Road Bike, Cycling Forums banner
1 - 15 of 15 Posts

·
Registered
Joined
·
103 Posts
Discussion Starter · #1 ·
Hi Folks,

I'm somewhat new to the mechanical scene. I currently have a 11-23 Ultegra 10 speed cassette on my bike. If I were to go with a 12-27 cassette, would I benefit in anyway or would it put me at a disadvantage compared to my current 11-23 cassette???
 

·
NeoRetroGrouch
Joined
·
6,493 Posts
sdkwan said:
Hi Folks,

I'm somewhat new to the mechanical scene. I currently have a 11-23 Ultegra 10 speed cassette on my bike. If I were to go with a 12-27 cassette, would I benefit in anyway or would it put me at a disadvantage compared to my current 11-23 cassette???
What is the goal? What gears are you currently missing? What gears don't you use? - TF
 

·
Registered
Joined
·
453 Posts
If you're doing more climbing then the 12-27 may help you get up some steeper hills. If you're riding on the flats more then the 11-23 will allow you to go faster for a given cadence. It all depends on your application.
 

·
Registered
Joined
·
103 Posts
Discussion Starter · #4 ·
I live in central NJ which is mainly flats with some rolling hills. There isn't any real killer hills that I know of. I'm in the process of getting a new wheelset so I have been thinking of getting a new cassette as well but wanted to understand the difference with the various gearings.
 

·
Still On Steel
Joined
·
2,396 Posts
According to the Shimano web site, these two Ultegra 10sp cassettes have these cogs:

11-23: 11, 12, 13, 14, 15, 16, 17, 19, 21, 23
12-27: 12, 13, 14, 15, 16, 17, 19, 21, 24, 27

which basically means you'd simply be trading your current highest cog, the 12, for the lower 27 granny. There is a slight change at the next-lowest cog (23 becomes 24) but everything in the middle, from the 13 to the 21, is exactly the same.

So it's as tubafreak says: do you need a lower gear for climbing? If not, you might as well stick with what you have. OTOH, if you find yourself hardly ever using the 11 -- I, for one, would certainly have little use for a gear that high -- going to the 12-27 won't cost you anything on the high end but might gain you something if you ever do encounter any bigger hills, say when you travel to some other area to do a ride.
 

·
Squirrel Hunter
Joined
·
3,854 Posts
12-23

sdkwan said:
I live in central NJ which is mainly flats with some rolling hills. There isn't any real killer hills that I know of...
Well if you have not found yourself wishing you had a bigger cog than your current 23t when you do climb and you plan to buy a cassette anyways then perhaps consider a 12-23. You will find yourself using the 18t cog a whole lot more than your current 11t cog.

If you think you will hit some killer hills either on your current routes or on a future vacation then consider the 12-27 in which you give up a rarely used 11t cog for a 27t climbing cog.
 

·
Squirrel Hunter
Joined
·
3,854 Posts
Yes

sdkwan said:
Is a 11-23 really that much more different from a 12-25???
If you are buying a new wheelset and plan to get a cassette anyways then I would say yes there is a difference and do not buy another 11-23. Based on what you have described so far if you are looking for an all purpose cassette to slap on and ride a 12-25 is a lot more practical than an 11-23. It is unlikely you use the 11t cog very often unless you are mashing or catch that rare downhill with a tailwind.

The first time you go to some hilly century out of town you will find that a 25t cog will let you get over the climbs easier than gutting it out with a 23t cog. Depending on what shape you are in and where you may go the 12-27 may be even better if climbing is in your future. If you know you will not be doing any climbs then I would go back to recommending the 12-23 and picking up the 18t cog that you will get a lot more use out of than an 11t cog.

Since you are getting a second wheelset I would recommend getting another cassette so you can quickly make a rear wheel change when you find that mystery flat before you head out of the garage some early morning or keep an old tire on the old rear for use on the trainer. Keep in mind that you can get a 105 level cassette to use on your Ultegra rig for a bit less money.
 

·
Registered
Joined
·
103 Posts
Discussion Starter · #11 ·
Keeping up with Junior said:
If you are buying a new wheelset and plan to get a cassette anyways then I would say yes there is a difference and do not buy another 11-23. Based on what you have described so far if you are looking for an all purpose cassette to slap on and ride a 12-25 is a lot more practical than an 11-23. It is unlikely you use the 11t cog very often unless you are mashing or catch that rare downhill with a tailwind.

The first time you go to some hilly century out of town you will find that a 25t cog will let you get over the climbs easier than gutting it out with a 23t cog. Depending on what shape you are in and where you may go the 12-27 may be even better if climbing is in your future. If you know you will not be doing any climbs then I would go back to recommending the 12-23 and picking up the 18t cog that you will get a lot more use out of than an 11t cog.

Since you are getting a second wheelset I would recommend getting another cassette so you can quickly make a rear wheel change when you find that mystery flat before you head out of the garage some early morning or keep an old tire on the old rear for use on the trainer. Keep in mind that you can get a 105 level cassette to use on your Ultegra rig for a bit less money.
Thanks for the advise. I'm thinking of going with a 12-27 now just so I have those extra gears for those monsters when needed. Now after I switch from a 11-23 to a 12-27 cassette, is there and tweaking to my rear D to compensate for the gearing change???
 

·
Registered
Joined
·
1,876 Posts
sdkwan said:
Now after I switch from a 11-23 to a 12-27 cassette, is there and tweaking to my rear D to compensate for the gearing change???
Probably not though it's possible that you could need to adjust the "B" screw to allow the upper derailleur pully to clear the 27. You should also check the chain length to make sure the derailleur doesn't "bottom out" with the chain running on the big ring and the 27 cog, just in case you accidentally get into that combination.

Al
 

·
Still On Steel
Joined
·
2,396 Posts
sdkwan said:
Now after I switch from a 11-23 to a 12-27 cassette, is there and tweaking to my rear D to compensate for the gearing change???
You may need to adjust the B-limit screw, so the jockey pulley on the rear der will clear the larger 27t cog:

http://www.parktool.com/repair/readhowto.asp?id=64

(Scroll about halfway down the page.)

BTW and FWIW, for a second set of wheels, I think the 12-27 is a good idea, as long as you don't feel a strong need for the 18t that KUWJ mentions. Most of us mortals don't need anything smaller than a 12t (both of my bikes have a 13t as the highest gear) but there's always a good chance a hill will come along that's big enough to make you wish you had something lower. I'm a lousy climber; my older, 8sp bike has a 13-26 and there were times even that wasn't enough ... which is why my newer, 10sp bike has a 13-29.
 

·
Registered
Joined
·
5,358 Posts
Derailleur probably won't need adjustment. Your chain may be too short though. Check that the derailleur cage isn't too stretched out when in the big ring/big cog combo. Put the bike on a stand (or hold it up), put the chain on the big ring and then shift gently onto the large cog. If the chain is too short it won't go in, and you can carefully back it out. You should not use this gear combo while riding but you want to be able to shift into it without destroying anything should you have a brain-fade moment.
 

·
Colorado Springs, CO
Joined
·
631 Posts
I went to a new IRD 28 tooth cassette (I think the low end was 11 teeth). Had to change the chain (new chain, made it longer than the old one using the Park Tool website chain length caculation formulas there), and only a very very minor tweak to the derailleur barrel adjuster to get it all to work/drop in the right spots while shifting. No major adjusting needed with any of the other derailleur adjusitng screws. All this switched out neatly with a new Mavic rear wheel too. I was amazed that it all fit so nicely without any hassle. Sure like that 28 tooth cog (with a triple). Makes climbing steep stuff really easy on the knees!
 
1 - 15 of 15 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top