Options for aero aluminum clincher wheels around $1000?

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yinya
Posts: 229
Joined: Tue Aug 07, 2007 9:06 pm

by yinya

I have the DT 1400 dicut wheels and breaking is amazing with BXPs but i can easily eat 1/3 of the front pad in a long dry day of steep mountains. That is okay. But what annoys me is that at some point the pads go "flat" and lose all their breaking power - i have now gone through 5 pairs of BXP pads like this after ~2500km of riding and I do not think I have got more than half out of any pad and now I have resorted to riding with extra pads in my pocket given the unpredictability of this. Love the wheels, mesmerized by this pad issue.


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NovemberDave
Posts: 231
Joined: Sat Oct 09, 2010 11:42 am
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by NovemberDave

yinya wrote:I have the DT 1400 dicut wheels and breaking is amazing with BXPs but i can easily eat 1/3 of the front pad in a long dry day of steep mountains. That is okay. But what annoys me is that at some point the pads go "flat" and lose all their breaking power - i have now gone through 5 pairs of BXP pads like this after ~2500km of riding and I do not think I have got more than half out of any pad and now I have resorted to riding with extra pads in my pocket given the unpredictability of this. Love the wheels, mesmerized by this pad issue.


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What's almost certainly happened is that your pads have become glazed. Take a coarse emery board or a piece of 100 or 120 grit sandpaper and sand the face of the pad. This will take off the glazing and expose fresh pad surface.

I would be very surprised if this doesn't allow you to get the remaining life out of those half used pads.

Whether rim or disc brake pads, they often benefit from this technique. It's very effective.

Once you do this, quickly re-bed the pads by doing a series of progressively harder stops. Your pads should work like a charm after that.

NovemberDave
Posts: 231
Joined: Sat Oct 09, 2010 11:42 am
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by NovemberDave

ergott wrote:
stormur wrote:V shaped rims are much better performers in both areas ( reducing drag at every yaw and lighter ).



I asked here many times for RELIABLE DATA which will prove I'm wrong... never get it.

Find some aero/hydro-nautic forum, read for a while ( it will take a lot of time, but fascinating knowledge ) and make own conclusion. Those forums are full of engineers who make a ( very decent ) living on "cheating" wind; and they do not want to sell you anything, nor are paid to "help" you making decision (99.9% of population simply can't afford stuff which they work on ).



What part of a boat are you comparing to a rim profile? Both the tire side and spoke side of a rim are leading edges and trailing edges. To further complicate things the front rim effects steering input. I don't know of a fair comparison to the shapes used in hydro-nautics.

Also in fairness to your request for data, I'd like to see some data supporting your claims.



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Boats that go really fast 1) have Reynolds numbers that are so wildly different from wheels that it makes any comparison meaningless and 2) are operating in two fluids (air and water) where the dynamics are just ridiculously different. Yes, the recent America's Cup foiling catamarans have extremely lean foil shapes, but the leading edge is always the leading edge. As Ergott points out correctly, this is the opposite of what you see in bike wheels which are bi-directional. And a foil traveling through dense water at 40 mph is just a different planet from a bike wheel moving through thin air at 30 mph.

Boats that actually travel through the water at reasonable comparable Reynolds numbers to what bike wheels see do best with fairly meaty foil shapes, similar to wider u-shaped wheels.

I have long been, and am currently, on race teams with some of the top sail designers in the world. I do sail test days with their designers and pros. Though he's in a management and not a design capacity, my brother holds a senior position at the world's overwhelmingly number one sail maker. This is a world I am extremely plugged into. For one thing, a sail moving through air NEVER sees a "yaw" angle (apparent wind angle in proper sailing-ese) of less than about 18* and 21 would be a better minimum. This just out of the gate means that a sail and a wheel are in two different spheres of operation.

There is crossover learning to be done between the two realms of boats and bikes, for absolutely sure, but the statement that boats prove that v shapes are superior is not valid.

yinya
Posts: 229
Joined: Tue Aug 07, 2007 9:06 pm

by yinya

Thank you NovemberDave, will try that next time it happens. Tossed the old ones already as I thought of it but I was afraid some of the "sand" from the sandpaper remains in the pads and impacts the finish on the rims.


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