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Need advice on fork rake(11 posts)

Need advice on fork rakegsxrawd
Jul 3, 2002 1:13 AM
getting a Ouzo Pro and i can't decide between the 43mm fork rake or 45. Is there that much of differance in 2mm of rake? It's going on a small size frame 52cm w/ a 53 top tube if it matters. How would i know what i need?
re: Need advice on fork rakePaul
Jul 3, 2002 2:59 AM
What's on your bike now? Or are you startig from scratch? I have a Look with a 40mm rake, and if you're not careful, you bang your foot on the tire, plus you get overlap on turns, and if your pedal is in the wrong position, you can get your foot jammed between the tire and frame. After awhile you learn how to handle this. The frame size is a 57 cm. On my C-Dale 58 cm, I have a 43 mm rake with no problem. So, be careful when you consider a small rake. Slightly different handling with different size rakes. Unless you race, get the one that doesn't give you the problems I described. My friends have the same fork you are considering, and get the same problems I described, but you get use to it. I would prefer the longer rake as I don't really see that much difference in handling.
what effect will straight forks havepukka
Jul 3, 2002 3:50 AM
i have a cannondale(56cm) with standard forks i dont know what rake they are but was thinking about putting straight carbon forks on it ,what will be the effect
what effect will straight forks havePicshooter
Jul 3, 2002 4:36 AM
"straight" forks have rake too.
what effect will straight forks havePaul
Jul 3, 2002 5:03 AM
From what I gather, by shorting the wheel base (trail as others refer to it), you would have better handling in the corners. My Look has an adjustable wheel base, and what I've been told, if I shorten the wheel base, increases the cornering ability.
I don't race, so I don't bother doing this. I would prefer to have the 43 mm rake. If you go to the C-Dale web site, it shows how fork rake is measured on their bikes. You should then be able to figure out your rake. LBS should also be able to tell you.

Why do you want to put a straight fork on your bike? Carbon forks with carbon steerers like the Ouzo Pro, are lighter then alloy steerers, and will help in climbing. But I've noticed my alloy steerer is more stable then my carbon steerer. I can feel some flex. New carbon steerers are 1 1/8 and I've heard, handle better.

If you're looking for a lighter bike, and are willing to put up with the problems I've mentioned with a shorter rake, then go for it. if not, keep what you have. Doesn't the Ouzo come in a 43mm rake?
Rake, Trail, WheelbaseChen2
Jul 3, 2002 6:14 AM
Wheelbase has nothing to do with rake or trail. Trail effects handling more than wheelbase. Trail depends on head tube angle and fork rake. A steep head tube angle decreases trail. Increasing rake decreases trail. Less trail will make a bike turn more quickly. More trail will cause a bike to be more prone to continue in a straight line. To know how a fork change will effect a particular bike you need to know what it's present trail is. Trail can be calculated if you know the formula; our friend "C-40" has posted that formula many times but I don't have it with me now. Just know that if you increase rake, decreasing trail, from what you now have it will cause your bike to turn more quickly, but the difference may be slight. The down side of this is that the bike may feel a bit squirrely on bumps or irregular pavement. If you know your bike's head tube angle and how steep it is compared to other bikes, that information could help you decide whether you would prefer more or less rake. My Trek with a 73.8 degree head tube angle is relatively steep, a lower rake like a 40 would help it track a straight line better. It came from the factory with a 43, I think.
Straight forks can have the same rake as curved forks or more or less. This is due to the angle in the crown area of the fork, just below the steerer.
rake and trail...C-40
Jul 3, 2002 6:42 AM
You need to post the head tube angle to calculate trail.

The formula for trail is (tire radius/tanH)- (sinH x rake). I use 336mm for the tire radius.

Builders don't agree on the amount of trail that is appropriate. Trek's for example have trail in the mid to upper 50mm range, while Colnagos are in the mid to upper 60mm range, with the amount of trail decreasing as frame size increases. My 54cm C-40 has about 68mm of trail. Colnagos have slower steering than Trek's.

Many manufacturers do reduce the amount of trail on larger sized frames to speed up the steering, so they will corner more quickly, like the smaller, shorter wheelbase frames.
heres my info ,helppukka
Jul 3, 2002 7:41 AM
cannondale 56cm frame
headtube angle 73 degrees
4.3cm fork rake
tail 5.9cm

if i put 4.0cm raked forks on would my foot hit the tyre as describe earlier ,in what way would it handle different
For what it's worth...Chen2
Jul 3, 2002 8:07 AM
A 73 degree head tube is not considered steep. Going from a 43mm rake to a 40mm rake would increase trail and help your bike continue to track in a straight line, but would also slow steering response. I would expect these changes to be slight. In your case I would stay with the 43mm rake. I doubt that a 3mm change in rake would make any noticeable difference in toe overlap either way. The change in wheelbase would also be negligible. IMHO
~Al
help...C-40
Jul 3, 2002 8:12 AM
The steering will be slightly slower, but still not as slow as a Colnago. The tire will be almost 3mm closer to your foot, but that's only about 1/8 of an inch. Not likely to be a problem.

I've ridden a 55cm Litespeed with the same 73 degree HTA and a 4.0cm rake and it handled fine. I prefer the steering to be a little slower. I've gone off the edge of the road riding a twitchy bike with too little trail.
thanks for info(nm)pukka
Jul 3, 2002 8:15 AM