Bicycle Mechanics - Carbon Forks w/ Aluminum Steerers - better?

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Philcycle
02-27-08, 07:50 PM
Are they better in the sence of headset bearings not eating into the carbon? Any major difference? Thanks!


HillRider
02-27-08, 08:15 PM
Headset bearings don't eat into any fork material unless they shatter. The bearings run on metal races either in the headset cups or as part of a bearing cartridge and never touch the steerer.

Aluminum steerers are less expensive but heavier albeit they can be lighter than forks with steel steerers. All carbon forks are the lightest but can be very pricey.

Wordbiker
02-27-08, 08:15 PM
Although carbon can be used to produce very strong items, such as DH handlebars, forks with carbon steerers are focused on saving weight, typically more so than forks with aluminum steerers.

Other than getting a fork rated for the rider's weight, there's not much functional difference.


AndrewP
02-27-08, 08:25 PM
I dont think there is any functional difference as the vibration damping happens in the fork blades.

mtbikerinpa
02-28-08, 08:40 PM
There is the reality that an aluminum steerer is far easier to produce, hence cheaper. It can also be more tolerant of ham-fisted mechanics who don't use torque wrenches.

HillRider
02-29-08, 08:27 AM
There is the reality that an aluminum steerer is far easier to produce, hence cheaper. It can also be more tolerant of ham-fisted mechanics who don't use torque wrenches.
Al and Cr-Mo steerers will also tolerate starnuts which will ruin most all-carbon steerer. Why all-carbon forks don't come standard with an expansion plug is a mystery to me.

Some carbon steerer forks come with a specific manufacturer-supplied starnut but most don't and using a regular one is sure to damage the fork.

Bobby Lex
02-29-08, 08:48 AM
Headset bearings don't eat into any fork material unless they shatter. The bearings run on metal races either in the headset cups or as part of a bearing cartridge and never touch the steerer.

Aluminum steerers are less expensive but heavier albeit they can be lighter than forks with steel steerers. All carbon forks are the lightest but can be very pricey.

A little off-topic, but the new Trek that everyone is drooling over uses a CARBON race for the headset bearings. Scares the $hit out of me!

Bob

HillRider
02-29-08, 12:44 PM
A little off-topic, but the new Trek that everyone is drooling over uses a CARBON race for the headset bearings. Scares the $hit out of me!

Bob
Is it really a "race" or just a seat for a cartridge bearing? If so, then the actual bearing balls run on the steel races built into the cartridge and never touch the carbon itself. I assume it's like integrated headsets in other frames and the bearings don't run on the frame material.

Bobby Lex
02-29-08, 02:02 PM
Is it really a "race" or just a seat for a cartridge bearing? If so, then the actual bearing balls run on the steel races built into the cartridge and never touch the carbon itself. I assume it's like integrated headsets in other frames and the bearings don't run on the frame material.

Here's how Trek describes it (from their website):

"Net Molded bearing race places the 1.5 inch bearing directly on the carbon crown race seat, removing the need for a traditional metal bearing race seat".

I'm not sure what this means exactly. If it is as you describe, it sounds o.k. But if the bearings actually sit and roll on a carbon race inside the headtube......:eek:

Bob

HillRider
02-29-08, 05:42 PM
Here's how Trek describes it (from their website):

"Net Molded bearing race places the 1.5 inch bearing directly on the carbon crown race seat, removing the need for a traditional metal bearing race seat".

I'm not sure what this means exactly. If it is as you describe, it sounds o.k. But if the bearings actually sit and roll on a carbon race inside the headtube......:eek:

Bob
It is a bit confusing but I still think they use cartridge bearings and the actual races are part of the cartridge.

"Integrated" headsets do just that and the bearing cartridges sit in pockets machined into the headtube and right on the frame material.

"Zero stack" headsets had shallow cups pressed into flairs machined into the head tube and maybe those are the "metal bearing race seats" Trek is referring to.

In both cases the balls don't really touch the frame material itself.

I hope my explanation is right. If not then I certainly agree with your alarm.

Joshua A.C. New
03-02-08, 10:54 AM
Yeah, a "1.5 inch" bearing is not made of 1.5" balls. It's gotta be an integrated headset made of carbon.

HillRider
03-02-08, 12:36 PM
Yeah, a "1.5 inch" bearing is not made of 1.5" balls. It's gotta be an integrated headset made of carbon.
The integrated headset isn't made of carbon, the lower end of the carbon headtube is moulded as a seat for a 1-1/2" diameter bearing cartridge.

Integrated headsets are basically a pair of bearing cartridges, a crown race, a compression cone and a top cap and compression bolt. The "cups" are molded as part of the headtube and are made of whatever material the headtube is; steel, carbon, Al or Ti.