Dr Pooley's Aero Bike Fit | How To Find Your Time Trial Position
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- เผยแพร่เมื่อ 20 พ.ย. 2018
- We often talk about aero gains as “free watts” - because if you can get more aero, you go faster for the same power. In this video, we'll look at how to set up and fine-tune your time trial position to optimise your aerodynamics. Who doesn't want free speed?
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A lot of riders, if they can afford it, will get a time trial bike for triathlon or time trials. The assumption is that a time trial bike is always faster - but that’s not always true. Set up wrong, a time trial bike is no more aero than your regular road bike. And the details of the position are super important for both aero position and power output.
Let’s start with body position - this is where you can save the most drag. The drag force is directly proportional to your frontal area, which is the size of your outline seen from directly in front. So if you can reduce your frontal area - usually by getting lower at the front so that your head and shoulders are in line with your bum - you will definitely reduce drag. It’s complicated by the fact that your drag is also proportional to your coefficient of drag, which can be described as the “smoothness” of your total shape - which is also affected by body position.
If you reduce your frontal area but increase your coefficient of drag, you won’t be making yourself faster. And the coefficient of drag is difficult to measure without a day spent in a wind tunnel - although you can do it with a carefully instrumented field test. But in general, unless you contort yourself into a really funny shape, you shouldn’t make your drag coefficient hugely worse by getting lower.
Do you have a time trial bike? Let us know in the comments. 👇
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Have you ever ridden a time trial? Let us know. 👇
No I bloodywell haven't. And hopefully I never will. I rode time trials in stage races and as I was usually, er, fairly lowly placed, tts were counted as a rest.
Time trials are truly horrible.
Well, Mr. Grumpy, you're really DAFT!
Yes, and I LOVE them! They are my favorite race category... that feeling of pure speed, the chance to get inside your own head and dig deep. The rest of the world disappears, and it is just me, my bike, and the road.
Ok, Eric. But you talk of pure speed. Time trials are not "fast."
If you want pure speed, take up track racing.
Don't get me wrong, I'm really delighted you enjoy tts.
Global Cycling Network If you count Le Tour De France 2017 game on Xbox One then yes I have, if not no I haven't.
who else want to see the evolution of Si's time trial with a series of him training to compete on a local TT?
Or maybe Ollie. . . #project49
I want to see him try for an hour record.
Yess
@@ZOB4 Project 49 was excellent - I'd be keen for GCN to do some multi-part articles like that
Yes please.
Emma is the best thing GCN ever added, such pro insight
well said
Besides her knowledge its nice to see how someone of smaller statue sets up her bike.
I would love to see some more TT style videos! Just imagine Lasty, Si, and Dan trying to get a TTT to work properly!
I love how blunt Emma was about the control tech promo
When Emmas speaks, I listen.
Love the jersey hanging in the background
4:58
Simon - “So what actually is your coefficient of drag”
Emma - “Well, the coefficient of drag is just a coefficient in the drag equation”
Queue Mr Spock eyebrow raise from Simon - GCN Classic!
Emma said that on purpose. Raised eyebrows are more aero.
It was bollox really
Very informative. I was hoping you would spend sometime discussing the saddle position as the saddle position changes quite considerably on a road bike position vs time trial position.
The Doctor is in! This is awesome - loving your presenting, Emma!
Great video - There aren't very many people who can speak with the level of authority that Emma can on this subject. Just a subtle reminder of that with that jersey in the background.
Cheers z, true! 🌈
I didn't even see the video. Lol. Her authority still came through loud and clear. :)
I actually needed help on this , thx GCN my joints will be happy now
Ema and Si are so fresh in this video. I really enjoy to see it. GCN miss Ema for sure!
Exactly the video I was looking for. Fitted of a 56" road bike and buying a 54" TT bike. Thank you!
I love that GCN don't dumb things down. Awesome video Emma!!!
As ever a very very good video, Si and Emma work so well together, thanks o you both
Well played, GCN. Nice one.
I really enjoyed this episode. Emma is cool stuff too. It’s neat listening to her experiences and knowledge.
I first experienced 180mm crank arms when I bought my XL Moonlander. I absolutely love them. I am only 6ft tall barefoot but am ALL leg (I forgot my pubic bone-to-floor measurement but it’s insane). So I’m always jacking my saddles up and shortening my stems. I’m wanting 180mm on all my bikes now after getting the XL framed Surly.
I was talking to a wind tunnel expert and he told me having your aero bars straight like that causes a scoop at the front creating a lot of drag. If you place the aero bars pointing up more you create a shape that breaks the wind and it also takes more stress off your back and you can actually get your head lower. Try it yourself
I made the same observation and tilted my bars up not only to close the distance between hands and head but to feel more comfortable turning the pedals. My times improved as a result. Plus, in watching the TdF this year i noticed many riders had the same bars tilted upwards type of set up as opposed to dead flat and low. Anecdotal evidence!
Requiredfields2 I noticed that aswell this year a lot more pros are starting to tilt their bars up. I used to always get strain on my back and it is now a lot more comfortable
This is great! Fascinating, and super presentation. Thanks Emma and Si..
2 years later, he's smashing the GCN team on a time trial bike!
Top video - stuffed with honesty and humour and pitched at a really relatable level. 👌 Well done Emma, Si and team.
Cheers Rory! Really appreciate your support 💪
WE ARE WATCHING THIS SPACE! And looking forward to seeing Si compete at a time trial and Emma in a cx race. Awesome! :P
YES!
It's a deal! :D
Project 49 w/Si, Emma and Ollie! Go onnnnnnnn.
Nope I'm just getting started and you guys are helping me a lot
Excellent video. I thought saddle choice, position & tilt might have been considered.
Any chance you could talk a bit about the difference between a pure time trial fit and a longer distance triathlon fit where comfort is more of an issue? Sounds like it would make a great video for your sister channel GTN.
I like how Emma had her CV / Resume hanging from the shelf in the background
This is perfect, thank you Emma & Simon. Love the magnet and coin idea! I might put a really super-powerful magnet in my jersey so I don't have to train up my neck muscles! I don't have TT bike but do use aero-bars on my local circuit.
yea clip ons work pretty okey
I'm sure that Si would not be long on a frame that small but still, a nice intro to the subject. What I thought was missing was some discussion about the concept of pad stack and reach and how to measure it. Currently working to better my fit on my new Trek Speed Concept.
Please do an in dpeth video on Q factor. You lightly mentioned IT band and knee pain, i would like to learn more. Thanks.
How about a video showing how turn a road bike into a TT bike. That would be cool.
Loved the video! Now I have to add eyebrow trimming to my pre-ride routine.
just shave em off. saves you 2 seconds
Good video ,Emma n simon.👍
Have you ever ridden a time trial? No, I have not and not sure my old body would cooperate. It was great watching the video and love Emma. She does a great job.
Well, Emma's real nice at giving Si her TT bike.. what a gal - that deserves a Lloydy beer 🍻 😋
Excellent!
Emma rocks! More Emma!
Come in Si, take Ollie on at a local 10! Sort the bike, training, nutrition and prep on the day. We'd love to see it.
I've riden a few TT's. Yeah it does take a bit of time getting used to the new body position but once you feel comfy in it your confidence gets much higher in it and you start generating more power and doing the best you can. It's you against the clock.
Nice video! _One caution:_ If you play with the Q-factor, be careful not to inadvertently move the chainline of the chainrings off-center from the cassette.
Shout out to my control tech cockpits on amazon... Really impressed with the bars, stem and seatposts Ive purchased from them.... Poor mans zipp
Looking forward to Si's timetrial race 👍
"Simon's bum creating tremendous amounts of turbulence." I couldn't help but revert back to a 10-year old male after hearing that. 💨 🤣🤣🤣
I had to pause the video for a minute to think of a hilarious reply to it, then thought it would be better to keep my mouth shut.
You need help
😂 Emma explains "coefficient of drag is" ...indepth scientific explanation.
Simon " so coefficient drag is my bum causing turbulence "
SAF1981 and Si totally missed Emma’s dig. No I don’t think your bum has any drag at all. Ergo Si, you have no a**.
YES!!! We’ve had the ‘learn to cyclocross’ series twice now - once with Matt and once with Emma. A series showing Si learning to TT would be awesome. Even better would be a Si, Ollie, Em three way #Project49. C’mon...you know you want to. Give the people what they wish for!!!!!
It's a corking idea....
My first thought is why not fit Si to a time trial bike that is the right size for him? Having said that the overall principles talked about are quite sound. I think you could have emphasized the Preying Mantis position a little more, which is now quite popular. Good luck if you do enter some TT's.
At last a TT Bike Video !!
*zoom zoom*
I would love a GCN video on getting around town on a tt bike. I have to go ten hilly km through town to get to open roads, and I sort of worry that it would be a struggle on a tt bike
Love it!!!!!
Thank you Dr Pooley! Emma is kool!
Interesting watch re bike sizing and Simon fitting. There are UCI rules to consider however also with Road TT bikes. Particularly ARTICLE 1.3.023 and the distance the extensions may extend from the centre of the bottom bracket. It is something that is checked in championship events here in NSW Australia.
Can I just say that I would happily watch Emma time trial all day... wish that we could just have her and Jon do a GCN Tech special all about time trials! She does make me think that if I was to invest a little bit of time and some money in a good pair or TT bars then I might be able to turn myself into a half decent time trialist... How good would it be to have Emma and Chris Boardman just go to town on time trials... that would be something! Excellent video as always Emma and thank you GCN for these... indulge the Science geek in us all... may that keep coming!
Cheers John, thanks for commenting! Glad you enjoyed this one - let us know how you get on TTing next year! 😉
More Time Trial content with Emma please!
Stay tuned Shaun, glad you enjoyed it!
GCN Video! GCN vs Cycling weekly TT Challenge?
Great video, it is sad that saddle options and settings are missing
Please do a "Si does time trialing" series!
Hmmm, stay tuned Habib!
Awesome! Wow
Not mentioned in the video are the UCI techincal rules for TT bike: saddle setback in relation to the BB and reach to the top of the skis from the vertical line of BB.
I always thought the "coefficient of drag" describes the flamboyancy of the outfit... 😁🤩💃🕺
Cutest doctor around😊
Please make a similar video, but for Merckx time trials. In other words, the fastest setup on a normal road bike.
How about GCN vs GTN time trial?
You guys are great to watch. But adding in discussion about saddles would have been a big benefit for those new to TT. Once you rotate your hips that far forward it puts pressure in new (and sensitive) places and your existing saddle may be miserable. TT saddles make all the difference.
As payback Emma should train Si on how to do TT's properly so that he can enter the local 10/25 mile TT's next year.
GCN, please can we have a TT Q&A at some point? Would be really helpful for us 'testers' amongst your viewers. - ta
Great idea Stephen!
Definitely miss Emma being on the show, just an amazing athlete and presenter
It’s great racing steam engines - Bristol to Bath is fun.
True!
Just watched this video again. As Emma mentioned Si doing a TT. I was wondering how his TT training is going. Dan's Sufferfest training was interesting. Also if Si was to use a TT bike to ride into work. Instead of the 10 minute shorter ride and slightly longer in bed be wiped out by the 5 minute longer ride because of the rucksack with Si's change of clothes?
Si please do at least a 10 mile TT with the TT position to see how you get on..would be great
Quick front end TT setup question (not so much about fit - more about height of base bar). I currently have a spacer beneath my stem and a small spacer beneath the rests. Am I likely to see any benefit from slamming the stem and putting a larger spacer under the rests to compensate. I've raced the season with this setup and my elbows are currently at what I feel is the best height for me (although I will experiment a bit more this winter) , so this would purely be an alteration of the base bar height. It probably makes no difference, but I just wondered if there is any air flow benefit in having the base bars lower? Thanks.
Great intro to a complex process. Everyone, do yourself a favour, get a fit from a qualified, experienced fitter and then go find a bike that fits those parameters with the most amount of adjustment in all directions from your Pad X/Pad Y coordinates. There's no point in being in an aero position if you're not comfortable and can't maintain it.
Please tell, how much important is Saddle height in TT Position on my existing road bike. I felt like touching my body with the knee when going to a TT Position. Please tell about this.
#torqueback question for Dr. Pooled. Is an aero position more important/efficient then an aero bike?
What about the limitations created by mobility during an aero fit? I am a triathlete and do the occasional time trial, and based on discussions with my fitter, I need to work on mobility in order to be able to lower my stem to get into a more aerodynamic position. I am just curious about it, because there was a lot of focus on frontal area, but not on the factors that may limit it in the same way you cannot just change your Q-factor without considering other possible issues. I also find the crank length discussion interesting. I am 5'5" and I ride 170mm cranks on all of my bikes, and I have had someone who does fit, but does not know my position say I need 165, and another person who did one of my fits in the past say I could use a 172.5 to compensate for a hip/knee issue.
_Is it just me or are pro helmets super cool!?_
What about using the glasses that Lloydy tried a while back?
Oh Emma, I believe Freud would have called you an driven overachiever. Anything you put effort into results in success.
Years ago, I had a time trial frame made for me. Not knowing what I know now, the frame size (64cm) I had the guy make for me was actually too big for a time trial bike. I have made several modifications to my steer tube and stem to get precious inches lower. At this point, I either Still not low enough to be really aero. At present, it looks like I have 1 of 2 choices. I can take about an inch off of my head tube to bring me that much lower or I can buy a smaller frame. I am a very tall rider at 6' 6" tall.. I'm looking for a frame that is around 57 -59 cm in order to attain that lower position. Any advice towards that end is most appreciated.
How much of this applies to long distance triathlon riding, say 70.3 and full IM distance? Should the average rider just stick to a road bike and rest on the bars throughout to offset any hand/shoulder pain over the 6hr+ ride? I have both bikes, but feel less confident descending on the triathlon bike.
Emma knows her shit!
Dear Emma, drag coefficient is a “physical” thing (5:08), it is number to quantify the resistance of a body moving inside a fluid medium. The formula is quite easy: Cd=F/(q.A), Cd or Drag equals to the force needed in travel direction divided by the dynamic pressure q times the frontal area A . Keep up the good work!
Emma Pooley is an engineer.
does this philosophy change at all for a long course triathlon? In other words, should there be any compromise between aero and comfort?
Have been looking for a TT bike any recommendations? Very informative video
Kaminokaze giant trinity
Trek Speed Concept is my fav. But honestly there are quite a number of great bikes and it's hard to go wrong.
Find a good bike fitter first. Then use their assistance at finding the best bike.
Did Si ever do a TT? If he did, I can't find the video.
Is there any drag difference between j bend and s bend in aero bars ?
Probably should have watched this video before I bought my bike.
Isn't the saddle too low for him? Looking at him pedalling at 16.48 his legs seem too bent, to me.
Being 5'8" (172.72cm) but with an inseam of only 28.25" (71.75cm) bike fitting appears to be a pain for me. I see all the charts and graphs starting what size frames etc to use, but my combination is never on them. How can I know for sure if l go for a fitting that the person actually knows what they are doing? Any suggestions, Emma, for a fellow sorry person?😁
How about saddle fore and aft?
How crucial is it to get a di2 version on a time trial bike? I have been told that it makes a huge difference on the time.
You have been told untruths. Di2 isn't more aero, or if it is it is by the most tiny amount
Main difference is you can shift from the basebar so maybe that gives you some time savings
what size is perfect for 175cm height?(for aero dynamic bike)
How to choose a TT specific frame size? How do road frame sizes translate to TT? #askgcn
So why doesn't someone couple a small video camera (like the backup cams in cars) with a screen incorporated into the aero bars so you can keep your head down comfortably and still see where you're going?
Well, there are maybe a few things:
1. Battery and screen weighs quite a bit.
2. You need a decent sized screen. If you have a 5 inch screen phone, look for a TH-cam video of an "on-board" cam of a bike ride and put it on full screen. Even cars look tiny when they're only 20m away.
3. Cameras don't do well with rapid lighting changes.
4. Depth perception might be an issue with small wide angle lenses.
Could time trail riders use mirrors or prisms so they could see forward without raising their heads?
Paul Tomblin yes some people do this. I’ve tried it, didn’t work for me, terrifying.
New space?
Actually the “most” important thing is to find a position that you can hold for the entire distance, purely finding the lowest most aero position is no good if you can’t peddle or hold the position.
I miss ema
I was absolutely doubtful when my local dealer fit me on a Liv bike (women's) one size smaller than my road bike... but he basically repeated all Emma said, now I'm only unsure about the color scheme lol
GCN quiz: How many more time trials are there in Si's past?