Reducing Rolling Resistance and drag
 

In may I will be competing in the local club's TT champs, in the U19 section. I am hoping for a good result, so I am looking at ways as to lower my Rolling resistance and wind drag.

I have Velomax Vista wheels with 30mm rims. A wheel upgrade is only possible with a sudden increase in finances.

Aerobars: I have borrowed long-term some Profile Air Strykes? the ones wit the flip up arm rests. I am pretty aero on them now, but I can flip my stem around to get the bars lower, and I believe I can get my back parallel to the ground.

Helmet: MET Psfero, not much can be done here really

Clothes: Standard shorts and shirt, contemplating the cost of skinsuit.

Frame: Cervelo Soloist 105 with aero tubing

Tyres: Michelin Pro-race
Tubes: 1x butyl and 1x latex? not sure.

Help would be appreciated,
regards,
Brendon

Rolling resistance: Tubular tires

Drag: rear disc wheel and aero front (HED or Zipp), single piece wind suit, shoe covers, aero bars properly fitted so you can stay in the tuck position for your entire ride.

Save not being able to shell out a couple grand for this stuff for a race....shoe covers, pump your Michelins up to about 140 lbs (American) if your rims can take it, and aero bars and have someone check your aero bar fit. TT bikes have a different geometry to move the rider closer to the front of the bike and retain a proper pedaling motion. You cannot move your seat closer to the aero bars (changes your pedaling motion) and leaving them where they are will restrict your breathing due to your bending at the waist further than you would in the drops. So the bars have to be set to retain your drop bar pedaling motion. Or you will struggle for maximum efficiency.

Bottom line...remember Lance at Algarve a few weeks ago. Old Pneumo helmet, no shoe covers, regular racing kit (no aero stuff) and he put a power meter on the bike...and still whipped everyone. All the techno stuff is great, but it's still the engine that's most important.

In addition to minding your tuck, don't overlook your width! In particular, keep your knees in close to the top tube.

rolling resistance can be optimised by finding the correct tyre pressure for your weight. Maximum is not necessarily faster.

Find a hill, at least 2km long. Mark that distance.

start at max air pressure and roll down hill in same seated position and measure time. DO not pedal.
Ride to top of hill and lower air pressure. repeat exercide till you find ideal pressure. try to do this exercise on one day and preferably when conditions arecalm and unchanging.

They sell disc coverings don't they? You can put them on over normal spoked wheels. Try google searching them

www.weightweenies.com should have some hints.

I believe that wheel covers are not UCI legal? these are proper club TT's. Thanks!

Problem here in NZL is that we have many varied and mainly rough chip seal roads, some of which are very ROUGH! To get decent performance overall I need to keep pressures slightly down to stop the bike from bouncing about, in particular when out of the saddle and cornering. I will try this though, as at the moment I am running edit:95 rear and 90 front. I am 152 lbs, one or two more at times.

Brendon

There has been some really good advice in the responses so far. The tyre pressure is certainly something that sould be set per the tyre makers recommendations. The other wheel related rotational drag issue that can be fixed for free and contrbutes more drag than does the flexing of the sidewall of your tyre, is the "Correct" cone adjustment. Something that I found interesting is that there are some competitive riders that won't use sealed bearing wheel hubs because they generate more rotational drag than cone and ball bearings types. But, a cone and ball bearing type must be adjusted correctly to reduce drag. I've not yet seen a new wheel set either purchased with a new bike or purchased separately, with the cones adjusted for minimum drag.

This isn't anything new, but it needs mentioning more often. Adjust the cone so it allows just the smallest amount of wheel wiggle (looseness) before setting your quick release to the locked position. With the quick release in the closed (locked) position, the wiggle should just dissappear. I've done this many times and I do it on new wheels as soon as I get them. It often times will take me several fine tweeking adjustments to get it just right. If you're doing the back wheel, make sure the chain isn't mounted.
The results are measureably better!! Prior to making these adjustments, I apply a fixed rotational force (I've rigged a little device for doing this) to make the wheel spin.
I measure (count) the total number of full rotations. I then perform that same measurement after the cone adjustments. The last wheel I did this to (about two weeks ago) was a new OpenPro from WheelSmith. The before adjustment rotations were 7. The after adjustment rotations were 15.

Oooooh!! I new that I had forgot to mention something interesting. I had looked at the comparative qualities between round spoke, bladed spoke, disc type wheels. The research article that I picked up on the internet indicated that a bladed spoke or a disc wheel has an advantage over a round spoke wheel. There is less wind turbulance created with the bladed spoke or the disc wheel. This results in lower wind resisitance. The really interesting part of this is that the edge over the round spokes only occurs in either no wind conditions or in the wind is absolutely perpendicular to the direction of travel. Any time there is any wind and your direction of travel moves away from the wind parrallel, the advantages of teh bladed or disc wheel begins to dissappear. They found that in relatively stiff crosswinds, the round spoked wheel had the least wind resistance. Boy, the more I read I realize the less I know.

Q. Why doesn't Velomax use bladed spokes?

We carefully considered using bladed spokes, but decided against it. In wind tunnel tests, bladed (and ovalized - hereafter "profiled") spokes have proven to be very effective. The caveat here is that they show their greatest advantages vis-a-vis round spokes when the airflow is from straight ahead. As soon as you introduce even a small component of side wind (yaw angle as low as 2 degrees), the larger surface area of profiled spokes acts either as a lifting surface, or develops airflow separation (with related generation of vortices), or both. The bottom line - creation of lift cannot be accomplished without corresponding increases in drag.

Simply stated, a profiled spoke in a static or head-on air stream can be very effective. However, a profiled spoke in a side wind is a propeller.

A round spoke always presents the same small profile to the air stream, whether the angle of attack is head on or from the side. When you consider the wind direction, speed of the bicycle, and rotational speed of the wheel, it becomes apparent that there is an alphabet soup of aerodynamic considerations happening throughout the course of the ride. For this reason, we believe that swaged (butted) spokes present the best real-world aerodynamic profile.

For those of us who can't understand all those big words you are using Don!

I am looking at the RENN 575
http://www.rennmultisport.com/~rennm...i?product=575a
I can buy it online for $608NZD - what would be the cost of importing this? Does anyone have some websites with info? I can pick up second hand tri-spoke sets here for $1000NZD - which would be the better investment?

Brendon

With all of the other crazy bike inventions you see, how about this.

Let's make a wheel with bladed spokes. The spokes will be able to rotate along their axis. There will be a linkage that will link them together and keep them pointing in the same direction. Now, we will have an air speed / direction sensor that will rotate the spokes as you get a crosswind, keeping the blades at the optimum angle.

Who care if it weighs 40 pounds?