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Thread: Do we have any smarty pants on the rosters with aerodynamics

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    Registered User fantapants's Avatar
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    Do we have any smarty pants on the rosters with aerodynamics

    As above, but with the slight bend of being slow speed.

    Bicycle speed. Not sure how much that changes things to be honest but have always been told in the industry it does.

    Looking for smart/learned folks to bounce ideas of regarding a bike build project for a 1000m time trial. event is short and expected speeds are slow (60kphr) but evrything helps right?

    Already chatted with the local rocket scientist bill thought id plumb the depths a bit further.

    Cheers lads

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    This made me remember an Olympics in the 90's where they were banging on about some new aerodynamic bike. Nothing to add myself apart from a quick search revealing http://campagnolodelta.blogspot.com....superbike.html

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    Yes. I'm building a velomobile, super aero human powered trike. What do you want to know?

    Also know how to do cooling system airflow, undertrays, check for attached flow, etc

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    Registered User fantapants's Avatar
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    Quote Originally Posted by jasonp1977 View Post
    This made me remember an Olympics in the 90's where they were banging on about some new aerodynamic bike. Nothing to add myself apart from a quick search revealing http://campagnolodelta.blogspot.com....superbike.html
    The swan

    Unfortunately the uci (international governing body) stepped in shortly after and eliminated any sort of functional creativity.

    So the beam bikes, regularly accepted as the most aero, are all banned except for triathlon.

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    Big drag reductions to be had from the wheel set EDIT mostly the front. Deeper the rims the better, up to and including fully enclosed. Balance this up against behaviour in a cross wind. If it's indoors, go nuts.

    The other one is rider position, but you probably need a wind tunnel to optimize this beyond the obvious tuck position with knees and elbows in.

    Further edit: Tight fitting lycra on the rider is obvious, less obvious is that body hair is a major source of drag. So bust out the razor. These last two suggestions courtesy of Junior, self proclaimed subject matter expert.
    Last edited by Sprinkles; 01-02-18 at 06:40 PM.

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    So... out with it. What's the competition and what are the rules?

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    Registered User fantapants's Avatar
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    Quote Originally Posted by Sprinkles View Post
    Big drag reductions to be had from the wheel set EDIT mostly the front. Deeper the rims the better, up to and including fully enclosed. Balance this up against behaviour in a cross wind. If it's indoors, go nuts.

    The other one is rider position, but you probably need a wind tunnel to optimize this beyond the obvious tuck position with knees and elbows in.

    Further edit: Tight fitting lycra on the rider is obvious, less obvious is that body hair is a major source of drag. So bust out the razor. These last two suggestions courtesy of Junior, self proclaimed subject matter expert.
    Interestingly a recent wind tunnel study claimed 8 percent gain by leaving leg hair on....

    Races are indoor so front wheels are solid discs.

    Curious as to how the diacs and air wpuld interact with fork blades in peoples minds.. ? Close blades or big gaps? Britain briefly played with wide splayed forks in 2012....


    Position will be developed with a friend of mine who is a very good bike fitter but will ultimately be limited by my physical disabilities and limotations. We will worl woth them but agreed my body is going to be the biggest factor lol

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    Registered User fantapants's Avatar
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    Quote Originally Posted by BLSTIC View Post
    So... out with it. What's the competition and what are the rules?
    Ok basics.

    Paracycling. Its a 1000m time trial standing start. Max speed maybe 60kphr.

    Frame must be traditional triple triangle design and esentially fairings are banned. Everything that is attached to the bicycle must be structural in nature.

    Similar in design such to the english tt rig.... But obviously no gears or brakes...

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    Registered User fantapants's Avatar
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    There has also been recent questions raised as to the ideas of how close the rear wheel should be to the cut outs...

    Recent practice and common sense woyld say ad close as possible but "look" and a few others known for smarts have been doing bikes with large gaps betwren the frame seatpost aand the rear wheel...

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    Registered User fantapants's Avatar
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    Have the stuipd helmet aorted

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    shave face - must be good for 3kmh

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    Down with ma homies Greg Rust's Avatar
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    There’s a trade off between hamstring flexibility to generate power and low handlebar height aero.
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    Registered User fantapants's Avatar
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    Quote Originally Posted by Greg Rust View Post
    There’s a trade off between hamstring flexibility to generate power and low handlebar height aero.
    Yeah i wont be sacrificing horse powrr at all.

    I have so little muscle strength to start with snd the speeds are so low i figure it would be counter productive to go chasing epic aero at expensive of constiricted power.

    But before we got there i think the tumours and stuff in the stomach will hsve become an impediment to low long before anyways lol

    Width of the front aero is something ill have to work hard on.

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    Oh ok. I won't be able to help much if you aren't using fairings.

    Except investigate short cranks. They open up the hip angle and straighten the leg. This allows you to lean down further for the same chest-squeezing (to get more aero for the same power) and puts less strain on your knees. The seat position rises by the distance you shorten the cranks, however if you're building your own frame or want to mess with wheel sizes you can lower the bottom bracket to compensate. Smaller diameter wheels may also fractionally reduce drag because the top of the wheel (which is travelling faster than the bike thus is responsible for disproportionately more drag than the bottom or the frame) is smaller than previously.

    You can easily compensate for the leverage change with gearing, many people forget that.

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    Perhaps look at F1 cars suspension, the wish bones are also used for aero. might be able to pick up some ideas from them.
    Another thought is around the goose neck and forks, all bikes seem to split straight out of the goose neck. My thought is keeping it straight for a bit and using for some aero
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    Down with ma homies Greg Rust's Avatar
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    So could you build a frame that is like a recumbant but leaning forward and without the dicks.

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    Registered User fantapants's Avatar
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    Quote Originally Posted by BLSTIC View Post
    Oh ok. I won't be able to help much if you aren't using fairings.

    Except investigate short cranks. They open up the hip angle and straighten the leg. This allows you to lean down further for the same chest-squeezing (to get more aero for the same power) and puts less strain on your knees. The seat position rises by the distance you shorten the cranks, however if you're building your own frame or want to mess with wheel sizes you can lower the bottom bracket to compensate. Smaller diameter wheels may also fractionally reduce drag because the top of the wheel (which is travelling faster than the bike thus is responsible for disproportionately more drag than the bottom or the frame) is smaller than previously.

    You can easily compensate for the leverage change with gearing, many people forget that.
    Wheel size is again set by rules,

    Crank length is again a funny one. I dont disagree with you, however in my specifoc situation, the leverage advantage of a longer crank is actually proven in the getting it going 100m start. This is inportant to me as my condition means i have terrible bloods. So will rely heavily on my start as an advantage over my conpetitors who have poor starts and good finish. I will be the opposite lol

    The lack of fairings is a pain. I have a little freedom for creativity if i can justify the existence of the fairing as a structural part of the bike. I just cant add stuff that is purely "fairing"

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    Registered User fantapants's Avatar
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    Quote Originally Posted by Tripper View Post
    Perhaps look at F1 cars suspension, the wish bones are also used for aero. might be able to pick up some ideas from them.
    Another thought is around the goose neck and forks, all bikes seem to split straight out of the goose neck. My thought is keeping it straight for a bit and using for some aero
    Have been google imaging my heart out... But this is where i get caught up in the low speed vrs high speed stuff... And trying to decipher myth from fact in the f1 world is do hard lol

    The forka i have planned are, in my head at least, very sinple and "clean" from an aero point at least....

    Again similar to rob english design but i dont think i can get as narrow in the elbows or as low.... My flexibility was good prior to everything and its something i work on, but with the stuff in my guts, i dont think ill have the capacity to get that low without sacrficing strength.

    ultimatly this race will be a comprimise, as i imagine all paracycle rides are.

    I seem to be gaining strength well. Weights is going well. But my fitness is going along shithouse. There is very little improvement and speaking to my specialist there isnt much to be expected from my lungs and heart. So for me, yhe kilo will be old school tactics of hit it super hard and heavy and simply hold on. Im aiming to try and utilise as big a gear as possible to help limit the effects of drop off...

    If i can drive a big gear off a good starting lap and let it roll itself out, im confident i can be competitive.

    So the bike needs to be stiff enough to cope. As was pointed out last night by someone, its not like im gonna be shane kelly strong, so focusing on smaller aero tubes might be worth the gains....

    I can get the front end down to 28mm front width in total i think.

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    I'm not sure how longer cranks could give you an edge on the start if your overall gain ratio was the same (the distance the pedal moves vs the outside of the wheel, relative to the frame. Accounts for all ratio changes: wheel size, gearing, and crank length). Unless you have to run a fixed gear ratio too, which is kinda bullshit if you do.

    Have you used a power meter (or a gym bike that has one) to see what strategy you can use to get the highest energy out of your body over the race? You may find that targeting lower acceleration initially (by willpower, not gearing) allows you to maintain higher power over the 'cruising' stage of the race. That's certainly how it works for me. I can do 600w for about 5 seconds then 150w after that, or I can do 400w for 15 seconds and maintain 200w for the next two minutes. I think the longest I can hold 300w for is about a minute and a half. I'm pretty unfit. Lycradudes can do that 300w continuously.
    Last edited by BLSTIC; 02-02-18 at 10:40 AM.

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    Registered User fantapants's Avatar
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    Quote Originally Posted by BLSTIC View Post
    I'm not sure how longer cranks could give you an edge on the start if your overall gain ratio was the same (the distance the pedal moves vs the outside of the wheel, relative to the frame. Accounts for all ratio changes: wheel size, gearing, and crank length). Unless you have to run a fixed gear ratio too, which is kinda bullshit if you do.

    Have you used a power meter (or a gym bike that has one) to see what strategy you can use to get the highest energy out of your body over the race? You may find that targeting lower acceleration initially (by willpower, not gearing) allows you to maintain higher power over the 'cruising' stage of the race. That's certainly how it works for me. I can do 600w for about 5 seconds then 150w after that, or I can do 400w for 15 seconds and maintain 200w for the next two minutes. I think the longest I can hold 300w for is about a minute and a half. I'm pretty unfit. Lycradudes can do that 300w continuously.
    Im not extremly intelligwnt with the engineering ill admit.

    The argument goes back forth that longer cranks gives more leverage.

    All the studies i have seen show that crank length has no bearing on rider power over the range of 120 through to 200 (tested range). These were all in a road riding test where gears were selectable.

    The only time crank length has been shown in studies to be beneficial is in the first 100m or so standing start situation on a fixed gear (so bmx or track where you cant change gear mid race) where consistently the research has shown measurable gains through crank length increeases.

    After that i get lost as to the explanations given.

    I know from personal experiance i can spin faster on short cranks. We used 120s at the ais for max speed tests ans gained something like 60rpm lol.

    As to the "pacing" plan we will try a few different tactics. I used to be pretty good at the final lap if i gave myself a breather for 75m... Just float on the pedal for a 1/4 lap and then dig again. But with my blood condition and damaged lungs etc we recon aiming on brute strength will be the best bet. Will see how the diferent gears and different tactics go and go from there. Id love to get a power meter.... But funding. I "may" need to get a shimano dual leg power meter to help provide evidence to the para guys that my left leg is actually fucked and im not faking it. If i can show the signifocant power differentisl profiles maybe they will feel better?


    The guys im competeing against are leg amputees and such. So i have a distinct advantage in the start of the race being able to get away clean and "relatively" fast... They will destroy me in the final lap, depending on how i can manage the lactic etc. The bigger gear can help as its easier to pig root a big gear than a little one lol

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    Ah ok. The crank length studies that I've read didn't allow for training. It was just random allocation of crank lengths on one day. No serious variance, but I couldn't help wonder what would happen to ones power if you had 135's or something for a month rather than a single day. Would it improve?

    My power was recorded on a gym bike, but the ones I use are weird. The resistance is a function of power (varies depending on rpm, lower rpm = higher torque resistance) and the power display is the 'target resistance' not 'measured power'. But it was a guide that seems accurate-ish based on my 'feats' compared to other known people

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    Registered User jezza323's Avatar
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    I assume you will be building the bike to suit fanta? Id just start by replicating the current track setups with a bit more upright geo to suit you, its really going to make 2/5ths of fuck all difference in the end, but fun to play with all the same! Are you planning to make forks? Or use something already available?
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    Registered User fantapants's Avatar
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    Quote Originally Posted by jezza323 View Post
    I assume you will be building the bike to suit fanta? Id just start by replicating the current track setups with a bit more upright geo to suit you, its really going to make 2/5ths of fuck all difference in the end, but fun to play with all the same! Are you planning to make forks? Or use something already available?
    Yeah building it from scratch with aero chromemolly from the states.

    Im well accepting of the fact its all worth about 4/5ths fuckall in the end REALLY... But the big thing for me is placebo. I believe very strongly in being happy with your equipment and if you feel like the tom tits, you will ride like the wind . So i figure if i put a bit of effort into the science of it rather than just "looks good aero" it will make me feel a bit better on the start line when i front up agaisnt the guys with 15 grand worth of french carbon fibre

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    A couple of other thoughts on crank length.

    You should be able to get cranks in 5mm increments, and mix crank length and chain rings to get your gearing just how you want it.

    Shorter cranks are sometimes used in other disciplines for ground clearance, this is normally only a consideration on bikes with lots of suspension travel, but as you are building your own frame just consider this in the context of your bottom bracket height.

    Totally agree about the need to be confident in your equipment, often your biggest competitor is “the little man in your head”. It’s worth putting the time in to get it right.

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    Registered User fantapants's Avatar
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    Yeah the bike will be time trial specific so no need to worry about ground clearance or cornering clearance as the boards are all banked ( although my training velodrome is not banked so i cant go too stupid)

    Have been reviewing the tt positions of the current pursuit and kilo riders. Dunno how successful ill be in chasing tjat sprt of position (im short as fuck and stocky, pkus with the et belly it all eorks against me... But i have something work towards lol...)

    Old mate glaetzer seems to be the slickest out there.... His times back it up with another sea level world record yesterday.



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    Hungry Hungry Hippo Tripper's Avatar
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    Wonder if there would be any aero advantaged to be had if the frame curved down around the front wheel. NFI if the rules would even allow that
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