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Campy front hub built with a radial pattern(11 posts)

Campy front hub built with a radial patternRSB
Sep 5, 2001 9:55 AM
Anyone have any experience with a Campy Record front hub built up with a radial spoke pattern? I have a bike with a wheel built this way, but Campy recommends not lacing the wheel this way because of the loading on the hub flanges (voided warranty).

A follow-up question: if I want to rebuild the wheel with a 2X pattern will I need to get new spokes due to the increased spoke length?
re: Campy front hub built with a radial patternnee Spoke Wrench
Sep 5, 2001 12:31 PM
Can't say from my own experience about radial laced Campy hubs breaking out the flanges, but Shimano won't warranty a hub laced that way either. Frankly, I just don't understand the allure of radial laced wheels.

You will definitely need new, longer spokes to relace your wheel 2 cross.
re: Campy front hub built with a radial patternLeisure
Sep 5, 2001 11:38 PM
To my knowledge Chris King is the only company that warranties their hubs when radially-laced. The only appeal of radial is visual; it rides harsher, has less steering precision, and is drastically harder on the hub. The weight-savings could be gained with thinner spokes and you would still end up with a longer-lasting wheel and hub with better ride quality and control. 2X is good--that's what I'd do, too. Spoke Wrench is right about you needing longer spokes. If the weight is an issue to you this is a good excuse to ask about using thinner spokes, especially since this is the front wheel.
re: Campy front hub built with a radial patternJofa
Sep 6, 2001 5:56 AM
Radial spoking is hard on the hub- the hub flange hasn't enough material to support the radial loads and will fracture from fatigue, whereas tangentially there is more than enough metal; but it makes no difference to ride quality or steering precision. The spokes will of course be a little shorter, and hence will stretch a little less for a given load: this decrease (from tangent spoking) has been calculated, and is roughly equivalent to the thickness of a sheet of copier paper.... put a sheet under your wheel and ride over it, and you'll see what I mean.

Wheels of any spoke type, tension, or arrangement don't flex detectably in use anyway. These variations are about durability. Tyres flex a lot: if you want precision pump your tyres up or fit smaller ones.

Jofa
re: Campy front hub built with a radial patternLeisure
Sep 7, 2001 4:29 AM
Okay, everyone: put your front (inflated) wheel against a wall and turn your handle bar into it. Look closely. 'Nuff said. Regarding ride quality and precision, what I'm talking about has nothing to do with tensile strength multiplied by negligible differences in length; it has to do with long-term loading leading to fatigue and deformation deteriorating ride quality. Assignment #2: A/B compare each type for a couple of rides (as I have). It's easiest to see when both wheels are of comparable age and a little broken in. I could go into lengthy discourse on the technical details of why, but oh God it would take forever, and some parts even I would be speculating on.
re: Campy front hub built with a radial patterncyclequip
Sep 6, 2001 2:49 AM
As long as the spoke tension isn't too high, the hub will hold out. Shouldn't be a problem. BTW, a radially spoked wheel with the spoke heads inside the flange is the stiffest spoking you can get, also the lightest and 2nd most aerodynamic. Radial spokes with the spoke heads outside the flange is slightly less stiff radially, (but still significantly stiffer than crossed spokes) and is the most aero. Also, handling is better, and according to Gerd Schraner the vertical compliance is the same as crossed spokes.
re: Campy front hub built with a radial patternJofa
Sep 6, 2001 6:05 AM
It's not high tension but cyclic loading that is the problem. On each wheel revolution the spokes are unloaded then reloaded as they pass the bottom of the wheel: this encourages fatigue fracture in the spoke and hub flange. The maximum (determined by spoke tension) and minimum (determined by rider weight) tensions which a spoke experiences are insignificant: it's that there is a disparity between them which causes the problems.

Jofa
Don't relace hubs in a different patternOnrhodes
Sep 6, 2001 5:45 AM
I've been told by a very reputable source (cat 1 USCF mechanic, mavic neutral support tech, and former professional mechanic for IME/Healthshare team, and mechanical engineer) that you should never ever ever relace a wheel in a different pattern after having previously built it another way. A brand new fresh hub has never had tension on it at all. But then you go and build up a wheel, tension the spokes, and all of a sudden this formerly left alone chunk of metal has major forces applied to it. Now you want to go and pull it in a different way by changing the spoking pattern. I've been told it could possibly warp the hub, or you may do damage to the flanges by starting to pull it in all different directions.
Probably some of you are going to disagree, but this guy I mentioned above is a very good source and has built hundreds (if not thousands) of wheels in his lifetime.
YepJofa
Sep 6, 2001 6:26 AM
He's right but it's for the spokes' sakes, not the the hub's. Spokes deform the soft aluminum of hubs at the elbow, and are then stress-relieved to this specific location. If you change them and put them elsewhere, they will be more likely to fail.
If you replace the spokes with new, hubs can be relaced any which way: though the spoke holes are deformed, tangent spoking never causes high fatigue loads in hubs, and the new spokes will find their own locations. This isn't recommended however, as spokes which have been functioning well for a while should be treasured, as the ones which were going to break will have been weeded out.

Jofa
YepLeisure
Sep 7, 2001 1:26 AM
The reputable mechanic should be right, but I would suggest it applies more in situations with well-worn hubs, particularly when broken-in in a cross-weave and then relaced radially. Remember this was "the big thing" recently, and probably accounts for much of the wheel-failures observed following relacing. The long-term disruptions in the metal lattice leave additional off-angle stress-risers that further compound overloading presented by relacing in radial fashion. Aluminum's poor fatigue resistance does not help; sheer strength (softness) and resiliency have to be treated as independant variables.
The Record hub we're looking at is a fairly unused hub; if the original spoke tension isn't terribly high and it has sustained no significant loading (riding), it should still be safe to relace in a cross-pattern which loads the hub well within its intended design. At the same time, I'm not going to arrogantly assume authority over the thousand-wheel-building mechie. I'm interested in what he would say about this specific scenario.
What works in reality is always most important. Discrepancies between what is observed and what is argued or calculated "in theory" are actually quite frequent, and are generally the result of innocent oversimplification. Calculations and theory are revised to better accomodate what is observed, not vice-versa.
re: Campy front hub built with a radial patternRSB
Sep 7, 2001 12:51 PM
Thanks to everyone for the information and help. Since the wheel has not been ridden more than a couple of miles I'm going to relace it with longer spokes 2X and try it. Thanks again.