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Aero Stuff

Tim Kendall

Speeding Up
Aug 11, 2013
42
11
The JBCF Time Trial champs is coming up, and I'll be riding a regular road bike with a disc on the rear, and clip-on bars... But, I am wondering if these have any real influence on performance.
I've heard that a Disc + Trispoke front could have a 15sec per kilo advantage!
 

theBlob

Bokeh master
Sep 28, 2011
2,982
1,650
I was surprised that just the bars made a decent impact on my speed. I can't speak for the wheels.
Best of luck!
 

FarEast

Maximum Pace
May 25, 2009
5,528
538
I think you need to put a wire frame down the front of your skin suit Tim to make your gut more aero.
 

GSAstuto

Maximum Pace
Oct 11, 2009
974
251
We did some tests on Arakawa with various wheel configs and std road bike w/dh bars. For as constant power as possible, over 2km (1km each way)...

1) Std 38mm wheel set as control.
2) Front tri spoke.
3) Rear tri spoke
4) Rear 88mm
Etc....

Best was rear deep dish and front trispoke. About 3-5s over std wheels per km.
Depending wnd, a lenticular rear wheel offers another 2-3 s/km.

These tests were largely uncontrolled and mainly averages over a lot of runs. But, we did notice consistent gains regardless of the rider.

Probably equally significant is capability to maintain highest optimum power based on feedback from an SRM device. Especially over longer course.

For std roadbike I'd consider getting as low frontal area as possible , largest depth rear rim, skin suit and aero helmet. And definitely have your power goals well known and set. Plus contingency for possible wind conditions.

if ur really OCD, then strip the chainlube and strip all the seals from ALL the bearings and just run with light PTFE lube. I'm running NTN and TP Tiramic's with no seals on the TT wheels. Also, shellac or track glued to further reduce tire compliance losses, or latex tube if ur on clinchers.
 

GSAstuto

Maximum Pace
Oct 11, 2009
974
251
@Tim, I've got some tri spokes kicking around if you want to mess with them. They are not that stiff - really pure TT wheels, but interesting to try out especially if the course is mostly smooth and straight. Another thing is to try to flush mount as much of the hardware as possible. Like skewers, nuts, bolts, etc. I come from the aerospace industry and as a younger A&P was relegated to HOURS spent filling and sanding rivet dimples on my Dad's friend's Pylon racer. At 300kph+ life is a little different, but the physics still apply. Another thing I see quite often is riders bringing in their wheels for tuning and finding many of the aero bladed spokes literally CROSSWIND!Ok - so , hold your hand out the window while traveling at 50kph - what do you feel? DRAG! Turn a few spokes crosswise and this is exactly the same DRAG! Aero spoked wheels aligned correctly give good savings in drag, aligned incorrectly give an massive INCREASE in drag.

Drag is everywhere. Mittens vs open finger gloves are better, closed mouth vs open. Etc etc etc. Every couple of grams starts to add up. Creating laminar flow under most yaw conditions is the goal. Don't have a wind tunnel? Then at least tape a hundred or so lengths of yarn on your bike and body and have a friend video tape you as you swoop by. Do this a few times and experiment with your body position. Your optimal aero position is generally MUCH lower than how you feel riding a normal road bike.
 

Gunjira

Maximum Pace
Oct 2, 2009
1,028
211
Almost bought the padova disc before. It's great value, especially considering that you can switch between TT derailleur and track fixed. Did it come with the adapter included?
 
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