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Jorgan
Joined: 12 Nov 2007
Posts: 16099
Location: alles was ich bin, alles was ich war
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 Posted: Thu Mar 16, 2017 9:54 am Post subject: |
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| Chrace wrote: | Going downhill at 30mph I start considering whether it's worth to keep pedaling, and certainly not at any significant power.  |
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: 1065
Location: Berks
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| Posted: Thu Mar 16, 2017 10:41 am Post subject: |
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| 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: 16099
Location: alles was ich bin, alles was ich war
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| Posted: Thu Mar 16, 2017 10:45 am Post subject: |
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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
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JaRok2300
Joined: 01 May 2014
Posts: 174
Location: Worcester, UK
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| Posted: Tue Jul 04, 2017 3:48 pm Post subject: |
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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....
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| Posted: Wed Jul 05, 2017 2:02 pm Post subject: |
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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
Posts: 2196
Location: Bromley
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| Posted: Wed Jul 05, 2017 4:58 pm Post subject: |
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| 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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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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Chrace
Joined: 28 Apr 2010
Posts: 2517
Location: Eating a Yorkie
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| Posted: Thu Jul 06, 2017 8:15 am Post subject: |
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| 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
Posts: 2196
Location: Bromley
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| Posted: Thu Jul 06, 2017 8:18 am Post subject: |
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| 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.
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Sweet.
And I'd recommend the Steak & Chorizo pie in Borough Market,
_________________
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
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| Posted: Thu Jul 06, 2017 9:40 am Post subject: |
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| 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.
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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! 
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TriSam
Joined: 26 Aug 2011
Posts: 1163
Location: Tunbridge Wells
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| Posted: Thu Jul 06, 2017 12:13 pm Post subject: |
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| If it's only for vanity reasons, FFWD decals are pretty easy to come by!
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Chrace
Joined: 28 Apr 2010
Posts: 2517
Location: Eating a Yorkie
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| Posted: Thu Jul 06, 2017 12:58 pm Post subject: |
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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: 231
Location: salisbury
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| Posted: Fri Jul 07, 2017 7:27 am Post subject: |
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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
Posts: 1240
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| Posted: Fri Jul 07, 2017 8:56 am Post subject: |
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| 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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