Gearing for Mountains
 

I'm trying to see if I can get a larger cassette for my back wheel for climbing in the mountains in Montana. Currently the largest cog is 28 and according to Shimano's site they don't make anything bigger for the Dura Ace line. Any recommendations? The bike is a Specialized Tarmac. Thanks

What chainrings are you running, and where in MT? Just use an Ultegra cassette if your derailleur can handle it.

If it is 11 speed, Dura Ace has a 11-30. Look here. Alternately you can go with the 11-34 Ultegra that Cypress suggested. Remember you might need a new chain to accommodate the larger cassette size.

Sadly, Dura-Ace 9000 was limited to 28, and 9100 seems to limit at 30 due to the rear derailleur size.

It might be most satisfying/cost efficient to change out the RD to a 105 or Ultegra that can take 34 and then swap to a 105/Ultegra cassette to take advantage of it all....

I'm using a 39 and 53 chainrings. Located in SW Montana.

Bozeman area? I lived there for 7 years. A 39x28 will clear most things in that area save for the nastier bits like Jackson Creek. If you need more, you'll have to switch to an Ultegra RD with a Ultegra cassette and a new chain. If it's newer Shimano stuff, you can also throw a 36t chainring on the front due to their proprietary bolt pattern. I run a 53/36 x 11-30 here in Oregon due to the roads not needing to be graded for snow travel (very steep stuff). A 36x28 is pretty darn climby and even moreso if you can get a 30 on the back.

Actually Big Sky. So dealing with nothing but up and down:) Sounds like from most comments I need to get rid of the Dura Ace and switch to Ultegra. If money isn't a big issue, wouldn't that be easier just to change out front and back to Ultegra?

No need to change the entire front end. All you'd need was a 36t chainring (if you want), a rear derailleur, a cassette, and a chain for the extra length. Everything else remains the same.

I have two bikes with Ultegra Di2. My Giant has compact gearing with 11x34 rear, and I use every gear when climbing/descending in the hills of the BlueRidge. There are some very steep sections with not a lot of room for error. I pray my chain doesn’t snap (I did snap my loose bottom bracket one time and it damaged the chain stay. It was an expensive repair......

Frame creaks and all, quite an adventure!

This is a genuine pressure test for a bicycle.

Put a compact or mid compact on that and solve your problems and save your knees

or even sub compact with rings from absolute black
https://absoluteblack.cc/oval-road-c...-for-110-4bcd/

You can get a road link if you want to keep your current RD.
https://www.wolftoothcomponents.com/products/roadlink
If you want to go to a bigger cassette and don't mind the bigger gaps between gears.

Then there is also the option of going a shimano GRX crank and FD and that offers you a 48/31 or 46/30 crank.

Run a 46/30 super compact. You'll keep the same tight spacing for flat rides but have lower gears for hills.

52x13 was a big enough gear for Eddy Merckx to dominate the pro peloton and you're no eddy.

That's halfway between 46x11 and 46x12.

46x11 doesn't get you to 30 mph at 90 rpm. The mountain roads of MT aren't all that steep, so OP might find himself spun out on downhills/windy false flats (depending on his riding style). Running CX/Gravel gearing on a road bike seems a bit overkill/specific.

Merckx probably turned way higher RPM's than OP, and he was limited by technology, not equipment choice. Nobody in the current pro peloton (including flyweight climbers) is running less than a 53x11, and many riders opt for a 54t large chainring.

It isn't really but I guess that depends on where you live and fitness. I live in Wv and spend maybe 0.034764% of my average rides at speeds over 30mph and I just coast when I spin out at 33ish mph. You still have the option to run a 48 big ring if you want a bit more top end.

I live in Oregon now and 7% (7.5 minutes) of my last ride was spend over 30 mph, most of it not coasting. On rolling terrain, do you have to coast down one side of a roller, then wait until you slow down enough to not be spun out before beginning to pedal up the next roller or flat area? That usually what happens to me on my gravel bike and it drives me nuts.

Hey guys (gals), I want to than k you for comparing me to Eddie :) That's really flattering to have my name in the same sentence (just kidding). I think I have enough information to go on from here, and again thanks for your help.

Some people on the forum talk about how we don't need high gears or we're not worthy of those gears, etc. To me, run the high gear you're comfortable with on the terrain you ride. On my compact crank bike I was not happy with 50x13 and was able to find a cassette with a 12 which helped on big rollers, windy descents and pacelines. On my standard crank bike I have a 52x11 and I only use the 11 on big descents.

Not really most of the rollers I come across I don't hit 30+ on but yeah on the ones I do I coast, doesn't bother me. When I bought the absolute black 46/30 rings for my 105 cranks that was about the only good option out there to get the climbing gears I wanted for gravel without going to a wide spaced cassette which I wanted to avoid since it spends more time on the road. If I were buying today I'd swap to a GRX crankset with 48/31 gearing which would be the best of both for me.