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good article about weight from the torelli website.(12 posts)

good article about weight from the torelli website.rufus
Aug 4, 2003 8:14 AM
http://www.torelli.com/tech/weight.shtml

He posited a 5 kilometer, 7% grade. That's a good, stiff climb. The legendary Stelvio climb averages 7.5%. He further assumed a rider who can kick out 250 watts. A 160 pound rider will take 19 minutes and 21 seconds to get up the hill. Every 5 pounds added make the trip up the hill take 30 seconds longer.

That means each added pound adds 6 seconds to the time it takes to get up this hill. That is only 6 seconds on a stiff, 20 minute climb.

So, given ouR roughly 3-pound range from a full steel bike to a super-light carbon or aluminum bike, the time difference up this hill would be 18 seconds from best to worst.
re: good article about weight from the torelli website.CalmedDownRonPruitt
Aug 4, 2003 8:30 AM
It would take me forever to get up that hill then is what you are saying.
...this assumes...JS Haiku Shop
Aug 4, 2003 9:40 AM
9.3 mph average speed on a 3.1 mile 7% climb.

in comparison, i was doing repeats a few weekends ago on a 3.5-mile 8% climb, and the whole down/up trip was taking about 40 minutes.

I weigh about 200 pounds and was riding a ~25 pound bike with ~1.5 pounds in the saddle bag and two 16-ounce water bottles (28.5 pounds roughly)--that's a rider/bike package of about 230 pounds.

descending, i'd guess my average speed was about 35 mph. that's about a 6 minute descent of 3.5 miles, unless my math is all whacked. that leaves 34 minutes for the climb, which is about a 6.17 mph average. then again, i climb like a cinder block, it was 90* at a very high humidity, i was sleep-deprived, hungover, and sore from the north georgia mountains two days before, so it's not surprising.

even without all those cop-out excuses, i don't know if i'd have been able to better 9.3 mph average over a 3.5-mile 8% grade. match it, maybe. now, if there was a beer truck just ahead, straining to make it up the road at about 12 mph, i might have broken a few records.

-J
ps: now head sore from math. nmJS Haiku Shop
Aug 4, 2003 9:41 AM
You did repeats on a hill that you could only climb at 6 mph?Sintesi
Aug 4, 2003 3:11 PM
I salute you Haiku shop.
re: good article about weight from the torelli website.commuterguy
Aug 4, 2003 9:52 AM
I think the key issue for bikers is defining what they want from their bike. The argument made is very rational, but it is also rational to buy the Trek 5900 if you want to be like Lance, even if you are 250 lbs. and are never going to compete.

Has anyone here directly compared the same high end steel frame with a high end steel fork and a high end carbon fork? I am curious how they would compare.
But why assume a rider produces a constant wattage?Mike P
Aug 4, 2003 11:12 AM
Wattage can not be assumed to be a constant, in my case anyway. I have this problem, and I do not think I am the only one, where the wattage I can produce decreases over time. And the decrease in wattage is greatest as I work up a hill at a hard pace. As wattage decreases, the time it takes to get up a hill increases. I do not think 5 lbs would equate to 30 seconds; it would be much more.

Mike
agreedThe Human G-Nome
Aug 4, 2003 11:18 AM
and even it that weren't true, 18 seconds is a huge number when you're talking about racing. a stiff, light frame makes a ton of difference.
agreed--if and only if you are racingcommuterguy
Aug 4, 2003 11:53 AM
If you are racing, 18 seconds can be important. If you are not, or if you want to maximize your chances during the 40 mph descent that follows the long, tough climb, the slightly heavier steel frame may be the better choice.

The other angle that is relevant here is cost: ti is more expensive than steel, and only marginally lighter; high-end aluminum tends to be pricier as well. If you have a fixed budget of $3K or less, the dough you save on the frame can be put towards lighter components, wheels with lower rotating weight, etc.
But why assume a rider produces a constant wattage?asgelle
Aug 4, 2003 12:05 PM
Wattage is assumed constant because it makes the calculation for time easier. The calculation can be performed for any power profile and while the total time to complete the climb will change, the conclusions will not. Also, if you are starting the climb at a power you cannot maintain to the top, (i.e., starting out above threshold then dropping below as you fatigue) your time will be slower than if you maintained your threshold power. This can be verified at www.analyticcycling.com
re: more power less timecyclopathic
Aug 4, 2003 12:43 PM
if you assume 450wt vs 250wt time difference will be 250/450 = 56%. Typical club rider produces ~350wt at LT. 250wt is a good number to use.
I think your wattage numbers are off.huez
Aug 4, 2003 2:35 PM
350 watts at LT is definitely not your typical club rider. Maybe 250 is. But I would guess even lower than that. This is purely based on what I can put out and what level I ride at.