|new/lighter wheels feel slower than old/heavier ones||colker|
Dec 4, 2001 6:16 PM
|new= daytona hubs/ mavic cxp 21 rims. old= dura ace/ campy omega v (semi aero) rims. |
the new ones are considerably lighter but they don't "hold" speed like my old set.
why?? teh aero rims? they suck when climbing!
Dec 5, 2001 1:49 AM
|Although I can't explain the climbing bit, I have noticed the same effect with my heavier spare wheels on the flat - I put it down to the flywheel effect of heavier rims, that have more enertia once you get them rolling.
Suck in what way when climbing?
Dec 5, 2001 3:47 AM
|the heavy wheels suck when climbing. once i lost speed, it was painfull to keep going. |
i guess you are right about the inertia. my goal now is too find a a pair of lighter semiaero rims than the campy omega. on the flats, for commuting and all around riding, those semis gave me a better ride than the mavics.
|Check these out||jw25|
Dec 5, 2001 11:19 AM
|light, aero rim from Bill Shook, one of the founders of American Classic. 420 grams for a 34mm rim is pretty attractive, and the price isn't bad at $79. Comes in 16 to 32 hole drillings. I'm just waiting to see some real-world reviews before plunking down the cash.
As for the flywheel effect, it's been argued here that aero is more important than light for most cycling, barring lots of climbing. I tend to agree, since the weight only plays a big part when accelerating, but there's enough designs out there that everyone can find what they're comfortable with.
|bill shook's aren't 420gr||cyclomoteur|
Dec 5, 2001 6:28 PM
|30+ mm is always +450gr|
Dec 5, 2001 3:00 PM
|You have discovered the "moment of inertia". Two wheels can be of identical weight with very different moments of inertia. The biggest contributor to the moment of inertia is the rim, since it's weight is a large distance from the center of rotation. Hubs have little effect on the moment of inertia.
Try spinning around while sitting in an office chair with you legs held out - then tuck you legs in, and notice the immediate increase in speed, due to the reduced moment of inertia.
Wheels with a large moment of inertia hold speed well, but are more difficult to accelerate to a given speed. Basically, it's a case that you can't have your cake and eat it too.
As for the difference in climbing, it must be your imagination. If the wheels are lighter, they can't make it more dificult to climb. I ride the same hills over and over. From one day to the next, my speeds vary widely depending on the wind conditions, my physical condition and my willingness to exert myself. There is no practical way to distinguish the effect of a wheelset with all of these variables.
|i meant the old wheels were worse at climbing||colker|
Dec 5, 2001 5:25 PM
|problem is i built a totally new bike, a pinnarello vuelta. had a cadore before. except for the stem, everything is new. the bike is lighter. stiffer. same geometry, same frame material but quality of the new frame is miles better. |
it's weird to feel the wheels are worse though...
|im sure your campy rims are lighter than your cxp-21's||53 x 18|
Dec 5, 2001 4:43 PM
|not by much but maybe 50 grams each.
could be true. according to damon rinard they weigh 426, 430, 467 grams (???) either this refers to different year production weights or has something to do with spoke hole count (perhaps double eyeletted).
i doubt that the cxp21's come in under 480 grams each.
as has been said your new wheels are probably lighter at the hubs but if your rims are heavier then what you feel could be true.
|What about spoke tension?||cyclequip|
Dec 6, 2001 4:26 AM
|Biggest cause of 'sluggish' wheels is soft spoking. The CXP 21 isn't the most responsive rim anyway.|
|it feels tight.||colker|
Dec 6, 2001 5:42 AM
|but i'll probably relace the hubs with a competent wheelbuilder on open pros.|
|dont rush into it||53 x 18|
Dec 6, 2001 6:26 AM
|i will sometimes ride friends and my own bikes to "feel" comparisons. i have ridden older and heavier bikes that feel faster and more rigid or all of a peice. but my speed was slower than i thought compared to my new sluggish feeling bike. there are so many different factors apart from the wheels that give a bike a certain feeling.
spoke tension, rim weight could be part of it but only more riding over the same road with a speedometer will be able to isolate whether your "feel" is correct. damping, angles, materials, position, tire types and pressure take a lot of getting used to.
i only say this as you may get new wheels built with open pro's and still have the same feeling. maybe offer someone else a ride of both and see what they think. or try a different set of wheels on yours similar to what you will be looking to use. it may be tricky to find a riding partner that has exactly what you need to compare with a campy cassette but not impossible.
try to compare things before spending more cash as well as checking how well your wheels are built.
Dec 6, 2001 8:23 AM
|even though the new bike is the same size, brand and material(lugged steel), they are very diferent. the vuelta is much lighter, stiffer and gives instant road feedback almost like aluminum: everything under the tires goes through the frame. |
damping and general ride vibe is totally different.
can i find a "friendly" rider who could lend me his wheels for some minutes? would i lend my best race wheels to an unknown?hmmm... maybe but i think you have a smart point.
|you never know...||53 x 18|
Dec 6, 2001 8:41 AM
|i had a new bike built up.
for the life of me i couldn't understand why it felt sluggish. everything about it was up there in terms of design and efficiency. light, quality components. a frame that everyone had suggested would be great for climbing and sprinting.
well.. it didnt climb well and coz everything was new it took me a while to realise that the bottom bracket wasnt fitted properly and was actually grinding all my energy away. noiseless and internal - so i didn't pick it up straight away. the whole time i thought it was my wheels which i couldn't understand as they were the lightest rims with race tubulars attached, fancy spokes
and hubs. kept nagging the wheelbuilder about tesnion and all sorts of things. then the bottom bracket made a big crunching sound and i knew my problem immediately. until then it hadnt even entered my mind.
with your concern you will find the cause and solution, but i hope it doesn't necessarily cost you $$$'s. especially as i know the feeling of throwing money into a build and being less than happy at why it doesn't work as well as it should.
|re: new/lighter wheels feel slower than old/heavier ones||Chen2|
Dec 6, 2001 2:23 PM
|The CXP 21's feel heavy and slow because they are. We've got some on Ultegra hubs, 32 spoke. They came on my wife's Trek 5220 new. I use them for training when I want to be hard on myself. And the rear wheel doesn't stay tru more than 100 miles.
|re: new/lighter wheels feel slower than old/heavier ones||Chen2|
Dec 6, 2001 2:30 PM
|Sorry, I didn't mean to sound like I was running down your wheels. My apologies.