8 is Great 9 is Fine

[Steve]

I've recently quelled an N+1 fixation by deciding to sit tight for the time being and focus my energy and bike budget on "optimizing" my current three, based on the type of riding each is best suited for   So, the whole 8-9 thing refers to upgrading  my Platypus from an 8 speed to a 9. 

The goal was to decrease my low gear from 19 GI to 18 for climbing on gravel.   Shimano appears to max out their 8 speed cassettes at 34 teeth, which is what I was running. I didn't want to make any changes with the 44/34/24 triple in the front so I started looking at 9 speed rear ends. As these things often go, that led to a close look at the gorgeous Deore XT M-789 8 speed rear derailleur that I initially hung on the frame - it  was maxed out with the 11-34 eight speed.  After mounting a 9 speed 11-36 Shimano cassette I swapped out the XT for a Microshift Advent 9.  Though it was an aesthetic downgrade it  performs superbly (so far), pulled with a Silver shifter. Of course, I also had to ante up for two 9 speed Sram chains to fit the Platy's chain stays.  

Next will be fatter tires (48mm RH Switchback Hills?) - BUT - I've also started eyeing  the seven speed rear end of the 1990 touring bike that sits alongside the Platypus. 

Hmm...maybe I just should have sprung for the N+1???

Steve in AVL

[Shannon Menkveld]

As an aside, the Shimano 9-speed 12-36 might be the single most versatile gear cluster ever made.

It's a 12-14-16-18-21-24-28-32-26, so you've got 13%, 14%, and 17% jumps between cogs. On a 700Cx32 tire, a 45t gives a 102 inch top gear, and a 48 gets you to 108.  

And the fun is just beginning!

If you want to build a 1x9 around-town bike, a 42t chainring gives a 32 - 95 inch range, and 42t rings are available for just about every BCD ever made.

For a sporting road bike, you've got a bunch of cool options:

If you use a 48/34 double, you get a 25 - 109 inch 2.5-step alpine.

If 1.5-step is more your style, you've got several choices. 48/39 is pretty sweet on 130 & 135 BCD cranks, with a 30-109 range and 5-8% steps across the cruising range. For smaller BCDs, you can do 42/34 and get 26 to 95 inches.

If you've always wanted to try a half-step double, but couldn't cope with the narrow range, the 12-36 is, again, the answer. 42/39, 45/42, and 48/45 all work. The gear ranges are 30-95, 32-102, and 34-109, respectively.

Triples?

Yeah, we can do triples. Just add a 24-30 tooth granny to any of the above, and BOB's yer Uncle. Let your derailleurs and shift pattern preference guide your choice. For a sport-touring bike, I'd probably go with the 45/42/30. 22 useful, non-duplicate gears from 18 to 102 inches. Half-step on the middle and outer rings, with a 3.5-step shift to and from the granny. Which, with either brifters or indexed bar-ends, is no problem. (Full disclosure: I have this crankset on my '85 League Fuji, with a 14-16-18-20-23-26 freewheel. Shifting is Suntour: AR double up front, 1980 Superbe out back, with Silver d/t levers. I like it a whole lot, even with the 87 inch high gear.)

To top it all off, Shimano 9-speed parts are good looking, plenty light, shift incredibly well, and are about as reliable as a shovel. And everything but the front derailleurs interchanges with everything else.

There's also an 8-speed 12-32, which I use on my mid-90s GT Karakoram with 42/34/22 rings for a 18 to 92 inch 1.5-step + granny. Shifting with LX Rapidfire levers is excellent. And, for the 10 speeders, SRAM makes an otherwise-identical 11-36. All of the chainring combos work the same for the 8 and 10-speeds as for the 12-36 9-speed, you just get less / more range.

--Shannon

[Steve]

Shannon, thanks for sharing your interesting info regarding various drivetrain configurations. The 35 year old touring rig I mentioned is set up with a 3x7 (50/44/24). Shifting between the half step(ish) rings works nicely to narrow the wide gaps of the seven speed 11-36 cassette. I did wind up swapping the original Deore LX RD for an Altus to accommodate the 36t cog. 

Apart from its affordability, I settled on the Microshift Advent 9 RD for its max cog rating of 46 teeth with a total capacity of 47 teeth. I like knowing that it should be versatile enough to serve any need I may have for even lower gearing, whether on the Platypus or another bike. Call it 'future proofing'. 

Steve

[Shannon Menkveld]

Steve -

That's a sweet setup. If it were mine, (which I wish it was... Trek 720s are legendary,) and if I wanted to keep the 124" 50x11 top gear, I'd switch the middle ring to a 45t. The 44 gives gear steps that change between 14, 10, and 6 percent with every shift. A 45t middle is closer to a true half-step on that cluster, with 8, 11, and 13% jumps... a useful improvement. 110mmx45t chainrings are plentiful and cheap. I think I paid 25 bucks or so for mine.

Another long discursion on gearing follows. Feel free to ignore it.

44/40 also looks good. You trade the 124" top gear for a still-plenty-high 109, and you get a 30" lowest gear on the middle ring instead of the 33" 44x36... so about 10% lower before you have to shift to the granny. And the granny shift is up 2 in the back, instead of up 3, which is nice.

46/42 might be the sweet spot with this cassette. 32 - 114" range. 9 out of 14 shifts are 10%, plus two 14s and an 8, dictated by the fact that cogs with fractional tooth counts are hard to find. And we get to keep the double upshift in the rear when going to the granny. This might be the ideal setup for a 126 mm bike that you don't want to cold-set, or that has a crank you want to use, but do want wider gearing. With a Wolf Tooth RoadLink, you even can use a short-cage road double rear derailleur.

A 46/34 double makes a nice 1.5-step with this cassette. 26 - 114 inches, no duplicates.

All in all, this is a very good and useful cassette. Thanks to everyone who made it happen.

--Shannon

[Garth]

And 7 is Heaven :-)   

I totally agree with Shannon about the 9sp 12-36 with it's particular combination of cogs for cassettes. A 12-14-16-18-21-24-28-32-36 progression is the only cassette I find suitable in actual riding. I don't even use the 12 or 36 on my Bomba, using the seven 14-32 cogs with 24/36/44 rings. I don't need a overly high or overly low gear, and I live in a area of many steep hills. If I lived in the high mountains with long descents maybe I could use a gear over 100 gear inches, but not necessary. Enjoy the ride. It's seemingly forgotten how riders used to be so much more versatile in their ability to spin very fast and yet power up climbs at very low rpms. Seems marketing and "choices" makes one soft ........ as does so much of "modern living". Heck, on another cycling forum the riders of the latest electronic shifting for bikes act like anyone who doesn't go along with it has something wrong with them. That's funny, I was thinking the same of them ! "Them them them, it's always them thar thems to blame for everything wrong in them thar World ! Ahahahaahaha ! So you see, everyone is the same leaky boat. 

I still prefer thread on freewheel hubs for their simplicity, gear choice, and shifting feel though. I have some NOS Sachs FW's in a 13-32 (13-15-17-20-24-28-32) which is my preferred progression. Suprisingly Sunrace makes a 7sp FW, 14-34 that is 14-16-18-21-24-28-34 that I find acceptable. Shimano and all the brands you never heard of use some sort of mega jump from 24 to 34, (loud buzzer sound) , them thar is all wrong !  Ahahaahahahahaa !