Seat Angle Question??

An anynymous poster wrote:

A shallow head tube angle will move the front wheel forward to mitigate
toe overlap, but the seat tube angle doesn't matter. The bottom bracket
is still in the same place if the seat tube angle was 72 deg. or 76
deg. A steep sat tube angle will move the riders arse and knee further
forward, but their feet down on the pedals don't move forward at all.

Depends how you look at it. If you keep the top tube length constant, a
steeper seat tube angle will move the bottom bracket back with respect
to the front wheel, the handlebars and the rider's butt.

Sheldon "Relativity" Brown
+-----------------------------------------------+
| Who has deceived thee as often as thyself? |
| -- Benjamin Franklin |
+-----------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

Sure, but when you fit someone up, don't you get their saddle, knee,
KOPS stuff delt with first, then move forward and work on tt lenght?

It's a strange concept, we're presuming tt has to be constant yet we're
ok with changing the seat tube angle. My feeling is one really can't be
tinkered with too much before the other has to be adjusted also.

I definetly don't envy shorter riders, as their bikes always seem to
have a compromise somewhere, but I also think way to much is made of
toe overlap. I once had a 58cm Italian frame with overlap, and although
it was a very quick handeling bike, the overlap was never an issue.
--Jim

Sure, but when you fit someone up, don't you get their saddle, knee,
KOPS stuff delt with first, then move forward and work on tt lenght?

It's a strange concept, we're presuming tt has to be constant yet we're
ok with changing the seat tube angle. My feeling is one really can't be
tinkered with too much before the other has to be adjusted also.

I definetly don't envy shorter riders, as their bikes always seem to
have a compromise somewhere, but I also think way to much is made of
toe overlap. I once had a 58cm Italian frame with overlap, and although
it was a very quick handeling bike, the overlap was never an issue.
--Jim

Anynymous? Anonymous. No I ain't, I signed it "Jim" What else you need,
my ssn?

"Jim" wrote:

Anynymous? Anonymous. No I ain't, I signed it "Jim" What else you need,
my ssn?

We have three "Jims" here at Harris Cyclery. Are you Jim Ammirato, Jim
DaSilva, or Jim Wirtanen? Or perhaps a different Jim altogether...?

Sheldon "Mystery" Brown
+------------------------------------------------+
| Too often we... enjoy the comfort of opinion |
| without the discomfort of thought. |
| -- John F. Kennedy |
+------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

On Tue, 25 Jan 2005 14:02:58 -0500, Sheldon Brown
wrote:

"Jim" wrote:

Anynymous? Anonymous. No I ain't, I signed it "Jim" What else you need,
my ssn?

We have three "Jims" here at Harris Cyclery. Are you Jim Ammirato, Jim
DaSilva, or Jim Wirtanen? Or perhaps a different Jim altogether...?

Sheldon "Mystery" Brown
+------------------------------------------------+
| Too often we... enjoy the comfort of opinion |
| without the discomfort of thought. |
| -- John F. Kennedy |
+------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

Dear Sheldon,

Mysteriously, there seem to be no Daves in your wanted
posters, despite their teeming numbers here on
rec.bicycles.tech:

http://sheldonbrown.com/harris/index.html#articles

Does Harris Cyclery discriminate on a first-name basis?

The closest Shakespeare came to a Dave is a trivial servant
named Davy in the second part of Henry IV.

Carl Fogel

Sheldon Brown wrote:
"Jim" wrote:

Anynymous? Anonymous. No I ain't, I signed it "Jim" What else you
need,
my ssn?

We have three "Jims" here at Harris Cyclery. Are you Jim Ammirato,
Jim
DaSilva, or Jim Wirtanen? Or perhaps a different Jim altogether...?
A different Jim altogrther is correct.

Jim "Jim" Potter

Carl Fogel wrote:
Dear Sheldon,

Mysteriously, there seem to be no Daves in your wanted
posters, despite their teeming numbers here on
rec.bicycles.tech:

"Dave's not here!"

Sheldon "C&C" Brown
+--------------------------------------------------+
| Some of my brother's paintings may be seen at: |
| http://junila.com |
+--------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com

ander- Smaller riders have shorter femurs and shorter lower legs = same
femur/lower leg ratio as larger riders = same optimum seat angle - KOPS
or not. BRBR

Ya can argue this but if you believe KOPS is a place to start, not a hard
constant(as most do, including the likes of DR Andy Pruitt), it is unlikely
that a short person can get his KOPS with a 72 degree seattube angle even with
a no set back seatpost.

ander- Steeper seat angles on smaller frame sizes has to do with what Sheldon

says. It's a precaution against toe-overlap and not based on fit and
position. BRBR

Sorry, don't see how not do I agree.
Take a look at:
http://bikefitting.com/English/Theory/SeatAngle.aspx

Hope you understand. English is not my first language. BRBR


Theory is right....

Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"