What makes a bike good for hills?

[hozn]

I think most people (bike reviewers, anyway) favor lateral frame stiffness (no bottom bracket wagging) when talking about climbing bikes. But whether this truly makes a bike faster or better on a climb is subject to debate (and there seems to be some science behind the assertion that more stiffness != more better).

Here are a few of the articles I’ve seen that seem to be worth a read:
– http://janheine.wordpress.com/2011/10/03/science-and-bicycles-frame-stiffness/
– http://janheine.wordpress.com/2011/02/27/a-journey-of-discovery-part-5-frame-stiffness/
– http://www.slowtwitch.com/Tech/Frame_Stiffness_2565.html
– And the not-linkable Bicycle Quarterly double-blind study that is mentioned by a number of blog posts on the topic.

Also a lighter bike would be a good hill-climbing bike, but there again are some caveats, since some heavier bikes may transmit power better than lighter bikes. Take a look at: http://davesbikeblog.squarespace.com/blog/2013/2/21/lighter-is-not-necessarily-faster.html

So a lot of the differences are likely just in your head. But since we aren’t doing double-blind studies, what’s in your head does matter.

My own observation is that when your frame is flexible enough so that you start rubbing your brake caliper on the wheels when you are out of the saddle, that is not going to be a great bike to ride up a hill. I really like climbing on my carbon road frame with a super stiff front end (tapered fork, beefy fork, 9mm thru axle, 45mm-deep/28-spoke wheels). I can pull back and forth on the bars and there is no caliper rub (disc brake bike) no discernible wheel flex. And the stiff BB area means I don’t feel the bike wagging side to side; I like that too. It feels great and Strava says I climb faster on it than my several-pounds-heavier titanium bike which is noticeably less stiff. Of course, that may be in my head, but whatever: it works.

I would add that having nice brakes is also useful on a hill-climbing bike. Assuming you need to descend the hills you climb, anyway. Disc brakes rock for that, especially with them carbon rims.

[DismalScientist]

This depends on the length of the rides. A light, stiff, aggressive bike would be best for short hill rides, but might pound the crap out of you on longer rides.

[hozn]

Well, carbon can be “laterally stiff and vertically compliant”. Maybe metal can too. As much as that is just marketing, I will say that other than aggressive geometry, my stiff carbon frame is just as comfortable over the bumps as my ti frame.

[DismalScientist]

My comment was based on geometry more than frame material. I found on longer rides I prefer my touring bike over more aggressive bikes.

[n18]

Lighter tires and tubes make climbing hills easier. It’s not the weight saving(although it’s nice), but lighter tires have less rolling resistance. Think of spinning by hand a car wheel vs a bike wheel. Which one resists rotating more? Lighter tires take less energy to spin. You could carry extra weight in your pannier bags that represents the tire weight saving, and you could still go uphill faster despite the total bike weight being the same.

For example, I changed the tires on my bike from Vera CityWide 700×35 with 60 TPI, which weighs about 500 grams each, to these tires(Continental Grand Prix 4000S II 700×25 with 330 TPI puncture protection), which weigh 225 grams, and the difference was easily noticeable. I noticed that I could accelerate faster on flat roads, and when going south/east on the W&OD from Hunter Mill RD to central Vienna, which is a steady slow uphill, that I could keep a steadier, faster pace. With heavier tires, any time I get tired and slow a bit, I waste energy to get back up to speed again, and this could become accumulative. With the new tires, I almost don’t slow down, and there are even lighter tires, but they don’t have much puncture protection.

Obviously, if you could manage going uphill at an exact constant speed with heavy tires, then rolling resistance doesn’t matter except for the initial spin, but in practice, “most” riders can’t keep a constant speed, and rolling resistance kicks in because there is a change in speed. This is the rotational equivalent of Newton’s first law of motion, which says that an object moving at a constant speed would remain at that speed unless acted upon by an external force. Likewise, a wheel would keep spinning forever at the same speed provided that there is no friction or air resistance or slowed down or sped up by an external force.

[hozn]

I think you are confusing rolling resistance (crr) with rotational inertia / force needed to “spin up” greater mass.

Rolling resistance will be just as relevant when moving at constant speed. Indeed the GP 4000S has very low rolling resistance, but lighter tires do not necessarily roll faster. Wider (and hence heavier) tires [of same type] theoretically roll faster *at same pressure*. How supple the tire is and tread compound, etc. are the significant factors for crr. And the tubes do make a difference — latex is better than butyl, for instance.

More important than weight is aerodynamics, though. Even for hills — except for very extreme mountain climbing.

See:

http://flocycling.blogspot.com/2014/01/flo-cycling-great-debate-aero-vs-weight.html?m=1

http://www.slowtwitch.com/Tech/Why_Wheel_Aerodynamics_Can_Outweigh_Wheel_Weight_and_Inertia_2106.html

[Harry Meatmotor]

@hozn 94307 wrote:

… And the tubes do make a difference — latex is better than butyl…

If you’re spending $60+ on a high TPI casing tire (typically double what a normal “nice” wire bead tire costs), why not spend twice as much on latex inner tubes? They make a shockingly big difference, and they offer better puncture resistance, too.

[hozn]

Yes, I admit that I have a 5-pack of latex tubes still unopened. O figure I will swap them in when I change my tires out, which will probably be spring.

[Author]

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