On Aug 6, 2011, at 4:17 PM, Michael Hechmer wrote: > People are way over thinking this question. Tire & rim weight are critical > when accelerating or going uphill. If you doubt this I suggest you get a 5 > and a 10 pound weight and spend some time simply lifting the weight in an > arms length from your body. Rim & tire weight has a big impact on how > "lively", eg, responsive a bike feels. Sure, some tires have lower rolling > resistance than others and as your rolling along on a long ride that can make > a difference. But "liveliness" is all about acceleration and climbing and > tire / rim weight trumps rolling resistance.
I have to respectfully disagree. If the difference between one tire/rim combo and another was 5 lbs/2270 g or 10 lbs/4540 g, the difference would be significant. Differences of 4 oz/100 grams are not very significant. Bikes don't accelerate very quickly even when ridden by pro racers, let alone the rest of us, so it's not that big a deal. When climbing, weight is weight. The steeper the hill the more this is true. Doesn't matter if the weight is on your rims or in your water bottle. Almost no one grouses about the 21 ounces/590 grams the water in a full water bottle weighs slowing them down, yet people claim to be able to feel 10 or 50 or 100 grams on their bike. It always cracks me up on the bike tech and racing newsgroups; it's one of the reasons I no longer read any mainstream bike publications. Even if we apply the notion that the weight on the periphery of the wheels counts as double in terms of energy cost to accelerate as compared to weight on the bike, if we mount a 100 g lighter tire the gain is still less than half of a full water bottle. And oddly enough rim weights are generally higher now, due to "aero" shapes and thicker walls to avoid the expense of having to put in spoke sockets, than they were years ago unless you're spending a lot of money on boutique, fragile wheels. Rolling resistance, OTOH, can be nearly 100% of what slows you down at very low speeds and 25% or more of the total drag we have to overcome at a cruising speed of 18 mph. It is a constant on the bike, unlike wind resistance or inclines. That's not only a difference on a long ride but at every moment, including when climbing. When climbing, because our speeds are lower, RR becomes a much larger percentage of the drag we have to overcome. It's worth paying attention to, but there too we have to balance various needs (e.g., durability and puncture resistance versus speed). Call it a difference in riding philosophy. -- You received this message because you are subscribed to the Google Groups "RBW Owners Bunch" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/rbw-owners-bunch?hl=en.
