njkayaker

You have a "racing" set-up. It's not clear why you ended up with that. It isn't likely to be the best for you (it's geared too high).

A fairly typical set0up for people is a "compact" crank with 50 and 34 tooth chain rings and a 11-25 tooth cassette. A 11-28 cassette isn't uncommon.

It's possible that you could use a 12-30 with the Ultegra rear derailler you have (but you'd likely need a chain too). Though, that might be a bit too wide for 9 speed (with fewer cogs, the gaps between gears might be larger than you'd like).

Icecyclist.com

12x27 is an excellent choice. That is what I run. You will notice the difference on long climbs.

Mortica

I just got off the phone with my boyfriend (who rides more than I do) and he had mentioned a 'compact crank' and that is what he has put on both of his bikes. From talking to him and reading what you just posted, this sounds to be a better solution for what I am wanting to do. I would like to build myself up to ride these hills, but also would love to keep this bike. I guess I am going to look and see what this 'compact crank' is going to run me.

Mortica

what is the difference between a 12-27 and a 11-28?...this is like a foreign language to me hahaha

caloso

The cheapest, easiest, and possibly best solution is to just get a 12-27 and a new chain. If that's low enough, great. If not, then consider a compact.

ThermionicScott 

It's not that hard to figure out -- most people just buy a bike, and they might not count up all the gear teeth like us dweebs.

Before recommending lots of radical parts swaps, we need to keep in mind that the 650C wheels drop the gearing somewhat -- her 39x23 low gear is exactly the same as a 39x25 gear on a 700x23 road bike, and a cassette with a 28T cog would give her a nice 34" low gear.

Mortica

Awesome!!! I will try that first.

Mortica

Awesome!!! I believe I will try this first and give it a whirl.

njkayaker

That's the range of tooth numbers of the gears on the cassette in back.

I'm just listing the smallest and largest gears on the cassette on the rear wheel. You list all of them here:

This is a 12-23 cassette. The cassette you have is basically just for racing.

With the smaller wheels, your gearing is lower.

Continuity

+1 On the cassette being the easiest/cheapest option to lower the gearing. If you kept the existing cassette and installed a 50/34 compact, it would lower your gearing nicely, but you would be left with the 'corn cob' gearing (i.e. the 1-tooth difference between (nearly all the) sprockets means you feel a very subtle difference between each gear, and it's range is more limited (i.e. from the lowest to the highest gear)).

Something like an 11-28, or a 13-28 would have a greater 'difference' between most gears (2 teeth), and it covers a broader range.

Then again, you might light the feel of that.

TBH, if there were an infinite number of gears on a bike, then such closely-spaced gearing would be fine for almost all uses, but in reality where you can only choose from a limited number of teeth in a defined range, I tend to find that greater gaps with more range are better (for general use).

As you've probably already sussed out, when cassettes are referred to as say 11-28, that means that it has 11 teeth on the smallest sprocket (highest gear) and 28 teeth on the largest. The more teeth, the lower the gear and easier to pedal.

With the older freewheels (as opposed to modern cassettes), you used to be able to choose all your sprockets on the rear 'off the peg' (literally - bike shops used to have a peg-board on the wall with all the differently-sized sprockets on them, and you'd choose which you wanted).

At the front, it's the other way round - the larger the chainring, the higher the gear, and vice versa.

njkayaker

Actually, for a fair number of years, you'd have to work at getting a standard crank on a new bike since most road bikes are sold with compacts. If you are buying from a shop, there isn't any excuse for ending up with the wrong crank. Anyway, she bought the bike used.

I missed the 650B wheels detail. A 39 x 28T equivalent is probably still too high.

The easiest thing to do is to change the cassette to a 28T. It's quite possible that she could go to a 30T too.

Al1943

Actually she didn't say 650B. It's a road bike and I would assume the rims are 650c, like on my wife's bike. This size is a great idea for smaller people because it allows for a shorter top tube as well as more stand-over height.
The lowest 9-speed road cassette offered by Shimano is the 12-27. It may be possible to buy an aftermarket or custom cassette like a 13-28 and run it with the 6500 rear derailleur.

pierce

even so, 39:27 (1.45:1) is quite a bit lower than 39:23 (1.7:1)

njkayaker

650C makes more sense. (I realize the advantages of the smaller wheels for shorter people.)

The SRAM 950 speed cassette ($28) is 11-28 and might work with the chain and derailler she has.

I used that cassette on a 105 SS derailleur (I believe) set-up for a 11-25 cassette (and a compact) with just swapping the cassette. (I would have noticed if the shifting was poor even with it being on the bike I wasn't riding.)

The gear-inch difference between 700c and 650c with 23mm tires is about 3 inches. That's around the typical difference btween low gears, which means the smaller wheel size makes the gearing about "one" lower than 700c.

Gear inches.

..... 700/23c....650/23c
.....39....34....39....34
23..44.6..38.8..41.2..35.9
25..41.0..35.7..37.9..33.1
28..36.6..31.9..33.9..29.1


I use a 11-28 on a 50/34 compact and I climb lots of hills.

With the 28 rear with the 39 chainring, she'd get two lower gears (but a "half step" larger than my lowest). Going to a compact would give her one even-lower gear (for a lot more money).

Yes. She'd have about two lower gears going from 23 to 27 or 28.

Mortica

Well, I was able to put a 12-27 cassette on this bike. Going to give it a try on the next group ride on Wednesday. thanks all for your help.

cny-bikeman

Good luck! Incidentally, your new low gear will be 15% easier to pedal than the old one - (1-23/27)*100=15%.

Mortica

I found it much easier to keep myself in a spin with this cassette without my knees or legs screaming at me hahaha. I am provably going to be looking into a new bike possibly, a 10 speed and going to find a frame that may fit me with a 700c tire instead of the 650c. If I do, I just might keep this bike I have now at home on a mag trainer.