12 Speed VS 16 Speed, or Whatever
-
No new posts
Moderators: k9car363, alicefoeller | Reply |
2004-06-23 7:59 PM |
Expert 833 Adrian, MI | Subject: 12 Speed VS 16 Speed, or Whatever I've been constantly told that it doesn't matter if you have a banged up 12 speed or a souped cannondale - what it all boils down to how hard you pedal. Is that really true, though? I think it might be if you're a newbie...but what if you're looking to post some good times? Wouldn't it be beneficial to have 16 speed, or higher, bike? I have a used miyata 12 speed road bike. It would seem to me that if you can shift to a higher gear, say 18, when going down a hill, that you can capitalize on your bonus speed because it takes longer for the bike to slow down. Moreover, you'll be able to tackle mild hills better...and thus be able to maintain a higher speed longer (would that be called carry over speed?). This is opposed to me, with a 12 speed bike that max's out rather quickly when going down hills. I think I pedal hard. But people still zoom by me. What really frustrated me was when I did a tri a few weeks back and a biker passed me when I was going 26MPH down a hill...that had to because he could shift higher, right? Do I need to buy a 18 speed bike to be able to maintain 20MPH and higher? Or is it possible (and is it realistic) to maintain 20MPH with a 12 speed? I can't help but think that being able to go faster for longer (20MPH) is intrinsically linked to bike speed/ potential. Thanks. |
|
2004-06-23 8:36 PM in reply to: #33343 |
3 | Subject: RE: 12 Speed VS 16 Speed, or Whatever The difference between a 12 speed and a 16 speed (or whatever) bicycle is not as much the range of the cassette in the rear, but more the spacing between the cogs. In a brief internet search you can have 6 speed rear cassettes that have a range that starts between 12 and 14 and goes to 19 to 34. So let's say a good guess is a 13-34 rear cassette on your current bike. The modern cassettes might be 11-21 or 13-23 for close gear ratios, or 11-34 for a really big ratio. So, we'll pick a 12-26 for "average." If the cogs are something like: **-13-**-15-**-18-**-24-*******-34 12-13-14-15-17-19-21-23-26 you are missing some top-end speed (but it's pretty hard to spin-out a 53-13) but what you're really missing is the ability to keep a constant cadence over subtley changing terrain. sandy |
2004-06-24 10:38 AM in reply to: #33343 |
Champion 6786 Two seat rocket plane | Subject: RE: 12 Speed VS 16 Speed, or Whatever Sandysandy got it right Heres the deal lets say you have a 12 speed bike and a 18 speed bike The 12 speed will have two chainrings up front and 6 cogs in the rear The 18 speed will like wise have two chainrings up front on the crankset but it will have 9 cogs in the rear on the freewheel/cassette The number of cogs has little to do with either the ultimate top-end speed potential or the ease with which (theoretically) the bike will climb. Think about that great Spinal Tap quote "but these amps go to 11" Bicycle gearing works this way the bigger the chainring and the smaller the cog the faster the bike can go, and the harder it will be to pedal conversely smaller chainring and bigger cog will result in a bike that goes slow, but is easier to pedal The standard vernacular term for measuriing the realitive size of chainrings and cogs is teeth Older 10-12 speed "racing" bikes typically featured a crankset with chainrings of 42 and 52 teeth and freewheels with cogs of 13-15-16-18-21-23 teeth occasionally you found a 12 tooth small cog touring freewheels might start with 14 and go to 27-28 (rarely but sometimes bigger) More modern bikes often have a 38/53 chainring setup and cogs of 11-13-14-15-17-19-20-21-23 or an 12-13-14-15-17-19-21-24-27 The ultimate speed potential of a 53x12 combination is higher than that of a 52x13 (if you have the legs to turn it.) likewise a 38x27 will make hills easier to climb than a 42x23 On the other hand, if you come across an old loaded touring bike with a pie-plate 14-32 freewheel and a 36 tooth in front, You're going to have a easy (if slow) climbing machine. Also, 53 (and larger) chainrings have been around for a long time too. freaky-small 11 tooth cogs are, however a more recent innovation. The taske-home message here is that look at the size of the gears, not the number of them. clear as mud? Edited by ride_like_u_stole_it 2004-06-24 10:39 AM |
2004-06-24 10:44 AM in reply to: #33343 |
Extreme Veteran 444 Fort Wayne, IN | Subject: RE: 12 Speed VS 16 Speed, or Whatever I didn't ask this question but I thank you both for supplying an answer to something I have often wondered about. I keep on learning and that is good. Thanks, Jim |
2004-06-24 8:31 PM in reply to: #33343 |
Veteran 209 | Subject: RE: 12 Speed VS 16 Speed, or Whatever Thanks for the lesson guys! Great info. |
2004-06-24 8:54 PM in reply to: #33343 |
New user 3 God Forsaken Long Island | Subject: RE: 12 Speed VS 16 Speed, or Whatever Sandy and Ride Like have given a great refresher of the physics of gears. There is another area of physics that may be holding you back on descents, however. Drag. The amount of aerodynamic drag varies in proportion to the square of your speed. That means that you experience 4 times as much drag when you accelerate from 13 mph to 26 mph. As you go faster and faster, drag becomes more and more an issue. This is why recumbant bicycles haven't been allowed to race "safety" bicycles in almost 100 years. The reclined position of the rider means that, given a similar construstion technology and a equally skilled rider, a recumbant can wipe the floor with a safety bicycle 7 days a week and twice on Sunday. It may be that those riders are passing you because they have managed to get in more aerodynamic positions. A common mistake riders make is to get low, but not think about width. If your knees and elbows are out wide, you can really hurt your speed. Practise riding low with your knees and elbows in as tight as is comfortable. |
|
2004-06-25 12:26 AM in reply to: #33343 |
Expert 833 Adrian, MI | Subject: RE: 12 Speed VS 16 Speed, or Whatever Much thanks to all that posted with advice. Amazing info, and in such detail! Thanks! I'll be honest though...being a bike newbie, I'm going to have to do some research to fully understand all the thoughtful replies. =) |