I'll be curious for our report. I have a 12-28 on a triple crank. I mostly use the middle ring up front & find my cadence often jumps 10-12 rpm when I shift in back. I'll probably need a new cassette in about 1000 miles and am thinking of getting a tighter group. My only concern is that while I don't often use the granny gear with the big cog, I do on occasion and am glad I have it when I do.

There is a fairly easy way to deal with this -- just keep multiple cassettes.

Swapping cassettes only takes a couple minutes if you have a cheap tool called a chain whip. In practice, you'll want the tighter cassette the vast majority of the time, but on the rare occasions when you expect to to need some seriously low gears, you can just mount the big cassette.

Incidentally, owning multiple cassettes is one of the reasons why you want a chain with a removable link since the correct chain length will be different for different cassettes.

Nice Tread,

I am have the same problem, my chain is jumping under load some times. I am going to measure the chain. I also need to look at the cassette to see if it is wore. It only seems to happen in the middle gears.

This is a sign that your cassette is worn. The reason it's jumping only in those gears is that those are the ones that are worn the most. If the chain you're using is new, just ride for a couple weeks and the problem may go away.

When you replace your cassette, be sure to replace the chain too.

Not sure if this has been covered yet (because I'm not going to read all of the responses).

If your LBS said "your chain is stretched" go to another shop. Chains do not stretch. They wear out. A chain can and should last you 1000's of miles before replacement.

Not going to happen. I mispoke before. My cassette is a 12-27. I may just go to a 12-23 or 12-25. I wonder how much difference there really is between 30x27 and 30x25 or 23. What do you guys think?

If you're at the point where you're in the 30-25 and you can't keep the cadence up, that extra 2 teeth will seem very worth it. I run a compact (50-34) with a 12-27 cassette. Although I can ride the hills in my area with the 34-25, there are places where my cadence would drop too low for sustained periods of time and this would often aggravate my knee. Adding 2 teeth wasn't very "manly", but it was worth it.

Bob

There is no practical difference between going from 12/27 to 12/25 for your purposes because all the cogs are the same except the last 2 cogs. The last 4 cogs on the 12/27 and 12/23 are different:

12/23 -- 12,13,14,15,16,17,18,19,21,23
12/27 -- 12,13,14,15,16,17,19,21,24,27

Note the 1T jumps that take you all the way except the last 2 cogs. With the 12/27, once you drop below the last 5 cogs, you have multitooth jumps. The difference would be nice but not super dramatic so I'd wait until the 12/27 wore out naturally before replacing.

I wouldn't ding them for this. Everyone knows they don't stretch, but this is just a colloquial expression that you'll hear all the time.

And I'll be honest, I don't know that he actually used the word stretched, he put this tool on my chain and showed me how the spacings were off. Stretched just seemed like the correct description to me.

Also, my baby got sent home sick from daycare yesterday, and I'm still on sick baby duty today. So I probably won't be able to give a ride report until this weekend. (it's killing me too, as I really want to try my new cassette out!)

That's my plan. In the meantime I might pretend I don't have the smallest cog & see how much I miss it.

This thread is like the eye of the hurricane that is the road forum. Polite, grateful OP and helpful responses. There definitely seems to be a trend of folks being encouraged to replace cassettes before they need to. Now, buying a new one to get different gearing - totally different, and an A1 example of necessary acquisition of bike schwag.

Ride Update - FINALLY! I got to take the bike out and try the new cassette. A couple observations:

The first has nothing to do with the size of the cassette (is size the correct term?), but more with just getting a new chain and cassette. They were definitely worn, as the difference is night and day. It may be that I just don't remember when the bike was new, but I don't think my gears ever changed this smoothly or quickly...I mean it was instant!

Now as far as changing to the 12-23, I can't thank you guys enough for that advice. Even if my cassette wasn't worn, it would still have been worth the money to me to make this switch. You guys are right, in flat Jacksonville, this sizing makes way more sense. Before, when I'd go up a mild (and mild might be exaggerating some) hill, or hit a headwind, I'd downshift a gear and my cadence would shoot up 10-15 rpm. Today it was more in the 4-6 rpm range, making it easier for me to keep a comfortable cadence and maintain my speed.

I do have a question regarding my front cassette. Now that I see what a difference a new rear cassette makes I'm wondering when/if I should consider replacing it. I noticed today that when I shift from the middle ring to the big ring it takes anywhere from 2-8 seconds to make the shift (with a lot of grinding noise during the process). I'm guessing this isn't normal, so is that a sign of wear? I obviously don't shift the front rings as much as I do the rear. In fact, with my new cassette I can stay in the middle ring pretty comfortably the whole ride. But just because I can doesn't mean it's the ideal , correct?

Anyway, you guys have been so helpful, and I couldn't be more satisfied with my new cassette!

Can't wait for tomorrow's ride!!

Have the LBS try to adjust your front derailleur first. If that doesn't fix it then maybe you need new rings, if you can replace the rings.