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thinking about doing some time trials this year and have kind of a silly question regarding aerodynamics. do water bottles make that much of a difference on the drag of the bike? I have heard to run both bottles even if one is emply and I'v heard not to run bottles at all on the short TT's? just didnt seem lke it would make a big difference to me but being new I will definitely need any advantage I can get. While I'm at it do the TT helmets make a worthwhile difference as well? thanks for the input
 

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Cpark
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smbrum said:
thinking about doing some time trials this year and have kind of a silly question regarding aerodynamics. do water bottles make that much of a difference on the drag of the bike? I have heard to run both bottles even if one is emply and I'v heard not to run bottles at all on the short TT's? just didnt seem lke it would make a big difference to me but being new I will definitely need any advantage I can get. While I'm at it do the TT helmets make a worthwhile difference as well? thanks for the input
I guess that depends on the speed, terrain, length of the course, frame shape, wind direction and how much time you want to save.
I used to use a camelbag under my skinsuit and do away with bottle/cage (about 10 years ago).
I can't imagine the time saving is substantial.....maybe around 5 seconds for a flat 40K?
 

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There was a wind tunnel study completed a few years ago by some MIT students that were cyclists and they found that running a water bottle was better than not running one.

However, that was on older TT bikes and regular road bikes....not the newer aero/wind tunnel designed bikes. With a new TT bike you are better off not running one on the bike, or using an aero designed bottle. For short ITT's...20K or less there is no need for one anyway over that it gets a bit debatable.

As for TT helmets...They do make a difference 30-45 seconds over a 40K ITT. The question is whether the $150.00 for a decent aero helmet is worth it to you. If you are going to be doing a lot of TT's or stage races, then every second counts and they are worth it. If you are just doing them for fun and baseline data...not much use in spending the money.
 

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Probably won't be enough to quantify at your/our level. For pros, where they are perfectly fit to their bike and have all the gear, they can look at that. Do you have a TT bike or are you just using clip-ons? If you are using clip-ons, then don't worry about it.

The biggest aerodynamic hurdle you will have is your TT position. If you don't have that down pat, don't worry about the little stuff.
 

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TAPUS is exactly right. The thing on your bike that makes the biggest difference in the Wind is your body. Make sure you have a highly aero position and you can hold it for the length of the race. Most people do not have the core strength to do it.

The body pike is a great exercise to help with your strenght. There is a free 5 minute cyclo-club link below.
 

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The OP was asking about water bottles (not his position on the bike...). The short answer is that a round bottle introduces drag due to the turbulent airflow in its wake. But, an aero bottle acts like a fairing and makes the bike faster than without it (look at the Garmin riders in the ToC ITT with empty aero bottles on their bikes). These are typically made by arundel (the chrono) http://www.arundelbike.com/chrono.html?p=1.1.1.5 Bontrager also makes one (with dimples).
 

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My point is--yes, it does make a difference. But unless you have a TT bike, a virtually perfect fit, TT helmet, skinsuit, wheels, etc, it probably isn't going to make enough of a difference.
 

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I agree with other posters that it is a small thing to worry about when compared to everything else. However, in answer to your question it is faster to have a seattube mounted bottle than no bottle at all.
See here, I think this guy has done the homework on where to put a bottle.
http://www.cyclingnews.com/photos/2...ornia09/california096/JD_09TOCstg6_leipheimer

And I know this guy was in the tunnel recently.
http://www.cyclingnews.com/photos/2...09/california09/california096/JD_09TOCstg6013

and this guy,
http://www.cyclingnews.com/photos/2...09/california09/california096/JD_09TOCstg6019

and this guy,
http://www.cyclingnews.com/photos/2...009/feb09/california09/california096/DSC_0208
 

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tt helmets work, IF you get one that works w/ your postion and body type. i used one in the kilo at masters track nats last year, and my bested my previous PR by 2.5 seconds, which is huge for a race lasting just over a minute. some of if HAD to be the helmet. my old PR was set about a month before nats...same bike, same track, same everything.
 
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