# Gear compensation for high altitude 7 day sportive?



## stoked (Aug 6, 2004)

So I've been putting in the miles and training hard for a 7 day event next month in the Alps. I live at sea level and use 50x34 11x28 for multi-day rides to save energy. I've done 147 miles past Sat with 12K elevation and 106miles with 10K elevation following day. If this thing was at sea level then I would be pretty confident about my form but altitude is my concern. ( I did get sick from it during a 4 day Inca Trail hike in Peru few years ago) Unfortunately I could only fly in 2 days before the event due to family, work vacation etc. 

I think I can run max 11x36 but don't want to run that big due to large jumps between MTB cogs. I am thinking 11x32 or max 11x34. 

Any suggestions /recommendations for gearing and also for riding at high altitude for a sea level rider?


----------



## ericm979 (Jun 26, 2005)

I live near sea level and run a 50/34 and 12-27 or 11-26 for most rides and races. When I do the Everest Challenge (two day stage race that climbs 29,035 feet and goes up to 10,000' repeatedly) I usually run a 12-30 cassette. But EC has some steep pitches near the end of each day that make it especially hard.

I've also done the Mt Evans hillclimb, which goes to 14,100 feet. I ran the regular 12-27 for that and didn't need the 24t or 27t. Mt Evans isn't steep, just long and high. Gearing requirements depend on the steepness of the climbs and how much you're doing each day. 

You will lose a certain amount of performance at altitude. It depends a lot on the individual- even with coming from sea level and no prior altitude experience, different people react quite differently. Having done it a lot I know that I am pretty good to 10k'. I'll be a little slower there but not too bad. 14k' was different. I really felt it there.

The Alps are not that high. I think the highest paved pass in Europe is around 9200' and most are in the 6000'-8000' range. 

If you're unsure then it's better to bring low gears and not need them than to not bring them and need them. A 12-30 may be a decent compromise, especially as many road derailleurs can handle them now. 32t may be too much and require you to go with a MTB derailleur for Shimano or an Apex for sram.


----------



## stoked (Aug 6, 2004)

Thanks for sharing your experience. My issue is that I am running DA Di2 and limited to 27T. I maxed out the b-screw and getting away with 28t cassette now. 2 days of long distance I am fine but not sure for 7 consecutive days. 

I ordered Ki2 RD (modified di2 rear der. with longer cage ) which I can run up to 36t. I think I'll leave the 28T on bike and also will bring along a 34T XT cassette just in case for a bad day.


----------



## Eyorerox (Feb 19, 2008)

50X34 with 12-27 is fine, alps (French?) not that steep or high just very long climbs
if you run a very low gear it will take for ever to get to the top, so if you are "strong" enough 34 27 is fine, altitude is not really a problem.


----------



## ericm979 (Jun 26, 2005)

Funny that Di2's spec isn't 28t like 7900. I know someone who got Di2 to shift a 32t cog with only a little rub, and eliminated that by using a 10t jockey wheel. 


The problem with having a cassette for a bad day is that you often don't know it'll be a bad day when you start.


----------



## 0.2HP (Jul 13, 2011)

Sounds like you need “Alpine” gearing. A cassette with the small sprockets spaced close together and bigger jumps between the bigger sprockets. (Also known as “touring” gearing.) Something like:

Shimano Tiagra 10 4600 Series 12 13 14 15 17 19 21 24 27 30

This way you ride in a 9 speed 12-27 cassette, a lot like your 10 speed 11-28, but if you have a bad day you can shift to the 30t bail out sprocket.

I am not endorsing either of these 2 retailers, but the above cassette is available here:

Cassettes from Harris Cyclery

Amazon.com: Shimano CS-4600 2011 Tiagra 10-Speed Road Bicycle Cassette: Sports & Outdoors

If you really want a 32t or 34t with tight spacing between the small sprockets, I think you are going to have to go custom. Take you current cassette off and look at it. See it you can separate the 11 and 12 tooth sprockets from the rest of the cassette. There may be 3 long, small diameter bolts holding the cassette together; you should be able to remove these with a small screwdriver or a 2 or 3 mm hex tool. If the 12t sprocket is permanently attached the following will not work, but if the 12t comes off: 

-	Get a 12t top position sprocket (with built in spacer) and a 32 or 34 with a loose spacer.
-	Take the 11 and 12 sprockets off your current cassette and put the new 12 tooth one on.
-	Put the loose spacer and the 32/34 the other end.

Shifting between the new sprockets and the rest of the cassette may not be the smoothest but it will work.

Again not an endorsement but loose sprockets/spacers are available here:

Shimano Hyperglide First Position Sprocket (Cog) - harriscyclery.net

Shimano Hyperglide Sprocket - harriscyclery.net

Good luck.


----------



## ericm979 (Jun 26, 2005)

I've done that on 9sp, but with 10sp it is not quite so easy.

For 10sp the innermost cog needs to be dished, not flat.

Also if you use a large solo cog you will probably need a hub with a steel or titanium freehub. The leverage on the large cog will be too much for an aluminium freehub.


----------



## stoked (Aug 6, 2004)

Thanks for suggestions with custom cassettes but not going to take a chance with that. Downside is an expensive RD failure and being out of the ride. 

I did look into tiagra cassette and and have one in hand but debating to use it. If I do use it, would be on my second bike with UDi2 setup which 30t will clear the RD upper pulley.

I still have few weeks for training so I might test out the 12x30 tiagra. I plan on doing another 2 centuries back to back on Aug4-5th. I'll ride with 12x30 on 3rd day to see how it goes.


----------



## Stuart B (Feb 26, 2006)

Bradley Wiggins DI2 setup for the mountains in the TDF he just won 

Wiggins' Shimano Di2 Long-Cage Derailleur | Pro Cycling News: This Just In | Bicycling.com


----------



## stoked (Aug 6, 2004)

The one Wiggo using is RD-7970 and not the new 9000 di2. 

The one that I ordered is pretty much the same hack by AceCo sport group K-edge 

K-Edge Ki2: Electronic Mountain Bike Shifting


----------



## mjm2369 (Jul 27, 2012)

good thread


----------



## stoked (Aug 6, 2004)

Stuart B said:


> Bradley Wiggins DI2 setup for the mountains in the TDF he just won
> 
> Wiggins' Shimano Di2 Long-Cage Derailleur | Pro Cycling News: This Just In | Bicycling.com


I got a similar setup now with k-edge long cage di2 RD. Shifting is very good on the stand with KMC xsl10 gold chain and I will take it for a spin this sunday. I decided to go with 50x34 and 11x32 Sram wifli cassette. It has the 23,25,28T that I am used to with all the miles I put in on a 11x28, plus a bail-out 32T just in case.

C24 wheels are also new addition as I am not bringing my carbon clinchers due to bad braking in rain and steep downhills. 
View attachment 262464


----------



## stoked (Aug 6, 2004)

*follow up on this thread.*

After finishing the Haute Route 2012 past Saturday I like to add that my gear choice for my riding style and form was perfect with 50/34 x 11-32. I saw some fitter riders pushing smaller gears but they were definitely struggling. 

I did get a mild altitude sickness but luckily it was a day before the race on a training ride. I was OK on the mountains for most part except for last few miles where I took off my garmin chest strap to get more air into lungs. Last few km's of Col Du Glandon really put a hurt on most of us where it never dropped below 11%. I finished in the middle of the pack of 600 riders.


----------



## MTBMaven (Dec 17, 2005)

Nice work Stoked! Can't wait to hear more about it.


----------

