Leadville Gearing and Aerodynamics

Hello everyone this is my first post here although I’ve been lurking for almost a year now. I am in the Leadville 100 for 2022 (sub 9 goal starting in purple corral) and wanted to ask the questions that have been swirling around in my mind since I knew I was in from the Leadville Stage Race back in August.

As I previously mentioned I did the Leadville Stage Race this last summer. Finished it in 9 hours. Beyond having a specific time goal I wanted to ride the entire course and not walk my bike at all which I was able to accomplish, although powerlines false summits really tested my resolve. There was 300 people at the event and I finished like 80th or somewhere near that. From looking at splits I noticed that on all the major climbs and descents I was in the top 30 on the day for Strava, but on all the flats was around 100-120. I have been training for maybe 10 months total so close to 8 months at the time of this race. I weigh 160 and had an FTP of 250. I’m comfortable in saying by this upcoming years Leadville 100 I will be around 300 with more training and dialed nutrition.

Gearing: I ride a 2020 Top Fuel 9.8 with Shimano XT 30 tooth chainring and I think it’s 10-51 cassette in the rear. I felt like to get up Columbine and Powerline I needed every bit of gearing I had, but on the flip side at the new single track bybass section inbound and some of the road spots I felt spun out and like I didn’t have enough gearing to paceline with the groups I was in. Assuming I get my FTP to 300 which for me will be a touch over 4w/kg should I adjust my gearing and if so by how much? Will going up in my gearing on a long day like Leadville take away from my climbing which is typically by biggest strength? I passed a ton of people going up Columbine and Powerline and don’t want to be joining the walking line.

Aero: In a race like this how much of a difference would something like bar ends or aerobars make? Would their benefits on the flats outweigh the weight penalty climbing? I am also considering using a skin suit with pockets this year and a giro vanquish helmet instead of my usual road jersey and helmet. On this front I guess I’m asking for the sweet spot between aero and comfort for close to 9 hours in the saddle?

Last thing is I think I will do the sustained power build phase followed by the XC Marathon speciality phase. Any experience with this combination for this race?

Thanks for the tips, who knows when I’ll do this again and want to ensure this attempt is sub 9 hours.

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I wish modern XC bikes had 2x drivetrains. That would make your (and my) problem easier. I rode this year, with a 32x52 Eagle, and would have used gears both shorter and taller for a substantial part of the race. I spend a lot of time (not many miles) on the 52, and a lot of miles (less time) on the 10. You can practice riding roads without aerobars, and still tucking. I ride with Innerbarends from SQlabs. SQlab Innerbarends® 411 | SQlab Online Shop. I spend most (probably close to 85%) of my time on them, and find that shifting and braking is still safe. Before it gets hairy, I grab the bars like normal. On the Innerbarends, it almost feels like riding on the hoods of a drop bar. Goodluck in 2022.


Those bar ends look better than most I’ve seen. Where did you mount them and at what angle?

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So if a picture is worth a thousand words,…don’t judge the background.


You didn’t say what size chain ring you have. [Edit - I reread the OPs post and see he indicated 30T].

The reality is you only have a few options - 30, 32, 34. For 4 W/kg, 32 is probably the sweet spot. (Or lower if you take Nates advice!).

Take a look at your average speed - we’re you really riding at above 25mph for sustained stretches where you needed to put down power, and not just coast? (32-10 at 90 rpm is about 25mph)

Keep in mind it’s better to optimize your gearing for the hours you’ll spend climbing vs the minutes you’ll spend at 25mph+.

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He said he’d a 30T with 10-51 out back.

According to http://www.bikecalc.com/speed_at_cadence 30:10 would give 41.5km/h (26mph?) at 110rpm.

If someone is looking at sub 9hr for Leadville then the above cadence doesn’t seem unreasonable. As @DaveWh says, are you really riding for sustained lengths of time at those sorts of speeds? They are approaching peloton speeds on road bikes. Also you say you “felt spun out” not that you did spin out.

Don’t know what distance Powerline is into the race, I’ve a feeling it’s close to the end, so think what you need to climb that after 8hrs+ on the go.

Going from 30T to 32T up front is a 7% increase in gearing, going from 250W to 300W is a 20% increase. Also there’s a 13% step on the cassette from the second lowest (45T) to the lowest (51T) so you could look at that and say “If I improve my power by 20% then I could put a 32T on the front and still be fine on Columbine and Powerline but I’ve a higher top speed for my max cadence” or you could say “If I improve my power by 20% and stick with the 30T but improve my pedalling for the top end then I’ve an extra 13% power at the low end”.


If I was to do Leadville again, I’d ride 30T with 10-50. I’m in the 9:30-10hr finisher range.

28T would be too low. At that point it’s easier to walk, as there’s only so slow you can ride up a rocky MTB trail and maintain balance and forward momentum to get over bumps / rocks on the trail.

Those are all excellent points about the gearing. It was rare to be over 25mph for extended periods. Maybe if I’m going at that pace while coasting that rest will serve me well at the Powerline climb at mile 80. At the same time if I’m increasing my power it makes sense I could also go up a chain ring size. Looking back I averaged 17.7 from Pipeline Aid to Powerline Base and 21.3 from Pipeline to Fish Hatchery. I power on Powerline was pretty low at 178 watts so maybe if I can pull that up 34T would be the choice. Just hard to know because there’s no way to replicate the Powerline climb and the specific conditions that come with it appearing at mile 80.

This was in the stage race? Keep in mind that you’ll have 60 miles in your legs by this point in the 100, and won’t be rolling as fast. Plus by that time of the day, there’ll be a headwind on this section.

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100% agree. With increased training and power I would run the 32T without question in the stage race if I were to do that again. I share your concerns with the unique challenge of the 100.

My AXS time/distance in gear. I was 140ish on race day + bike and gear, and my bike doesn’t accept a 30T chainring. With a ramp estimated FPT around 245W. I tried, but it would rub/grind the chainstay connection at the bottom bracket. I had ridden/walked the beast climbs enough to know and wish I had a 30T chainring. All of them require pedal efforts in excess of threshold power for me, this includes all the passing and jostling up St. Kevin’s. On the road descent from St. Kevin’s outbound, i peaked in excess of 40mph, coasting. Having a gear to pedal at that speed would be nearly useless. Gear 1 is 52T, gear 12 is 10T, a lot of distance on that tiny cog.

Regarding the power needed to climb powerline, you could always ride tempo (or endurance) for 7 hours, then do an FPT test. Sounds like fun. Recovery might take a while. :hot_face:


You used a 32T?

Yup. 30t doesnt fit.

You’ve received some great advice from the posters above that have done the race.

I’d just add one thing for you to think about. It sounds like you currently don’t have sub-9 fitness, or I should say you don’t have 32T fitness right now. so to me the extra fitness between now and next year would allow you to ride the 30T with the strength and confidence that you rode it this year (for the 100mile instead of stages).

By all means buy the 32T and try them both out back to back, but don’t underestimate the effect of fatigue and commit yourself too early to a plan that might not be right by then.

30T is still fast and takes nothing away from your awesomeness :grin:.

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That’s good advice. I could care less how many teeth the crank has I just want whatever is fastest overall!