performance roadbikes?"


you mean longer head tubes? because if the frame designed knows their
business, they'll know the head tube [and attendant jointing] is highly
stressed and therefore subject to substantial flex and fatigue. longer
head tubes exacerbate the problem.
  #8  
Old October 2nd 06, 02:30 PM posted to rec.bicycles.tech
Mark Hickey
external usenet poster
 
Posts: 1,083
Default Thoughts about head tube

"William O'Hara" wrote:

Say you have two otherwise identical frame, one with a 12cm head tube
and one with a 13cm head tube. You set up the latter with a 12cm stem
and 1cm of spacers for the proper fit. To put the bars in the same
position on the former, you'd simply use another cm of spacers, and
the stem (and bars) would end up in precisely the same position.
Hence, there's no effect on handling one way or the other.

Other than that, the question becomes "does moving the bars up a
couple inches change the handling", and the short answer is "yes".


What about ride quality?


Depends on whether it makes the bike fit better or not. It's
impossible to say otherwise, since it's an independent variable.

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame
  #9  
Old October 2nd 06, 02:31 PM posted to rec.bicycles.tech
Mark Hickey
external usenet poster
 
Posts: 1,083
Default Thoughts about head tube

"William O'Hara" wrote:

Other than that, the question becomes "does moving the bars up a
couple inches change the handling", and the short answer is "yes".


I see there is a difference between your "team frame" and the
regular road frame. You used a different downtube and you have
the musucular chain stays. Why the design differences? The regular
road looks pretty good to me. I'm actually thinking that perhaps
I should get the 62 or 64 for a new bike.


The differences are the S-stays and the oversize oval down tube. That
provides a bit more BB stiffness and better heel-to-stay clearance
(which isn't an issue for most riders). There won't be any difference
in "ride quality" however.

Mark Hickey
Habanero Cycles
http://www.habcycles.com
Home of the $795 ti frame
  #10  
Old October 3rd 06, 12:38 AM posted to rec.bicycles.tech
Phil Holman
external usenet poster
 
Posts: 478
Default Thoughts about head tube


"jim beam" wrote in message
t...
William O'Hara wrote:
jim beam wrote in
t:
William O'Hara wrote:
I'm trying to figure this out. Is a taller head tube going
to produce better handling(combined with less rake on fork)?
if you mean "softer", yes. if you mean immediacy of response, no.
longer tubes, anywhere on the bike, make for a more springy frame.
obviously, you won't notice much between frames that only have a few
mm difference between the top and down tube spacings on the head
tube
[the dimension that matters], but that's how the engineering
principle
works.


If this is case, then why don't more bikes go in this direction?
Isn't this desired with the "comfort performance roadbikes?"


you mean longer head tubes? because if the frame designed knows their
business, they'll know the head tube [and attendant jointing] is
highly stressed and therefore subject to substantial flex and fatigue.
longer head tubes exacerbate the problem.


I'm not so sure. A longer head tube is torsionally softer and will allow
more out of plane/lateral deflection of the frame elements but I don't
see how this translates to higher stresses/fatigue. It does however
result in a poorer handling frame when cornering.

Phil H


 




Thread Tools
Display Modes

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

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Kona Coiler 04 head tube broken Fabio Mountain Biking 3 June 26th 06 06:58 PM
FS: NOS Colnagos and never ridden 50th Anniversary Schwinn Paramount Frank Marketplace 0 January 6th 05 07:45 AM
Bicycle helmets help prevent serious head injury among children, part one. John Doe UK 3 November 30th 04 04:46 PM
Does public health care pay for your head injuries? John Doe UK 187 November 30th 04 03:51 PM
Threaded versus threadless headset Hjalmar Duklęt General 64 August 29th 03 06:55 PM


All times are GMT +1. The time now is 05:51 AM.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Copyright ©2004-2024 CycleBanter.com.
The comments are property of their posters.