|Where do I start?||JELLIOTWELLS|
Aug 14, 2003 6:34 AM
|I own a 2001 Specialized Allez 'A1' mostly Tiagra (deraillers, brakes etc.) , and Ritchey (hubs, stem, etc.). I realize this is not the hottest road machine out there, but it serves my purposes for now. I would like to replace the bike but can't justify the costs to my wife. So the next alternative is to upgrade some components. My main objective is reducing weight. Where is the best place to start, considering I have a $200-$300 budget? Wheels, Fork, Seatpost, Seat, Crankset? Also any suggestions that would fit my budget would be helpful.|
|re: Where do I start?||thefish|
Aug 14, 2003 7:35 AM
|With 2-300 bux I would do this- Get FSA pro team issue cranks. That alone should knock off 100+grams of rotating mass. Eliminating rotating mass is more important than "dead" mass. Also, I'd get a Dura-ace/Ultegra rear cog....that should also shave off some mass.
Now, if you don't wanna do the cranks, then I suggest getting a full carbon fork...which in most cases can save you 100+ grams of dead weight and provide better aero characteristics.
Changing out your wheels on that budget would not prove too beneficial. If you had $500 to spend on wheels, that would be the best upgrade (Velomax ascent II ~1400g) ....again in most cases you can shave off 200+ grams of rotating massfrom replacing the wheels!
The cheapest way to shave rotating mass is getting lighter tubes/tires. This will only run you $100 or so (100g). Then you could get a CF seatpost/stem (100g).
My choice would be the cranks. There are very few cranks out there that weight less than FSA 555g cranks. For comparo Shimano 105 double weighs 654g (2003 model).
|Crank/pedal/hub weight is not "rotating"||Kerry Irons|
Aug 14, 2003 5:34 PM
|The added kinetic energy to spin cranks, pedals, or hubs is virtually nothing. Rims/tires are rotating at 20 mph or so, while pedals/cranks are rotating at 4 mph. KE = mv^2/2. 20 squared = 400. 4 squared = 16. Rotating KE from pedals cranks is 2% for an equal weight in rim/tire. Forget about it.|
|Crank/pedal/hub weight is not "rotating"||thefish|
Aug 15, 2003 7:39 AM
|Hubs, BB, cranks, pedals, skewers, cassette= 350g+200g+555g+250g+25g+156g= 1.536Kg
Rims( since spokes rotate at different velocities I will discount them for sake of simplicity) tubes, tires= 700g, 200g,440g= 1.3Kg
KE=(1.536Kg)(3.6Km/h)^2 /2 (assuming 60RPM on a 170mm crank)
KE= (1.3Kg)(7.2Km/h)^2 /2 (assuming every .5 pedal stroke =1 rotation....different gears will result in different threoretcal KE; while you may be moving 30km/h or so any one point on the rim is moving twice the speed of your pedaling)
Yes, the wheels are a better choice for upgrading...I never said they weren't,; however the cranks and etc. still do have a good effect on the energy required to move your bike. Cranks and hubs and etc account for 30% of the KE required to move the rims and etc.
In other words, if you have $500 to spend on wheels by all means ....it is probably your best choice...but w/ only 2-300 bux...you decide.
|Your math is very weak = totally wrong!||Kerry Irons|
Aug 15, 2003 4:04 PM
|Since when is the bike only going 7.2 km/hr (4.5 mph)? Since when is the entire BB turning at any speed (only the axle turns, and if the axle is 2 cm in diameter, then the velocity at the outer surface is 0.37 kph @ 100 rpm). Even if we take your totally bogus assumption that the entire weight of the hubs, pedals, BB, skewers, and cassette are rotating at 100 rpm (6.4 kph) at the end of the crank arm (!), assuming the bike (and therefore rim, tire, tube) is going 32 kph, your own incorrect assumptions show that wheel KE = 870 while "other" KE = 27. That is less than 3% due to non-wheel weight, and you've inflated your mass number rediculously. Try again.|
|Your math is very weak = totally wrong!||thefish|
Aug 16, 2003 4:17 AM
|I do agree....my math was cheesely done =P since the BB and etc are rotating @ different speeds. But notice this; the cranks become more and more relevant at lower speeds ....i.e. 1-7KM/h. So, for that initial jump, the cranks are relevant. But, become less and less relevant at higher speeds ....since the wheels are rotating much faster than your pedals are (i.e. the gearing has changed; therefore it's no longer 1:2....but more like 1:6.
SO, while you may only be pedaling 3.2km/h at the crank, your wheels could be going much much faster due to gearing. My assumptions only tried to cover one velocity, I was wrong because it changes as velocity changes(gearing and etc.)
Wheels=very important past 7km/h
Take into consideration the only time a roadie is ever going to be going that slow is 1. Off the start 2. Up a very very steep hill. On the other hand, for MTB riders, a lighter crank is probably a good choice because they don't have high speeds (unless downhill).
|First things first...||Marketing Dept|
Aug 14, 2003 7:39 AM
|Are any of the components broken or not functioning well?
If yes, then the $$ should go to replacements.
If everything is working well, I suggest pour it all in a nice wheelset. For $300.00 you can go pretty exotic and light weight, say 1800grams for the pair.
Or better yet, find a set of Open Pro/Ultegra wheelset for >$200.00 and get a light weight set of tires and tubes.
Reducing rotational weight is always the best place to start in reducing weight. The Open Pro/Ultegra set is light (realitive term)and indestructable.
|First things first...the wheels||pedalAZ|
Aug 15, 2003 10:04 AM
|I just got a handbuilt set of wheels for under $400 that weigh 1,480 grams on my digital scale. Sun Venus aero rims, Wheelsmith spokes, alloy nipples, American Classic hubs. Sounds like that set could save you nearly a pound of rotating weight.|
Aug 14, 2003 8:00 AM
|I keep hearing of Ultegra/Open Pro wheelsets from Colorado Cyclist for about $200.00. That's where I would spend my upgrade money. That other stuff may make your bike look prettier, but it won't make it go any faster.|
|with ultralight tubes. nm||lotterypick|
Aug 14, 2003 8:24 AM