Trek speed concept bicycle (aeromodding bicycle)

[jtbo]

Factory aeromodded bicycle:
Speed Concept 9 Series - Trek Bicycle

Now that gives me some ideas, I could use thin plastic from washer fluid canisters to make tubes in my bicycle similar to what Trek has made to their frame to be.

What do you think, does such small things really help?

I would think that making some form above the rear wheel might do wonders as I have larger frontal area than my bike, so that making air to leave me optimal way would probably be more beneficial than toying with tubes of bicycle?

Open wheeler race cars have section behind the driver such that I would imagine that would be good to put behind cycler, above rear wheel, maybe even bit lower.

I have already placed order of triathlon type steering bar which should bring me to optimal riding position.

I did also read about scraper bike culture, which some may be familiar of, my most interest was aero improvement of wheels as can be seen from this article's photo:
Scraper Bike Culture Provides Lessons for Sustainable Businesses

I wonder if every odd 'triangle' is taped, would that do improvement for aero?
Maybe taping whole wheel would be better, but maybe it would be possible to make cover from some light and thin stuff, like washer fluid canisters, they are just rather small in size so it will take quite bit of joining to get full disc, however I see there is front wheel with only small part covered in Trek bicycle, maybe that is most important bit and will not cause issues with cross winds.

Maybe I should do some coast down testing to determine aero before and after, but I'm horribly out of shape so going 70kph might not be possible, but maybe 30-20kph and then 15-5kph would be good ranges to test rolling resistance and air resistance.

[Stubone]

I think the wheel disks should be one piece, apparently the rim part tapers too quickly on a standard rim and spokes are apparently poor aerodynamically. google tailbox and you will find lots. They say you don't get enough air resistance to worry about until about 30kph, I say 20+.... But if you really want aero get a recumbent.

[jtbo]

Originally Posted by Stubone

I think the wheel disks should be one piece, apparently the rim part tapers too quickly on a standard rim and spokes are apparently poor aerodynamically. google tailbox and you will find lots. They say you don't get enough air resistance to worry about until about 30kph, I say 20+.... But if you really want aero get a recumbent.

Recumbent costs thousands, but at some point I will build something like that, velomobile, but it might take a while to source all needed parts and materials.

Only reason I think about aero is wind, it seem to be always from opposite direction and even small wind is already killing half from my speed at long hills.

Current riding position is rather upright, so that should be fixed in few weeks as new parts come.

There is list how much which thing reduces aerodynamic drag:
Bicycles and Aerodynamics

I did search a bit of tailboxes, came up with this place:
Commuter Bicycle Pics

There is at least two images from aeromodded bicycle and those mods seem to be working for him, got few ideas to get front fender more aero friendly as well as rear fender. I need fenders as there is often rain.

I think only lower front beam might need some work from body, rest I can get combined to rear fender covering and backbox, at least so I think and that should improve things a bit.

Currently wind can take my speed from 25 to 15km/h (if really strong even close to 10kph), every 10% improvement would be around 1kph against wind.

This should give nice perspective, it is very same as my current situation and what I would like to achieve or maybe even bit better if possible.
Measuring Aerodynamic Drag

That would be half the air resistance, maybe, if mods work enough well, that should mean that wind affects only half as much as it affects now so it would be half as annoying also, but maybe with tailbox it could be even better?

Of course summer brings large change as I can use something else than winter clothing, alone there is going to be rather large effect. Triathlon handle bars will allow me to get lower position than in that measurement page time trial machine has, maybe I should put air guide below handle bar so that air goes more around me.

[Grant-53]

The Trek shape can be applied to a full body fairing like that of wphamilton but with a nose piece. My cone and waste basket fairing pictured in the bike pic thread improved my easy cruise speed from 10 mph to 15 mph. The fairing should cover from the shoulder to just above the knee. This will cost less than a recumbant and be just as slick. Make sure your brakes are in top condition. See also the recumbent.com forum thread on building an upright racer. The pictures of upright Mike and upright David.

[jtbo]

Originally Posted by Grant-53

The Trek shape can be applied to a full body fairing like that of wphamilton but with a nose piece. My cone and waste basket fairing pictured in the bike pic thread improved my easy cruise speed from 10 mph to 15 mph. The fairing should cover from the shoulder to just above the knee. This will cost less than a recumbant and be just as slick. Make sure your brakes are in top condition. See also the recumbent.com forum thread on building an upright racer. The pictures of upright Mike and upright David.

That is very interesting result, even simple fairing seem to be great help

As it was calm day/morning, I did test bit of aerodynamics. I don't know if my results are really true and solid, but I did measure speed and time with GPS and put data to proven formula.

Cd of 1.492 is what program did claim.

I did tape measure myself and bike, estimated frontal area to be around 0.966m^2, that gives CdA of 1.441272.

Awful lot higher than earlier linked under CdA of 0.8.

CRR of 0.004, maybe possible, tires are not very special ones, 37mm and 32mm.
Front MITROC 28" Ur 32-622 m/v M-201
Rear Nokian Rollspeed 37-622 28"
Thead of those is rather smooth with center narrow smoother area, they do roll really well from my opinion.

Graph from coast down test:


This is fastest that I can do that 4km distance, coming back is always easy, but to go that fast I had to cycle so fast that I could literally taste blood in my mouth, so if I manage to do that trip any faster there has to be improvement in somewhere, this should be then baseline. At the end there is coast down test too.


When I get new handlebars I do another test, will be interesting to see if there is much change. Hopefully weather would be close to same so I could use same clothing too.

I did use Tomtom sat nav and tripmaster software running on it, to gather log, attached navigator to handle bars with metal wire, crude, but efficient.
Altitude data from Tomtom is bit inaccurate most of the time, but compared to phone + Maveric, I get 1Hz resolution and also speed logged, which Maveric does not log.

[Grant-53]

Log temperature, weight, and tire pressure as well. Stan's tubeless tire conversion can cut rolling friction in half. The frontal area could be estimated by taking a head on picture and printing it on graph paper. There is plenty of good information available on bicycle aerodynamics online.

[bikin' Ed]

In an upright riding position over 80% of aero drag is the rider. Get fit so you can achieve an aero tuck for more of the ride. Aero helmets are available. Mount water bottle in front of seat tube. Wear close fitting clothes and no gloves.

If you are not that fit,then an aero bike won't help much. Aero benefits on a bike begin to matter at about 13 mph--barely. You won't realize any real world gains until 25 or 30 mph.

[jtbo]

You can't make bones much smaller, shoulder width is such that I hit door frames constantly.

Losing water bottle would help even more, but I don't use one to begin with, also no pump etc. but those are just tiny little bits with slight or no real effect. Things that you start tinker after big things are sorted.

Like driving position. Also most important is how air leaves, front is always less important than rear, surface area being of course most important, which will be sorted when new bars arrive.

But rear of bicycle is problematic area still, even simple fairings there will reduce air resistance a lot.

Width of fairing should be width of leg and rest of body, then taper inwards from the sides and down from the top side, to make air leave well, just as with car with kamm or boat tail.

Simply best however is getting rid of upright position, when I tested bending over the handlebars so that I was more or less in the position of triathlon cyclist I gained speed without pedaling in places where before I slowed down with pedaling.

From bicycle alone 10% reduction should be fairly easy, of course it will not have much effect, but when you get wind blowing against you with strong gusts, any small help is plenty.

However Trek bicycle costs around 10 000 or more, I think that you can get nearly as good aero with 10 if being creative and true recycling, by using materials otherwise would be put into garbage, like plastic containers of washer fluid etc.

Weight is then another thing, but that has not much to do with aero.

With helmet, you can easily add aero shape to your existing helmet, there is no need to buy new and add to consuming mayhem, you can get as good aero with almost no cost than those fancy helmets costing 400 or whatever they cost.

My measurements tell that aero affects from speed above 11kph when upright position, that is 0kph travelling speed on most days as there is going to be headwind that is more.

All those claims about no benefit before 25mph are in lab, with no wind, any amount of wind will reduce speed where gain is easily felt, typical wind gusts are more than 13mph so you get benefit even when riding 1kph.

This can be easily observed from coast down test I posted, testing was done at the morning with rare no wind condition, around 11kph slowing down started to be more linear, speeds faster than that had clearly wind resistance adding to slowdown.
So 13mph (20kph) being limit where effects can be felt barely is not true with upright position, maybe more true with triathlon position with already good aero and tiny human being.

If you cut frontal area to nearly half, it will have effect from very beginning of movement and that is close to what happens when you change driving position, it is part of aero improvements and part of mods to bike as you need new bars to achieve lower riding position.

I would say everything matters, some more, some less, cyclist remains however largest restriction, but mods to bike can make restrictions caused by cyclist to be smaller as well, that is what mods made by Grant-53 are doing, those are mods to bike, but are not making bike itself to be more aero, but are helping cyclist to be more aero. If bicycle would be measured with and without those mods it would probably have more drag alone, because of increased frontal area, but add cyclists in and frontal area is no longer increased and air leaves more cleanly, so it is improvement.

Because I live at very hilly area, here it is very hard to find even 100 meters of flat road, any improvement of coast down, with minimal added weight, is going to improve average speed and distance I'm able to travel, also when you input wind to equation it will improve those aspects much more than what it might first appear when looking typical examples that always seem to forget that rather steady head wind, which seem to find all these roads from middle of forests to travel on.

[Grant-53]

There is a wealth of informations available on bike aerodynamics now available on line. What peaked my interest was the article in Scientific American in the 1980's that showed the racers tuck having the same frontal area as a recumbent! Even a common steel frame bike with homemade aerobars can be very effective. Modifications including wheel covers, tube fairing, and fitted clothing can be done cheaply. Even if you don't want to go all out, just moving the end bar grips inboard to 5 inches from the center gives me a second hand position on my city bike good for a 1 mph improvement at 10 mph.

I recommend Edmond Burke's 'High Tech Cycling' and Lennard Zinn on triathalete bike position and maintainence.

[jtbo]

Triathlon bar came today from China, 18 euros delivered.

3 speed grandmother bicycle is in service (actually rear wheel only), Renault bicycle lost pedal which efficiently destroyed crank too, so I had only two single speed grandmother bicycles left + 1 that is in pieces as I'm not sure if I start restauration on that one (it is heavily rusted from 50's or early 60's).


Today it was very windy, staying on one place felt like riding normal speed at calm day as I visited shop with grandmother bike (that one is from somewhere from 60's) gust tend to cut speed right immediately to half.

So I put triathlon bar to newer single speed grandmother bicycle, it is from somewhere mid 80's I guess.


With triathlon bars equipped 1980's grandmother bike I managed to ride same route bit faster than earlier with less wind with Renault bicycle, that is 21 gears vs one gear, also it is upright vs triathlon position.

Gearing was way too short most of the time, I could coast half of trip both ways, climbing that hill was of course harder than coming back, but still wind has virtually no impact to my riding, surely strong gusts I could feel and those took speed down a bit, but I could coast down to headwind too, which resulted bicycle stopping in seconds when trying same at upright position.

That much wind has effect even at those relatively low speeds, such single gear bicycle is not the fastest because of gearing, those are made for elderly people for easy slow bicycling.

Should of taken GPS with me to take some speed readings down.

Soon I can bicycle with t-shirt or long sleeves instead of huge overcoat as temperatures rise a bit, then I should get better performance because I don't need to wear that parachute.

I think that aerodynamic panniers are way to go next, I need panniers for shopping so might do some metal wire bending and cover thing with old cloth or two, then spray paint over it, that should be better than my current panniers that are not form keeping type and those have nothing aero about them.

I did research some of that and most of what I find are made so that there is taper at front and straight edge at rear, thing is, legs are front of those panniers so why to even bother making any taper to front? Making template matching shape to rear should provide much more drag reduction than those over 300 costing commercial items, one or two old sheets and some enough thick metal wire are rather cheap, need just weld frame from metal wire and those should be easy to take off too, when not needed.

Silly thing happened at the morning while bicycling on upright position, big truck came against me, while it passed it send so strong gust of air towards me that I had to pedal at full power to prevent bicycle from literally stopping, now I'll say that at any speed aero is important when you account such events to equation, those kind of events are just routine on road, same goes for other wind gusts etc. That is why I'm strongly against generalization of aero being not meaningful unless travelling fast enough, more proper would be to say that aero is not meaningful until above certain air speed, which is completely different from ground speed.

You can gain from aero even if moving backwards, that is if you don't want to go any faster backwards and try to keep speed in check by pedalling forward, that is purely silly and perhaps very difficult to achieve, but still with aero only thing that matters is airspeed, something sadly so often forgotten in discussions of aero, with cars and other things.