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Jorgan




Joined: 12 Nov 2007
Posts: 16090
Location: alles was ich bin, alles was ich war

PostPosted: Thu Mar 16, 2017 9:54 am    Post subject: Reply with quote

Chrace wrote:
Going downhill at 30mph I start considering whether it's worth to keep pedaling, and certainly not at any significant power. Smile


I generally just get into a tuck when I'm going faster than I can pedal - it's more aero...AND saves energy! It's here that I'll often close-down people ahead quite rapidly; that and I can handle a bike fairly well for a triaflete.

Knowing fast technical descents can also net you time, even if you just drive the course before the race.
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Cat5 in the Hat




Joined: 14 Mar 2011
Posts: 1064
Location: Berks

PostPosted: Thu Mar 16, 2017 10:41 am    Post subject: Reply with quote

JaRok2300 wrote:
Is there not an argument that slower riders benefit just as much (if not more) than faster ones because, although the absolute saving from aero is less, they benefit from it over a longer period of time.
I definitely get the comment about making a statement, I only recently bought a disc cover and second hand aero helmet for exactly that reason. Not sure if it was because I got any faster or just thicker skinned.


Kind of.

Aerodynamically they will benefit from the aero saving for longer. However as drag increases at the square of velocity (velocity that the testing was carried out at) any drag savings at a lower velocity will be minimal.

The drag savings vs velocity is exponential.
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Jorgan




Joined: 12 Nov 2007
Posts: 16090
Location: alles was ich bin, alles was ich war

PostPosted: Thu Mar 16, 2017 10:45 am    Post subject: Reply with quote

The bottom line, is that everyone can benefit from better aerodynamics to some extent.
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PCP




Joined: 13 Oct 2012
Posts: 1591
Location: Manchester

PostPosted: Thu Mar 16, 2017 11:18 am    Post subject: Reply with quote

I've been tweaking a few things on my bike to get a better position and more comfortable as I was a bit squashed. I nudged my saddle back, moved my bars/pads forward tilted the bars up a little to raise my hands. All these changes over a few months and independent of each other.
I am a lot more comfortable with no power sacrifice and am able to hold aero for longer periods.

Also had a poor fitting helmet (coming down over eyes and had to adjust it several times on the move) so am selling these:

https://garneau.com/int/en/p-09-aero-helmet-i
https://garneau.com/ca/en/vorttice-aero-cycling-helmet-c

To fund this -
http://www.chainreactioncycles.com/met-drone-tt-helmet-mtn-quebeca-edition-2015/rp-prod129647?gs=1&utm_source=google&utm_term=&utm_campaign=Chain%20Reaction-UK-PLA-PLA-All-DT-SE-Shopping%20QLB%20Manufacturer%20Desktop&utm_medium=base&utm_content=mkwid%7CsSEhtbg74_dc%7Cpcrid%7C161845658788%7Cpkw%7C%7Cpmt%7C%7Cprd%7C464894UK
I have tried this on and it is a much better fit, great visibility for me and fits my position quite well too.

When it gets delivered I'll get a couple of pics up for you to all slaughter Laughing
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JaRok2300




Joined: 01 May 2014
Posts: 174
Location: Worcester, UK

PostPosted: Tue Jul 04, 2017 3:48 pm    Post subject: Reply with quote

Been following the aero shootout thread on ST which fairly predictably put all the superbikes within a gnat's **** of each other.

However, an interesting sideline was a discussion about the scalability of the aero benefits at different speeds.

The argument was that time savings over a distance are pretty consistent irrespective of the bike speed with the example below given for IM Cairns, by a guy who runs one of these "Best Bike Split" calculation type sites.

40kph, 4:30 bike, 10W aero savings equates to a time saving of 1:46.
27kph, 6:30 bike, the same aero benefit above would only result in ~3W but time saving would be 2:09.

The rationale included the longer time the benefit is experienced over, the lower speed meaning less watts are needed to go faster and the greater yaw angle for slower riders.

Neither is exactly earth shattering but a disc cover and 2nd hand aero helmet are pretty cheap speed compared to 15k bikes.
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earthling




Joined: 26 Feb 2011
Posts: 1796
Location: Born to tri, forced to work....

PostPosted: Wed Jul 05, 2017 2:02 pm    Post subject: Reply with quote

I was following the aero shootout on ST as well and think the results are pretty good.

The aspect that jumps out at me initially is disc brakes. The spreadsheet Jorgan links to says 'shame' but the Cervelo P5x uses them to great effect.

Aero really is all about testing - your position is so unique to you, and your kit is all about your fit. You cannot just assume something will not be aero (within reason) it's all about integration, your personal fit/equipment match and finding time/patience to test test test for yourself.

You definitely can have P5x 'aeroness' on a budget if you are prepared to put in the time and effort. You definitely can completely f**k up your results on a P5x if you just assume you have bought the best so you will be fast.
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Tin Pot




Joined: 08 Jul 2013
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PostPosted: Wed Jul 05, 2017 4:58 pm    Post subject: Reply with quote

JaRok2300 wrote:
Been following the aero shootout thread on ST which fairly predictably put all the superbikes within a gnat's **** of each other.

However, an interesting sideline was a discussion about the scalability of the aero benefits at different speeds.

The argument was that time savings over a distance are pretty consistent irrespective of the bike speed with the example below given for IM Cairns, by a guy who runs one of these "Best Bike Split" calculation type sites.

40kph, 4:30 bike, 10W aero savings equates to a time saving of 1:46.
27kph, 6:30 bike, the same aero benefit above would only result in ~3W but time saving would be 2:09.

The rationale included the longer time the benefit is experienced over, the lower speed meaning less watts are needed to go faster and the greater yaw angle for slower riders.

Neither is exactly earth shattering but a disc cover and 2nd hand aero helmet are pretty cheap speed compared to 15k bikes.


Yeah, I noticed that as well - conversation was about fluid dynamics I think, they mentioned some constant, but didn't clearly note the mechanism at work.

Interesting, and good to have an explanation of why the testing is always done at high speed - to make detection of differences less prone to error.
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Chrace




Joined: 28 Apr 2010
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Location: Eating a Yorkie

PostPosted: Thu Jul 06, 2017 8:15 am    Post subject: Reply with quote

Jorgan wrote:
Chrace wrote:
Surplus income and midlife crisis makes pie-habit irrelevant and bling the king.


Best buy a disc then! In reality, I think a lot of people are 'afraid' of buying a piece of kit like a disc, because it makes a statement. Yet they hope no-one will notice them pedaling their P5 at 16 mph.

Got the disc. Now I can eat more pies.


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Tin Pot




Joined: 08 Jul 2013
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PostPosted: Thu Jul 06, 2017 8:18 am    Post subject: Reply with quote

Chrace wrote:
Jorgan wrote:
Chrace wrote:
Surplus income and midlife crisis makes pie-habit irrelevant and bling the king.


Best buy a disc then! In reality, I think a lot of people are 'afraid' of buying a piece of kit like a disc, because it makes a statement. Yet they hope no-one will notice them pedaling their P5 at 16 mph.

Got the disc. Now I can eat more pies.



Sweet.

And I'd recommend the Steak & Chorizo pie in Borough Market,
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Iron '16 14h30
Half Iron '17 7h39!, 6h28 '16 5h53
Olympic '16 3h18 '15 3h33, '13 3h36
Sprint '16 1h17, '14 1h40, '13 2h01
Half Mara '16 2h04, '14 2h07
10 Mile TT '16 00:26:30
Trail 10K '16 54:01 '13 54:46
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stenard




Joined: 04 Sep 2013
Posts: 1240

PostPosted: Thu Jul 06, 2017 9:40 am    Post subject: Reply with quote

Chrace wrote:
Jorgan wrote:
Chrace wrote:
Surplus income and midlife crisis makes pie-habit irrelevant and bling the king.


Best buy a disc then! In reality, I think a lot of people are 'afraid' of buying a piece of kit like a disc, because it makes a statement. Yet they hope no-one will notice them pedaling their P5 at 16 mph.

Got the disc. Now I can eat more pies.


Got the same disc second hand off a club member just before the Cotswold 113. Logic says that must have contributed to my unexpected time.

I do like the fact you have the matching front. Must try and locate one of those, even if I am swapping one 50mm deep front for another! Rolling Eyes
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TriSam




Joined: 26 Aug 2011
Posts: 1163
Location: Tunbridge Wells

PostPosted: Thu Jul 06, 2017 12:13 pm    Post subject: Reply with quote

If it's only for vanity reasons, FFWD decals are pretty easy to come by!
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Chrace




Joined: 28 Apr 2010
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Location: Eating a Yorkie

PostPosted: Thu Jul 06, 2017 12:58 pm    Post subject: Reply with quote

Flippin 'eck guys, get your bling knowledge sorted. That's a 60 front! Don't give a darn if it's quicker but the bragging rights over a 50 are immense.

I got that disc from Evans. Some poor apprentice must have dropped it on a hard edge and made a dent in the alloy rim. I've straightened it out and haven't noticed anything. Price was 490 though, which I did notice. Brand new otherwise with bag, skewers, tape, etc.
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mattsurf




Joined: 28 Sep 2016
Posts: 230
Location: salisbury

PostPosted: Fri Jul 07, 2017 7:27 am    Post subject: Reply with quote

At Outlaw, I passed loads of bikes with Disc wheels, however, I was only passed twice myself, both bike had discs. The second bike that passed me took 4 minutes off my cycle time. I noticed that on a gentle uphill section I was able to repass him pretty easily (maybe he wasn't a good climber), however, I was quickly passed again and maintain a distance of at least 12m behind, there was no way I was staying in touch on the flat.

Anyway, I have been thinking about a disc wheel for a while, and I am now the proud owner of a set of Walker Brothers wheels, bought from a retiring TT rider
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stenard




Joined: 04 Sep 2013
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PostPosted: Fri Jul 07, 2017 8:56 am    Post subject: Reply with quote

Chrace wrote:
Flippin 'eck guys, get your bling knowledge sorted. That's a 60 front! Don't give a darn if it's quicker but the bragging rights over a 50 are immense.

I got that disc from Evans. Some poor apprentice must have dropped it on a hard edge and made a dent in the alloy rim. I've straightened it out and haven't noticed anything. Price was 490 though, which I did notice. Brand new otherwise with bag, skewers, tape, etc.

True. Temporary brain malfunction ... the model name of F6R kinda implies it's a 60!

Got mine second hand, but at a similar price (450) and effectively brand new. It had just one one IM. Compromise was that the rear mech had rubbed. I reckon I could polish the marks out over time, but tbh I'm not that fussed (probably the wrong thing to be saying in response to a criticism of my bling knowledge!)
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