I'm about 9 months into road cycling for my health (doctor's orders initially, but I'm liking cycling a lot now), so my fitness level is so that with a 105 50/34 compact crank and a 105 11-28 cogset I regularly use the 34 ring and 17 cog on level road. My trouble is that an upshift from the 17 cog to the 15 cog is too long for me most of the time. I wish Shimano 105 came in a 28-24-21-19-17-16-15-14-13-12 cogset option, the reason being that the upshift from 17 to 16 would make sense at my fitness level. Also, I'd like to keep the 28 cog as I have used it uphill, but I have never had to use the 11 cog at all. I've not tried any other cogset at all so I'd like to hear the opinions of experienced riders. I Googled and see that there's a 12-27 cogset for the 105 which will give me the 16 cog. My question is, will the 27 cog be almost like the 28 cog for me going uphill? Or should I just keep my current 11-28 cogset and shut up and ride more until I've more strength to handle the jump when shifting from the 17 cog to the 15 cog? Thanks in advance.

I'd just stick with the cassette you have.

When you're riding the 34/17, what's your cadence? Chances are you'd be better off just increasing cadence instead of obsessing about shifting to a higher gear.

Another vote for ride what you have, going from 15 to 17 is not really that big of a jump.

That said, I love my 12-23 as it has very minimal jumps.

I am thinking a triple would have been a better choice for you at this point. However there are other options for you with the set up you have. A mountain bike cassette to 34 or even 36 can be had You will need to change out your RD to a long one. I have that set up for mountains and it works great. Good luck.

Get the 12-27 and put it on...I have 5 different cassette that I use.

One that I liked early on is 14-25

is this a typo? because your description of the cassette includes a 16 tooth cog and if so, the answer is obviously to shift to the 16 tooth cog rather than the 15 tooth cog.

but if it's not a typo i still have an answer for you.

according to sheldon's gearinch calc, your 34/17 combo is 52.8 gearinches and your 34/16 combo is 56.1 gearinches. and your 50/24 combo is right in between at 55.0 gearinches.

he pretty clearly says that he has an 11-28. the part you quoted is the cassette he wants, a 12-28.

Personally, I would keep what you have. I would never give up the 11t cog. I was riding my rain bike today that has a 13-26 and I kept finding myself wanting to shift to something harder every time I went down a hill.

if you want to buy the 12-27 and combine the back half of the 11-28 with the front half of the 12-27 and you will have what you want.

i agree. i was wrong.

unfortunately, the OP doesn't state what cogs he actually has. my point, and i still think it may be valid, is that he may actually have a suitable combo that would work for him involving his 50t chainring. but until he lists what cogs he's got, my point can't be made either way.

but you are right. i misread the post. (damn runon paragraph, not that that's any excuse, or that there is anything wrong with that!)

on further reflection, my first recommendation still holds, (i think, fingers crossed). the OP might try the 50/24 combo. it falls between the 34/15 and 34/17. feel free (anybody) to double check my work.

I've been riding and racing for years. I prefer the 12-27 because it's got the 16t cog. The jump from 17t to 15t is a little large. I can keep up on descents in races just fine with a 50x12, except in the rare situation of a gradual descent with a stiff tail wind. I've done just one race that's like that.

Get the gearing you need. That's why they offer different ratios.

Give the 12-27 a try if you see a good deal on one. I typically run 12-27 on the wheel I use for fast group rides and races (with std 53-39 rings). I think it's the most flexible cassette and it suprises me shimano only offers it in 105. I think you need to go to a 11-23 in Ultegra to get the 16. I ride an 11-28 on my training wheel, and I don't notice the difference between the 27 and 28, but do miss the 16 a bit.

This one!

The three largest cogs are "fixed". Purchase a 12-27, (which has that 16t), and when you put it on your hub, slip on your existing fixed 21-24-28 cog, then the loose cogs from the 12-27. You'll lose the 11t, but as you say, it is rarely used. You can probably live without it. You'll use the 16t a lot more than the 11t.

The other, less expensive way to go is to order a 16t sprocket and a 12t lock ring and spacer from your LBS. Then build your cluster with the 21-24-28 fixed cogs first; then the 19, 17, 16, 15, 14, 13, and 12. Go to the Shimano web site and download the 105 cluster spec sheet. Here: https://www.shimano.com.au/media/tech...9830703168.pdf

Print out the spec sheet and take it to your LBS with the two part numbers highlighted, telling them that you want to order these two parts. You'll probably have to pay extra shipping and handling, but it worth it to get what you want. I think you want part numbers:

Y1Z81600N - Sprocket Wheel 16T
Y1YN98020 - Lock Ring & Spacer for 12T Top Gear (Number "1" on the spec sheet, not number "2". Number 1 is the lock ring and the spacer, 2 is the spacer only.)

These are for the 105, CS-5700 clusters. The spec sheet will also help you on the installation order of the spacers and cogs.

Disclaimer: I have done this with Ultegra and Dura-Ace clusters, not 105. Don't take my word for what to order. Download the spec sheet and determine for yourself what you need to order to get the gearing you want.

p.s. If your LBS doesn't want to order the parts, or say they can't ... go to a different shop. If they are a Shimano dealer, they can order the parts ... they just might not want to because there won't be much margin/profit in the order.

As an alternative, if you're sure you don't need the 11, consider a SRAM 12-28 cassette such as a PG-1050. 12,13,14,15,16,17,19,22,25,28. Personally, I don't like the mix-&-match approach since the shift ramps may no longer sync up with the neighboring cogs.

I also feel the same way about the first couple 2-tooth jumps in my cassette, currently a 9-speed 11-28. It's the main motivating factor in my desire to upgrade that bike to 10sp this spring.

The big reason I went to a ten speed setup was that 16t cog. That was about two years ago, and it was worthwhile IMO.

Going to a SRAM 12-28 is one option. Another is a Tiagra ten speed 12-28. The functional difference between 105 and ten speed Tiagra is a slight (unnoticeable) increase in weight. The Tiagra is less expensive than the SRAM. I recently bought and installed a ten speed Tiagra 12-30 on one of my bikes, and it shifts as well as the Ultegra cassette it replaced.

As an aside...I recently bought an older Bianchi with an eight speed drivetrain and a 13-26 cassette. It has a gap where the 16t cog should be, but with a few thousand more miles in my legs, it's not as much of a bother as it was.

another, cheaper, simpler option. change your inner ring to a 36t.

the ratio you're after is 34x16, which is 55.8 gear inches. if you had a 36t inner cog: 36x17 = 55.7 gear inches, which is essentially the same. compact chainrings are cheap, and easily changed, this would be a good, easy gearing experiment for you.

you aren't locked into 105. You can use most any Sram or Shimano cassette cassette. Why not get a Teagra or Sram 12-28?

he really doesn't even have a problem. he's already got a 54.8 GI. (50x24)
in fact the 54.8 is calculated assuming a 23mm tire. if he's got a 28mm tire it IS 55.8. maybe i'm missing something. if so, somebody please tell me!

I've had many triples over the years on both road and mtn bikes. Compared to doubles/compact set-ups, they are slow and finicky. Compacts with a ten gear cassette are so much better.

I don't like this solution because in 6 months or less he's going to want to upshift again and guess what... still has the 17t to 15t jump. Oops.

Any 10 speed sram or shimano cassette with 12t final cog should do it. They should all have 15,16,17. The 11t is what causes the 16 to be deleted. I think others have said some or maybe all of this, in separate posts.

Thank you for the advice, I'll follow it. My cadence is pretty good at 34/17 on level roads, somewhere between 80 and 90 on average, but I'll follow your advice and just ride some more and patiently build some more strength in my legs. Thanks again.

Thank you very much! It's exactly the kind of advice/experience I was looking to receive. You are very helpful, sir! Thank you.

Thank you too for this insight, I'm learning a lot! Thank you again.

I'm partial to 14-21 5 speed freewheels. Coupled to a 42/52, what more do you need?

You're welcome. In the old days, back in the late 60's and 70's, we always built our own clusters, (that's what we called them - guess they are called cassettes now). Then, it was ten speeds, five cogs and two chainrings. Triples were very rare. We figured out our own ratios and ordered the rings and sprockets we wanted. So, seeing the Shimano spec sheets and part numbers for each sprocket, I knew that I could order the exact rings I wanted. I like the Ultegra clusters. They are at a good price point to weight, and simple enough to build up a 12-28, which is what I run on two of my bikes. Yes, as you say, that 16T is missed if it isn't there, and I can live without that 11T.