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Discussion Starter · #1 ·
I currently have Campy Chorus, the cassette is a 12/25. The cassette will soon be replaced. It has been suggested that I go with a 13/26. I live in an area that has lots of short, but steep climbs. I've be told that a 13/26 would be a plus in terms of not having to shift down to the small chainring as often for the climbs. I'm concerned that it may result in lost speed on the flats. Will this make a marked difference? What is the best option? Advice please. :confused:
 

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So your advisors are suggesting you ride steep hills on the 53/26 regularly?

I respectfully disagree. We're talking about modern Campy here... it's not so difficult to shift down to the small ring. In fact, us Campy fans love that trick where you tap both thumb buttons at the same time, dump from big ring to small and end up in the perfect gear, no momentum lost.

But I digress.

I use a 26 when I'm doing really steep stuff, but to mean that means I'll be in the 39x26, not the 53x26.

And you won't notice any difference on your top-end speed either way. Go here and do some MPH / cadence calculations.

www.sheldonbrown.com/gears
 

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You say you ride lots of short steep climbs. Is the 39x25 ever not low enough? i.e., do you ever wish you had a lower gear? If not, then don't change.

On the other hand, do you use the 53x12 much? Does it always feel like a big enough gear, one you'll never spin out? If so, then it might be a wasted gear, and the 13 will be tall enough, and by switching you'll gain a tiny bit of bailout gear on the low end without costing you anything significant at the top.

And as Creaky said, the easier shifting thing is kind of a myth left over from the old days when front shifting could be very finicky. With modern chains, and clever chainring profiles with their ramps and pins, it's no big deal. Shifting in front is a bit more fussy than in back, so if your gearing and your terrain has you doing it constantly, you might want to address it, but this cassette change wouldn't fix that anyway. You'd need to go to a compact crank with smaller rings to move the range enough to make a difference.
 

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Discussion Starter · #4 ·
Both CK and JC, thank you for the advice. I don't have a need to go lower than 39x25 for climbs. 53x12 is used, but not commonly, mostly for short distances when there's a surge in the group. As you mentioned, I was thinking that the 13 would offer a slight bailout at the low end. I understand the bit about a compact crank. Bottomline, it sounds like the change that I mentioned would not have a significant impact.
 

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I mostly use 12/25 on my Campy 10-speed drive train. I do a weekly "hill ride" in the summer months with a lot of short, steep climbs (and a few longer, moderate climbs). I bought a 13/26 to use for the hill ride, but got rid of it after a couple of months. ( I put it on a build for a women's bike for a friend). Here's why: I benefited from the 26 (vs. 25) less than I missed the 12 (vs. 13).

What I found is that I can power up short, steep climbs in a 39x25 pretty well. There are one or two climbs where I would *prefer* to have a 26, but its not that big a difference.

On some of the moderate downhills (and even some of the flats with the wind behind), I found that I was not able to maintain top speeed in the 13 like I could in the 12. True, I don't ride the 12 all that much. But when a buddy is speeding away on a downhill and you're struggling to keep up, it sure comes in handy!

I wound up buying a 13 x 29 to replace the 13 x 26. I use it on a wheelset that I reserve for trips to very hilly areas, where the 29 gear will make a much bigger difference on the uphills than the 26, and the 13 is the same on the other end.

I am a bigger, stronger, middle-aged rider. I am more of a "masher" than someone who naturally likes to maintain a high cadence. I know that there are many who argue that a 13 high-end is just fine; that you should just spin faster to make up for it. Well, that just doesn't work as well for me. And with the 12x25, I still have the 13 if I want to spin faster at the same speed . . . .

Hope this helps.
 

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"I'm concerned that it may result in lost speed on the flats"

I have difficulty holding 30 mph on the flats for any amount of time.
A 13 should be good for any group ride that averages 30+ mph. You might start to spin out at 36/37 mph though.
 

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You probably will not notice a difference between the 25 and 26. The bigger reason to use the 13/26 is the 18 tooth cog. If you don't need a 12 then a 13/16 is always a better choose than the 12/25. Other than the 25-26, the difference is swapping the 12 for a 18.
 

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I agree with Bianchi-the real advantage of a 13-26 is not climbing but having an 18 for use in both chainrings. A very useful gear. Additionally, the 26 is an advantage over the 25, not when climbing but on really windy days when i want to go easy or at least not use any more effort than I can avoid. Having said all this, lately I've been using the 12-25 'cause the group can get really fast sometimes and I want to keep the HR as low as I can for the effort put out. If you don use the 12, go for the 13-26. I have a 13-29 for the really steep hills-20%+ stuff.:cryin:
 

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Bianchi67 said:
You probably will not notice a difference between the 25 and 26. The bigger reason to use the 13/26 is the 18 tooth cog. If you don't need a 12 then a 13/16 is always a better choose than the 12/25. Other than the 25-26, the difference is swapping the 12 for a 18.
If you don't use the 12, then for sure the addition of the 18 in the 13x26 is a plus.

For me, I'm in the big chainring most of the time. The 53x12 through 53 x 17 take me through most flats to moderate rises, unless the wind is strong and straight in my face. When a hill comes, I decide whether its a "roller" or a short, steeper hill that I can power up w/o shifting down to the small chainring. If it is, I stay in the 53 and welcome the slightly bigger drops to lower gears (x19, x21, x23, and x25) as I move up the roller or steep, short hill; crest, and move back into the higher rear gears on the downhill.

If, however, the hill I'm approaching is a longer or even steeper climb, then once my cadence drops in 53x17, I drop to the smaller chaingring in front and shift to the bigger gears (meaning the smaller-diameter) cogs on the rear cassette. Picking up with the second "biggest" (smallest-diameter) rear gear on the 12x25 -- which is the 13-tooth (to avoid small-small crosschaining), I have almost the same gear ratio as a 53x18 (5.7 vs. 5.6). As I move up the hill and the cadence drops, I can downshift from there to progressively easier x14, x15, x16 gears and so on.

Approached in this way, I don't really miss the 18. If its a really windy day and I head into the wind, I might have to shift both front and rear derailleurs to get a relatively easy flat road gear that I would otherwise be able to achieve with an 18-tooth cog while staying in the 53 chainring, but this is a rare inconvenience, and worth it to pick up the 12-tooth in my book.

But if that 12 is no use to you, by all means the 13x26 (or x29 if you have bigger hills).
 
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