On Feb 2, 2010, at 9:22 PM, james black wrote:
On Mon, Feb 1, 2010 at 23:36, Grant Petersen <gr...@rivbike.com>
wrote:
TCO ends up being a problem---in my opinion---only in theoretics,
but not in
practice. THere are some builders who would disagree; and although
in the
spirit of diplomacy and reasonableness and "agreeing to disagree"
and all
that, I accept that....I can't understand it. To fear TCO or to
regard it as
Dangerous....well, it's ust something that to me doesn't make any
sense.
I also disagree - I strongly dislike toe clip overlap, having
encountered it on a few frames (I usually ride long-raked 60-62cm
frames now, so have little problem). It can be a problem
trackstanding, riding slowly, turning sharply while riding a fixed
gear, riding offroad, and climbing slowly. If it doesn't make you
crash, it's still annoying, inconvenient, and I don't want to sit
around while riding constantly thinking, "Oh, I better be careful not
to jamb my shoe into my fender". Bicycles should not cause this kind
of low-grade anxiety. It's unnecessary - if a bike has TCO, the wheels
are too big. Design it out with smaller wheels!
Easier said than done. Any standard bike 60 cm or smaller will have
to have 559 wheels- even 650B isn't small enough to guarantee no
TCO. Most people find those aesthetics unacceptable as the small
wheels makes the bike look like a toy in their eyes (I ride a '96 60
cm All Rounder with 559s, so I get that reaction a lot).
Bicycle design involves compromises. You can eliminate TCO with a 68
degree head angle and 70 mm fork offset. But most people don't want
to ride the bikes that would result from that geometry (You'll find
that geometry on millions of old British 3 speeds. They handle like
wheelbarrows but no TCO). You can eliminate TCO with a 62 cm top
tube and normal angles, but nobody under 6 feet tall will be able to
ride it and it'll look funny on a 56 cm frame. Or you can use a
naked 23 mm wide tire instead of a 45 mm tire with fenders. Or you
can build frames with tiny trail due to huge fork offsets (but I
won't buy 'em. I had that geometry years ago, don't want it again.
55 mm trail is just about right).
Sorry folks, but TCO is a necessary design compromise in many cases.
Get a pencil, some graph paper, a compass, a straightedge and draw up
some proportional drawings of bikes. You'll see the hopeless problem
pretty quickly. It's easy to say "get rid of TCO" but it's well-nigh
impossible to do so in every instance without designing something
like the Moulton. I've done enough frame design to have worked this
out for myself.
I've got bikes with TCO, having size 13 feet and not liking to pedal
on my tippy toes results in this. I haven't have a crash or a near
crash in years, the last being riding fixed on the street on my old
track bike (zero toe overlap problems on the velodrome, which is
where such bikes belong. They don't belong on the street, speaking
from experience) years ago. I'm used to the TCO since most of the
bikes I've owned since I was 14 have had TCO, I don't pedal through
corners at low speeds and have low enough gears- and thankfully
enough strength- to not have to weave back and forth up hills. My
riding style is adapted to the reality of my bikes. It's just not a
problem.
I think there are a number of us who want our cake and get to eat it
too: sporty fast geometry with 45 mm tires, full fenders and no
TCO. I'd say "pick two." Some enchiladas can't be readily served
whole.
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