Why can your feet hit the front tire on some road bikes?

Davej wrote:
Seems like a design flaw to me but it had to be intentional.

You mainly run into this on compact frame road bikes, which should be
avoided for several other reasons as well.

Frank Krygowski wrote:

Chalo wrote:

The size of the front wheel is an arbitrary value. *The fact that most
manufacturers would rather have shorter riders suffer toe overlap than
use a wheel size appropriate to the rider's size displays... a failure
of imagination.

Not necessarily. *It may be that they made a design decision that you
happen to disagree with.

My daughter is most comfortable on her Terry bike with a 24" front
wheel. *She, my wife and I did a coast-to-coast tour a few years ago.
A sharp rock put a nearly unrepairable gash in that tire, the only
non-700 one on the trip. *This happened in South Dakota, where bike
shops are about as common as zeppelin repair shops. *At that point, I
was wishing Terry had found another solution to the overlap problem -
one with a little less "imagination."

Our solution to the tire gash was laborious hand-stitching and
creative booting of the tire, plus having Terry air-ship a replacement
tire to the closest bike shop, over 150 miles away. *It worked out OK,
but if she'd had 26" or 700c, we'd have had it fixed within 20 miles.

Terry used an ISO 520 tire for that bike. That's their problem, and
the problem of their buyers. If it had been ISO 559 (as you noted) or
even ISO 507, then you'd not have faced such a needless ordeal.
There's also the likelihood that if manufacturers more commonly used
smaller wheels for smaller bikes, then tires in those sizes would be
far less exotic.

There is very little excuse, in my opinion, for using different
diameter tires on the same bike unless coping with an absurd layout
(recumbents) or exercising artistic prerogative (choppers). If Terry
had been more concerned with chassis dynamics and less with marketing-
driven product distinction, they'd have used ISO 559 at both ends.

Putting a five-foot rider on 700c wheels doesn't make any more sense
than putting 700c wheels on a kid's bike. It can be done, but it
creates more and bigger problems than it addresses.

Chalo

SMS wrote:

Davej wrote:

Seems like a design flaw to me but it had to be intentional.

You mainly run into this on compact frame road bikes, which should be
avoided for several other reasons as well.

The term "compact frame" as usually used refers to a road bike frame
with a sloping top tube, and does not imply anything about the front
center or relative head and seat tube angles. Are you talking about a
compact frame in this sense of the term, or do you mean a short
wheelbase (racing, sport, criterium etc.) bike?

Chalo

On Oct 5, 10:04*pm, Davej wrote:
Seems like a design flaw to me but it had to be intentional.

Dear Dave,

Here's a nice example of a few "intentional" design features:

http://utopiaparkway.com/ba/images/bicycles/4.jpg

For some reason, the 1885 BSA safety bicycle didn't catch on, despite
its pedals near its small front tire, a rear spoon brake, some clever
remote steering, a highwheeler handlebar to allow high knee action, an
interesting cross frame, a lightweight drilled-tooth front sprocket, a
handsome rear mounting step, a reversed fork, a pair of solid tires,
and 40-spoke rear and 18-spoke front wheels.

Heck, it even had fenders fore and aft and a nifty mount for a lamp.

Cheers,

Carl Fogel

SMS wrote:
You mainly run into this on compact frame road bikes, which should be
avoided for several other reasons as well.

That's odd since a sloping top tube has absolutely nothing to do with
this.

Davej wrote:
Seems like a design flaw to me but it had to be intentional.

It naturally happens on smaller frames with 700c wheels. Many riders
prefer the feel of having the front wheel "tucked in" (ie short front
center and wheelbase), so it can occur on larger frames as well.

"Ron Ruff" wrote in message
...
SMS wrote:
You mainly run into this on compact frame road bikes, which should be
avoided for several other reasons as well.

That's odd since a sloping top tube has absolutely nothing to do with
this.

He forgot to mention it's also a feature of Aluminium frames and threadless
steerers...

In article
,
Chalo wrote:

Mike Jacoubowsky wrote:

Chalo wrote:

Davej wrote:

Seems like a design flaw to me but it had to be intentional.

Like so many other details of bike frame design, I attribute this
characteristic to a failure of imagination.

It's the same failure of imagination that puts identical length
chainstays and the same seat angle on a 68cm frame as on a 52cm
frame. *I reckon that most such mistakes are perpetrated by folks who
ride 56-60cm frames themselves.

The distance between your foot and the front tire is determined by many
things-

#1: Length of crank arm
#2: Length of foot
#3: Size of front wheel

The size of the front wheel is an arbitrary value. The fact that most
manufacturers would rather have shorter riders suffer toe overlap than
use a wheel size appropriate to the rider's size displays... a failure
of imagination.

I am a shorter rider and would never take on a bicycle
with smaller wheels. Mostly because larger wheels roll
better. My feet overlap the front tire swing, and I don't
care. I execute slow speed maneuvers without incident or bother.

--
Michael Press

On Oct 6, 1:49*pm, Chalo wrote:

Terry used an ISO 520 tire for that bike. *That's their problem, and
the problem of their buyers. *If it had been ISO 559 (as you noted) or
even ISO 507, then you'd not have faced such a needless ordeal.
There's also the likelihood that if manufacturers more commonly used
smaller wheels for smaller bikes, then tires in those sizes would be
far less exotic.

I wondered if the reason for the odd 520 sizing was to get narrower
tires. I don't have a good feel for what widths are available in
different rim diameters. The bike (a Symmetry) came set up as a
"road," not touring, bike.

There is very little excuse, in my opinion, for using different
diameter tires on the same bike unless coping with an absurd layout
(recumbents) or exercising artistic prerogative (choppers). *If Terry
had been more concerned with chassis dynamics and less with marketing-
driven product distinction, they'd have used ISO 559 at both ends.

I think the reason is partly historical. IIRC, Terry copied Bill
Boston's idea to use the small front, and like him, kept the 700c rear
because in those days, you needed it to get a reasonably high top
gear.

Now, of course, we're in the era where Shimano makes cassettes capable
of insanely high gears. So yes, it would be way more sensible to have
equal wheels, whatever the size. And yes, maybe the unequal wheels
are now just Terry's version of Hetchins "curly stays."

- Frank Krygowski

Per Davej:
Seems like a design flaw to me but it had to be intentional.

*My* feet? Because they're size fifteens.
--
PeteCresswell