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I'm looking to buy a Shimano 7800 group and don't know whether to use a 11-23 or 12-23 cassette. I am a racer and always used a 12-23. Are there any advantages or disadvantages in either cassette or has anyone prefered one over the other?
 

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If you have 12-23 9-speed right now and you get a 11-23 10-speed it's exactly the same cassette with an 11 cog added to the small end. It will feel exactly the same except give you more range.

If you go 12-23 9-speed to 12-23 10-speed it will be the same gearing range but with one extra cog thrown in that makes the gear spacing tighter.

7800 is 10 speed right?

Ben
 

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Discussion Starter · #3 ·
Yes, 7800 is 10-speed. Is there an advantage in having the extra gear in the middle? I figure the 11 at the end will be slightly faster than a 12 right.
 

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Do you spin @ 53 X 12?

Gear calculator shows 100 rpm @ 53 X 12 - 55.6 KPH with standard road wheels.

It's actually a pretty big jump to the 11t. Do you routinely go over 60 kph?

Getting a 12-23- gets you a 18t cog. Personally, I'd rather have a straight block from the 12t to the 19t cog.

Mike
 

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how often you'd need 18t?

maybe grinding some long 4.5% climb in big ring or 6.5% in small in headwind. BTW 7800 cranks come in 53/54/55/56-42t, you can get 12-25 or 12-27 cass and 42 small, consider.
 

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My preference would be for the 12-23 on flat courses and the 11-23 on mountainous ones assuming I could climb the mountains in the 23.

My logic may be backwards. But I'm certainly not at a level where I would expect to be turning 53x11 on flat in a race, but could see down a mountain in a race. Realistically if I was at all worried I'd be grabbing the 12-25 for the mountainous race.

I find I appreciate tightly spaced gears when fighting a headwind. Having exactly the right gear seems to make it a little easier to bear.

Ben
 

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I would like a 12-25 or 12-27. Which on line store carries a full selection 10 speed Dura Ace cassettes? How much for one of those puppies anyway?
 

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42 x 25 is the same ratio as 39 x 23 and 42 x 27 is like 39 x 25 very close.
Some pros choose to run 42 over 39 in spring classics it makes much smoother transition, and 48/42 was pretty much universal in 10sp era (that's when we had 5 cogs in the back ;).

Agree tighter gear cluster is better, however 53 x 18 very close to 39 x 13, and gap btw 39 x 17 and 39 x 19 will be a problem only under specific conditions: 6-6.5% constant grade with headwind, so I am not sure how useful it'll be for racing. On break if you reserve to 53 x 18 in headwind, you gave up and about to get caught. 53 x 11 could be very useful going downhill, out of corners and to keep legs warm. For 39 x 27, hey some of us are old, fat, gave up racing, have only one bike and lazy to swap cogs.
 

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Exactly! The 11t is an ego cog.

Spoke Wrench said:
The 11 will only be faster than the 12 if you are strong enough to turn the crank.
An 11 tooth cog is completely a waste of steel for most human riders. Even some of those in the pro ranks. It is purely an ego cog. It makes you feel good to have it in your cluster, and it allows for component manufacturers to use the small cog in the weights of their cassettes. But it is a complete waste of time. Most people can't turn it fast enough to make it worthwhile over a 12 tooth. I used to be a pretty fast Cat 2 sprinter and I couldn't turn it fast enough to choose it over a 12. I guess if you are using a compact drivetrain with a 48 or 50 tooth large chainring, it's fine, but if you are using a 52 or 53, skip it. You would be much better server by having an 18 tooth in the middle (or whatever cog they leave out to give you the 11.)

I know as soon as this post goes up, at least 4 people are going to say they can turn and actually need an 11. I say that's BS. If you can spin out a 53x12 at over 150 rpms, get off this damn board and start leading out Petacchi.

Russ
 

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I wish Campy made a Record 12-23 as well. All they have is 11-23 or 12-25.....I don't need the bigger gear and I sure don't need the 11....was riding with a group of Hells Angels at 30mph just a few days ago through a little village in 17T....I was spinning pretty well and drew slightly surprised looks.....then again it might have been cause my bike was so different from theirs.
 

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Spicoli,

I always used a 12-23 on my 9-speed also (w/ 53/39 front), and I'm going with 12-25 on my new 10-speed. The steep hills will be a little more bearable as a result, and I still get to have that all important 16t that caused me to choose the 12-23 in the first place. I considered adding the 18t instead of the 25t, but as others have pointed out it doesn't add much that's not already there and is a low frequency need. I did not ever consider the 11t - but then I'm not Petachi's lead-out man, maybe you are.
 

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I'd MUCH rather have the 18T cog in there - it's a great "cruising" gear for me, and often the jump from 17T to 19T is too big. I've NEVER needed an 11T cog, as someone above has said.

The only reason I can see to get an 11-23 or 11-21 cogset is if you're trying to cut weight in every possible way, or if you can't get the 18T gear in other cogsets, (like with Campy 10s you have to buy the 11T cogsets or the 13-26 to get the 18T; the 12-25 and 13-29 don't have it). :(
 

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russw19 said:
An 11 tooth cog is completely a waste of steel for most human riders.

I know as soon as this post goes up, at least 4 people are going to say they can turn and actually need an 11. I say that's BS. If you can spin out a 53x12 at over 150 rpms, get off this damn board and start leading out Petacchi.

Russ
Though it may never have occured to you, there are times in a race where you have to go very fast downhill to catch back on to the pack. In another thread, I referred to chasing back onto the pack down the Sapillo or the back side of Gates Pass. In both cases, I was pedaling at speeds over 40 mph. A 53x12 gives a speed of 42 mph at 120 rpm so it is not out of line to say one needs an 11 for these cases. The fact that you're point of comparison is leading out Petacchi shows me you haven't thought this through very well.
 

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I don't know, man. I don't know from gear inches and resulting speeds and stuff, but I've never spun out my 12. I suppose I was surprised now and then how close I came (not very, but closer than I thought I'd come, anyway), but I never have spun it out, and I don't know anyone who has. I also suppose it may depend on the nature of the descent and exactly how fast this race is, but that's a pretty narrow "need." Most racers, and certainly most recreational riders, will never have any need for an 11. My guess is, if you don't know by now that you need an 11 and exactly why you need it, you don't need it.
 

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Just get a 12-25!

It's the same as your 12-23 w/ the 25 stuck on the end.

It has saved me more and been used more to stay w/ the group, than having to try and catch back on to the group on the descent!
 

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asgelle said:
Though it may never have occured to you, there are times in a race where you have to go very fast downhill to catch back on to the pack. In another thread, I referred to chasing back onto the pack down the Sapillo or the back side of Gates Pass. In both cases, I was pedaling at speeds over 40 mph. A 53x12 gives a speed of 42 mph at 120 rpm so it is not out of line to say one needs an 11 for these cases. The fact that you're point of comparison is leading out Petacchi shows me you haven't thought this through very well.

Actually, I have thought this thru very well. You don't really need an 11. When you were chasing that pack downhill, how was your tuck? Did you do what most of us do and spin the 53x12 for about 5 seconds as fast as you could, then coast for a second, then spin, then coast? I have drafted a truck on flat land at 60 mph and have hit 52 in a downhill sprint in a Pro/1/2 race. Both of which I did on a 53x12. If you could have spun that 53x12 at 120 rpm's on that downhill and that was it, you weren't even close to spinning out that gear. After you spin out that gear at say 180 rpm's or higher where you would really NEED that 11, come back and talk to me about thinking things thru. The part about leading out Patacchi was a joke that was lost on you. But that doesn't surprise me. You may not be a sprinter big enough to turn the gears those guys turn. I want you to know right now, I DO NOT mean that as an insult, but it is my speculation. Do you know why top sprinters sprint in the saddle? It is so that they can turn over a gear as large as a 53x12 with the speed they need to be not only fast, but efficient. That is also why top sprinters often come from track backgrounds. It is because you need to turn that gear at 150 or so rpm's to be good. If you are sprinting out of the saddle, you are turning a gear at most likely 100 or so rpm's and that is way to slow to do anything. You can't accelerate properly with that low of a cadence and you won't top out very fast either. If you can turn over a 53x12 at 150 rpm's, you may be one of about 200 riders worldwide who needs that 11 tooth (the exception of compact chainrings being the only other reason to use an 11)

You should really take a look at some sites like analytic cycling's website about going downhill fast. Once the road points downward with enough slope that you would spin out a 53x12, you don't need to pedal anyways. You won't go any faster. Pedal out of the apex of corners, but if the pack is in front of you and you are off the back, don't waste your energy spinning the pedals to catch them. You will be much better served to tuck your body out of the wind and out brake them in and out of corners if you want to catch back up. I don't want to turn this into a flame war, but you really don't need an 11 tooth cog anymore than you need a set of ksyrium wheels. Cyclists have been riding faster than 40 mph on downhills for a much longer period of time than Campy and Shimano have been trying to sell you an 11 tooth. It's for weight weenie wars over cassette weights. I don't see that as being a hard thing to figure out, unless you like buying into hype.

BTW, according to the model on analyticcycling, spinning a 53x12 downhill at 150 rpms gives a speed of 52.30 mph and the 53x11 gives a speed of 57.05. Spin the 12 at 164 rpms and you go faster than the 11 at 150. The amount you have to increase your cadence to match the speed of the smaller cog gets smaller as the cadence lowers. Your speed of 42 mph at 120 rpms with the 12 is accurate, but in order to go the same speed as you would hit at that cadence with the 11, you only need to spin the 12 at 130rpms. If you are going downhill and the hill is that steep, you should have ZERO problems spinning that 12 just that much faster. The whole thing about you using a downhill example where the resistance of the wind is less than the downward pull of gravity to show your point in your comparision also shows that you didn't think this thru very well. The point of leading out Petacchi, or anyone for that matter, is just to show that you have to be strong enough to turn the gear, which is what Kerry Irons said and I agreed with. Analytic Cycling even says on their website that you should learn to spin at 125 rpms before you buy an 11 tooth cog.

Russ


*edit... I just wanted to point out that I am not trying to pick a fight, so please don't read into this post that way, and don't respond that way either or the whole point of the discussion will quickly be lost.
 
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