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30 mm rim vs. 21 mm, big aero advantage or not a big deal?(3 posts)

30 mm rim vs. 21 mm, big aero advantage or not a big deal?Swat Dawg
Dec 15, 2002 1:08 AM
I have been looking at getting either a set of Velomax Orion Comps, or Tempest Comps. I am wondering if the 30 mm rim on the tempests makes that much difference to the aerodynamics of the wheel vs. the Orions that have a 21 mm deep rim, but are 200 grams lighter. I have read the discussion on weight vs. aero and understand that aero is usually the biggest advantage, but how deep does the rim need to be before this benefit becomes manifest. Also, the tempest is 18 F and 24 R spoked, while the Orion is 24 F and 28 R. This I would think would probably be the greatest aerodynamic difference, but then again I see plenty of people riding with 32/32 open pros doing real well. I want the wheels to be durable enough for training and advantageous for racing. So what do you think? Thanks

Swat Dawg
re: 30 mm rim vs. 21 mm, big aero advantage or not a big deal?CARBON110
Dec 15, 2002 6:06 AM
What up Dawg! I like the picture you posted below this post... nice bike! Anyway, I am obsessed wth wheels and can give you the best answer you will find. If these are the two wheelsets you are deciding between.... go with the ORIONS. Why? Well, 30mm vs 21mm doesnt really matter , except perhaps for looks, but wheel spoke ount doooes matter... in a different way. 18 spokes are VERY low spokes and NOT ment for training. Most wheelsets that offer these spoke counts should be used only for climbing days, training rides that include a great deal of mtns or races more importantly. In this cas the 24 spoke and 200g ( which is substantial ) is a much better choice. Low spoke counts dont matter when your talking about aero dynamics, but they do matter when your talking about stiffnesss. Unless they are kevlar or you weigh in at 110-120 lbs they will compromise your performance more times than help. I weigh 127lbs during the summer and 132lbs in winter and wouldnt think of using 18 spokes up front even tougfh many whee manufactures offer it. Hard accelerations in a race, attacking or just reacting to surges in a group , I want stiffness. This is why people like bladed spokes. They weigh more but offer superior stiffness. On the oher hand that does not mean you need them. So, having seen a pic of you on your mtn bike, I would go with Orions if these are the two wheelsets you really like. Myself, an avid racer and looking forward to my best race year to come, I like the following for wheelsets that you might take a look at :

Only aero wheel for lght riders I think that is worth $$
is HED ALPS.... until Zipp gets its carbon and rim issue fixed

There are alot of climbing wheels out there that due the job well.... just remember, 18 spokes isnt good for anything unless your superlight .. under 120lbs... and 24 spokes are a good spoke count. Most aero wheels have HIGH spoke count since Steve HED prooved that spoke count is minimal in a wheels aero advantage providing that weel has a depth of over 52mm. Anything less than 52mm is not much of an advantage, but looks very cool. In addition, he said real aero dynamics take place at 58mm deep but 52mm does provide more benefits and a rider on an aero wheel ( + 52mm deep ) can save up to 5% more energy by the finishing sprint. Of course you can save at lest that much by hiding in the pack, being an effecient at pedaling, or just staying relaxed and not expending unnecessary energy.
by the way...CARBON110
Dec 15, 2002 6:11 AM
HED LPS.... just for aero wheels tht are clinchers ... there are lots of good tubular aero wheels.... for climbing clinchers check out.... nimble.org, american clissic 420 wheelsets, ksyriums, topolino wheelsets, cane creek team with TI spokes... velomax are good wheels I hear though... good luck!!