With most reasonable tri bikes (say $2000 or more), the stock rims are typically pretty reasonable as I understand it. With that said, how much of an improvement can the average triathlon expect to gain switching from the stock rims on a tri bike to, say, some Zipp 404s on the front and back? Let’s assume we are keeping the same tires, say some 23mm slicks. We are not talking about a pro here, just a weekend warrior type.
It varies some, but not a tremendous amount. I’d put it this way- enough to get you on the podium in a close race where you may have been 4th otherwise…
There are other items that are lower hanging fruit such as position, bottle / hydration setup, aero helmet, clothing choice, tires/tubes, etc.
Depends on how fast you can ride…under 20 mph not a ton. Over 20 a bit more noticeable. Over 25 mph even more.
They will make girls throw themselves at you and your wildest dreams come true…
Depends on how fast you can ride…under 20 mph not a ton. Over 20 a bit more noticeable. Over 25 mph even more.
Wrong.
A lot of variables impact this, but figure roughly 1:30 savings in a 40k.
Most tri bikes (other than those at the very top end) come with cheap, heavy wheels since many people will either get race wheels, or already have a pair (ex. bikes don’t come with rear discs).
Well, let’s use the example of the Felt tri bike line.
Most come with a 40mm deep stock wheelset +/-
Throw a really narrow front tyre on the front TTR wheel - a Continental Supersonic 622/20, for example.
Put a wheel cover on the back, and a Continental GP4000s tyre on.
Use latex tubes.
That’s a fast, affordable set up right there that won’t be holding anyone back.
Depends on how fast you can ride…under 20 mph not a ton. Over 20 a bit more noticeable. Over 25 mph even more.
Play around with this calculator: http://www.cyclingpowerlab.com/componentaerodynamics.aspx
A lot of variables impact this, but figure roughly 1:30 savings in a 40k.
Wow, I cant believe people would pay $2000 for a ~1% increase if they were not in the top 1% already. You can gain a hell of a lot more than 1:30 by simply trying harder. 
I mean, how many races have you done in which you could honestly say if your life depended on it, there is no way you could have pushed harder? Probably zero. We are not talking about a mechanical engine here where its max output is a well-defined and calculable value. The max output of a human is extremely variable and extremely dependent simply on how much pain the athlete can ignore. Pushing yourself harder and ignoring a greater amount of agony can increase your output alone.
“I mean, how many races have you done in which you could honestly say if your life depended on it, there is no way you could have pushed harder?”
Not many…but you are allowed to both try harder and improve your aerodynamics.
But let’s conservatively say :45 seconds/hour savings. That would ~2’ in a HIM. Every race you’ll do, you’ll know you could have been finished 2’ sooner. That guy you’re sprinting down the finishing chute with? He’d be a 1/4 mile behind…I train way too hard to be having that hanging over me.
FWIW, I spent $400 for race wheels, wheel cover on the rear and a used H3 on the front. More aero than most of the $2000 wheelsets that are out there. Used this setup for 5 years and sold the H3 for $300. It doesn’t have to be a $2000 question.
Depends on how fast you can ride…under 20 mph not a ton. Over 20 a bit more noticeable. Over 25 mph even more.
This is false. In fact the slower rider will tend to see more benefit as average yaw angles are higher.
To the OP you can use the rule of thumb:
50g drag @30mph = 5watts @30mph = .5seconds saved per kilometer at any mph
Depending on the shape of your stock rim and it’s spokes and how windy it is you might save anywhere from just 20g of drag or so to 150g+ by swapping to 404s
There is a lot of data compiled on aeroweenie.com so you can get an idea
How much of a difference does a rear wheel disc cover make relative to buying new rims? I hear a disc cover on a stock rim is more aerodynamic than an 808 with no cover.
Pushing harder and buying a race wheel are completely orthogonal. That means doing one has no impact on the other. You can do both, and should.
1:30 in a 40kTT would commonly bet the difference between 10th and 1st. A 1% difference in time in cycling represents more than a 1% difference in fitness, since it takes a lot more power to go 1% faster. Also, 1:30 over an hour is more like 2%
To go 1:30 faster over 40k if you were already at around the hour mark would require about 20 more watts. It is extremely rare that someone practiced at it paces so badly that they could do an extra 20 watts through force of will. 20 watts for a reasonably seasoned athlete represents a huge increase in fitness. Something you would be unlikely to achieve in a year of hard work.
I don’t know why I am typing so many words to respond to someone suggesting you not bother to put wheels on your bike to go faster. Plus you don’t need to spend $2,000 anyway.
Wow, I cant believe people would pay $2000 for a ~1% increase if they were not in the top 1% already. You can gain a hell of a lot more than 1:30 by simply trying harder. I mean, how many races have you done in which you could honestly say if your life depended on it, there is no way you could have pushed harder? Probably zero. We are not talking about a mechanical engine here where its max output is a well-defined and calculable value. The max output of a human is extremely variable and extremely dependent simply on how much pain the athlete can ignore. Pushing yourself harder and ignoring a greater amount of agony can increase your output alone.
How much of a difference does a rear wheel disc cover make relative to buying new rims? I hear a disc cover on a stock rim is more aerodynamic than an 808 with no cover.
Good question, here is a link to data from the aeroweenie.com site:
http://www.wheelbuilder.com/aerodisc-data.html
You can see that at low yaw angles (not much wind), not that big of a difference. You might improve that a bit by using tape instead the bolts to attach it. But still, if there is no wind most wheels are close. As the wind picks up, BIG differences.
A wheelcover is a great bang for the buck improvement and offers no handling difficulty like deep front rims do.
I agree with you and that’s the reason I decided to make a big investment in a new bike this year. I feel like I’ve really stepped up my training so much and have been doing tri’s for a few years already that I’m at a point where I don’t want to be let down by my equipment.
you are allowed to both try harder and improve your aerodynamics.
at the same TIME?!?!?!?
Game changer!
Seriously though if you want a budget race wheel setup, pick an affordable 30mm front wheel with a nice smooth shape and good aero spokes (Flo 30, Mavic Cosmic Elite, Zipp 101 etc), then use a disc cover on the rear
As long as there aren’t a lot of crosswinds on the day you won’t give up much time.
you are allowed to both try harder and improve your aerodynamics.
at the same TIME?!?!?!?
Depends on how fast you can ride…under 20 mph not a ton. Over 20 a bit more noticeable. Over 25 mph even more.
Nope - http://www.cervelo.com/en/engineering/thinking-and-processes/slow-vs-fast-riders.html
Depends on how fast you can ride…under 20 mph not a ton. Over 20 a bit more noticeable. Over 25 mph even more.
They will make girls throw themselves at you and your wildest dreams come true…
Depends on how fast you can ride…under 20 mph not a ton. Over 20 a bit more noticeable. Over 25 mph even more.
Wrong.
not even through my morning coffee before my 30 mile bike ride and the twitchers are off and racing…this place is epic!
So let’s dumb this down a little, all things being equal. Same rider, same conditions, same bike on the same IM course, race wheels vs non, how many minutes can one save going with wheels? Ballpark numbers here, what are we talking?
Ballpark: 5 minutes, give or take 2 minutes.