Fixed gear/track frame geometry

Michael Press said:

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.

Quoted message said:

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 said:

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.

Quoted message said:

Quoted message said:

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 <[email hidden]> wrote in message news:<[email hidden]>...

Quoted message said:

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 said:

Benjamin Lewis said:

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

Quoted message said:

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.

Quoted message said:

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

Quoted message said:

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 said:

Quoted message said:

Quoted message said:

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
+---------------------------------------------------------------------+
| Check out the Shostakovich 24 Preludes & Fugues for Piano, Op. 87. |
| Sort of like "Das Wohltemperierte Klavier" on drugs. Way cool! |
+---------------------------------------------------------------------+
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

(Phil Brown) said:

Quoted message said:

Quoted message said:

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.

Michael Press said:

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?

OK, lots of stuff here. Some prefer a road-type geometry, since most
fixie riding is on the road. Track bikes tend to be steeper (mine's about
74-75 degrees, but the geometry is not as radical as a time-trial or tri
bike. Is there a special reason for this? Probably, but mostly because
the "quickness" of the handling is more valuable on the track than the
added comfort (maybe?) of slacker angles. This does not mean that a track
frame will necessarily be hard to control. I was riding with a guy today,
and he was talking about my bike, and said that, well, with that geometry
you certainly can't ride no-hands. So, I did, just to show him. That
bike, even with the steeper angles, has always handled like a dream.

Track bikes also have high bottom brackets, for an obvious reason. That
way they are less likely to drag a pedal on the banking when riding
slowly, or to do so on the road cornering fast.

Some people want a slightly smaller track frame than road frame, but this
I think goes back to the days when road frames tended to be bigger than
they are today. Mine is exactly the same size (seat and toptube) as my
road bike. I like the consistency. I also have the same seat and bars,
and same crank length, on both.

--

David L. Johnson

__o | the people can always be brought to the bidding of the leaders.
_`\(,_ | That is easy. All you have to do is tell them they are being
(_)/ (_) | attacked, and denounce the peacemakers for lack of patriotism
and exposing the country to danger. It works the same in any
<country. -- Hermann Goering

Quoted message said:

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

My track teacher/coach, Rick Denman at the Olympic Velodrome in Carson, now
sadly gone, tought me that trick and I can tell you it works.
Phil Brown

Sheldon Brown said:

Benjamin Lewis said:

Quoted message said:

> 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.

Thanks. That's a good start, but it seems a bit simplified. For example,
I imagine if two bicycles have the same trail but different head tube
angles, they will handle differently. I've also tried out a couple chopper
style bikes that had such extreme head tube angles that there was a very
noticeable drop in the front end whenever the handlebars were turned.

--
Benjamin Lewis

All what we got here is American made.
It's a little bit cheesy, but it's nicely displayed. -- FZ

In article <[email hidden]>, Michael Press

Quoted message said:

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

Here's a couple of coppers.... I've had several frames that at one time
or another have been built up as fixies. All fall between 56 to 58 cm
in size. One was an older MTB frame, the others; various road frames.
Among the roadies: a tourer with 45 cm chainstays and several road
frames sporting more or less typical racing head and seat tube angles.

I loved 'em all for different reasons. Fixie A with the short wheelbase
had sprint bull horn bars and was a delight in tight city traffic and
corners. Fixie B (the tourer) had drop bars, Brook's saddle, 28c tires
with full fenders and an upright seating posture; it's comfort was
unsurpassed on 100+ km rides.... The purpose for which I built the
bikes (riding Doh! ;-) was integral in determining the suitability of
the frame used. It also influenced the choice of secondary components
and their setup; stems, tires, handlebars... These also dramatically
alter the ride characteristics of bike.

No news there. But it's good to remember that there's a symbiotic
relationship between frame geometry and the handling characteristics of
the bike. So consider the frame geo but, more importantly, also think
over in what capacity the fixie will be used; commuting, velodrome
racing etc, short recreational rides.... This should be the key factor.

If you intend it for general road use then (apart from geometry)
consider the following

- will the frame build up without toe touch?
- does it allow for a wide range of tires (> 23c)
- Is the fork crown drilled for a front brake
- what's the spacing of the rear DOs etc...

You love the feel of your Cannondale. Start from a simmilar frame and
keep in mind the type of riding proposed for the fixie.

luke

Benjamin Lewis said:

Quoted message said:

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

Quoted message said:

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.

Bicycling Science by Whitt and Wilson, which has been recently revised
with a new edition by Jim Papadopolous (former r.b.t contributor) and
David Wilson. I'd look for the new version, the old version is quite
out of date and according to some of the engineers in this newsgroup
had some serious errors. Haven't seen the new version yet. There is
a pretty comprehensive discussion of steering geometry in the old
version which seems fairly accurate.

(Phil Brown) said:

Quoted message said:

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

My track teacher/coach, Rick Denman at the Olympic Velodrome in
Carson, now sadly gone, tought me that trick and I can tell you it
works.

I know the trick you mean, it's just that a steeply banked track is
practically a straight line all the way around; the steering required
is very very minimal compared to cornering on a flat surface. Indeed
on a steep track like Blaine, you have to lean the bike away from the
track surface to avoid hitting the uptrack pedal.

David L. Johnson said:

I was riding with a guy today,
and he was talking about my bike, and said that, well, with that geometry
you certainly can't ride no-hands. So, I did, just to show him. That
bike, even with the steeper angles, has always handled like a dream.

heh, my track bike is also in the 74-75 degree range, can easily be ridden
no-handed and handles pretty well. it's comfortable on long rides and altho
i've never ridden a century i've done dozens of metrics on it.

people worry too much. or quite possibly i'm a mutant.

Quoted message said:

Track bikes also have high bottom brackets, for an obvious reason. That
way they are less likely to drag a pedal on the banking when riding
slowly, or to do so on the road cornering fast.

since i do most of my utility riding on a track bike, i've gotten my
reference for how much angle i can pedal through from that bike which has
led me to clip while pedaling through turns on the other bike a few times.
oops.

Quoted message said:

Some people want a slightly smaller track frame than road frame, but this
I think goes back to the days when road frames tended to be bigger than
they are today. Mine is exactly the same size (seat and toptube) as my
road bike. I like the consistency. I also have the same seat and bars,
and same crank length, on both.

same frame size, same seat, similiar bars and smaller crank length (165 v.
175) for me. the smaller length feels different but not so much. not a
big deal.
--
david reuteler
[email hidden]

Tim McNamara said:

Bicycling Science by Whitt and Wilson, which has been recently revised
with a new edition by Jim Papadopolous (former r.b.t contributor) and
David Wilson. I'd look for the new version, the old version is quite
out of date and according to some of the engineers in this newsgroup
had some serious errors. Haven't seen the new version yet. There is
a pretty comprehensive discussion of steering geometry in the old
version which seems fairly accurate.

Thanks. We have the old (2nd) edition in our library, so I'll have a look
at that first.

--
Benjamin Lewis

Basic Definitions of Science:
If it's green or wiggles, it's biology.
If it stinks, it's chemistry.
If it doesn't work, it's physics.

Luke said:

If you intend it for general road use then (apart from geometry)
consider the following

- will the frame build up without toe touch?

Not a problem, really. Both my road and track bikes touch. It is not an
issue except at very slow speeds, and then it is not a problem.

Quoted message said:

does it allow for a wide range of tires (> 23c)

Good thing to think about for a commuter. My track bike allows for 25,
but wider would be nice for commuting.

Quoted message said:

- Is the fork crown
drilled for a front brake

Easy to fix, with a drill.

Quoted message said:

- what's the spacing of the rear DOs etc...

Not really a problem. Hubs are still made for everything from the old 110
track standard my frame has, to 135 mountain-bike standard.

--

David L. Johnson

__o | It doesn't get any easier, you just go faster. --Greg LeMond
_`\(,_ |
(_)/ (_) |

David Reuteler said:

David L. Johnson said:

I was riding with a guy today, and he was talking about my bike,
and said that, well, with that geometry you certainly can't ride
no-hands. So, I did, just to show him. That bike, even with the
steeper angles, has always handled like a dream.

heh, my track bike is also in the 74-75 degree range, can easily be
ridden no-handed and handles pretty well. it's comfortable on long
rides and altho i've never ridden a century i've done dozens of
metrics on it.

I just did a fairly hilly metric century on my track bike, inspired by
this thread, actually. (David will recognize the roads- Gateway Trail
to Oakdale, to Lake Elmo, through Afton up to the park entrance, then
70th to Military Road and back through downtown St. Paul along the
Point Douglas Road path to Shepard Road). I cheat a bit, though, and
use an old Bendix coaster brake hub (probably 50 years old) that I
built up into a wheel. Surprisingly smooth hub. Beautiful day for a
ride!

Quoted message said:

people worry too much. or quite possibly i'm a mutant.

Why can't both be true? ;-)

Quoted message said:

Quoted message said:

Some people want a slightly smaller track frame than road frame,
but this I think goes back to the days when road frames tended to
be bigger than they are today. Mine is exactly the same size (seat
and toptube) as my road bike. I like the consistency. I also have
the same seat and bars, and same crank length, on both.

same frame size, same seat, similiar bars and smaller crank length
(165 v. 175) for me. the smaller length feels different but not so
much. not a big deal.

I don't notice that the 165s on the track bike make riding any more
difficult than the 175s I use on the rest of my bikes. In fact, my
knees seem to like them. Despite having only a 67" gear up all the
hills, some of which are reasonably steep, my legs felt really good
this morning.