Fork Rake/handling

andy said:

My wife rides a 48cm frame, 700c, w/ a 72 degree head tube angle. She
currently has a fork w/ a 43mm rake and I was wondering if installing a fork
w/ a 40mm rake would make the bike handle "more stable" as described on
Sheldon's website? Would this change be noticeable?
If so, can anyone point me toward an inexpensive 40mm rake carbon fork?

Maybe, maybe not. Clearance is another interrelated variable

I'm not big on changing rakes generally. Did you ever have
the frame/fork alignment checked?
--
Andrew Muzi
www.yellowjersey.org
Open every day since 1 April, 1971

In article <[email hidden]>,
"andy" <trifox13atcovaddotnet> says...

Quoted message said:

My wife rides a 48cm frame, 700c, w/ a 72 degree head tube angle. She
currently has a fork w/ a 43mm rake and I was wondering if installing a fork
w/ a 40mm rake would make the bike handle "more stable" as described on
Sheldon's website? Would this change be noticeable?

You also need to consider height -- unless the new fork puts the head
tube at exactly the same height as the old one, you've changed the head
tube angle as well as the fork rake.

In my experience, most people don't much notice a 3mm difference in rake.

--
[email hidden] is Joshua Putnam
<http://www.phred.org/~josh/>
Books for Bicycle Mechanics and Tinkerers:
<http://www.phred.org/~josh/bike/bikebooks.html>

serenaslu said:

unless I am mis-understanding what you are saying, the proposed change
would typically make a given bike's handling -more- responsive but
-less -stable by most defintions.

No, less "rake" (fork offset) results in more trail and more stability. But
going from 43mm to 40mm of offset isn't going to make much difference.

http://www.phred.org/~josh/bike/trail.html

If she's using real skinny tires, switching to 25mm or 28mm tires at 95 psi
may give the bike a more stable feel.

Art Harris

Arthur Harris said:

serenaslu said:

unless I am mis-understanding what you are saying, the proposed
change would typically make a given bike's handling -more-
responsive but -less -stable by most defintions.

No, less "rake" (fork offset) results in more trail and more
stability. But going from 43mm to 40mm of offset isn't going to make
much difference.

http://www.phred.org/~josh/bike/trail.html

If she's using real skinny tires, switching to 25mm or 28mm tires at
95 psi may give the bike a more stable feel.

That's a good point. There are several ways to increase trail on a
gven bike. One of them is to replace the fork with one with less
offset. Most readily vailable aftermarket forks come in offsets of
40, 43 or 45 mm which work pretty well with head tube angles from 72
to 74 degrees- which also means differences are fairly minimal,
unfortunately.

The other option is to increase the wheel diameter by putting larger
tires on the bike. There are a couple of factors at work here-
geometric (increased trail) and mechanical (larger tires tend to have
lower inflation pressures than skinny tires- 120 psi for 700 x 18 but
abotu 100 psi for 700 x 28).