I built a new wheelset for one of my singles to replace its ancient Rolf Vector wheelset. I went 20H radial front with 110kgf and 24H 2 cross rear with 120 kgf drive side. Rims are Kinlin XC279 and spokes are CX-Ray.The bike is a carbon Trek 5200 which I bought new. I weigh about 145 and am fairly light on the front end. I've been using 90 lbs. front and 100 lbs. rear on 23mm 4kIIs tires.

The new front seems to transmit much more vibration than my old Rolf 18H radial front. The rear feels fine. If I have the dimensions of the Rolf spokes correct, my Park TM says it is tensioned to ~65kgf.

My question is: should I back off the tension on the front? If so, to what? It seems kinda crazy to have such high pitched spokes on such a lightly loaded wheel. Of course I could also back off on the tire pressure but I liked how the bike handled at these pressures with the Rolfs. I understand that many riders use lower pressures with wider rims like the Kinlin. Still, the question of spoke tension remains.

I'll be out of town tomorrow, but will respond to suggestions as necessary on Monday. Thanks in advance.

fewer spokes, more tension. Try lower pressure on the front. About 75psi.

Once you get into the working range, increasing or decreasing spoke tension will have zero effect on vibration, or wheel strength. X change in load creates Y deflection in spokes, regardless of the starting place. What does change things is the total cross section of the spokes, so fewer thicker spokes will act similarly to more thinner spokes. If (next time around) you want a less rigid wheel, use thinner spokes.

The rim/tire combination may be the issue here. In a well proportioned combination the tire leaves the rim going outward rather than vertically. That creates 2 spring zones and the walls are primed to bow outward to absorb radial forces.

When the tire is narrow with respect to the rim, the near vertical sidewalls tend to be stiffer, than the rounder profile the same tire would have on a narrow rim.

I'm biting my tongue here, nor saying that one is better or worse. I'll let conventional wisdom and 100+ years of pneumatic tire history say that for me. OTOH - many people have very strong preferences for the narrow tire/wide rim combination, and extol some of the very properties I criticize, so I'll leave it to each to suit their own preferences.

I don't think there are thinner spokes. IIRC, the CX-Rays are drawn to an 18g cross sectional area - they weigh ~1.5g less (~20%) than a road-length 14-15 spoke. The dimensions multiply out to 1.98, but that ignores the shape. That's one of the odd things: just looking at them, the CX-Rays must be less than 1/2 the total cross section of the Rolf spokes.

Be that as it may, I think the vibration is, as you say, probably due to the vertical sidewall. I'll try them at lower pressures. I love the rim/tire cross section. Looks very aero and in my brief tests, seems to go even better on descents than the Rolfs did. I also didn't like those big flat blades in a cross wind or when being buffeted by trucks on fast descents. These wheels should be much better.

Thats Nice enjoy your trip .



my 3 radial spoked front wheels have all been 349 - Brompton.

a 20 spoke (95 MK 2, steel Hub) A28 spoke, New standard wheel, and the replacement

a Schmidt New XS , Cleverly designed in Germany to be flangeless and use straight Spokes.

Are the new rims wider than the previous rims? If so, you've increased the total volume chamber even if you are using the same tire. I've experienced this with same tires on two different width rims. In my case the wider rim needed much less pressure. Once I found the happy PSI, the changed profile of the tire on the wider rim feels much more stable when cornering.


I see you've stated that you will experiment with pressure. Let us know what you discover. I'm curious to hear about other people experience.

Bump.

The rims are wider, 23mm outside. Same rims we run on our tandem, but different tires and weight. I finally got in a good ride on that bike. 80 lbs. in front and 100 in the rear makes it ride like silk. No buzz, takes chipseal and road irregularities nicely, corners well, no pinch flats. Thanks to all for suggestions.

The bike is still fast. This past Sunday, I got my first ever climbing cup on its first group ride in 9 years. I remember that hill. Our fastest guy was out front by couple hundred feet. As soon as I saw the hill I came up on the preceding bit of flat, accelerated and then hammered up the hill, downshifting and passing him. I heard some FD noise and tried to trim, then realized I was still in the big ring, so sat for a second, went to middle, and had at it again. Only a 3 minute hill. The bike is amazing. It just goes. 52-39-26 in front, 12-25 in back.

The new wheels are laterally stiffer than the old Rolfs and feel a little faster.