A few specific points:

• I agree that urban cycling / commuting will involve a lot of stops and starts, and will have a lot of acceleration. I'd also agree that in terms of road feel, a snappier bike will feel better and be more fun for that specific environment if you're constantly stopping and starting (hence all the track frames around NYC). However, the effect of weight is so small that other interruptions and variants will overwhelm any performance impact of the added weight. Geometry can also have as much to do with "feeling snappy" as wheel weight -- possibly more.

• I thought it was screamingly obvious that when I suggested using a power meter to compare the performance of 2 bikes, I was talking about comparing periods of consistent power output (e.g. "10 minutes @ 200 watts").

• Subjective perceptions of rider efforts are notoriously inaccurate. You can't tell based on feel if you are below, at or above LT. You can't tell based on feel what your average or max heart rate is. You have no idea of your actual power output at any time. You can't tell your actual speed, or rate of acceleration, or bike's weight based on feel. Stories abound of mismatches between perceived effort and data collected by HRM's and/or power meters.

Plus, various physiological, environmental and psychological factors -- especially expectations -- can strongly bias a subjective perception. That's why if you are serious about training, you need a HRM and/or power meter to objectively record your efforts.


And for staephj1:

• If you're getting dropped on a club ride, it's not because you have an extra 5 pounds on the bike. It's the engine. You know it, I know it, and everyone else on the ride knows it.

• I would hope it was screamingly obvious that I didn't mention the HPV World Record as an example of a "general" or "typical" cycling effort. The point was to illustrate that friction, primarily drag, is the biggest factor that effects performance. If you read up a little on the Diablo, by the way, you'll see that they do everything they can to reduce friction; to break their previous record, they pumped up the tires to reduce rolling resistance rather than toss 5 pounds overboard.

(By the way, TT's and solo rides are far more abundant than you suggest in your posts.)

• I'd hope we can agree that for most "general" rides, 38 seconds over 20 minutes is not only insignificant, but almost certainly overshadowed by other factors like rider fitness and drag. Most "general" riders don't even have the tools to accurately measure a change like that, let alone isolate it to one specific cause.

If 38 seconds out of 20 minutes is critical, it's not because it's a large amount of time, it's because you happen to be in one of the situations where small changes in performance are significant (let alone actually measured).


Last but not least... I'm no longer accepting the assumption that "added weight produces a significant performance loss on the flats" without some kind of proof. (The losses on a climb are pretty well understood, and may or may not be significant depending on the context.) So if you want me to believe that an extra 5 or 10 pounds is actually going to make a difference, prove it. One possible option is:

- quantify the effect of adding weight as best you can, in various scenarios
- compare it to the effect of an increase in drag
- compare it to the effect of an increase in RR
- and if weight does prove to be a primary or even notable factor, compare your results to this guy here, along with how and why you differentiate from his findings.

Or: Get a power meter, plant a 10 pound weight in your downtube, and quantify the results. It ought to cost you about 1-2 watts.

Have fun with that.