Fixed gear/track frame geometry

I'm starting to research buying a new bike to indulge my newfound
fixed gear addiction. (My existing fixie is my '88 Miyata road bike
with tri geometry, a way too short top tube, worn out drivetrain parts
and a hack of a fixie hub - epoxied freewheel. It'll cost enough
money to get the fit and parts right that I'd rather start new).
Price isn't an issue.

I assumed I'd want a frame with similar geometry to my road bikes,
73/73. I notice that the Cannondale and Fuji track bikes have 74.5
head tube and 73 or 72.5 seat tube angles. Why so steep head tube
angles? Is that preferred for actual velodrome riding for some
reason, perhaps sprinting? The top tubes are still longish, 57cm for
the 56 cm Cannondale frame.

Any suggestions on frame size (I ride 57 and 58 cm road bikes now) -
any reason to step down in frame size like you do on a cyclocross
frame?

BTW, my favorite bike is my aluminum Cannondale road bike with
Spinergy Spox wheels - I love the stiff frame, and the composite
spokes dampen the road shock. My ideal new fixie would be a regular
new Cannondale road frame with Spox wheels with the freehub replaced
with the Surly cassette hub converter, except that the regular road
frames have vertical dropouts. I'd consider the road frame with the
White eccentric hub to solve the dropout problem, but seems like at
that point I might as well get the track frame. That brings me back
to the geometry issue I asked about above....

Thanks,
Michael

Michael Press writes:

I notice that the Cannondale and Fuji track bikes have 74.5 head
tube and 73 or 72.5 seat tube angles. Why so steep head tube
angles? Is that preferred for actual velodrome riding for some
reason, perhaps sprinting?

Track racers really don't turn the bars- riding on a steeply banked
velodrome, you basically keep riding in a straight line all the way
around the track. Track bikes tend to have steep head tubes and seat
tubes (75/75 is not all that unusual in a track bike) and very little
fork offset (sometimes called rake), giving them a fairly large trail.
My track bike is exceptionally easy to ride no-handed as a result.

The position on a track bike is not really intended for comfort, as
few events last longer than a few minutes- a 50 or 75 lap points race
being about as long as track events get which is under 20 km and will
last at most about 20-25 minutes. At least until you get to 6 day
events and such, but it's not likely that any of us will be doing
that.

Any suggestions on frame size (I ride 57 and 58 cm road bikes now) -
any reason to step down in frame size like you do on a cyclocross
frame?

No. Same as your road bike (I also think that since most people are
riding undersized road bikes, they may as well use the same size for
'cross).

My advice is to test ride and see what you're the most comfortable
riding. If you're riding this on the road, then a more road-like
seat tube angle will probably help you find a comfortable position
for longer rides.

Tim McNamara wrote:

Track racers really don't turn the bars- riding on a steeply banked
velodrome, you basically keep riding in a straight line all the way
around the track. Track bikes tend to have steep head tubes and seat
tubes (75/75 is not all that unusual in a track bike) and very little
fork offset (sometimes called rake), giving them a fairly large trail.
My track bike is exceptionally easy to ride no-handed as a result.

Is there an (a?) FAQ somewhere that discusses the definitions of rake,
trail, and other such parameters, and their effects to the user? (And if
not, there should be one!)

--
Benjamin Lewis

A small, but vocal, contingent even argues that tin is superior, but they
are held by most to be the lunatic fringe of Foil Deflector Beanie science.

Track racers really don't turn the bars- riding on a steeply banked
velodrome, you basically keep riding in a straight line all the way
around the track.

That's not really true. Yo do have to steer a track bike, just not much. The
trick is to drop your inside elbow as you enter the turn, giving you a bit of
steering. Works on the road, too.
Phil Brown

Benjamin Lewis wrote in message ...

Is there an (a?) FAQ somewhere that discusses the definitions of rake,
trail, and other such parameters, and their effects to the user? (And if
not, there should be one!)

"Rake" means different things to bicycle and motorcycle people.
"Trail" is the distance from the intersection of the steering axis to
the center of the contact patch of the tire. These dimensions and
their interactions are the subject of at least one upper level
engineering course:
http://www.calpoly.edu/~wpatters/
and the subject of much debate. I doubt they can be reduced to a FAQ.

Jeff Wills

Jeff Wills wrote:

Benjamin Lewis wrote:

Is there an (a?) FAQ somewhere that discusses the definitions of rake,
trail, and other such parameters, and their effects to the user? (And
if not, there should be one!)

"Rake" means different things to bicycle and motorcycle people.
"Trail" is the distance from the intersection of the steering axis to
the center of the contact patch of the tire. These dimensions and
their interactions are the subject of at least one upper level
engineering course:
http://www.calpoly.edu/~wpatters/
and the subject of much debate. I doubt they can be reduced to a FAQ.

I'd be satisfied with a lengthy discourse, too

Ideally I'd like to learn more about this without leaving my seat, but if
anyone can suggest any good books on the subject that might be available in
the library I'd appreciate that too.

--
Benjamin Lewis

Although the moon is smaller than the earth, it is farther away.

--On Sunday, June 06, 2004 12:57 PM -0700 Benjamin Lewis
wrote:

Ideally I'd like to learn more about this without leaving my seat, but if
anyone can suggest any good books on the subject that might be available
in the library I'd appreciate that too.

Fundamentals of Vehicle Dynamics, by Thomas D. Gillespie

I'm not sure this covers bikes and motorcycles, but its a good resource
anyway. a good engineering library (such as one at a university) should
have a copy.

Mike
Mechanical Engineering 2006, Carnegie Mellon University
Remove nospam to reply.

wrote:

--On Sunday, June 06, 2004 12:57 PM -0700 Benjamin Lewis
wrote:

Ideally I'd like to learn more about this without leaving my seat, but
if anyone can suggest any good books on the subject that might be
available in the library I'd appreciate that too.

Fundamentals of Vehicle Dynamics, by Thomas D. Gillespie

I'm not sure this covers bikes and motorcycles, but its a good resource
anyway. a good engineering library (such as one at a university) should
have a copy.

Thanks. It's not at my university library, but there's a copy at another
nearby university, so I may check it out if I can't find something more
convenient or bicycle specific. I also see a couple of books in our
library with promising titles.

--
Benjamin Lewis

Although the moon is smaller than the earth, it is farther away.

Benjamin Lewis wrote:

Is there an (a?) FAQ somewhere that discusses the definitions of rake,
trail, and other such parameters, and their effects to the user? (And
if not, there should be one!)

Look up "Trail" in my Bicycle Glossary, there's a link to a good article
on this.

Sheldon "http://sheldonbrown.com/glossary" Brown
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unged (Phil Brown) writes:


Track racers really don't turn the bars- riding on a steeply
banked velodrome, you basically keep riding in a straight line all
the way around the track.

That's not really true. Yo do have to steer a track bike, just not
much. The trick is to drop your inside elbow as you enter the turn,
giving you a bit of steering. Works on the road, too.

Having put in thousands of laps on the NSC velodrome in Blaine MN,
I'll beg to differ with you.