DT 1.1 vs CXP 33

BikingBrian

I'm building up a set of race wheels and would like some advice about the rims. I'll be using Record hubs and CX Rays with brass nipples.
Rims - is there any real difference for the DTs vs the Mavics? I guess what I'm asking is, is the tiny aero difference of the CXPs something to consider?
Yes, I know I'm picking nits! But I lost my last race last year by 0.12 seconds, and I can't afford deep-rim carbon wheels. Also, I'm not interested in prebuilt wheels; I want something that is rebuildable and hubs that will last a long time.
Any thoughts?

Thanks.

Peter@vecchios

CXPs are stronger, because of their triangular shape(and heavier by a wee bit) than the double eyelet 1.1. Both are good rims but after building both, the best in terms of quality out of the box is the DT, hands down.
For comparison, the DT 1.1(dbl) is more akin to the OpenPro and the CXP to the DT 1.2(altho no eyelets).
BTW, even with $2500 wunderwheels, you may have still lost by .12 seconds. Gotta push that bike.

alfeng

Campagnolo hubs are great, but DT/Hugi 240 hubs (non-ceramic) are something you should consider because they really do have seem to have minimal bearing resistance when loaded.

OR, if want to continue to use Record hubs (obviously, nothing wrong with that choice), then consider changing the grease to something closer to transmission/whatever oil & re-"grease" frequently ... that's what the OIL HOLE is for.

The lower "bearing" (actually, lube, in the case of the Campy) friction might make up for some of the 0.12 seconds ... or, not.

BTW. Isn't 0.12 seconds a lot more than a bike's length?

artemidorus

At 60 km/h it's 2m.

__________________
"All that we see and seem is but a dream, within a dream..."

BikingBrian

Ha ha, yes, you are right, I just need a little more oomph in my sprint
Thanks again for the great advice, Peter.

BikingBrian

I've always wondered whether people actually used those port holes

BikingBrian

Yep!

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dhk2

Peter, please explain why are DT rims better quality "hands down". Are you talking about radial and lateral runout, a welded joint, balance, braking surface and finish....that kind of stuff? I'm not trying to argue, but looking to be educated. My rims in recent memory have been ISO Matrix, MA-40, MA-3, and now Easton Circuits...nothing fancy.

531Aussie

I'd go for the CXP33s, because they'd be a tiny bit stiffer due to the extra ~4mm or so, depth. I had one RR1.1, which I found a little flexy, but I've have had a few CXP33s, and I liked them

By the way, it's best to use 14mm spoke nipples on CXP33s (instead of 12mm) to reduce the chance of scratching the rim with the spoke key.

Balderick

Brian,

I have had both rims - the DTs built up on DT hubs and the CXPs on Ultegra hubs, and both 32 spoke, and both sets built by the good wheel builders.

The DT hubs cracked the rim for most drive side spokes within a few months - classic pull through. They were the double eyelet version and the braking surfaces were quite worn after a few months.

I then had the CXPs built. Over 8 months and no spokes pulling through - trouble free save for a bent rear rim following a hard hit with a pot hole as 65 kph - nothing will come unscathed through that.

Subjectively I preferred the "feel" of the DTs, which were also or seemed to be slightly lighter. The CXPs are nice wheels, though. I do not notice any difference in the aero qualities.

By way of reference, I weigh 99 - 104 kg (depends on how many work business lunches I go to) and train, commute and race on the same wheels regardless of the weather. I also put out a high amount o torque and reasonably high amount of power, but that probbably means I am inefficient and rough.

I was going to get the R1.2s when I saw the CXPs. Weighed the two rims and the CXPs were lighter, and I was (correctly) assurred the CXPs and R1.2s would be equally reliable.

You really can't go wrong. My suggestion is that if you are lighter or smoother, go for the DTs but otherwise go for the CXPs.

531Aussie

Most people would probably share this view, but I don't. I managed to crack 2 CXP33 rears within about 6 months, and I haven't even knocked any of my DTRR1.2s out of true yet, in about 2 years! I like the DTs so much I now have 4 pairs of them!! I've put them on my four best bikes with Dura-Ace and Ultegra hubs

I say go for the DT1.2s over the CXP33s -- they look better, they're stiffer, I reckon they're stronger, and they're usually a tiny bit cheaper. I'd put the 1.2s in the same 'bomb proof' class as Velocity Deep Vs, Mavic CXP30s, and Rigida DP18s. The only thing some people wouldn't like is the weight: ~575g, but they come in 20, 24, 28 and 32 hole, sothe weight weenies can cut some grams with fewer spokes, and/or light, fancy hubs

Peter@vecchios

When I do a tune with Record hubs that doesn't include opening up hubs for overhaul, I squirt grease into those as well as the little hole, covered by a teeny set screw, in the freehub body. This does not sub for a good take apart and clean but it is always good to have grasso in the hubs.

Peter@vecchios

When you first start building a wheel, it becomes pretty obvious how flat and round the rim is from the start. If it is very flat and round, building it is faster, easier and the resulting wheel has much more even tension. DT rims are amazingly flat and round from the start, much more than any Mavic product. I rate Velocity as second best, still very good and none of them use a welded seam. Welded seam and machined braking surface is an answer to a not asked question, IMO. All it does is make the rim more expensive w/o any true benefits.

dhk2

Peter, thanks for the info. Agree "very flat and round" is best for a rim, and that the tolerances the rim is built to are important to the final quality of the wheel.

Asked about the seam joint because of balance concerns. My Circuit rims are a good bit heavier at the joint opposite the valve stem hole; assume that's due to the steel pins. The resulting out of balance condition gave a noticeable vertical hop in the rear wheel when spun up in a test stand.

I balanced mine by adding weight to tune out that hop. Believe the ride is smoother and grip is better on 40-50 mph descents with a balanced wheel/tire assembly. Would of course prefer to have a balanced rim from the factory rather than wrapping soldier around the spokes. If DT's come balanced, that's another big plus in my book.