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Aero - cost effective and most important upgrades

simbil1simbil1 Posts: 620
edited June 2008 in Workshop
How do I get more aero on a normal racing bike?

Things I've considered:

Position - aero clip on bars
Frame (won't be buying but would be interested to hear how much of a difference it could make)

Any experience on what difference any of the above makes would be really useful :)


  • MorpethMorpeth Posts: 104
    Are we taliking TT riding here?
  • simbil1simbil1 Posts: 620
    Triathlon, so effectively TT I guess, except there will be limits on how much clothing can be changed in transition.
  • Get your position analysed by a professional.

    That will be the best value for money.

    85% of the drag is you and 70% of your effort is overcoming this drag alone.

    After that Get some fast wheels. Deep section with good hubs
  • Monty DogMonty Dog Posts: 20,614
    Position first and certainly tri-bars - you may need to fit a shorter, sloping stem and perhaps an inline seatpost to get yourself more 'forward'. Aero wheels will only start to make a difference if you can hold a speed in excess of 25mph - so unless you can ride a 10 mile TT in less than 24 minutes, hold off on the aero wheels. An aero helmet will help more than any clothing - provided you can hold your tuck.
    Make mine an Italian, with Campagnolo on the side..
  • araceraracer Posts: 1,649
    Monty Dog wrote:
    An aero helmet will help more than any clothing - provided you can hold your tuck.
    More than the wheels too.
  • methodmethod Posts: 784
    Monty Dog wrote:
    Position first and certainly tri-bars - you may need to fit a shorter, sloping stem and perhaps an inline seatpost to get yourself more 'forward'. Aero wheels will only start to make a difference if you can hold a speed in excess of 25mph - so unless you can ride a 10 mile TT in less than 24 minutes, hold off on the aero wheels. An aero helmet will help more than any clothing - provided you can hold your tuck.

    The bit about the wheels isn't true, an aero wheel helps at any speed.
  • simbil1simbil1 Posts: 620
    Thanks for the replies.

    So putting the list in order of highest cost:

    Position - aero clip on bars, stem, seat post, pro fitting

    From the answers so far, it would see that position is the most important followed by helmet and wheels. As good aero wheels seem to cost a lot, the best things to focus on seem to be the helmet and the position?
  • acorn_useracorn_user Posts: 1,137
    Gipiemme Techno 716 wheels are really deep, and possibly quite aero, and inexpensive since they are alloy, not carbon. They are a bit heavy, but that does not matter that much for TT (and back in the day, teams used to ride their Campagnolo Shamals in the mountains!).
  • cougiecougie Posts: 22,512
    What races are you doing though ? Some tris can be very hot and hilly and that could make an aero helmet a no-goer.

    But yeah - position is key, so sort that and get some tribars. Then get an aero helmet.
    Then have a look at aero wheels.

    I wouldnt get really censored about it though or sopend 1000s - most people dont train properly and thats probably the best thing to do.
  • Monty DogMonty Dog Posts: 20,614
    Wrong! You appear to be selective in your interpretation and for whatever reason feel that a new bike is going to make the difference when actually you have to work on the engine first.
    1st=position - get tri-bars and maybe an adjustable stem to start tuning your position. Only when you find that you have reached a plateau / or can no longer got lower / flatter should you start looking for a more aero frame - and it will be an 'informed' choice not buying something because you 'think' it will make you faster. Adapting to a new position takes time - so don't expect immediate results.
    Aero wheels can help but only at higher speeds and don't make as much difference at lower speeds - particularly if your position is akin to a brick. Go to a triathlon and there are guys still doing 75minute 40km bike splits with fancy carbon wheels.
    An aero helmet can help, but only if you can hold the right position too.
    Make mine an Italian, with Campagnolo on the side..
  • simbil1simbil1 Posts: 620
    Thanks for the response and I appreciate the advice.
    Just to be clear that list was in order of cost and not in order of what is most effective and economic based on the advice so far. As I said at the end, I'll focus on position (tri-bars etc and my coach can help with the actual ride position) and a helmet. I'm not sure about the helmet as I tend to drop my gaze so I'll see how that goes.
    This will be my first season of tri's and I plan to do Sherborne in 3 years (aim high right?) :)
  • chrisw12chrisw12 Posts: 1,246
    Don't forget, lots of little details can add up and cost you nothing money wise as well. For example 'apparently' a loose flapping number can be quite aero costly. Also think about clothing (perhaps not an issue in triathlon) but tight is best, don't go wearing baggy cycling tops.

    Also when you do race, think about tools, food and drink placement, there's little point having an aero bike and then loading it up like a pack mule.

    Ok not quite what you asked but worth thinking about if you want to try and get as aero as possible on a budget.
  • simbil1simbil1 Posts: 620
    Thanks Chris. I've noticed a lot of tri riders have the drink mounted behind the saddle - is that worth while?
  • araceraracer Posts: 1,649
    Not if you've got frame bottle mounts - wind tunnel tests have shown that bottles behind the saddle are slower.
  • methodmethod Posts: 784
    aracer wrote:
    Not if you've got frame bottle mounts - wind tunnel tests have shown that bottles behind the saddle are slower.

    Not neccessarily, it depends where behind the saddle they are, but they can be slower.
  • araceraracer Posts: 1,649
    I'd love to see a wind tunnel report which suggests any behind the saddle position is better (given that putting a bottle in the frame is generally more aero than not having one there). That's a serious, not a sarcastic comment, as I have behind the saddle bottles on my TT bike, given there are no frame mounts (hence I'm suggesting what I have is worse!)
  • methodmethod Posts: 784
    I found this from Slowtwitch, probably lots more if you search further.

    These bits are from John Cobb, so you can trust the results.

    With out getting into the specifics of a brand by brand of frame, discussion, a front Profile bottle is generally a good choice. The length of the straw will matter and it should be as short as is useable. Having those dual straws or a very long front straw can cause more drag than a good front wheel can save. Rear systems can be measurebly faster than no rear systems but the shape of the top of the water bottle is usually the main deciding factor. For systems that ride the bottles up higher above the back, flat top bottles are very important. For systems that carry the bottle very low, rounded top bottles are the answer. Having all you "stuff" strapped to the rear system is a completely bad plan. The on going frame question/ answer is ...... I would use a bottle on the seat tube most any time and not fear the results, downtubes bottles are not always the best choice. Camelbaks that are completely filled up are not very good aero wise. We use camelbaks for 40k TT's but only put in a few ounces of fluid. Putting a Camelbak bladder in the hollow tail section of the TT helmet works very well.
    New Blog -


    I finished a week of testing riders two weeks ago and we had run some of these test. Here are some numbers to look at. These are the average drag in Grams for a sweep of "0" - "20" degrees.
    [1] - 5'9" male @175lbs - Trek TTX w/ Trek aero bottle on seat tube. 3072gr.
    [2] - Trek TTX w/ No bottles 3059gr. ** 20 gr. is nothing that will show up in the real world.
    [3] Cervelo P3 No rider - Round Rocket Science bottle on Down tube - 1024gr.
    [4] P3 No rider - Trek aero bottle on down tube - 1079gr.
    [5] P3 No rider - No frame bottles - rear Hygro tail - 1198gr. Not having a rider probably was not a fair test for the rear setup.
  • methodmethod Posts: 784
    This was what I was looking for: ... ttles.html

    The cost of water bottles
    7.7.03 by John Cobb
    The pursuit of better technology is a humbling experience. For more than a decade I’ve traveled to wind tunnels to perform tests on bikes and race cars and the athletes that ride and drive them, all in an attempt to demystify the conundrum of air in motion. The aerodynamic cost or benefit of water bottles has been a popular topic on internet forums in recent months, and my experience in testing them—the subject of this article—was humbling because my results differed from my preconceptions, and from my public comments on the subject prior to doing the testing.

    Back in '86 or '87 I tested water bottles in various locations on bikes and we learned some good things. Almost all the bikes at that time, however, had round tubing. Most of the bikes were made of steel. That tubing was not very large and the down and seat tubes were only just over an inch in diameter. There were a few aero tubes out of steel, but they were small—just under a half inch wide by one and a quarter inches tall. This is half the size of today’s aero aluminum and carbon shapes, in both the X and Y axis. These smaller tubes didn't test well with standard round bottles attached to them. We also didn't know anything about the relation of side winds to overall drag.

    As the interest in the knowledge of aerodynamics picked up we were testing all kinds of things: equipment, body shapes, wheels, frames, helmets, and just an ongoing list of cycling-related products. As part of all this testing, a few—most notably Jim Martin—developed computer programs that helped us translate the effect of drag to one’s bike time. I believe these time/drag calculaters are getting pretty good, and I’ll apply some of them further in this article.

    This most recent testing on several water bottle configurations took place at the Texas A&M wind tunnel. I chose a Quintana Roo Tiphoon in 55cm, which in terms of shape and style is a pretty representative bike. It had shaped aero tubes and was set up for triathlon racing, with Mavic Kysrium wheels front and rear, Syntace C2 clip-ons, pursuit bars, bar-end shifters and a round seat post with about 6cm showing. My test pilot was Bryan Cowan, who runs our Shreveport Bicycle Sports store. He's 5'10" and weighs about 150 lbs., races at the Ironman distance and occasionally joins me for a Krispy Kreme donut.

    This was a pretty typical race setup, so as a reference point I started by testing the “base line” bike, with no bottles or cages anywhere, just rider and bike. I had decided that for this and all the water bottle tests I would use a "bell curve” to try to estimate a real-world effort. I estimated, in other words, the percentage of time that I guessed each wind angle would be felt on the bike during a representative ride, so as to approximate the winds faced in a typical race. I used "0" yaw (meaning the rider would face no side winds), all the way up to 30 degrees of yaw, at 5-degree increments. I decided that 0 = 15%, meaning that no side winds would be experienced by the rider during 15% of his ride. He’d experience a 5-degree yaw 20% of the time (5 = 20%), and the balance of this hypothetical ride broke down this way: 10 = 20%, 15 = 15%, 20 = 15%, 25 = 10%, and 30 = 5%.

    As further explanation, the bottles referenced in the testing below were only the standard, round bottles you're most used to, in the smaller size (not the tall, 25 oz. bottles). The only exception to this was when we tested a front bottle, and the one we chose was Profile Design's between the handlebar model. Our reference to "high" and "low" behind-the-seat bottles denotes the two different styles of bottle carriers today. By "low" we mean those in which the tops of the bottles are at about the same level as the top of the saddle, and "high" means the bottom of these bottles is almost at the height of the top of the saddle. In both cases we tested two bottles side-by-side in their carriers.

    One of the more impactful things we have learned over the years is that small changes in one area of the bike affects other areas, e.g., a rider’s legs might change the results of how wind affects a particular bike tube. To be as real-life as possible, then, I placed Brian aboard for these tests, and on a bike set-up that was not tuned for minimal drag, but in a good, comfortable and powerful Ironman set-up. The baseline run for the bike and rider was 7.537 lbs. of drag at 30mph, and I felt this was pretty typical of the drag a good bike and rider would generate for that distance (except for the difference various aerodynamic wheels would represent). This means that every exposed square inch of surface, bike and rider, has a force of 7.537 lb. to overcome at this speed (I realize that 30mph is not a typical Ironman speed. It is the speed used in wind tunnel tests performed by most of the industry, and we use it to be able to compare with the studies we and others are doing).

    There were several things I wanted to test: standard water bottles, front bottles, Camelbacs/Hydropacs, rear-bottle setups and aero bottles. I didn't quite get it all done—the economics of $500 per wind tunnel hour impinges on the degree of comprehension in our tests—but I did test the things I felt were most important. We realize that people make important equipment decisions based on testing like ours, so we spent a good bit of time trying to be sure the results we did achieve were pretty accurate.

    I'm going to publish two sets of numbers below, one is for a 40k distance using a 225-watt average and the other is for an Ironman distance using a 150-watt average. I think these are pretty typical numbers for a decent age-group athlete over these two distances. The drum roll please…

    Ave. Drag 40 km 112 mi
    base bike, no bottles 7.537 1:07:26 5:56:48
    down tube bottle only 7.370 1:06:58 5:54:29
    seat tube bottle only 7.433 1:07:09 5:55:22
    bottles on both tubes 7.598 1:07:36 5:57:38
    Profile bottle only 7.337 1:06:53 5:54:01
    Hydropac w/40oz. only 7.556 1:07:29 5:57:01
    Never Reach only 7.561 1:07:30 5:57:07
    behind-seat low bottles 7.658 1:07:45 5:58:27
    behind-seat high bottles 7.578 1:07:32 5:57:27

    What does all this mean? Well, you need fluids to finish triathlons, and it turns out that having a down tube bottle on an aero frame isn't all that bad. It also means that I, once again, must eat humble pie, because I have been preaching that frame bottles are bad. Interestingly enough, having both down and seat tube bottles is in fact bad, so I was half right. I was surprised how effective the down tube bottle was. My guess is that it breaks the air around the seat tube, so the bike acts more like a frame with no seat tube, so, less drag (Softrides are examples of this phenomenon).

    I was initially skeptical about these results, so we got out the smoke wand and put some wool tufts on the frame in various places. If you videotape the smoke and slow the replay you can see how all this might work. I could not see it by just watching the smoke, hence our need to slow everything down. Then you could see the interaction of the tubes, the bottles and the rider’s legs. I went back through some of my early years testing and realized we never tested frames and bottles with riders—only the bare bikes—so I'm pretty sure it's the rider that makes for a lot of these changes, combined with the much larger aero tubing.

    What about all the different front- and rear-mounted water systems? We’ve got more testing to do in these areas, but the benefits of carrying enough fluid so as to keep properly hydrated far outweigh the aero differences. I think the handiness of the "Never Reach" system, as an example, makes these something to consider—whatever system makes fluid easy for you to drink from, and doesn't eject your bottles, would be a wise choice.

    As always, I plan to do some more testing and try to continue to unravel some of these mysteries. I didn't get the aero shaped frame bottles tested, for example. I had done a good bit of that a few years earlier when I was designing a new frame for Lance, and found that an aero bottle worked very well on his seat tube. But aero frame-tube bottles aren't readily available at this time, so I've deferred that testing for now.
  • simbil1simbil1 Posts: 620
    Interesting stuff - thanks guys.
  • SDPSDP Posts: 665
    living in the real world best improvements are in order

    TRI BARS/correct posn**
    well fitting clothes
    rear wheel ( disc or deep sec )
    ** specific frame
    good aero cage/bottle ( arundel ??)
    aero chain rings
    cable routing ....
  • araceraracer Posts: 1,649
    As I mentioned before, the helmet is worth more than the front wheel.

    method - the report in your second post pretty much agrees with my comments - either of the behind saddle setups are worse than a bottle on the downtube.
  • methodmethod Posts: 784
    certainly looks that way.
  • araceraracer Posts: 1,649
    method wrote:
    certainly looks that way.
    :? I thought you were disagreeing with me!
  • methodmethod Posts: 784
    i was to a point, I thought I'd read somewhere it depends on the positioning, it looks like it does, but isn't better than tube mounted.

    I'm happy to admit when I'm wrong!
  • andy_wrxandy_wrx Posts: 3,396
    I initially thought a seat-tube mounted bottle would be more aero than one on the downtube, then found I couldn't (alright, daren't - I tried it and scared the hell out of myself :shock: ) reach it from on the aerobars.

    So I decided that mounting it on the downtube, being able to reach it from the aerobars, drink from it and return it back to the downtube, was going to be far more aero than having to get off the aerobars onto the horns to reach it and drink !


    Spending thousands on carbon disc wheels looks faster, but getting a decent position is going to gain the time, and doesn't cost much if anything at all.

    It needs to be a position which is comfortable enough to stay in for the whole race.
    If your back's killing you and you have to get up off the bars, that's not very aero...

    If you're a triathlete doing Ironman for 112miles and then running a marathon afterwards, then that position might be a bit less extreme than could be endured for a 10mile TT

    Have a look on at some of the bikefit articles, see what they say in terms of roadbike, TT bike and 'multi-sport' positions
  • simbil1simbil1 Posts: 620
    Cheers Andy, not being able to reach a saddle mounted bottle does sound like a bit of a downer!
    Tri bars should be arriving tomorrow :)

    I had a good read of the tech section on slowtwitch - there's a lot of good stuff there.
  • Jeff JonesJeff Jones Posts: 1,865 Editor
    method wrote:
    Ave. Drag 40 km 112 mi
    base bike, no bottles 7.537 1:07:26 5:56:48
    down tube bottle only 7.370 1:06:58 5:54:29
    seat tube bottle only 7.433 1:07:09 5:55:22
    Right that's it, I'm moving my bottle from the seat tube back to the down tube :wink:

    Seriously, even if it doesn't save 9sec/hr purely on the basis of drag, it's easier to grab when you've "assumed the position".

    I'm surprised that they ever tested stuff like rear-mounted bottles without a rider on board.
    Jeff Jones

    Product manager, Sports
  • araceraracer Posts: 1,649
    Jeff Jones wrote:
    I'm surprised that they ever tested stuff like rear-mounted bottles without a rider on board.
    Agreed - that does seem a good way to waste money on tunnel time, given the whole point is to sit in the rider wind shadow.
  • ShavedlegsShavedlegs Posts: 310
    I agree with pretty much what everyone is saying, you need a good comfortable tuck which calls for aero bars, and a helmet would be next on my list.

    What no one has mentioned is that Profile Design do a forward angle seat post, effectively making your seat tube more at a 78 degree similar to a Tri bike. The steeper angle will help with the tuck, getting more power and test have shown you can run better afterwards.

    A TT specific saddle may be an idea, you'll need to hold that tuck for some time, so comfort is a consideration.

  • bahzobbahzob Posts: 2,195
    Check out the following link on the extremely good Tri-Talk site.

    It ranks various items in terms of overall effectiveness and cost per second saved.

    Also has a link to the podcast which went into more detail about the list.

    Re water bottles Tri-Talk seems pretty authoritive re these: For time trialling best seems to be to have a Profile bottle on the tribars as apparently even if it's empty it improves aerodynamics. It also had an update on the John Cobb tests mentioned above in the context of looking at a newly launched dimpled bottle.

    "That test that John Cobb did was from 2003. Much has changed since then. It is hard to find a real tri bike now that does not have a true aero seat post. Very few tri seat posts and tubes are cylinders any more. In 2003, when the first tests were done, this was not the case. If your bike is a true tri bike with an aero down tube and seat tube and seat post, I would not place a water bottle on the frame. You are best with the aero drink up front and high mounted water bottles in the back. If it is a standard road bike that you have converted to a tri bike, and the seat and down tube are standard rounded cylinders, then yes, a dimpled water bottle seems to be the way to go. Or, if you are doing an Ironman, and you need lots of fluids with you, you may have to use the water bottles on the frame even on your tri bike, and then these dimples aero bottles would be a good idea."
    Martin S. Newbury RC
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