With 25 votes in so far my poll results are as follows:
- 68% of those who clicked said that they’d be riding Compact gearing.
- 16% went with ‘other‘.
- 8% are nuts or strong enough to go with Standard (53/39)
- And another 8% say they’ll try something in the middle.
Far more interesting, though, was the amazing variety of comments this article produced. Boys do love their gear ratios…
Here is a summary for you. There is some great information in there for those who have/had the same questions I had about what to do about gears. Read the comments section of that article to get the whole story.
The first big question seemed to be whether to take along two cranksets (or individual chainrings) or two cassettes. Opinions differed, with some suggesting to leave the front alone and take along an 11-25 cluster (I have 12-27 on the bike now), and others telling me to keep the 
cassette as is and change out the chainrings (50/34 right now) to 52/36.
Next up were the many opinions on what is right for the Alps, or more correctly, 7 straight days in them. Again, the range was impressive. Comments started at as much as 32 for the cassette (MTB gearing that one rider says he noticed others using last year in HR), to 36/25. The majority, however, seemed to be gravitating towards a standard Compact (so 34/27, 28 or 29 as the easiest gearing). 
There was also the question of the other end of spectrum, i.e. top-end speed. Rich Velo, who finished 5th overall in last year’s HR, suggested a 50 on the front might not be enough. He rode 52/36 the last two years of the event. Others (in particular Schrodingerscat) 
advocated gearing for the climbs, not the descents, stating that we will be spending the vast majority of our time going up, not down.
What wasn’t explicitly said, but implied in all opinions I hope, was the most important point of all when talking about what sort of gears you need – who you are. The same climb that is done in 3 hours in the granniest of grannies by one person can be smashed in an hour in the 39/17 by 
another. I don’t think I’m being too simplistic by stating that the stronger and lighter you are, the bigger gearing you will want to use (all other things – like suffering ability – being equal).
Conclusions? First, I am not convinced I’ll need more that the 50 on the front, but I wouldn’t argue much if I could accomplish it easily and cheaply either. For climbing I am pretty sure that my 12-27 will be 
enough, even over a week of punishment, so I might try to start Haute Route with 50/34, 11-25 and keep the 12-27 in reserve in case I need it. I’ve also got a multi-day big-mountain suffer-fête planned for sometime in July, so I’ll have a much better idea of necessities after that.
Thanks everyone for your excellent comments.
The Vicious Cycle 
yes, I think your final choice makes sense. keep the crankset you have but change the cassette to 11-25, then, if you get tired as the race goes on, put the 12-27 back on. Cheapest and easiest…
Sounds neat and simple. The tools for that job aren’t too big or heavy either.
My head hurts.
Glad I’m not the only one.
Out of curiosity, are you imagining any downside to running an 11-28 or 29 beyond a few jumps that are bigger than the options you are gravitating toward? One tooth in the back is WAY more significant than one up front. What do you really lose by going with a 28 or 29 and not needing it? I can’t count the number of times I’ve seen riders curse their choice to run 23s and 25s. In contrast, I’ve NEVER seems rider curse their 28 or larger cogs as ‘too low.’ It’s not a pissing contest, it’s a bike ride. Low gears let you ride within yourself longer.
For descending, unless you feel the need to pedal beyond 70kph, you’ll be good with a 50×11. It’s faster to tuck above 70, always.
Well, the only thing I could say there is that I don’t think I’ll need the 28 or 29. I don’t know for sure, of course, but I’ll be pretty confident in a few months. And even though it’s not a pissing contest, it IS a bike race, and I think most of us would like to get each day over with as fast as possible.
I agree with you on the descents, but if I have a gear that allows me to pedal at 60 kph that could be handy, I think.
Have you done the Haute Route, by the way, Matt? If so, did you ride 11-28 or 29?
I’m with Rich. Compact crankset with two casettes (11/25 and 12/27) will provide the best flexibility depending on how the conditions play out. I’d love to think I still have the legs and engine to push a 53/39 crankset, but those days are gone. Thanks for posting the question as it solidified what I’m going to do.
Thanks for giving me the idea for the question!
That’s a great plan.
Thanks. I’d like to say it was mine, but the credit goes elsewhere.
Why not just ride compact 11/28
25 is pretty game. I might be spinning past you on the hills
Campy doesn’t make 11-28, unfortunately. And go ahead, Dane, you won’t be the only one passing me on the hills, I’m sure. What did you ride last year, by the way? Also, I’d love to hear how much time you spent in the 28 because your results were excellent.
I rode compact 12/27 last year because I was told a 27 was the max you could go on Di2. It have loved a 28 or higher at points though ( last 3km of glandon stand out). I probably pressed the button hoping for an easier gear 50 times a day.
That said I’ll be riding compact 11/27 this year and hopefully be lighter with a few more miles in the legs
That’s very handy info, Dane, because I don’t think I’m a stronger rider than you are. I’ll think long and hard about the change (or not change). Cheers.
Your final choice sounds good, I cycled the alps last summer on a 50/34 and 12-25 I coped fine but my friend had a rear 9 speed sram cassette of 11-34, he found this a LOT easier on the climbs and downhills and was able to go much faster with it. I have since changed to that cassette and I find the change massive, I’d definitely recommend an 11-34 on the rear!
Thanks, Alex. The 34 sounds nice and comfy, but I think I’d finish outside the time limit each day if I were in it! I just did a quick gear/cadence/speed calculation and, assuming a cadence of 75 (what I usually climb at), here are the speeds I could (in theory) achieve in different sprockets:
34/34 = 9.4 kph
34/27 = 11.8 kph
34/25 = 12.8 kph
Now, of course this means nothing unless you have the legs to push the smaller sprocket, but the difference is substantial if you do. I guess that’s what all this training is about 😉
Yeah at the end of the day its the legs that matter! Good luck with the training. I rarely use the 34 tooth sprocket as it is far to easy for most climbs but the range in gear ratios is good if you want to give your legs a rest for a couple of minutes then change up and smash it once youve recovered, that’s how I like to attack haha 🙂
Remind me, are you doing the Haute Route this year? I’ve taken a spin on your blog, but don’t remember.
Unfortunately I am not this year, hopefully next, I already have other trips organised but I have enjoyed reading about your preparation for it!