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Re: Bigham hour attempt- 19Aug [turdburgler] [ In reply to ]
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Some more info -

https://www.youtube.com/watch?v=LzJUDSy3DDI
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Re: Bigham hour attempt- 19Aug [Shambolic] [ In reply to ]
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Shambolic wrote:
BigBoyND wrote:
Any reason for the massive drop basebar? Not like he is using it in a TT. If there is a minimum bar width, you'd present a lower frontal area is it was straight.

My guess is it would be the optimal position and ability for him to get a massive 64x14 gear from a standing start away and up to speed before transitioning to aero. Time gains there would offset any minor aero penalties for the base bar.

Looking at that shape, I could see it helping shape the air around his legs by creating a vortex. For us normal people, frontal area makes a big difference, for the best of the best, it's a lot more subtle and the movement of the air itself matters.

See your bike fit. https://bikefitr.appspot.com/
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Re: Bigham hour attempt- 19Aug [LewisElliot] [ In reply to ]
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LewisElliot wrote:
In one of the youtube videos I watched, Bigham said that he's experimented with no base bar at all because (and I'm paraphrasing) it would "make sense to be faster" but it turns out they've tested, and tested again, that the "wave" the basebars create for the legs actually makes for a lower CDA.

That's very interesting! I'm surprised but probably shouldn't be; because airflow is very controlled on the track vs outdoor TTs, subtle things like this can have a greater impact.

Drifting OT a bit, but looking at the new Specialized TT helmet I'm guessing they found that the side "wings" are doing something to help flow attachment over the shoulders. There may be more aero advancement still possible around things like this...


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Re: Bigham hour attempt- 19Aug [Stubob] [ In reply to ]
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Stubob wrote:
Looking at that shape, I could see it helping shape the air around his legs by creating a vortex. For us normal people, frontal area makes a big difference, for the best of the best, it's a lot more subtle and the movement of the air itself matters.
In the GCN YouTube video they reference the very low Q factor on Bigham's bike. Obree's knees were so close together (very narrow BB) that he had to eliminate the top tube on the frame, and mount the chain stays high up on the seat tube to give clearance for the cranks.
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Re: Bigham hour attempt- 19Aug [rruff] [ In reply to ]
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Helmets are a whole other thing, but I recall Bigham also mentioned something regarding integration that was almost as surprising as the basebar being more aero than nothing at all. He said he's finding helmets are very "kit specific" for him, again something that mostly applies to the very controlled environment of an indoor velodrome. That shocked me though, as we know aero helmets are quite rider-specific for obvious reasons, but the skinsuit he's wearing? He was saying that depending on how a given kit fits with a certain material, and how much the helmet pushes airflow in that direction, he has to re-test his bin of fast helmets when he gets a newer, and presumably faster kit. I recall him saying the data can vary "a lot", which at this level maybe means a couple a watts!

I went to Manchester Track World Champs one year and roomed with Dean Phillips (3k Masters World Record holder) who has been extensively testing himself since 2003, back then I think he said with a PowerTap. From asking him endless questions, the main thing I gathered from him was that passing the "looks aero" test is just baseline, but from there you just have to test everything and in those details there can be surprising findings. So much of the outcome of those tests can be counter intuitive, but when applied almost always convey in results and faster times.
Last edited by: LewisElliot: Aug 26, 22 4:40
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Re: Bigham hour attempt- 19Aug [Hanginon] [ In reply to ]
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Hanginon wrote:
In the GCN YouTube video they reference the very low Q factor on Bigham's bike. Obree's knees were so close together (very narrow BB) that he had to eliminate the top tube on the frame, and mount the chain stays high up on the seat tube to give clearance for the cranks.

As I recall they said his bike was 130-something mm, which isn't all that narrow (my TT bike is in that range), but road norm is ~150. Narrow Q has been known to usually improve CdA since at least Obree's time. Lance experimented with it but didn't like it. The cheap way to achieve this is with old Dura Ace square taper cranks.

Narrow feels better to me, but there are practical limits. On my current frame I needed to go from a 103 to 107mm so the crank arms wouldn't hit the frame. Chainstay clearance with your feet can be another limiter if you pedal heels-in at all.
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Re: Bigham hour attempt- 19Aug [LewisElliot] [ In reply to ]
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LewisElliot wrote:
Helmets are a whole other thing, but I recall Bigham also mentioned something regarding integration that was almost as surprising as the basebar being more aero than nothing at al

This makes sense, esp if you look at some of the emerging designs for TT/track bikes and how they position the forks and stays.
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Re: Bigham hour attempt- 19Aug [DonV] [ In reply to ]
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Regarding the basebar, does Ribble or whoever have a patent on that aero road drop bar with the intentional aero bulges in the middle of it? They claimed that was faster or something. Is that appearing on their bike's base bar for TT bikes?
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Re: Bigham hour attempt- 19Aug [rruff] [ In reply to ]
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rruff wrote:
Hanginon wrote:
In the GCN YouTube video they reference the very low Q factor on Bigham's bike. Obree's knees were so close together (very narrow BB) that he had to eliminate the top tube on the frame, and mount the chain stays high up on the seat tube to give clearance for the cranks.


As I recall they said his bike was 130-something mm, which isn't all that narrow (my TT bike is in that range), but road norm is ~150. Narrow Q has been known to usually improve CdA since at least Obree's time. Lance experimented with it but didn't like it. The cheap way to achieve this is with old Dura Ace square taper cranks.

Narrow feels better to me, but there are practical limits. On my current frame I needed to go from a 103 to 107mm so the crank arms wouldn't hit the frame. Chainstay clearance with your feet can be another limiter if you pedal heels-in at all.

It's funny because when I was a kid we were taught 'knees to the stem' type pedaling, and to this day my knees track up and over the top tube. It pains me to see Lionel's pedaling style with his knees sticking out like he's doing yoga.
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Re: Bigham hour attempt- 19Aug [mathematics] [ In reply to ]
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mathematics[/quote wrote:


It's funny because when I was a kid we were taught 'knees to the stem' type pedaling, and to this day my knees track up and over the top tube. It pains me to see Lionel's pedaling style with his knees sticking out like he's doing yoga.

Ha! Exactly the same. It's almost sensory feedback at this point after almost two decades.

Which is annoying with a bento box on my Felt, as my right knee grazes the "lid" of the box so I have to continually retape it every couple of weeks to push it in a few mms so it's not catching on my knee and lifting open.
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Re: Bigham hour attempt- 19Aug [mathematics] [ In reply to ]
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mathematics wrote:
It's funny because when I was a kid we were taught 'knees to the stem' type pedaling, and to this day my knees track up and over the top tube
...but don't forget, we were on bikes with a narrow TA/Stronglight/Campagnolo crankset, and 120mm rear dropout spacing.
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Re: Bigham hour attempt- 19Aug [LewisElliot] [ In reply to ]
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LewisElliot wrote:
Helmets are a whole other thing, but I recall Bigham also mentioned something regarding integration that was almost as surprising as the basebar being more aero than nothing at all. He said he's finding helmets are very "kit specific" for him, again something that mostly applies to the very controlled environment of an indoor velodrome. That shocked me though, as we know aero helmets are quite rider-specific for obvious reasons, but the skinsuit he's wearing? He was saying that depending on how a given kit fits with a certain material, and how much the helmet pushes airflow in that direction, he has to re-test his bin of fast helmets when he gets a newer, and presumably faster kit. I recall him saying the data can vary "a lot", which at this level maybe means a couple a watts!
.

This has been well known within the British time trial scene for some time. The skinsuit is the most major innovation in my view over the last 10 years and I’ve changed my suits major pattern three times in the last 6 years and each one of these resulted in a helmet change. The issue though is determining which piece of equipment or position you change first to then influence the others. I generally go position first, then suit, then helmet but that may not always be right.
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