Hyaboosta

I ride in New England and its kinda hilly in areas around here and wanted thoughts on weather the 12-27 is to low of a gear set? I am using a 11-23 now and ist way to tall.

jschen

If in doubt, go lower. Between those two, get the 12-27 over the 12-25. The only difference is that your lowest two gears would be 24 and 27 rather than 23 and 25.

FrankBattle 

Height? Weight? Are you somewhat strong? Do you like to climb?

The 27 will give you a nice low gear, but so will the 25, if you are willing to ride through the pain ..

I have both. But I haven't used the 27 in a few years, though I am glad it's in the tool box. I live upstate NY and on top of a hill. I LOVE to climb and have had no problems keeping up with people 60% my size uphill. If you can afford it, get both. Nothing wrong with having options ..

I actually do have the 23 also. If I know the ride is rolling, with no major climbs, I slap that on. I haven't had to use it also in a year.

johnny99

No way to answer your question without knowing your fitness level. But if you are asking because of a lack of confidence in your fitness, then you should probably choose the lower gears.

merlinextraligh

If the 23 is "way too tall" the 25 will not be a huge difference. Hence, I'd go with the 27.


If you want to put a finer point on it, play around here: https://www.sheldonbrown.com/gears/

urbanknight

imo you will barely notice the difference between a 23 and a 25. I didn't even notice all that much when I switched from a 23 to a 26, so I ended up removing a middle cog and adding a 29 instead! (yes, that made a difference). Unless you're feeling like that 23 is just a "hair" too hard, you want something noticeable like the 27.

Camilo

I'm of the school that agrees: "If you're asking, go lower" or "when in doubt, go lower".

However, understand that changing a cassette is not a major cost even if you have the bike shop do it. It is definitely something you can do yourself. If you get the 27 then decide you don't really need it (or vice versa), it's a $30-$60 part depending on the group level you're trying to match. So, it's not a big deal if you change your mind later.

kring

I'm in CT and all I ride are hills.. Go with the 27.

Snicklefritz

What is your cadence when you are climbing some of this stuff? Looking at cadence is a good way to figure out if you need lower gearing or not. If you're already doing 75-80 or so, then don't worry too much. If you were getting bogged down at 60 or around there, then some lower options would probably be nice.

I have a compact on my bike, 50-34 with a 12-27. My bike came with a standard double, but I wanted the compact to get some lower gearing. The only time I use the two lowest gears are on long extended climbs or very short steep stuff (15%+). The two low gears help me keep a good cadence going up that stuff.

For flat and rolling terrain I much prefer a tighter cassette. The 12-27 has some gaps in it which can be a pain when doing workouts where I want to have a specific cadence on flat terrain. Get two cassettes like some other people have said and just swap it out yourself depending on what you're going to be doing.

Dubbayoo

If a 23 is 'way too tall' then a 25 won't feel drastically different. Go with the 27. I just got one for SoCal yesterday.

jschen

Gearing: (parentheses for 10-speed vs 9-speed)

11-23: 11-12-13-14-15-(16)-17-19-21-23
12-25: 11-12-13-14-15-(16)-17-19-21-23-25
12-27: 11-12-13-14-15-(16)-17-19-21-24-27

No difference when riding flat ground unless you actually can push a 50-11 on flat ground, in which case you're probably not complaining about lack of gears for hills.

Hyaboosta

6'3" 180lbs, left knee problem from getting hit by a Cab in Boston on a bike years back, I LIKE THE HILLS THOUGH but I ride recreationally. Will do prob a couple thousand miles this summer.

Hyaboosta

The change is also to go a little lighter from Ultega to Dura Ace, I did a simalar thing on my Mntn Bike going to XTR and it seemed to make a difference. I am in really good shape for a 40 year old. I just get the burn possibly a little fast on the hills now weather that is a diet thing or not I dont know but for now the gears are the easy way out.

sean565

DA cassettes are $190 and weigh 173g and Ultegra cassettes are $70 and weigh 217g. Spend the $123 savings on something more practical than saving 43g. Drink Diet Coke instead of regular Coke for a day or two and you will realize the weight savings.

Hyaboosta

Lol

Snicklefritz

yeah, I can see the numbers there, but there are times when I want to have a certain cadence and I can feel the difference between the last couple ones even though they are small.

FrankBattle 

Get both (25 & 27).

If money becomes an issue, then sell the one you end up not liking.

bssjackson

I have both. The 27 came on my specialized and I bought the 25. Although I have yet to use the 25, they had to order it and it hasnt come in. The 27 is more than enough for me though I have not gone into the 27 tooth yet

stapfam

Better to be this way than to want a lower gear. That hill at the end of a ride is going to turn up eventually.

Homebrew01

I'll take your 11-23 ..... I'd rather have a 12-21 for racing though.

ericgu

If you're switching cassettes, there's little downside to a 12-27. That will be nearly 20 percent lower than your current gear, which means you'd be spinning at 96 RPM rather than 80 RPM.

Jay Gloab

Does a wider-range cassette affect the smoothness of RD shifting? I have an 11-23 cassette that shifts super-smooth and fast, but I'd really like some lower gears, as I have a 50/36 compact double crank and I'm fairly new to this. As I don't have knee problems, I think I'd prefer to suffer through hammering up hills until I'm strong enough to spin up them in the gears I have if changing the cassette would mess up my shifting.

dekindy

Can you change between a 23 and 27 without changing the chain length?

VanceMac

29

(Unless you have a compact, then 27 will be sufficient.)

Psimet2001 

12-27 - gold standard for rec cyclists sporting 10spd Shimy drivetrains everywhere.