Mattyb13

2017 Specialized Diverge Comp Carbon. Awesome bike. Built a little more for the climbing/diverse gravel route. Been a great road bike. I have been trying to make it a faster and faster road bike.

Stock Cassette: Shimano 105, 11-speed, 11-32t
Stock Chainrings: Praxis 48/32t

I am looking for more top end speed capability out of my bike.
I upgraded my front rings to Praxis 50/34t. Helped and Better.

Still want more.

I am considering upgrading my cassette.
Would this fit/Help?: Shimano Ultegra R8000 Bicycle Cassette 11-30T

IF not, I would love recommendations on Cassette upgrades that would A. Fit, and B. Help me with some more top end speed.

Wheels: DT R460 Disc SCS

I REALLY appreciate any advice here.
Thank you!!!

Dean V

11-30 has the same top gear (11t) as what you already have.
The gearing on the bike isn't really the limiter anyway.
You just need to train at pedalling faster and harder.

Leinster

What Dean said. The 11-30 will fit, but won’t help your top end speed. Save the cash for the cassette and invest in a cadence sensor (if you don’t already have one) and consider a power meter.

caloso

50x11 on a 700c/25mm tire is 119 gear inches. That works out to 42.8mph at 120rpm.

Work on the engine, not the transmission.

big john

How fast are you going in 50x11?

datlas 

This. 42+ MPH is plenty of top end.

big john

Well, he might not be able to do 120 rpm. A lot of inexperienced riders tend to mash.

datlas 

True.

I do believe the new SRAM 12 speed has a 10t option but that's going to be WAY more trouble that it's worth. OP should work on spinning/cadence as suggested. If for some reason he still wants more top end he could get a 53T front chainring, of course.

big john

I still want to know how fast he is going in the 50x11. That's the high gear I use and it's plenty most of the time. If the descent is really steep I just coast anyway. The OP is in Florida so I don't know where he could use a giant gear.

Shimagnolo

Never underestimate the speed potential when you have a hurricane providing the tailwind!

woodcraft

I use a 48/34 set up. The top end speed capability is fine- start to spin out over 35 mph.

I'd like more middle end speed capability- sustained 22-24 mph on the flat.

Unfortunately, there's no magic gear ratio to get me there.

terrymorse 

You actually use your 50x11? I sure don't--at least not on a level grade. 50x15 is about my highest useful gear on the flat, which gets me going about 26 mph (but not for long).

Gears higher than that (50x14, 50x13, 50x12, 50x11) on flat terrain are just hypothetical.

big john

Sure, on rollers or slight descents. I have a 52x11 on another bike and during a tailwind one day I was passing people who were surprised by that!

terrymorse 

Asking in advance for permission to draft you.

big john

I used to be strong on the flats. Always sucked on climbs but could pull pretty well when it leveled out. These days, not so much, but I'm working on it.

popeye

On fast rollers I kick butt with a 53.

merlinextraligh

While I get, and basically agree with, the sentiment behind your post, I find a 50x11 more than hypothetical even on flat ground.

One, sprint finish particularly with a big group and a lead out, you definitely want more than 50x15.

Another non hypothetical, time trialing with a tail wind. To maintain a speed in the high 20’s at a cadence that does not have too high aerobic cost you want more than 50x15.

And just being able to stand for a butt break at a relatively low candence and 20 mph you need a bigger gear.

All that said I agree with the point that the OP doesn’t need bigger gears.

zjrog

The rider I used to be, says the OP needs to needs to learn to spin. The rider I am now, has finally learned to spin.

I have two bikes, setup completely different. My old steel bike has a compact 50/34 and 12-30. I have spun it out on the trainer, at 42 mph and 120 rpm. For 30 seconds... On the street, I've hit 28 but for less than 30 seconds. But I can maintain 20 easily without killing myself mashing or over spinning.

The other is nice aluminum bike, 53/39 also 12-30. Never had it on the trainer. Only recently started riding it. Last week I got to sprint it chasing a guy, I never caught him, but Strava showed me at 38.7 MPH. Somehow, I stayed over 25 for a good minute. Yes, it was a slight downhill. I've had no issue holding 23 for a couple minutes on flat ground.

Nowhere near the rider I used to be. But trying to be smarter this time around... Looking forward to spinning on the trainer this winter..

big chainring 

Well, when it comes to gearing, look back to the greats in cycling history. In 1956 Ray Booty, "the boot", was the first man to break 4 hours in a 100 mile TT. His record of 3 hrs 53min 28 sec, stood for 34 years.

As was the custom for many english riders back in the day, he rode his bike to the race on the previous day....a 100 miles.

25+ mph for 4 hours. What was his gearing?, 84inch fixed, or equivalent to a 50x16.

Psimet2001 

I caught an "SCS" in the original post. Don't care that the model says it's not but with SCS you're running what is essentially a cross bike. You put a 50 on it. You want to go faster.
1. Spin. You're mashing.
2. Put a 53 on it (have we really come to the point where people have forgotten that a 53 is considered a "full sized" crank?) - you already have an 11. That's as big as you can go on your setup.
3. Get an actual road bike instead of a cross bike masquerading as a road bike.

Hermes

During this time of year, I do low cadence / big gear work on flat terrain to build strength and adaptation on the road and time trial bike. So I use the 50/11 on my road bike and 54/11 on my TT bike a lot.

datlas 

I don't know if we will ever get an answer. I hate it when that happens!

ThermionicScott 

Looks like Specialized calls it a "gravel bike", so it's not quite as silly a choice as a 'cross bike.

79pmooney

My experience is that top speed (barring very fast downhills) is a matter more of the right gear than how big it is. Most racers will agree. While they all have that big top gear, much more important is the small steps between gears so they can get exactly the right one for that day, that stretch of road, that wind, etc. I raced it the days of 5 and 6-speed FWs. 13 teeth was as small as they came. But far more important to me was having the 14, the 15 and the 15. (I rode a 53 or 54 in front depending on the race.)

So the OP is running an 11-32 11-speed. 32, 28, 25, 23, 21, 19, 17, 15, 13, 12, 11? For fast riding and flatter roads, why not run a 11-25 (or even better, a 12-25) and have 14, 16 (and 18) tooth cogs? If it were me, I'd make up a second wheelset with the smaller, closer cassette, nice road rims and some fast tires.

Not having the large cogs is a reminder as soon as you get on the bike that you are riding a fast one and have to step up to it. On the days you are not feeling it, just take the gravel wheels. If you have to have it all, there is another solution. Keep the small cassette but make the crankset a triple. I ran a 53-42-28 triple and a racing FW/cassette for decades. I'm getting old, so the same cassettes now get paired with a 50-38-24.

Ben

79pmooney

102 RPM. 84" would be a 53 x 17. Now if you were doing this on a geared bike, you would like to have the 16 and 18 as options. (See my previous post.)

I rode a race of 105.6 hilly miles in 3 hours and 58 minutes years ago. Only used my 13 downhill and perhaps the final mile. (A bigger gear would have made no difference.) The time I spent in the break, I used the 14 and 15. Yes I was riding a 54 but 54-14 is the same as a 50 x 13.

Ben