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TT-Do you really need 2 chainrings?

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TT-Do you really need 2 chainrings?

Old 11-04-06, 03:31 PM
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TT-Do you really need 2 chainrings?

Im debating if I should put 2 chainrings on my tt bike or 1. I use the tt bike only on flats to rolling. Please help.
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Old 11-04-06, 03:37 PM
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You don't need both but if it's already there - what do you gain by taking it off? and vice versa.
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Old 11-04-06, 03:39 PM
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It depends on what you prefer, a second chainring wouldn't hurt, but it probably wouldn't help much aero-wise. I'm TTist, but once I get the right cluster in the rear, I don't need the small chainring, I can take 20+% grades in the large ring, so if you have enough power, go for it.
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Old 11-04-06, 03:52 PM
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Originally Posted by Dial_tone
You don't need both but if it's already there - what do you gain by taking it off? and vice versa.
+1

More importantly, do you need a 50, 52, 53 or 55?
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Old 11-04-06, 03:59 PM
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Originally Posted by CrimsonKarter21
I can take 20+% grades in the large ring, so if you have enough power, go for it.
First we go to analyticcycling.com:

Speed For Given Power
Speed For These Parameters 2.65 m/s = 5.9 mph
Power 400 watts
Frontal Area 0.5 m2
Coefficient Wind Drag 0.5 Dimensionless
Air Density 1.226 kg/m3
Weight Rider & Bike 75 kg
Coefficient of Rolling 0.004 Dimensionless
Slope of Hill 0.2 decimal

Then we take 5.9 mph to Sheldon Brown and since I'm lazy, I look up speed at 40 rpm. I see that a 53x25 gives 6.6 mph. So I figure you're turning less than 40 rpm using a totally inappropriate gear, you're monstrously powerful to TT at over 400W, your hills are so short, you're letting momentum carry you over the top (in which case you're not really riding the hill), or just perhaps you misjudge the grade of hills.
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Old 11-04-06, 04:03 PM
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I guess you really dont need two rings but its a hassle taking off the rings and putting them back on. I'd just leave 'em there.
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Old 11-04-06, 04:15 PM
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The answer is, you might as well.
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Old 11-04-06, 04:17 PM
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Originally Posted by Juklano
Im debating if I should put 2 chainrings on my tt bike or 1. I use the tt bike only on flats to rolling. Please help.
I guess you dont live/race where there are hills. My last time trial had about a 20% grade climb thrown in it.
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Old 11-04-06, 05:19 PM
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Flat time trials are NOT about bike wieght. Leave it on.
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Old 11-04-06, 05:20 PM
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Originally Posted by CrimsonKarter21
I can take 20+% grades in the large ring,

I would like to see you do that.
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Old 11-04-06, 06:05 PM
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Originally Posted by CrimsonKarter21
I can take 20+% grades in the large ring
...and what ProTour team do you race for?
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Old 11-04-06, 06:08 PM
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Originally Posted by cat4ever
I would like to see you do that.
I couldn't take a 20% hill on the big ring of a compact.

Keep in mind, if you remove the 2nd ring and accidently knock that front derailleur you're down 20 seconds putting that chain back on...way more than you save by removing it.

Last edited by Dubbayoo; 11-04-06 at 08:47 PM.
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Old 11-04-06, 06:48 PM
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Originally Posted by CrimsonKarter21
It depends on what you prefer, a second chainring wouldn't hurt, but it probably wouldn't help much aero-wise. I'm TTist, but once I get the right cluster in the rear, I don't need the small chainring, I can take 20+% grades in the large ring, so if you have enough power, go for it.

and then you wake up.
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Old 11-04-06, 06:59 PM
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Originally Posted by Dial_tone
Keep in mind, if you remove the 2nd ring and accidently knock that front derailleur you're down 20 second putting that chain back on...way more than you save by removing it.
Excellent point. I wasn't thinking about that at all...
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Old 11-04-06, 07:02 PM
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limiter screws could solve the derailler issue, and an upgraded power dial could solve the 20+% grade issue
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Old 11-04-06, 07:04 PM
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Originally Posted by PenguinDeD
limiter screws could solve the derailler issue, and an upgraded power dial could solve the 20+% grade issue
Everyone is out of the dials that go to 11

I'm still using the outdated dials that go to 9.
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Old 11-04-06, 07:21 PM
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This one goes to eleven: https://www.cyclingnews.com/road/2002...02/?id=results
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Old 11-04-06, 07:41 PM
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if you are taking off the second chainring, what the hell do you need to keep the derailler on for?
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Old 11-04-06, 08:14 PM
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Originally Posted by goldfish
if you are taking off the second chainring, what the hell do you need to keep the derailler on for?
To keep the chain from jumping off the chainring. re: David Millar, 2003 Tour de France Prolouge.
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Old 11-04-06, 08:18 PM
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Now you might want to make the big and little ring closer - I have a 42 on the middle ring of my triple (gasp) and it's great for what I might call rolling ascents. So you could go with a 53/42 and that might cover all you'll ever really see, including headwinds.
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Old 11-05-06, 06:36 PM
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Originally Posted by Dial_tone
I couldn't take a 20% hill on the big ring of a compact.

Keep in mind, if you remove the 2nd ring and accidently knock that front derailleur you're down 20 seconds putting that chain back on...way more than you save by removing it.
That happened to David Millar in the TdF prologue a few years ago. Only took him 3 seconds to put the chain back on (damned impressive to those mechanically challenged folks like me). Still cost him the yellow jersey though.
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Old 11-05-06, 09:27 PM
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I see no real reason why you would bother taking off the smaller chainring, pointless pain in the ass. Just don't use it if you don't need it.

Interesting about the dial to 11, my tri club's shirt this year has "This is Purdue Triathlon" in the appropriate font with a big dial set to 11 on the front, and on the back it says "we go to eleven" it's pretty sweet.
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Old 11-05-06, 10:52 PM
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Originally Posted by sathomasga
That happened to David Millar in the TdF prologue a few years ago. Only took him 3 seconds to put the chain back on (damned impressive to those mechanically challenged folks like me). Still cost him the yellow jersey though.
I was thinking the same thing...I would just leave it alone. but going with a closer chainring is a great idea, you could find a 44.

but if you were to get rid of the small ring, why have to brakes?
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Old 11-05-06, 11:32 PM
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Originally Posted by fogrider
I was thinking the same thing...I would just leave it alone. but going with a closer chainring is a great idea, you could find a 44.

but if you were to get rid of the small ring, why have to brakes?
what does one have to do with the other?
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Old 11-06-06, 06:57 AM
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Originally Posted by Dial_tone
what does one have to do with the other?
I think maybe the thought was if you're losing the small ring, why have a rear brake? If you were going to go for weight savings anyway. Rewire the shifters, (or not if they're european wired), remove a whole brifter/brake set. Leave the front brakes/rear der. set.

I'm still stuck on climbing 20% in the big ring. Maybe he's running 39/30 in the front. Probably not though, probably tell us it's a 55.
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