Here's a question for cycling scholars and industry scientists...

What are the most significant performance items of bike and bike/human (but not just human) performance? As a layman, I might put a few in this order:

1. Frame size and fit
For efficient power transfer and good aerodynamics. I might mention aerobars under this category: simply better than drops in terms of the all-important aero performance.
2. Wheel aerodynamics
Especially critical is the front wheel. A good front wheel saves time and is generally more important than wheel weight or strength.
3. Rolling resistance
Why are there no publicly available charts comparing rolling resistance of various hubs under various weight loads (with a benchmark tire as a constant)? Buyers have to guess which wheels roll better than others. Does it matter? Is there much variation here?
4. Bike weight
For acceleration and hills, this is important if you're talking about wide weight ranges of 6 pounds or more. Yes?
5. Frame integrity/stiffness
Call me naive, but it seems to me that in terms of effiient power transfer, there isn't a whole lot of improvement an excellent frame can give you over an average frame. If you wanted to put this in terms of seconds over 40km, this difference might be thrown into the category of leg hair versus no leg hair.
6. Frame aerodynamics
Again not big of a deal, it seems to me, though I would love to see a Cervelo P3 and SoftRide FASTT up against a typical road bike frame in a wind tunnel for seconds saved over 40k.
7. Component quality
Almost negligible in terms of overall performance. I'm not sure why people spend so much money on these though it's clear most people care far less about performance than style.

I'm just throwing this out after doing some reading. I'm not an industry scientist and would love to hear your comments if you take more than an armchair interest in bicycle performance. I know that the vast majority of cyclists either don't care or care about the wrong things but hey, to each his or her own.

Aerodynamics and power-to-weight ratio. Oh, and endurance may be a bit important.

Your question is too vague. The benefits of these items varies a lot depending on who is riding and what are their goals. Good fit matters to everyone, but the benefits of aerodynamics and weight depend on your speed, fitness level, and riding technique. Also, many issues are interrelated, for example higher quality levels will give you lower weight and improved stiffness.

Define "performance"... If a bike gets me there faster, but the cogs are grinding the whole way, did the bike "perform" well?

If "performace" means getting to the finish line quickest, I'd say that:

1. Rider aerodynamics are most important in a race where drafting is not allowed.

2. Weight is most important on climbs.


Duh.


But more expensive shifters, etc. do "perform" better. They may not make you finish quicker, but they "perform" better.

I would generally agree, not having much expertise in the area either. I would add tire-to-ground friction in rolling resistance, though, not just hubs.

and then we get into correct tire pressure, and all sorts of fun things.

Check out: https://www.cervelo.com/content.aspx?...i=Aerodynamics

This estimates the time differences over a 40K TT with various variables.

I'll also add the following from a <cringe> article in Bicycling Magazine about MIT's cycling team.

MIT Cycling Team

According to the article:

- Bike accounts for 15% - 25% of drag; about 75% is from your body
- Non-aero helmet creates 4 times the drag of a non-aero wheel
- If you race, how you attach your number has a bigger effect than an aero wheel (they glue their's on)
- Having a water bottle on the seat tube is better than not having one, and is much more aero than a water bottle on the down tube
- Wearing gloves in a time trial will slow you down more than using a non-aero front wheel

Another interesting link:

Bicycles and Aerodynamics

I hadn't seen the MIT article, thanks.

The two articles seem to have very different numbers for front wheel drag versus helmet drag -- 1:4 vs. 1:1. I wonder why this is? The MIT team found wearing gloves caused greater drag than an "aero versus non-aero front wheel" which doesn't say anything good about their test. This is very hard to believe given both conventional wisdom and amount of wheel testing, most proprietary, already out there.


One summary bit on this thread is that it would stand to reason that the same rider tested riding solo over a fixed length course and comfortable in an aero position, would ride significantly faster on a Motobecane Nemesis ($1000) than on a Bianchi L'Una ($5000), Trek Madone SSL ($10,000) or LiteSpeed Vortex Record ($7000) simply because of the aero frame and aero position of the rider's body.

If rider aerodynamics were improved without decreasing rider power, then absolutely 100% yes. Assuming same rolling resistance and drivetrain losses.

Only at zero degrees yaw. Under any realistically plausible scenario, this is not the case. This has been debunked.