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Building your own lightweight wheels
 

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Nick Payne
Joined: 10 Jan 2004
Posts: 2377
Location: Canberra, Australia

6/7/18 3:55 PM

Building your own lightweight wheels

I recently purchased a Merckx Mourenx disc frame on closeout, and as the only thru axle disc wheels I had were for MTB, I went looking for a pair of wheels, but didn't find anything that appealed at any sort of a reasonable price. I eventually decided I could do the job better myself, and built my own set of 24/28 spoke wheels, using:

DT Swiss 240s 28h rear hub (on sale cheap)
Hope RS4 straight pull 24h front hub (also on sale cheap)
Light Bicycle RRU25 carbon rims - 18mm internal width, 25mm depth
Sapim CX-Ray spokes and DT Squorx nipples

Built-up weight, according to my kitchen scales, with tubeless rim tape but without valves installed, is 650g front wheel and 780g rear wheel (1430g total), which is about 130g lighter than the Dura-Ace disc wheels that I looked at as a possible (and rather more expensive) alternative. Total cost of the components was about $AU960 ($US730). I got Light Bicycle to apply their logo to the rims in orange, as that will match the Mourenx frame which is largely orange.

<a href='https://photos.google.com/share/AF1QipMx9kQ1jW4imRVGKIdVb31CKHRRonZRIpvgQyUBq9HfX6p5RLMLGFpX7sSADricNA?key=SDQ1WlY3T25Fb0FYcEpYc1NzOEVWU3E5d3pWTTNn&source=ctrlq.org'><img src='https://lh3.googleusercontent.com/YSSW66JhjhirpmN3SHrs6n4__U9gejQDinV2nKUT5Cl5YxgpBcPxshrUWw-sSbVAKLi8MPUJ3pNkEA81jhnNsxvRkTc4D2TOqnME3QWv08QKle6x_6In0yp1hxHLgCD-5KWSRpvKOA=w1200' /></a>

<a href='https://photos.google.com/share/AF1QipPfhutAcHlg-PYP2CItn7Fyasvl3uoaCnARJB7b-C5PkLhHdIYKPaiXkKaqOp709g?key=aTJEbDItN0RGVzJEN2JreVd6SHZmTGVTenZrcDZn&source=ctrlq.org'><img src='https://lh3.googleusercontent.com/uzK382LAep--8UZXaKJ7QV7q1yS8PmKIE-nLcfTyvVbwvTtOTWiPr7S1jDIe-D444QoJfvciyUgy2B0Tq7VPcifWhottWguF-Qjx61Dee6Egps4U7qYgRT31Li0mMKG8eLafCK8rqw=w1200' /></a>

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Craig
Joined: 12 Jan 2004
Posts: 548

6/7/18 5:43 PM

Good weight. I suppose I could do the math, or I could just ask, how much $?

Curious, I don't own through axle wheels, nor will I likely ever own them unless I don't have a choice, what's the weight difference between a decently light quick release and a decently light through axle system? Intuition makes me think through axles weigh more? Plus heavier dropouts? Offset by greater power efficiency, I'm sure, power savings offsetting weight penalties....

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Sparky
Joined: 08 Dec 2003
Posts: 16693
Location: Portland, OR

6/7/18 6:05 PM

How much do you weigh? I did a 28h 2x Shimano CX75 set and took one ride up my street. So after 300' I came back t the shop and replaced the front disc side spokes to 3x.

Keep in mind that disc wheel leading spokes are doing a lot of work when you grab the brakes than RIM brake wheels. And you have lost the symmetrical front bracing angles to the disc offset.

I sold those off and stuck with 32h 3x. I did use 14/15 leading disc sides, and rear trailing and the rest 15/17.

You using brass nips? I would... I went as far as using brass on the 14/15s and forged alloy on the 14/17s.

I am pretty sure seeing your bike pic you are not as big as me. Weight wise I dunno.

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Nick Payne
Joined: 10 Jan 2004
Posts: 2377
Location: Canberra, Australia

6/7/18 7:23 PM

@Craig - cost specified in my original post: ~$US730. Thru axles are better than QR for preventing brake rub with disc wheels when sprinting or climbing out of the saddle.

As for weight comparison - the DT Swiss MTB wheels I have came with endcaps and skewers for both QR and thru axle. The QR endcaps weigh ~5g more than the thru axle endcaps and the QR skewer weighs 15g less than the thru axle skewer, so the weight difference there is negligible. Where you add weight is with the brakes - you probably add somewhere around one pound or a bit less for disc brakes compared to rim brakes. Plus the frame/fork probably has to be beefed up a bit at the non-drive side chainstay and fork blade to accommodate the caliper and take the stress of the disc brake.

There's also the (possibly spurious) problem that applying a disc brake on a front QR wheel tries to force the disc side of the axle out of the dropout. That's why you see some QR disc forks that have the dropouts flipped around, so that the wheel comes out to the front rather than slightly to the rear, as on this Easton fork:



@Sparky - yeah, 28h should be built 3x (these are), but 2x for 24h. With straight pull hubs, you have no choice about the spoke crossings as the hub drilling for the straight pull spokes enforces the number of crosses - with 28h they're usually 3x and you build them with the spokes interlaced, 24h or 20h are 2x and the spokes are not interlaced. I only weigh 65kg/143lbs, and I've had zero problems in a couple of years use of a pair of DT Swiss 28 spoke MTB disc wheels that use alloy nipples. For the wheels I just built, I used brass nipples on the rear and alloy on the front.


Last edited by Nick Payne on 6/10/18 3:19 AM; edited 1 time in total

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Sparky
Joined: 08 Dec 2003
Posts: 16693
Location: Portland, OR

6/7/18 7:33 PM

"had zero problems in a couple of years use of a pair of DT Swiss 28 spoke MTB disc wheels that use alloy nipples."

I see on those road tires? Stopping on pavement VS loose dirt and leading disc side spokes... I do have a bunch more weight to haul down that you certainly.

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Brian Nystrom
Joined: 26 Jan 2004
Posts: 4163
Location: Nashua, NH

6/9/18 7:20 AM

How do you like the rims?

How good does the quality appear to be? I've been watching the steady improvement in Chinese carbon rims and I'm considering trying some.

At your weight, I'm surprised that you didn't go with their RM29C06 in their standard 360 gr. layup. I can understand not wanting to spend the extra $104 per rim for the 280 gr. Flyweight layup.

https://www.lightbicycle.com/bead-hook-less-rims-carbon-29er-light-bike-rim-tubeless-compatible.html

Oddly, they don't list your rims on their North American website.


Last edited by Brian Nystrom on 6/10/18 10:38 AM; edited 1 time in total

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Nick Payne
Joined: 10 Jan 2004
Posts: 2377
Location: Canberra, Australia

6/9/18 3:17 PM

The quality of the rims is excellent. I showed the unbuilt rims to a friend who's probably the best bike mechanic in this city, and he was quite impressed with them. This is the second pair of wheels I've built using their rims - my touring/gravel disc bike has a pair of their wider 650b rims. They seem to build to order, as there's a several week lead time between ordering the rims and shipping of them, and you can periodically check the order status on their website to see what stage (layup, molding, machining, sanding, painting, etc) they're at.


quote:
At your weight, I'm surprised that you didn't go with their RM29C06 in their standard 360 gr. layup.
Those rims are hookless and only rated for a max tyre pressure of 40psi - I'm using these wheels on a road bike with 28mm tyres, so I went for the rims with hooks, which are rated to 160psi. Plus the RM29C06 have an internal width of 22mm - according to the ETRTO chart for what width tyres can be safely used on what width rims, that width shouldn't be used for a tyre narrower than 35mm.



Edit: the chart above is taken from this quite interesting page: http://engineerstalk.mavic.com/en/the-right-tyre-width-on-the-right-rim-width/

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Jesus Saves
Joined: 16 Jun 2005
Posts: 1131
Location: South of Heaven

6/9/18 9:39 PM

Tolerance level

Nice wheelset! One measure of quality I find building a wheel is how close to (nearly) perfect true where the seems meet for an Aluminum rim. I bet your wheels are essentially seemless.

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Brian Nystrom
Joined: 26 Jan 2004
Posts: 4163
Location: Nashua, NH

6/10/18 10:43 AM

All carbon rims are seamless, but there can be dramatic differences in how straight and consistent they are. Unlike extruded aluminum rims, issues aren't limited to the seam area. One benefit of disc brakes is that the tolerances of the rims don't need to be as tight as for rim brake rims, but they should be nonetheless.

I was a bit baffled by the pressure recommendations for their tubeless-ready rims. Tubeless tires fit so tightly that it really shouldn't make any difference whether a rim's bead is hooked or hookless. Stan's Iron Cross rims also have a low max pressure recommendation, but have a very definite hook to their beads. Go figure.

Looking at the Mavic chart, they recommend much wider rims with hookless beads. I guess that sort of makes sense, but I'd like to see recommendations from other manufacturers, as Mavic always seems to have their own agenda.

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