Road Bike, Cycling Forums banner
1 - 9 of 9 Posts

·
Registered
Joined
·
63 Posts
Discussion Starter · #1 ·
i'm planning on upgrading the fork on my '05 roubaix elite. i'll probably ebay the old fork and don't want to mangle the steerer trying to remove the crown race. does anyone know the dimensions of that race? universal cycles carries a good assortment.
 

·
Registered
Joined
·
269 Posts
Umm, the fork on the bike is full carbon, why do you want to change it. It is 1 and 1/8 headset, does that help?
 

·
Registered
Joined
·
63 Posts
Discussion Starter · #3 ·
it's a 500 + gram all carbon fork. i know it's 1 1/8th. but not all integrated headsets use the same diameter race. my last frame i switched the straight bladed oem for an ouzo pro and the ride was much improved.
 

·
Registered
Joined
·
2,914 Posts
Umm, the fork on the bike is full carbon, why do you want to change it.
it's a 500 + gram all carbon fork.
Plus, if it's anything like the one on my '06 Roubaix Pro, it's like two wet noodles.

I'm really considering replacing mine too. I'm a gear head and relatively well off, so I'll probably just buy the Park Tools crown race puller. If not, just take your fork to a shop and have them do it. They shouldn't charge that much. Keep us posted, unless I beat you to it. :)
 

·
Registered
Joined
·
647 Posts
if i recall, the rake of the Roubaix fork makes it harder to replace...it's been a while since i had to deal with it, but i want to say that the fork has something like 49mm of rake.
 

·
Registered
Joined
·
63 Posts
Discussion Starter · #6 ·
45mm will be fine. that's 4mm (< .2") less offset. may quicken the steering a tad. doubt that i'll even notice tho.
 

·
Registered
Joined
·
78 Posts
lechat67 said:
45mm will be fine. that's 4mm (< .2") less offset. may quicken the steering a tad. doubt that i'll even notice tho.
You might not notice the difference. However, that change would slow the steering a bit. Stability is related to the trail of the contact patch behind the steering axis. Decreasing the rake will increase the trail, which makes the bike slightly more stable. Bikes like the Roubaix and Felt Z1 have longer wheelbases. To keep the steering from sharp, they compensate with increased rake.

See for example
http://en.wikipedia.org/wiki/Bicycle_and_motorcycle_dynamics
http://velonews.com/article/7322
 

·
Cycling induced anoesis
Joined
·
13,006 Posts
cartmaniac said:
You might not notice the difference. However, that change would slow the steering a bit. Stability is related to the trail of the contact patch behind the steering axis. Decreasing the rake will increase the trail, which makes the bike slightly more stable. Bikes like the Roubaix and Felt Z1 have longer wheelbases. To keep the steering from sharp, they compensate with increased rake.

See for example
http://en.wikipedia.org/wiki/Bicycle_and_motorcycle_dynamics
http://velonews.com/article/7322
IMO if the difference is imperceptible, it's too small to fret over. For certain, you're stating facts, but in real world terms (all else being equal) a 49 mm to 45 mm change in rake won't matter. When I trashed a fork (actually, it was a black lab), I went from an OEM 47 mm to a Nashbar 43 mm - no perceived difference. This is due in part to the fact that many facets of a bikes geo contribute to ride (yes, even ride)/ handling. Chainstay length, HT angle, BB drop among others, all play a part.

But as long as we're talking relative minutia here, one other measurement that is worth noting is fork crown to axle length. Every 5 mm difference changes HT angle about .33 degrees. Same deal, though. Keep the measurement within 5 mm's and no perceptible difference in handling.
 
1 - 9 of 9 Posts
Top