Cross forks rake?

[aroskin]

Hi-
I have a Serotta ti cyclocross, looking to put a new fork on her. The Alpha-Q is a 47mm rake- what is that going to do to the handling?!? seems really out there? My Serotta is a 73.5 seattube with a 72 head tube, if that helps. Does anyone know what a 47mm rake will do? Thanks!
Keep up the excellent work Ben and the gang !
(For all those who read these boards on the fence about a Serotta- I have owned, 3 Merlins, then a Seven, now the Serotta Cross, it is the nicest bike I have ever owned! Serotta tubing and welding is sooo much more advance than litespeed/merlin, and seven just look at the torpedo seat stays!)

[Bruce K]

If you haven't bought your fork yet, my Concours Cross was built with an Alpha Q and handled fine. It now has a has a Ritchey cross fork on it and I like it better. The Ritchey is a little lighter and the bike seems to handle better with it.

BK

[aroskin]

Ouch- I just bought the alpha-q, BTW what is the rake on the ritchey? After doing some research online it looks like the slacker the headtube angle the longer the rake (hopefully) My Serotta has a slack 72 (for a 56st/58.5 tt) I have a 44 rake now and it seems goofy compared to my Argon 18 road bike. We shall see!

[aroskin]

Found this great link- calculates trail from know rake and heatube angles
http://www.kreuzotter.de/english/elenk.htm

Trail N:
Distance between the contact point (center of the contact patch) of the front wheel on the floor and the point where the "virtually" elongated steering axis meets the ground.

The smaller the fork offset (the straighter the fork) the longer the trail - contrary to a wide-spread conviction.

Also Zinn's book explains why more rake makes a faster handling bike (less trail)

[FierteTi52]

.

[aroskin]

I now know why the bike is handling funny- the slack 72 headtube angle with the 44 mm rake I have on now makes a 65mm trail- super stable but really slow. I think the 47mm Alpha-q will bring it to 62mm trail (depending on tires), I read that 57 is ideal...for a road race bike. My Serotta is built for long haul riding so I think the 47mm rake/62mm trail will take the "funny" out of her (I was complaining that the 44mm rake fork I put on her made her feel funny, I did notice that she was crazy stable on the downhills!)

Too much of a good thing is bad, too much ridding is never enough! esp. on my Serotta!

Word!