So in some of the discussion around the new 105 di2 coming in 50/34 11-34 at launch I have seen a lot suggest “that’s not racing gearing” (me included). I live in an area where most climbs around 2-3 minutes and 5-8%, more rolling terrain than real ‘mountain climbs’. My current bike has 52/36 and I rode it with 11-28 for a season and then switched to 11-30 and will use the 30T on rare occasions (generally for 2-3 minutes per week of riding), my previous bike (which I rode over the winter and leave on the trainer now) had 53/39 11-28 and I did find the gearing too heavy for me on the hardest climbs and felt sweet relief when the spring thaw came and could switch over to the bike with lighter gearing.
11-34T is essentially the same as 11-30 so no issues there but is there a way to tell if maybe I am better suited based on my power to a specific gearing or is it just perception or cadence based? Maybe, despite being a racer a 50/34 would be fine for me or even better than 52/36. Current FTP is 204 (up from 168 in December) at 57.2kg so 3.56w/kg.
Is there like an online calculator or something that you can determine what gearing would suit you based on power or w/kg?
t what you need in to top range to not spin out 50/11 at 110 cadence should give you around 64 km/h while 52/11 around 66.5 km/h if that difference is important to you the yeah you need the bigger crankset. But yeah a lot of racers want the bigger crankset to have a bit better chainline for higher speeds. If you live in mostly flat/Rolling area then they are fine. But if you live in Hilly and mountenous region you are better served with the smaller ones, especially if you are under 4W/kg imo. you can ride climbs at a comfortable cadence and power.
Shimano probably still want’s to position Ultegra as the racers Groupset and 105 for enthusiast riders…
There are plenty of calculators you can use to give an idea of your speed at various gearing and cadence ranges - I tend to look at this first. i.e., I can do 50 or 60rpm to get over short climbs if needed but I would rather not be sitting at that for a long time. Here’s one: https://www.gear-calculator.com/ and another: BikeCalc.com - Speed at all Cadences for any Gear and Wheel
There’s also power calculators where you can get a rough idea of the power needed to sustain that speed on different gradients e.g., http://bikecalculator.com/
Combining the two will basically do as you are asking - I need X watts to sustain Y kph on Z gradient, and my gearing implies a certain cadence for that speed (which may or may not be OK depending on you).
Personally - 34:30 sounds OK for the sort of short climbs you are describing. We have a lot of short climbs at ~15-20% (UK peak district), and I like my 34:32 lowest combination there. I still have to be out of the saddle at v low cadence for some of them. We also have some longer ~15-20 min steady climbs where the 32 isn’t needed.
So looking at some recent rides, it looks like my max speed is usually ~63 km/h, I would say >55km/h I’m tucking in on descents rather than pedalling until things start to level off.
At cadence of 100, seems like the difference between 50-11 and 52-11 is 52km/h vs 54km/h. Maybe I do want the 52 to get up to speed on descents… I definitely don’t roll along on the flat at 50 km/h but on descents I am pedalling at >50km/h.
Also hoping that I can continue a similar progression in my FTP (added 36w since December) so that by next May when 2023 race season starts I will be ~240w FTP (if at similar weight 4.17 w/kg).
I thought I had read something saying you’re better off tucking once you’re descending over 50 km/h, but I don’t remember the number that specifically nor where I read it 
Personally - if I was racing and worried about being able to sprint etc it might be different, but I am not really bothered about spinning out above 52 km/h for example for normal riding. More worried about making sure I have the right bottom end than top end.
Gearing is based on distance since 1 revolution moves the bike a certain distance. So it’s a question about the cadence you prefer and the speeds that you expect to be traveling. You absolute power and the terrain you ride imply different speeds. W/kg is relevant mostly when your doing steep enough gradient.
So just use a basic online gearing chart like others have suggested. As yourself what range of speeds do you imagine you will travel regularly.
Based on OP’s stated absolute power, a compact crank is best. I can’t see the need for over a 50T big ring.
A few things beforehand: sentences like “this is not race gearing” or some such is plain non-sense. Forget about all that.
Here is what I did when I chose gearing for my current road bike (and it worked out very, very well):
- Observe the gears you use, what cadences you prefer to use and what kind of jumps between the gears you’d need.
- Gearing crucially depends on the terrain you like to ride, not just your fitness. On the ride (endurance ride along the coastline) I did this morning, no way I’d need as big a cassette as I have now.
- Don’t choose gearing for the days when the sun is shining, the birds are singing, you are super fit and you have slept 12 hours. Gears have to work in all circumstances, i. e. also when you are trying to stay in Z2 at a small hill.
- In my case my cruising gears on the flats were 50:15–50:13 at about 100 rpm self-selected cadence (at speeds between 36–50 km/h). I’d use 50:11 only on downhill sections as an overdrive. When I tried 52:11 on a loaner, it was the exact same thing.
- I live in Japan, i. e. even though I am close to the coast, I am also very close to proper mountains. I’d use all gears up until 34:32. I’d need the 34:32 mostly on endurance rides, though.
- I had set my eyes on a 1x setup with a 10-36 cassette. Relevant chainring options had 40-46 teeth. 46 was quickly discarded, I didn’t need as many gears at the top. My most likely options were the two sizes in the middle, 42 and 44 teeth. I prioritized climbing gears, so I opted for 42 teeth.
- My tool of choice was Gear Calculator, super useful. You can ask it to show speed or gear ratios. If you have paid attention to the cadences you typically use, you can adjust the slider accordingly. Just make sure to separate your cadence on the flats from your climbing cadence.
With my current setup (42-tooth chainring and 10-36 cassette), I spin out at 65-66 km/h (at 120 rpm). If I were doing sprints at Alviso, then this would not be enough. But I am not. Nor am I racing a lot on closed roads.
53:11 and 52:11 seem unnecessary to me, especially with an FTP of 204 W. If you are fine with 52:30 = 50:28 = 44:36, then go for that. Secret tip: try SRAM’s 11-speed cassettes. Even when I was running Shimano, I had a SRAM 11-32 cassette. From what you write, it seems unnecessary to me that you switch to one of Shimano’s 12-speed drivetrains. In fact, you could easily switch to a 1x SRAM drivetrain. (Come to the light side, my friend … 
).
That doesn’t seem correct: according to Gear Calculator at 100 rpm in 50:11 you’d do close to 59 km/h and in 50:12 54 km/h. When I was on a compact crank, I’d usually select 50:13 on the flats at about 50 km/h.
Didn’t over think it, tried 46/33 and 10-33 and its a keeper. Option to put 10-36 if I lose fitness before a big climbing ride. At 3W/kg its low enough for 10% climbs and high enough to ride 25-30mph for an hour. I’m not looking to save 5-10W on a TT at 30mph.
IMHO on 2x that’s the config to get if you don’t want to think about gearing. Just make sure to get a WIDE rear derailleur when you are opting for a Force or Red groupset. (Nobody cares about the 10-26 cassette anyway). Since you are on Rival, that’s natively supported anyway.
I sold my 10-26 to a guy that wanted it for his crit racing bike.
I see. I don’t think I have ever heard of anyone (else) using that cassette. Out of curiosity, why did you get a 10-26 cassette?
PS It’s a bit of a pity that by default SRAM’s Force and Red rear derailleurs are not the WIDE ones, but the regular “short cage” ones. I think so many more customers would benefit from being able to put on a 10-36 cassette than a 10-26 cassette.
I would recommend re-reading @OreoCookie 's post, meditating on it and re-reading it a couple more times.
Ideal gearing for an individual is going to depend on preferred cadences, power output, terrain, preference for gear jump size. I also think http://www.gear-calculator.com/ is a great tool to play around with and I have been recently used it to scope out changes to the bike I take to the mountains. Why? I moved and the nearby mountains have steeper climbs and I prefer to have a little more low end. I will probably go from 48x11-40 (which has been great for 4 years on 2 bikes) to 50/34x11-34. At 5wkg. I’d prefer to go lower but have some constraints by not wanting to replace my crankset / powermeter and limit the number of components I need to purchase. I think I would be happy with a 48/32 on the front.
The whole ‘racing gearing’ thing always cracks me up. People complained about compact gearing becoming standard on bikes instead of ‘standard’ road gearing. I think it was great and gave more people more useful gears in general. If anything, subcompact like 32/48 might be even better. I’ve done the local hammerfest group ride with the 48x11-40 and don’t get spun out on the flats or downhills. There is no ‘racing gearing’, there is the gearing I choose to ride because it is optimal for my needs (terrain, power output, etc.) and I would race with the same gearing. In fact, I might go do a crit with my 48x11 and am pretty sure I’m not going to spin it out.
I’ve thought about switching from Shimano to SRAM, but I don’t like the feel of the drivetrain when I’m on a cog with a small number of teeth (11-12 mainly.). How does the 10t feel?
I remember somebody dancing away from Froome and Wiggins in that little race called the Vuelta on a 11-34; no idea what he had at the front and I think he was found to be on something else too 
I’m mainly in 12 and 13, for example below is a 5 minute hard push on a group ride.
Front ring is 46, and during that 5-minutes it was all in 13 and 12 on the rear cassette (dark blue fill on speed chart):
At speeds like that I’ll sometimes drop to 11.
FWIW, I’m just shy of 4w/kg, and live on the outskirts of the Chilterns in the UK - lots of short, steep hills, and a fair bit of wind, but no climbs >2.5km.
This is what my gear use looked like on a c.110km, z2, average-ly hilly ride. Av. power c.190 or about 2.65w/kg
That’s based on on 48/35 and 10-33 gearing. If you look, you’ll see the 10t and 11t have had very little use. The 33t has seen a bit of use when I’ve tried to stay below VO2 max on some steeper hills. For this type of riding, in honesty I’d probably have been better off with 46-33 up front.
Below is a harder, hilly group ride. This was about 3 hours, av. power 220w (3.15w/kg):
Here, the 33t has still got used (lots of steep hills on this one!), but the 10t has seen a little bit more use. 48/35 and 10-33 was pretty much bang on here, but I’d definitely have got away with 46/33.
For an upcoming 215k sportive, I’ll be putting a 10-36 in the back.
My takeaway: more people need a 1:1 or close lowest gear than they would care to admit, unless they live somewhere very flat. Very few people need a top gear much harder than 4.5:1 if they’re not racing. I really do think a 50/34 and 11-32 or 11-34 covers it for the very substantial majority of cyclists.
Yeah, and you are quite a specimen at 5 W/kg!
This is something people forget. I’m also reasonably fit and my gearing is much lower than you’d expect based on my numbers. People focus so much on top gears and are afraid of spinning out, and I just keep thinking why especially Shimano but also SRAM offer such hard gearing for its customers. Makes no sense to me.
Same here. Racing gearing makes zero sense for regular people: why should someone at 3 or even 4.5 W/kg have the same gearing as someone who is at 6 W/kg? You shouldn’t!
If you spin out at 30 mph (about 50 km/h), you should work a little on higher cadences, that’s a bit early if you are in 48:11. In any case, on public roads I usually am very careful going much faster than this, at a certain point it really becomes a safety concern.
I used to do this but found it limited my max speed on descents, since I’ve started pedalling up to ~55 km/h I find I am able to get up to ~63 km/h max rather than a 57-58 on descents.
I’ve always thought of myself as a weak descender but at my race yesterday in the rain, I kept gapping my group on the larger descent.
Yes I was using a different calculator for those numbers than this, one that had green, blue and red squares on a big chart, where I got those numbers that are different than these results.
I see using this one with 25s, 50-11 would give me 58.2 km/h which seems sufficient for me, I would say I start coasting on descents now ~56 km/h (used to start coasting around 50 but found I wasn’t hitting the top speed of others and pedalling up to the mid 50’s seems to have helped my max on descents).
I only know of one guy who runs 1x in my area (3T Strada) he pulled out of the race yesterday as he was struggling with the climbing. He has told me before that sometimes he misses 2x but I suspect he also has tough gearing as he is a Cat A/1.