toolguy

Which bike would be easier to climb a 20% grade? A road bike that weighs 19lbs with a low gear of 29.6 gear inches or a touring bike that weighs 30lbs with a low gear of 18.4 gear inches.

MichaelW

Without a load, the lower gear of the touring bike would be much easier. You would also go more slowly.

toolguy

What is the break even point where 10 lbs heavier is of set by an easier gear? Can it be calculated?

Bekologist

it can be calculated in blood, sweat and tears.

pdlamb

If I remember how to do vector analysis correctly (which is no longer guaranteed!), the break point on a 20% slope is around 57 pound difference in load.

toolguy

Please explain further.

kayakdiver

Most tourists in my experience could worry about the weight around the middle instead of the bike Would make both bike and climbing easier. That being said... I will climb faster with my Giant TCR SL3 than my Novara regardless of how steep it is. Maybe not as much as I believe in my head but the difference is noticeable.

Giant TCR SL3= 15.6 lbs small seat bag
Novara= almost 35 lbs with racks

John N

Heck, I don't know if I could even ride up a 20% grade of any lengthy distance with a 29" gear anymore. Used to be able to romp up hills like that in a 43" gear 30 years ago but age happens. Youth really is wasted on the young .

BigAura

All other things being equal then lighter weight takes less energy over the same distance. That said, it's really about the engine.

xyzzy834

I think the OP is questioning which bike can climb the 20% grade more quickly unloaded. We need more information about the length of the 20% grade. That's a huge incline. In 500 horizontal feet, you'll climb the equivalent of a 10 story building vertically.

The first issue is whether the climb is short enough and the OP is strong enough to muscle a lightweight bike to the top in a 30" gear at all. If not, but the OP can get a heavier 18" geared bike to the top, the answer is clear.

I say the longer the grade, to the point of a theoretical infinitely long climb, the quicker it can be climbed on a heavier bike with a lower gear. Especially where heavier is only 11 lbs more weight for the bike which is a relatively low percentage of both bike and rider and 50% reduction in pedaling effort.

valygrl

From experience:

It's easier for me to ride the last mile up Lefthand Canyon to Ward,which is about 15%, on my unloaded 34 pound tour bike with mountain bike gearing (22x34) than it is to ride it on my 17.5 pound road bike with a low road triple (30x27).

But it's a LOT slower.

toolguy

Thanks everybody for your help. It sounds like the light bike is easier if it's a short hill and the low geared heavier bike is easier if the hill is long.

Speedo

A 20% grade is STEEP. It would hurt my knees to do something that steep on a bike with a 29.6 inch low. Unless it was very short, I would simply avoid the climb. Even with a 30 pound bike, an 18.4 inch gear would make a 20% grade doable for me. Not easy, certainly, but doable.

Here's a place to go to try it out: https://www.everytrail.com/view_trip.php?trip_id=270977

Kingsley Hill Road is one of Bicycling Magazine's toughest stretches of road in the U.S.

Speedo

positron

"ease" refers to how hard you are working.

if you work just as hard on the two bikes, you will go faster on the lighter bike.
if you go the same speed on the two bikes, it will be "easier" on the light bike.

Gearing is irrelevant other than helping you be able to go more slowly while spinning.

Speedo

You are either a superb athlete, or you don't know what you are talking about.

If you have to provide the power to get up the hill with few high pressure pedal strokes you will be using fast twitch (anaerobic) muscle fibers. You will exhaust them quickly. By using low gears you are using slow twitch (aerobic) muscle fibers. You can continue pedaling at a higher rate, but lower pressure per stroke. As a superbly trained athlete, you might still be using slow twitch muscles at those relatively higher gears, but for normal people it makes a difference.

The same power output can result in very different rates of exhausting the muscles. Low gears are your friend.

Speedo

digger531

There are so many wrongs with this statement I don't know where to begin.

gorshkov

The heavier, lower-geared bike will require a smaller power output to get you up the hill. That seems to be the best way to interpret the question.

The power is the product of the force required to keep you going up the hill and your speed. Assuming that the cadence is constant, the speed will be proportional to the gearing. If we also assume that you are keeping your speed constant, and ignore mechanical losses and wind resistance, then the force required will be equal to the weight multiplied by the grade of the hill. If we were only to consider the weight of the bicycle, this would be a break-even choice on the power output, but we have the rider's weight as well. If the rider weighs 160, then the weight difference is 190 vs 179 lbs, which makes much less of a difference than the 35% change in gear ratios.

fietsbob

But with the bike with tour camping gear on it you can keep going onward to somewhere new,
rather than a training loop going home each night.

positron

you just gave a much more technical interpretation of what I was trying to say:

that with low gearing you can "spin" (pedal relatively evenly and quickly) while climbing slowly. yes, the physiological reasons of why this is "easier" are based on differentmuscle fiber types. I didnt realize we needed physiology to answer this question though . Trust me, I am aware of what gears do.

I meant that gears are irrelevant to the question, because with the same gearing, the light bike is "easier" to climb. in other words, it all boils down to how much weight you are trying to lift up a given hill. (thanks physics) less weight is easier to lift against gravity (or in this case roll).

he has a few variables that he wants to compare- gearing: high versus low
and weight: heavy versus light. Speed of climbing gets mentioned in there too...

but you cannot compare them all at once, hence my other post, which basically says that at a given gearing and cadence for a particular hill, the light bike will always be easier.

"easy" as asked by the OP has one implication, how hard is he working? want hill climbing to be easier? then pedal as slowly as you can on either bike.... at some point you wont be working hard enough to stay upright.

want to climb the hill fast? then pedal hard, but it wont be easy.

work needed, which is defined by the hill (which we will assume is the same with either bike), and the gearing ratio (which we will assume is the same on either bike for a given climb comparison), combined with the total load- which is greater on the heavier bike...

If the question is what bike can ride more slowly up the hill, it will obviously be the one with the lowest gearing. This doesn't change the fact that you are trying to lift a certain mass up a certain hill. you will be spinning out trying to ride 3mph, and it will require as much or more work to lift this mass slowly.

if you want to talk about extreme low ends of gearing, then whatever bike has the lowest gearing will help you ride up the hill. It will be slow, and, at some point, it will become "easier" to just walk up the hill.

Speedo

As I understand you, your argument is that a certain amount of energy is needed to get up the hill. If ridden at the same speed, the lighter package, lighter bike with rider, requires less energy and so is "easier". Taken in that very narrow construct, how much delivered energy is required, I agree. But where you go badly astray is that you continue to neglect that we are talking about human beings riding bicycles up a STEEP hill. Our ability to deliver power without exhausting ourselves IS the issue. The efficiency of the engine is key to our perception of how easy it is. On a STEEP hill like the one in question, the efficiency advantage of the lower gears will swamp the weight penalty of the heavier bike.

By your argument, professional bike racers should all ride single speed bicycles. Those gears only add weight, and you claim that they only help you ride more slowly. So a professional bike racer, wanting to go as fast as possible would be better off with only a single big honkin' gear. Hmmm. Last I checked TdF rider always have a pretty full compliment of gears because they recognize that they are most efficient delivering power at relatively high pedal cadence.

Okay, I'm going to reveal my (not so secret) secret weapon here. I have redone the drive trains on all of my bikes so that they have at least a 22 inch low. I ride a lot with friends who are stronger riders. If we are riding together in modest hills they will ride away from me. But then a funny thing happens. When we get to long steep hills, I can still be riding seated comfortably and spinning efficiently, and they are standing, pushing not-so-low low gears, exhausting their fast twitch muscles. I go riding past them, not breathing particularly hard, while they are huffing and puffing. Now I'm not a better athlete, but I am producing power efficiently, while they are not. So, lower gears result in FASTER speed up the steep hill. What amazes me is that these friends will compliment me on my hill climbing prowess. I point out the difference in gearing, and they will, like you, insist that that doesn't matter.

I'll wait for you at the top.

Speedo

positron

Im not disagreeing with you speedo. I also ride a low geared bike or five.
and Im not claiming that TDF riders should ride single speed bikes. (clearly I never said this, though they OBVIOUSLY go to great lengths to minimize weight on the mountain stages- which supports my line of reasoning)
nor am I saying anyone should stay in one high gear and mash up hills. (clearly I never said this)

Im merely trying to make simple and logical a very non-specific question. OP asked "what is easier, heavy + low-gear or light + high-gear". Responses were on the order of "lighter is faster" or "lower gear is easier to ride up a grade..."

All im saying is the more weight you lift, the more work you do.
therefore, strictly speaking, lighter is ALWAYS easier (less total work/energy) on a given hill.

however there are other issues which you point out, including the changing mechanical advantage of different gears, or different physiological concerns. And I agree with you there is a maximum level of efficiency to shoot for when riding - I am a cadence rider and like ~90 RPM

spinning fast might seem easier to the body, but I assure you it involves more energy expenditure due to the compounding effects of efficiency losses with each crank spin, changing momentum of a leg's mass etc.

Seeming "easier" and requiring less work are not the same thing: as you put it: the real world issue of humans riding bikes uphill or whatever it was.

but in a discussion we need to separate all these issues before comparing riding two different bikes up a hill, or else we will not really get at an understanding of the issue.


To summarize my contention:

heavier mass means more work.
therefore:
lighter is always less costly energetically.

however other considerations (mechanical and physiological) can alter the best strategy for a particular rider.

which is to say to the OP: "Until you are more specific with what you mean by your question, and what you mean by "easier", it depends..."

Speedo

Every Memorial Day weekend my wife and I go out to the Berkshires to bike. I've never done Kingsley Hill road, one of Bicyling Magazine's top five "walls". But, this thread has motivated me. So, this is what I'm doing on May 28th! I'm bringing the New World Tourist. 26 pounds with an 18 inch low gear.

Speedo

toolguy

Did you notice I have a New World Tourist too.

acantor

I am not sure I have ever encountered a 20% grade, although they exist. In very hilly Charlevoix in Quebec, there is at least one 20%-er. I read on this forum that there are roads in England (or was it Wales?) with 25% grades. My guess is that 99% of bicycle tourists who attempt these hills would need to walk, regardless of gearing and weight.

I have climbed 18% grades carrying 9 or 10 kg, and found them extremely difficult, even with my granniest granny gear. That the temperature that day was 32+ degrees C. (90 degrees F) did not help! I needed to take a break every minute or two. I don't think I would be able to climb anything steeper. A degree or two makes a difference; I have made it up 16% grades OK, but really struggled with that 18%.

Speedo

I hadn't noticed. Is that your 30 lbs 18.4" gear bike?

I'm curious about the genesis of this thread. Are you planning on doing some sort of challenge ride where you have to climb a 20% grade hill?

Speedo