Increase trail or longer front center

John Verheul wrote:
"Callistus Valerius" wrote in message
ink.net...
With less trail the bike can turn on it's own, but sometimes
makes you feel uneasy because you feel like a passenger on a run-away
train.

This is the sensation I have...I'm thinking more and more it's the trail.



Interestingly, this discussion motivated me to try keeping my weight further back when I descend, reducing front wheel load. I think it helped.

Dan

In article ,
"John Verheul" wrote:

Since moving out west (US) a couple years ago, practice as I might I just
can't quite descend with riders who are otherwise of my ability. Recently,
I've also been having a hard time cornering in criteriums at high speeds
(over 30mph). Lower speed laps I'm fine, but I'm closing gaps on fast laps,
and getting caught when I attack because I'm just not carrying as much speed
as my competition.

I practice plenty (have a 14 mile climb behind my house with switchbacks,
and a local training crit), and it's my 21st season of racing, so I'm going
to assume I've maximized the skills area as much as I can. The bike is also
fine when at training speeds, it's just in relatively high speed
descending/cornering situations I cannot get around the turns as quickly as
I'd like.

I'm slightly taller than average at 6'1", and don't use a lot of setback on
my road bike (7-8cm), so I suspected I might have too much weight on the
front wheel. Bathroom scale measurements indicate I don't. It's right around
43/57 front/rear.

So now I'm looking at frame geometry. I'm using a frame that has a steep
74' head angle, and a 45mm raked fork. With a 23c tire that's only about
4.9cm of trail, very low by most standards. Bike also has a pretty short
front-center of 60cm (on a 60cm frame).

My options to improve handling as I see it a

1) Get a 40 or 43mm raked fork, which would increase trail to 5.1 or 5.4
respectively, more in what most people seem to feel is a more average range
for a racing bike.

2) Get a frame with a longer front center to move cg even further back in
the wheelbase, thus keeping more weight off the front wheel in steep
descending corners (but perhaps leading to front wheel washout in flat crit
corners?).

Any opinions? If I pick option 1, would you get a 40 or 43 rake fork, and
why?

Another comment from a non-racer in northern
California. I have an old steel frame and a new steel
frame, both with ~71 deg angles. Old is a Raleigh
International, it is slower into corners, but feels
rock solid. The new oversize steel frame is quick into
corners, and rock solid. The fork offsets are 55 and 45
mm respectively.

My technique. Unload the inside pedal, get fully out of
the saddle, unload the outside hand, put my attention
on the two contact patches, and watch where I want to
go. The feeling is that I am light on the bicycle and
not forcing anything. It is at the point when I unload
the outside hand that the turn begins in earnest.

I practice this at low speed, 15-25 km/hr on my
residential street doing U-turns in mid-block and
dOnuts in intersections, creeping up on the absolute
maximum tilt and rate of turn. My music teacher said
that if I want to play it fast, first I must be able to
play it slow. Through practice I am taking turns flat
out where I used to back off, and catching up
(temporarily!) with riders on full out race frames who
are much faster than me.

--
Michael Press
(not a pot smoker)

Followup: Replaced the 45mm fork with a 40, same model. Bike feels 100%
better after the last 3 days of deliberately finding fast descents with
tight turns (I live in the southern Rockies). Solid & stable, much like the
last bike I really felt that way on. Trail on that bike as well as the bike
now is 54 (close to Tim M's "ideal" of 55).

Thanks everyone for the thoughts and helping me hash it out, it helped a
lot.

John Verheul