ThermionicScott 

Sure thing. I haven't done much tinkering with custom cassettes (yet!), but I've been planning to try grinding down that wide spline on the cogs to see how much of a difference the orientation actually makes. It's kind of fun to look closely at these things.

rmfnla

As I said, I have built up lots and have never experienced anything but smooth shifting...

ypsetihw

I know this is a blast from the past thread, but I thought I would add that I just did this to my bike just now. The exact same gearing the OP suggested, 11 spd shimano 5800 12-28 (12,13,14,15,16,17,19, 21, 23,25, 28). I had been mulling this over for the last couple weeks, I had both cassettes on hand, and I just ordered a new chain today, so I figured this was a good time to play with my gearing.

I used the small sprockets from 12-17 from a 12-25 cassette and the large sprockets from the 11-28(19-28). Both 11 speed cassettes have the 17t in the same 6th position dead center of the cluster, and all of the cogs are loose except the 3 largest are riveted together and the first two are different. It was a simple matter of choosing cogs you wanted and putting them on the cassette body in the correct order with spacers, and installing the lock ring as usual. It was a very easy job and it took me longer to clean up the cogs than it did to disassemble and reassemble them.

ypsetihw

FWIW I think the 12-28 or even 13-32 is a more useful combo for most riders, and I don't know why bike companies don't spec this on more bikes (or even offer it aftermarket). Same with sub-compact chainrings. Most people don't even need a 50, and a 34 can still go very fast. I think a more practical gearing for urban commuters and touring/adventure/enduro road bikes would be more like 32/46 with a 13-32 cassette. This would allow the largest usable range for 80% of bike riders while maintaining tight gear spacing.

My commuter is currently a 1x7 33Tx12-28 in the rear (it's an 8 speed cassette with the 11t locked out due to frame clearance). At 120rpm it does 26mph, which is more than I need considering the full fenders, rack, trailer hitch, and dual panniers. It still climbs well under load and has a very simple and elegant drivetrain. I'm actually considering a cheap 12-32 8 speed cassette which configured for clearance would give me 33Tx13-32 7 speed, nearly 1:1.

nikoncmk

thanks... gonna do that but need to check that ultgera 11s has the same riveted clusters.

nfmisso

My custom cassette build is an 8 speed 14-32 with 52/39 chain rings. The 14-32 was made from a Shimano 13-26, a 32T from a cheap Shimano 11-32 and a Miche 14T first position cog. 14.15.17.19.21.23.26.32 Friction shifter with a Shimano M592 RD.

ypsetihw

it should be exactly the same, the ultegra just weighs a few grams less. I would guess you could even mix cogs from 5800 and 6800.

I have a few hundred miles on this setup and it absolutely rules. the 50/34 12-28 gives me great range with excellent close spacing, I never have to shift out of the big ring unless I'm climbing, my most used commuter cogs 23/21/19 have a much more acceptable chain line, and I don't have to change a thing from daily riding to racing, because the higher gears are single step.

shimano needs to get on board with this, the 11t is useless for 90% of people who ride bikes. why not spec this on everything?!

nz_aj

I'm also wanting a 12-28, but with closer midrange ratios 12-13-14-15-16-17-18-19-21-24-28.
I intend to modify a 12-25 by adding part # Y1RK98030 which is the 21-24-28 sprocket unit from a CS-M8000 11-42 cassette.
While this is a MTB cassette I note that it uses the same 2.18mm spacers as road. It may need some machining down of the spider on the spoke side.

Another option would be to add the 22-25-28 from an SRAM 11-28 cassette. While this has the same 19-22 jump, I'd prefer the more linear 19-21 as per the above.

SoSmellyAir

After finding this thread, I tried to stand on the shoulders of giants to make a custom Ultegra 12-28 cassette, but could not make it shift perfectly smoothly.

My Cannondale Synapse came with FSA 50/34 subcompact chain rings and an 11-speed Shimano 105 (CS-5800) 11-32 cassette. Like many, I do not recall ever using the 11T or the 12T cogs. The 32T cog mostly allows me to avoid shifting onto the small chain ring, but is hardly mandatory for my local terrain. An Ultegra 14-28 cassette omits the 32T cog and offers closer ratios in the middle, but is limited to a top speed of 28.5 mph at a cadence of 100 rpm. According to Strava, I have exceeded 30 mph occasionally, likely during GPS glitches when going downhill with a tailwind. A 12-25 cassette likewise offers closer ratios in the middle, but might make it a bit difficult to start uphill from a standstill in the big chain ring.

So a 12-28 cassette may be the Goldilocks setup but Shimano only offers a Dura-Ace version. It seems a little wasteful to buy one for a bike with a 105 groupset. There are also numerous online customer reviews complaining about the creaking when on the two biggest cogs in Dura-Ace cassettes. So I began looking into building a 12-28 cassette from other Shimano cassettes and found this thread.

According to the Shimano Dealer’s Manual (https://si.shimano.com/pdfs/dm/DM-RACS001-01-ENG.pdf):

Dura-Ace CS-R9100 12T-28T

12B 13B 14A 15A 16A 17C (19C 21C 23C) (25B 28A)

Ultegra CS-R8000 11T-28T

11A 12A 13A 14A 15A 17B (19C 21C) (23C 25B 28A)

Ultegra CS-R8000 12T-25T

12A 13A 14A 15A 16A 17C (18B 19D) (21B 23B 25A)

Combining the six smallest cogs from the 12-25 cassette with the five biggest cogs (on two spider rings) from the 11-28 cassette even maintains the 16A to 17C to 19C sequence in the Dura-Ace version. So I bought these two Ultegra cassettes to be the donors. The 12-25 cassette even came with 12B and 13B cogs, so that all cogs in the custom cassette perfectly match their counterparts in the Dura-Ace version.

Unfortunately, the above works better in theory than practice. The 17C to 19C shift misses about once every four or five times and leaves the chain rattling on the 17C cog. Another push on the STI lever moves the chain onto the 21C cog, skipping the 19C cog altogether. No issues with the 19C to 17C shift. Using the 17B cog (from the 11-28 cassette) instead of the 17C cog (from the 12-25 cassette) moves the problem onto the 16A to 17B shift, where the missed shift occurs slightly less often than the missed 17C to 19C shift. Again, no issues with the 17B to 16A shift. So it seems slightly better to have only a single tooth difference at the downshift from one donor cassette to the other.

I soon got tired of the missed downshift (between the donor cassettes) and the compensating effort to feather the shifter just so to pull off that downshift. The whole point of a custom cassette was to reduce disruption to my cadence. So now I use only the 12-25 cassette, leaving me with an extra, slightly used 11-28 Ultegra cassette. Yes, that means I usually have to shift onto the small chain ring before I come to a stop.

ShannonM

Yeah, I'm way late to this party. Still, the topic is of interest, and your experience is unusual, so I wondered:

What you describe sounds to me exactly what happens when you replace only the cassette in a long-established drivetrain, and the rest of the parts get offended and sulky and won't play with the new kid. But I've also heard of full overhauls failing in exactly this way.

This is why all that one can say about mixing cassettes is, "It almost always works." The "almost" is doing all the work there. Yours didn't. It's an exception. Exceptions are interesting. I'd be curious to know more.

--Shannon

PS: I'm a confirmed necromancer. Mostly because of my deep and abiding loathing of VBulletin's search engine. (Actual quote from the developers: "Search sucks. Deal with it." That was more than 15 years ago.) Reviving dead threads that have relevant information in them is almost always preferable to starting a new one, because the more threads there are to search through, the worse search sucks.

SoSmellyAir

Since this failed experiment, I have upgraded to an Ultegra chain, and just started to wax the chain as well. I suppose I can reassemble the hybrid cassette and give it another go once I have the waxing down, but I have since gotten stronger and can manage both big climbs in my area with the 12-25 cassette, so I have little incentive to wear half of each donor cassette. I will update this thread if I ever get it working.

ShannonM

That's the problem with combining two cassettes. You get the gearing you want, but you're left with some cogs that, even if you could put them together into a full set that you could sell, it's almost certainly going to have really dumb gearing.

For example, I have an NIB Suntour New Winner in my box o' parts that seems like it might be the leftovers from a kit bash... 7 speed 14-15-16-17-18-22-26. There appears to be no set of chainrings that makes sense with it.

--Shannon

adamrice 

Here's a sideways suggestion: rather than frankensteining together a cassette, change your chainrings. The OP was going for a 12-28, which has a slightly lower high end than the 11t that has become conventional.

If you've got a 52/36 in front, changing to a 48/32 is equivalent to switching from an 11t to 12t top end. If you've got a 50/34 in front, you'd change to 46/30 to get the same effect. You'd probably need different cranks for 46/30, but you would be able to mount 48/32 on typical road 4-arm road cranks. I've got 46/30 × 11-30; apart from an Easton crank, it's a Dura Ace drivetrain and it works like a charm. The front mech doesn't follow the curve of the chainrings perfectly, but front shifting seems fine.

SoSmellyAir

A 34T is the smallest chain ring available for my 110 BCD (5 point star) crankset, which I do not want to change.

ShannonM

33T 110 chainrings exist. T/A, of course, and at least one other cheaper option whose brand escapes me. May not have much in the way of shift aids, but the inner ring on a double doesn't really need them, IMHO.

The 9 speed 11-28 has kinda weird spacing... 14-17% on the bottom 6 cogs (28-14), and then 8-9% on the top 4 (14-11). The 46/33 doesn't look too bad. There's one duplicate, 33x13 and 46x18. This might be a good place to do most of your front shifting, actually... kind of an underdrive / overdrive setup, where you choose your gear range while you're still on the flats, depending on which chainring you're going to be using for the next section. Duplicate gears in the cruising range are usually bad mojo, but this seems to be an exception. I dunno, it might ride worse than it looks... the proof is in the pedaling.

Insert obligatory plug for the graphical gear calculator here. It's the only one I use anymore... one of the best examples of a purpose-specific web tool I've seen.

--Shannon

SoSmellyAir

A single tooth difference does not seem worth the effort and expense to swap (to a potentially mismatched) chain ring.

I have an 11 speed setup; that said, the 11 speed Shimano 11-28 skips the 16T cog, which many find essential.

ShannonM

That changes everything. DIsregard everything I said, except the bit about the graphical gear calculator, which is just fun to play with. (If you're a nerd, anyway.)

Sorry for the screw-up.

--Shannon

SoSmellyAir

No worries. I understand that prior to 10 speed cassettes, it seems like everyone and their mother can build functional custom cassettes from individual cogs and/or multiple donor cassettes, but I was not able to replicate the 11 speed successes described earlier in this thread; maybe because I have a GS derailleur rather than an SS derailleur which would be a (slightly) better match for the cassette ranges I want to use.

tFUnK

Short version: get a 12-2x (x=1,3,5,7) cassette (that has the 16t), and use the first 5 cogs with the last 5 cogs of an 11-28t cassette.