Gearing question for 6 Gap Century (or any long climbing event)

Will be doing 6 Gap in a couple of months, 100 miles with 12k+ feet of climbing. Where I live is pancake flat so I currently run a 52/36 Praxis Zayante Carbon crankset with an 11/28 cassette (Dura Ace mechanical).

  1. Can I run an 11/32 with the Dura Ace mechanical RD? Shimano says no but would it be ok for a one day affair as long as I don’t cross chain?

  2. I’d like to avoid dropping $150+ on new chainrings for one day, am I good with 52/36 or should I play it safe with 50/34? (Praxis only sells chainrings in pairs)

  3. Any other gear related tips for an event like this?

Ive done hog pen and wolf pen and some of the other climb on 6 gap with a 36 up front and a 30 in the back, I was fine. Just because you come from a flat area doesnt mean you need extra low gears, it all about the engine pushing the gears. Back in my racing days, i often got beat by florida riders in the mountains

1 Like

This really comes down to how fit are you defined as what is your watt/KG.

For example: back when I was in my 20s and racing (and weighed 140lbs and could do squat sets at 225lbs) I climbed Alpe d’huez with a 52/39 x 12-23. It was the very early 90s, and that’s what race gearing was. Could I do that today? Hardly.

1 Like

Getting a 105 GS (medium cage) RD and an 11-34 cassette for the day might be cheaper than new cranks. Especially if you can borrow this off a friend who has N+1 bikes, and won’t miss it in the short term.

Also, practice some low cadence work on some of your trainer sessions - especially some shorter sweet spot intervals. Start at 80 rpm, then over successive weeks work your way down to 70, 60, 50 rpm, and some out of the saddle work.

2 Likes

i’m doing something similar at the end of the month, the greylock century in northwest MA that’s 105 miles and 12k o’ climbing. did a recon of just the metric course and found for my abilities i was over geared with a 52/36 front and an 11-32 rear. If you’re super strong then sure hit that but i sure as hell ain’t so i went and bought another x-spider for my carbon zyante with 48/32 and took my 11-34 cassette from my gravel rig for use with my ultegra. Should hopefully give me some more spinny options up the steep or long stuff.

Interesting, I may have to find a bridge near me and do repeats to get a feel for my climbing fitness and what gearing works for me personally. My FTP is at 3.4 w/kg, but I have no idea how to translate that to appropriate gearing for climbing.

I like the idea of doing some low cadence work on the trainer to prep, will definitely be sure to work in some of those sessions.

Lou26, I ride up in the Gaps as it is within an hour from my house. I am 160lbs and my FTP is around 3.74 w/kg. I run Ultegra Di2 with 52/36 and 11-32. There are times when I click the shifter looking for another gear and find out I am in the easiest one. Good luck.

1 Like

You should be able to use this https://www.cyclingabout.com/gradient-threshold-steepest-hill/ to figure out with your power / gearing info on the climbs.

@Lou26 its all about the gradient. If there are short steep pitches you can just stand. But if there are sustained steep gradients then you may benefit from low gearing.
If youre up for spending money to change your equipment for this ride (and subsequent big climbing rides) then buy a cheap 105 medium cage rear derailleur.

I normally ride a 53/36 (standard) x 11-32 but rarely use the 32 (even when climbing). Doesn’t hurt to have tho

1 Like

When I last did 6 Gap I had a 50/34x11/32 at around 3.8w/kg and 172lbs. To me, cadence = recovery, and there is very little chance to spin on Hogpen. If I had more gears I would have used them for sure. Better to have and not need than to grind and wear yourself out.

Of course I wasn’t on the pointy end of the ride and hadn’t really trained specifically for it that year so that might change my opinion a little. It was really hot the year I did it (2019) as well. If/when I go back I will probably use the same gearing but train a little better for the event. Hope that helps…

I’ve done 6gaps numerous times. I usually have a 34 or 36 small front ring and a 11-30/11-32 rear cassette. A couple pitches required me to spin around 70ish rpm but it’s never for very long.

This year they are doing the steep side of hogpen. It’s shorter but steep at around 10% for 2.5miles. Ive only done it once in a z2/tempo pace and it took about 22 mins compared to my best time up the normal hogpen route is only 38 mins.

:slight_smile:

I am around 3.8 kg. I used a 52/36 at 6 gap last year. Just ordered the 50/34 for this year.

I have a 32 on the rear as well. I do prefer the higher cadences though.

I can run a 36 on my mechanical Ultegra, however it is a medium cage and DA only comes in a short cage. That said, my buddy is running a short-cage Ultegra mechanical and is using a 32T for The Rift next week.

Cross-chaining is not the issue, it is the upper jockey wheel hitting the cassette that is the problem.

So try it and see…if it doesn’t work, you can add a Wolf Tooth RD adapter and run a 32T no problem. I just installed one for my Ultegra so I can run a 40T cassette at The Rift. 5 minute job and works perfectly. Didn’t even have to change the chain.

1 Like

I have previously used a 11-32 with a Dura-Ace Di2 rear mech with no issues. You do have to wind the b-screw in a little bit more than usual. If you poke around on YouTube, you’ll most likely find multiple examples of people using larger-than-specced cassettes with the current crop of Shimano rear mechs. Shimano is conservative in their official specifications of cassettes/rear mechs.

1 Like

Oh wow didn’t know they changed the route! I’ve rode up the “back side” of Hogpen before, it’s definitely steep and pretty constant from what I remember!

Yes. I did this for more than a year on both Shimano DA 9000 & 9100. Works fine. Adjust B limit screw most of the way in keep from cross-chaining. I put a slightly longer chain on and was able to cross chain without permanent equipment damage… just sounded a little bad and was an immediate reminder to get out of that 53-32 gear in the rare case I was accidentally in it.

I don’t know about praxis but with Shimano you can put a 34t chainring with a 53t chainring. Shifting quality is marginally diminished but only so far that it would matter for top level racing. Totally fine for me.

If you can’t make the gearing changes, and happen to have longer cranks lying around, that can help with the feel of it all. Much easier to operate at 50-80rpm at threshold power using 175mm cranks by comparison to 155mm cranks.

Here are some of my favorite related sites:
https://www.gribble.org/cycling/power_v_speed.html?units=imperial&rp_wr=140&rp_wb=18&rp_a=4.5&rp_cd=0.5&rp_dtl=2&ep_crr=0.0002&ep_rho=0.07&ep_g=5&ep_headwind=0&p2v=240&v2p=22

http://bikecalc-staging.herokuapp.com/speed_at_cadence

1 Like