Quest to save 50 watts

2 messages
13/03/2019 at 19:09

I have been enjoying triathlons for a few years now and made the leap to a TT bike last year. I am 39 years old and have a healthy competitive streak. As a child/teen i was a club swimmer and have an FTP of around 240 and run 5k in under 21 mins. So i wont be bothering any elite triathletes, but im good enough to have fun and do ok in my age group at local events.

I love the numbers so i want to find some free speed on the bike through marginal gains. Here is plan to gain 50 watts though improved aerodynamics and rolling resistance.

My starting point setup is as follows:

Dolan Scala TT bike, 50mm Mavic cosmic wheels, semi-aero helmet, tri-suit, calf guards, GP4000 tyres, power meter, regular inner tubes, regular number belt, normal 105 chain with wet lube, 175 cranks, regular bottle/cage. 

Proposed changes:

  1. aero trisuit - 6w
  2. TT specific helmet -5w
  3. nopinz calf guards - 3w
  4. nopinz aero number belt - 3w
  5. aerocoach disc rear wheel- 6w
  6. aerocoach front wheel - 6w
  7. latex tubes- 2w
  8. corsa speed tyres - 4w
  9. 165 cranks* - 2w
  10. aeria ultimate hydration** - 3w
  11. lowered aeira stem + tighter elbows - 3w
  12. speed waxed chain - 4w
  13. aero wheel skewers - 1w

this makes approx 48 watts of savings. I have estimates the individual wattages as most of the 'claimed' test figures are a lot higher, but are based at 40-45kph. As my cycle legs in a triathlons have previously averaged around 35kph the aero benefits are considerably reduced.

So how much time will i save?? and how much faster will i go??

last season i did most of my sprint triathlons at dorney lake, pan flat but sometimes windy and measures 21.2km. i averaged around 200 watts for the bike leg.

using the bike calculator app. assuming light wind. a 21.2km bike leg would suggest a time of 36.41 and a average speed of 34.7kph. which is very close to by splits for both the 2018 season opener in May and seasons end events in September.

Using the same app increasing the watts by 48 would result in a time of 33.39 and an average speed of 37.9mph. (its seems quite an unrealistic figures)

I dont think i will be able to afford all the upgrades before May's Sprint Tri at dorney lake. but i hope to have them all by September. 

What do you guys think? Is it all just media hype and are these claimed marginal gains just designed to empty our bank accounts?

Any other ideas on how to save a few Watts? i am pretty much doing all the training i can fit in with a busy family/work life. Other things i have considered are oversized jockey wheels and ceramic bottom bracket. But the cost/watt saved is quite high.

* shorter 165 cranks will in theroy help reduce my frontal area and enable me to adopt a lower more aero position

** The aeria profile design front mount bottle/stem will tidy up the cables and i will lose the regular bottle/cage.

18/03/2019 at 10:06
Choc, was interested in your post. I too have an ftp of around 240. I did Nottingham, last year, also round a boating lake, averaging 196W but my speed was 37.3kmph. I am considerably older than you though. The speed you wish to attain having spent big. I have Kronostok 6/8 wheels, wear a Giro Air Attack helmet and ride a standard tri bike with standard components.

Do you want to race faster and come off the bike faster or do you want to save 50W of drag? The two aren't always the same. You decide.

If you want to race faster then priorities for you money are firstly to get a proper bike fit with someone who knows about triathlon. Triathlon and road TT are not the same. going lower and narrower 'may' reduce drag but are more likely to compromise your ability to produce power. Losses can easily be great than aero gains and greater hip flexion riding can result in a poor run as well as reduced leg function. The same may go for shorter cranks. Being comfortable on the bike in an aero position is what will gain you speed. If you fidget or move you will lose it.

Second. Get a coach so that you can output more power sustainably. You can get a lot of good coaching for the price of an aero helmet.

Third. Don't always trust the manufacturers figures. Equipment reviews such as carried out by this sites hosts are not perfect but can be trusted to be independent and to rank thing pretty well. Group tests are best. Not all manufacturers provide kit for tests and I think, although I may be wrong, some will withdraw before publication if things don't look good.

So after bike fit and coach the things you should focus on are an aero helmet which can save as much as a set of wheels. Long pointy ones are best but if you are likely to move your head much then a stubby one will work better. Next come the wheels: Deep section. Tubeless are quicker (supposedly). I'm assuming your tri suit isn't baggy and doesn't flap about in the wind. Also do you really need to drink during a sprint tri bike leg?

To answer one of your questions. Yes, there is a lot of hype. Businesses will always put the best spin on their products. After getting aero wheels for my tri bike, which are pretty fundamental anyway, the best spend was an ISM Adam Prologue saddle. It allows me to sit in an aero position for hours at a time. I also invest time in flexibility, mobility and muscle activation.

Hope this is of interest.
Cheers, Harry
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