's Forum Archives - General

Archive Home >> General(1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 )

Is 12-27 too big(19 posts)

Is 12-27 too bigtoronto-rider
Aug 15, 2002 9:22 PM
I recently purchased a used bike. It had an 11-21 cassette. I was supposed to change it with a 12-25 but the store made a mistake and put on a 12-27. I have only done one ride with the new cassette and it seemed OK. The ride did consist of more hills than I would normally do on a ride.
Should I ask the store to replace the 12-27 with a 12-25 before it's too late or should I just stick to the 12-27.
It was their mistake so they should replace itPODIUMBOUNDdotCA
Aug 15, 2002 9:33 PM
It was their mistake and since you only went for one ride they should change it no questions asked. A bigger gear never hurt!

Aug 15, 2002 9:33 PM
Is this your first bike? Otherwise, what were your previously riding? Are you in shape? Is your riding area very hilly? Is this bike 9 speed?

I have always used a 23 as the largest cog, so I am pretty used to it. I don't ever see myself going to a 21. My opinion is the 25 probably is the best compromise, so if that's what you originally wanted, maybe you should ask for it.

A 27 is the largest that most people want to run until they start heading into triple territory.
Aug 16, 2002 5:58 AM
This is my 1st road bike in 8 years. I am a mtb rider/racer so I would regard myself as being fearly fit with good strength. IS the 12-27 therfore a waste?
Depends againFez
Aug 16, 2002 6:31 AM
The 12-25 is probably the best choice if you want an all around cassette with good spacing and light weight. I believe many Ultegra level complete bikes are speced with it.

I don't like the 27. Not so much because the 27 is too big of a plate to carry, but mainly because the cassette has too wide of a gap in the gears and I believe one poster said it was missing the 16.

Since you're in good shape, I would guess you would only need the 27 if you are going up some ball busting hills.

Simple answer: ask the shop for the 25.

I ride a 12-23 and consider myself a spinner and I seem to get by fine and I'm not even in very good shape.
re: Dependscyclopathic
Aug 16, 2002 6:42 AM
hard to say. If the terrain around Toronto as bad as Fingerlakes upstate NY, then you might wanna add triples on top 12-27. ;) In flat lands 11-21 would be all you'd ever need.

Since you're mtber you're probably used to sitting on climbs. If you use road to train for MTB I'd suggest lower then usual gear, you'll spend more time sitting. On other hand if you ride HT and like to climb standing there's no point.
keep 12-27cyclopathic
Aug 16, 2002 4:08 AM
the diff btw 12-25 and 12-27 is last 2 cogs 23/25 vs 24/27. Either way you're not likely to spend much time they're bail out gears. Gear jump from 21 to 24 is on high side, still it is about the same as from 15 to 17. However it doesn't cause as much discomfort as missing 16t on flats does; very unlikely you'd find a hill where you need 23 (or 25) and cannot go with 24.

On other hand 27 is 8% lower and can make the diff btw riding walking.
What is so great about a 16?GMS
Aug 16, 2002 9:40 AM
More than one person has mentioned that the lack of the 16, specifically, is a critically important factor. Why is 16 so important? What's wrong with 15 or 17?

What is so great about a 16?LC
Aug 16, 2002 10:02 AM
The 16 is right in the middle of the cassette where a strong rider and his 53T ring spends alot of time. If a slight wind or grade or differing position in a pace line calls for a gear change, the jump from 15 to 17 is too much change in cadence.
btw both 12-25 and 12-27 miss 16t nmcyclopathic
Aug 16, 2002 10:14 AM
Not necessarily true.Len J
Aug 16, 2002 10:59 AM
Weather or not you spend alot of time in the 16 depends on speed and cadence.

at 80 RPM 53/16 = 21.3 MPH: 39/16 = 15.7 MPH
at 100 RPM 53/16 = 26.6 MPH: 39/16 = 19.6 MPH

I happen to ride at between 100 & 105 rpm & spend most of my time in 39/ 15 14 0r 13 or 53/ 17 19 or 21 when I am riding hard. Remember most of my riding is in the flats.

The point I'm trying to make (in a most confused manner) is that once you know what cadence you run & what speed you think you are going to be spending the most time in & finally what terrain you will be riding in, then you can match your gearing to it. A 16 for a spinner who rides 20 to 25 MPH predominatly wouldn't miss a 16 (with a 53/39), someone who mashed at 75 to 80 rpm couldn't live without a 16.

Len, you need to ride more with MB1cyclopathic
Aug 17, 2002 5:25 AM
then your cadence will drop to ~70RPM ;o
I used to ride at 105-115; after a couple of years it dropped down to 65-85. And it isn't that bad many ultra veterans ride at 40-60.

agree 16 may not necessarily be in your powerband, but 15 to 17 is a big 13.3% jump still; just like 21 to 24 (14.2%)
Oh that is Bullsh$#!!!!!!!!!Lazywriter
Aug 16, 2002 4:49 PM
Gear choice is so subjective and if it were x,y or z that you were "giving up", people will say, "oh I miss the x".
Don't get me wrong, I love some gears more than others, but if I am riding a 23, 25 or a 27, I am gonna have all the gears I need for all situations with the 27. The advantage of the 27 of course is that it is always there for when you need it on hills. I am no slower on a 27 because I am missing "sweet 16". Give me a break. 1
12-25 is a good compromise. I went with a 12-27 on my Litespeed Vortex from a 12-23 on my Classic and yes, I need to adjust accordingly, but it is only a click away. If you get used to any ratio, you will feel the difference when you changs and like most people you will miss what you were accustomed to. After a while you will acclimate and forget what the other gearring was like and the new gearing will be the one that "feel right".
Other OptionsChen2
Aug 16, 2002 6:00 AM
You could keep the 12-27, replace the 12 and 13 with a 13 with built in spacer, add a 16 in the middle. Or you could do the same thing with a 12-25. The parts needed are available from Or better still, have your LBS replace the 12-27 with a 13-25 Ultegra, it comes with a 16.
Agree w/ Chen2, I've got a 13-25 on order...NJRoad
Aug 16, 2002 9:31 AM
I found that even the 12 didn't get used much. In North Jersey you're either going up or down and the downs are too twisty and I wouldn't use it (yes I'm chicken, so what?) With the 13-25 you get 13-14-15-16-17-19-21-23-25, which is great for 90% of the ride with 2 bailouts for the steep stuff. If I was in better shaped I'd go for the 13-23 so that I could get the 18.
Depends.Len J
Aug 16, 2002 6:40 AM
Remember a comprimise doesn't always sole the real problem.

If you're willing to spend a little more time & money, I would recommend that you keep the 12-27 and buy a 12-23 (or 21) as well as a chain wip & tool to change cassettes. This would allow you to use the 12-27 when you were doing hilly rides & the 12-23 when you were doing flatter rides. Changing cogs is easy and a 2 minute job.

This way you have the right tool for the terrain you are riding on. Long term (assuming you use both cogs equally) it won't cost you any more than the tools because you will have to replace worn cogs less frequently.

Good luck

27 works for me; don't know about youSilverback
Aug 16, 2002 7:39 AM
As an aging veteran who lives in the mountains, I think you can never have too low a gear. But I can't speak for you.
re: Is 12-27 too bigLC
Aug 16, 2002 9:57 AM
I don't use the 27 often, but when I need it...I really need it! The nice thing is that the 24 seems just right for most hills and you get better chain alignment with a double not using that last big cog. If you ever plan on doing that 5,000 ft climb up Mt. Son-of-a-gun one day you will want that 27. The 12-25 and the 12-27 are both missing a 16 cog, so you should have a 12-23 for the flat rides where you might miss your sweet 16!
re: sweet 16.. and 18cyclopathic
Aug 16, 2002 10:44 AM
I own 2 cass 12-27 Ultegra and 13-23 105. btw those 2 you can build 12-21, 12-23 or 13-27. 12-21 or 13-23 are good for TT, 13-27 for centuries. With 12-27 you can substitute 16t 12/39 or 13/42, a bit more shifting