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-   -   Where to focus efforts for fastest commute (http://www.bikeforums.net/commuting/940395-where-focus-efforts-fastest-commute.html)

storckm 03-27-14 07:23 PM

Where to focus efforts for fastest commute
 
So as I was riding along yesterday, I began to wonder, as follows:

Given that I am only capable of a limited amount of effort, and that the more effort I put forth at one time, the less I can put forth at another, is it faster to put more effort into flat or downhill sections where I can go faster, or into climbs (if you can call anything in central Ohio a climb), where I go fairly slow, no matter how much effort I put forth.

My thoughts are that, since the faster I go, the more of my effort goes into fighting with the wind, it makes more sense to put a lot of effort into climbing, and take it easy when descending (or battling a headwind). It would seem easier to increase my speed given proportion climbing than it would descending.

Is this right, or am I overlooking something?

fietsbob 03-27-14 07:27 PM

... getting started earlier in the morning?

jyl 03-27-14 10:10 PM

This tool might help

Bike Calculator

And

veloroutes.org - create a bike route map with elevation profile

gregf83 03-27-14 11:19 PM

If you want to maximize speed (minimize time) over a fixed distance you go a little harder on hills and into the wind. It's not really worth going a lot harder since the added stress is not linear, i.e. riding at 300W for 2 min up a hill and then coasting down the other side at 0W for 1min is far more stressful than riding at a steady 200W.

My advice would be to try and ride with a steady effort. You'll naturally end up going a little harder on hills and into the wind.

wphamilton 03-27-14 11:53 PM

Quote:

Originally Posted by storckm (Post 16618246)
So as I was riding along yesterday, I began to wonder, as follows:

Given that I am only capable of a limited amount of effort, and that the more effort I put forth at one time, the less I can put forth at another, is it faster to put more effort into flat or downhill sections where I can go faster, or into climbs (if you can call anything in central Ohio a climb), where I go fairly slow, no matter how much effort I put forth.

My thoughts are that, since the faster I go, the more of my effort goes into fighting with the wind, it makes more sense to put a lot of effort into climbing, and take it easy when descending (or battling a headwind). It would seem easier to increase my speed given proportion climbing than it would descending.

Is this right, or am I overlooking something?

I believe this is completely correct.

tsl 03-28-14 01:52 AM

Quote:

Originally Posted by storckm (Post 16618246)
more of my effort goes into fighting with the wind

Given the upright posture of your Schwinn Range commuter bike, there's a limit to how fast you can push through the air. If you're thinking about being faster on the commute, maybe it's time to think about a drop bar bike. Battling the wind is exactly what drove me from my hybrid to drop bar bikes. Best cycling decision I ever made.

Walter S 03-28-14 03:02 AM

Going up hills, effort increases your speed by a larger proportion. So effort pays off more there. For example, let's say 150 watts gets you up the hill at 3 mph. Since most of your drag is proportional at that low speed, doing 300 watts makes you go nearly 6 mph.

Conversely, on the flats or a little downhill, 150 -> 300 might send you from 20 mph to say, 28 mph. So the effort increases speed less than 50% instead of nearly 100%.

And since uphill hill is slower than down, you'll spend more time doing it. So the effort has a more dramatic proportional impact on your speed, and you spend more time at that higher speed. So conserving energy as you approach climbs and then putting out a less sustainable effort during the climb has the biggest impact on overall speed.

downwinded 03-28-14 04:28 AM

Quote:

Originally Posted by tsl (Post 16618947)
Given the upright posture of your Schwinn Range commuter bike, there's a limit to how fast you can push through the air. If you're thinking about being faster on the commute, maybe it's time to think about a drop bar bike. Battling the wind is exactly what drove me from my hybrid to drop bar bikes. Best cycling decision I ever made.

Bingo!

jrickards 03-28-14 07:20 AM

Quote:

Originally Posted by Walter S (Post 16618979)
And since uphill hill is slower than down, you'll spend more time doing it. So the effort has a more dramatic proportional impact on your speed, and you spend more time at that higher speed. So conserving energy as you approach climbs and then putting out a less sustainable effort during the climb has the biggest impact on overall speed.

I've read something similar although what I read was more in context of racing where it seems to be more beneficial to drop someone on the hills (it certainly would be from a psychological perspective), the effort in fact is disproportionate to the total speed gain. The author went on to say that if you're simply challenging yourself, conserve your energy going uphill and then put in the effort downhill and on the flats.

gregf83 03-28-14 07:39 AM

Quote:

Originally Posted by jrickards (Post 16619300)
I've read something similar although what I read was more in context of racing where it seems to be more beneficial to drop someone on the hills (it certainly would be from a psychological perspective), the effort in fact is disproportionate to the total speed gain. The author went on to say that if you're simply challenging yourself, conserve your energy going uphill and then put in the effort downhill and on the flats.

In racing you can attack on a hill because the group chasing you will have less of an advantage than they would on the flats where they can share the load and most of the riders are shielded from the wind.

You may have mis-remembered what you read or it was just wrong but if you want to go faster it never makes sense to go easier on a hill.

As others have said though, whether you push 5-10% harder on a hill is a red herring if you're riding an upright bike with baggy clothes. I notice a 3-5min penalty on days when I wear a rain jacket (too baggy). The bottom line: if you want to spend less time on your commute get yourself in an aero position with tight fitting clothes. Adjusting your pace on hills is just fine tuning that will have far less impact than the aero improvements you could make.

mgw4jc 03-28-14 07:48 AM

And don't forget to shave your legs.

CharlyAlfaRomeo 03-28-14 08:07 AM

Focus your efforts uphill AND into the wind. However unless your commute is quite long it really isn't going to make a difference.

achoo 03-28-14 08:08 AM

Quote:

Originally Posted by jrickards (Post 16619300)
I've read something similar although what I read was more in context of racing where it seems to be more beneficial to drop someone on the hills (it certainly would be from a psychological perspective), the effort in fact is disproportionate to the total speed gain. The author went on to say that if you're simply challenging yourself, conserve your energy going uphill and then put in the effort downhill and on the flats.

What do you mean by "challenging yourself"?

I also don't get what you mean by "the effort in fact is disproportionate to the total speed gain". Because it's on the uphills where speed gains are much more proportional to effort (power level). Double your power up a hill, you'll go just about twice as fast. Double your power on a downhill and you might go from 40 to 42 mph.

And no, that's no exaggeration.

Uphill, you're going slow enough that drag is negligible, and almost all your effort is spent lifting you and your bike against the force of gravity. And that's a linear force - double your power and you go up twice as fast.

But downhill? Two things happen. First, drag is by far the most significant force holding you back. By far. And the power to overcome drag is a function of speed cubed. It ain't linear. Double your power on the flats and you go only about 25% faster.

It's more complicated going downhill because you're getting a significant assist from gravity. Go down a 10% grade and you'll coast somewhere around 40 mph depending on how aerodynamic you are. For a 150 lb rider, that's the equivalent of pedaling hard enough to put out about 1500W.

On any significantly steep downhill, your power output is just messing around the margins. Why expend a ton of effort to go from 42 to 44 mph for the 2 minutes it takes to go down a hill that took you 10 minutes to climb?

But if you expend the effort climbing, you'll get up that hill in 7 minutes instead of 10.

pdlamb 03-28-14 08:10 AM

Not to mention, check your route. If there's a direct route with stop signs or traffic lights every block, and another route that's slightly longer but only has you stop every couple miles, the route with less stopping will be faster.

alan s 03-28-14 08:25 AM

Drafting faster bikes is the easiest way to go faster. Just make sure the rider in front is OK with it. And, don't think a different bike or drop bars are necessary. Most bikes can be set up to be much more efficient. On a flat bar MTB, I'm more aerodynamic than most road bikes out there, because I set the bike up that way.

caloso 03-28-14 08:30 AM

Focus on timing the stoplights.

CommuteCommando 03-28-14 08:46 AM

Quote:

Originally Posted by mgw4jc (Post 16619368)
And don't forget to shave your legs.

The Italians all do it.

(What a funny country. The women don't save their's);)

Quote:

Originally Posted by achoo (Post 16619402)
But downhill? Two things happen. First, drag is by far the most significant force holding you back. By far. And the power to overcome drag is a function of speed cubed. It ain't linear. Double your power on the flats and you go only about 25% faster.

It's more complicated going downhill because you're getting a significant assist from gravity. Go down a 10% grade and you'll coast somewhere around 40 mph depending on how aerodynamic you are. For a 150 lb rider, that's the equivalent of pedaling hard enough to put out about 1500W.

On any significantly steep downhill, your power output is just messing around the margins. Why expend a ton of effort to go from 42 to 44 mph for the 2 minutes it takes to go down a hill that took you 10 minutes to climb?

But if you expend the effort climbing, you'll get up that hill in 7 minutes instead of 10.

This^. If you watch the pro racers, you will often see them coasting on the descents, or they're softpedaling to keep the legs loose, recovering to hammer it on the hills and flats. Also notice that when they are coasting on the descents, the crank is horizontal, which is aerodynamically "cleaner" than having one leg resting on the down stroke pedal.

WonderMonkey 03-28-14 08:51 AM

Depending on how big the hills are if you go down one I would put a moderate amount of effort into gaining speed then carry that into the uphill.

jrickards 03-28-14 09:11 AM

Quote:

Originally Posted by achoo (Post 16619402)
What do you mean by "challenging yourself"?

Not challenging someone else, as in a race.

Quote:

Originally Posted by achoo (Post 16619402)
I also don't get what you mean by "the effort in fact is disproportionate to the total speed gain". Because it's on the uphills where speed gains are much more proportional to effort (power level). Double your power up a hill, you'll go just about twice as fast. Double your power on a downhill and you might go from 40 to 42 mph.

And no, that's no exaggeration.

Uphill, you're going slow enough that drag is negligible, and almost all your effort is spent lifting you and your bike against the force of gravity. And that's a linear force - double your power and you go up twice as fast.

But downhill? Two things happen. First, drag is by far the most significant force holding you back. By far. And the power to overcome drag is a function of speed cubed. It ain't linear. Double your power on the flats and you go only about 25% faster.

It's more complicated going downhill because you're getting a significant assist from gravity. Go down a 10% grade and you'll coast somewhere around 40 mph depending on how aerodynamic you are. For a 150 lb rider, that's the equivalent of pedaling hard enough to put out about 1500W.

On any significantly steep downhill, your power output is just messing around the margins. Why expend a ton of effort to go from 42 to 44 mph for the 2 minutes it takes to go down a hill that took you 10 minutes to climb?

But if you expend the effort climbing, you'll get up that hill in 7 minutes instead of 10.

OK, maybe I had it wrong. I'll have to go back to that book again. I clearly remember the author saying to conserve energy going uphill and then spend it downhill and on the flats.

CommuteCommando 03-28-14 09:13 AM

1 Attachment(s)
Quote:

Originally Posted by WonderMonkey (Post 16619557)
Depending on how big the hills are if you go down one I would put a moderate amount of effort into gaining speed then carry that into the uphill.

This tactic works well on really short, rolling terrain. Sustained climbs and descents of as little as a hundred yards or more are better to work on the uphill, rest on the down.

http://bikeforums.net/attachment.php...hmentid=371413

This is Gleneyre Dr. in Newport Beach. I like to hammer down the short decent in the foreground so that inertia carries me through the following steep rise, that I stand for. This gives me enough speed coming out the top that I can settle in an cruise to the next little roller. You can see there are a couple more like it further down.

jrickards 03-28-14 09:14 AM

Quote:

Originally Posted by gregf83 (Post 16619345)
You may have mis-remembered what you read or it was just wrong but if you want to go faster it never makes sense to go easier on a hill.

Maybe I'm wrong, or maybe, I'm in that same race as you and trying to give you bad advice!! :lol:

I'll check the book tonight.

Leebo 03-28-14 09:23 AM

Some bike details would be helpful. Schwinn range? Tire type, bike weight, gear, drivetrain, commute distance & elevation etc.

storckm 03-28-14 09:37 AM

Quote:

Originally Posted by tsl (Post 16618947)
Given the upright posture of your Schwinn Range commuter bike, there's a limit to how fast you can push through the air. If you're thinking about being faster on the commute, maybe it's time to think about a drop bar bike. Battling the wind is exactly what drove me from my hybrid to drop bar bikes. Best cycling decision I ever made.

Actually, I've got drop bars on that bicycle (I can't stand flat bars), but when I was thinking about this, I was riding my Yuba Mundo (with trekking handlebars).
On the whole, I'm not really worried about how fast I go, but on occasion I am running late, or need to make a quicker trip.
I wonder if anyone has accurately calculated differences made by things like shaved legs, clothing, etc. I wonder if part of the effect is mental.
The bike calculator is pretty fun, thanks, jyl.

rumrunn6 03-28-14 09:48 AM

have you google-mapped your shortest distance?

FBinNY 03-28-14 10:03 AM

Since most of the drag comes from wind resistance which is proportional to the square of speed, the most efficient way to ride is at constant wind speed. The effort spent to ride faster, will not be offset by the energy saved riding slower later. So, train yourself not to fight headwinds too much, while taking fullest advantage of any tailwinds.

Hills are a different story. The object is to avoid losing time, yet not exhaust yourself to where you need a long recovery at low effort. I divide hills into two categories, bite size and longer. A bite size hill is one you can take at a single go, maintaining good speed and cresting without gearing down much. It can be a short steep wall you simply sprint, or something a bit longer, that might need a downshift, but can be pushed up in a relatively big gear most of the way without your legs giving out.

Attack bite size hills hitting the bottom fast and using reserve power to take you to the top. You may be a bit flagged at the top, but you've lost little time, and can afford a short recovery.

Longer hills are the opposite, here the need to stay fresh enough to ride after climbing overrides climbing time concerns. Find a gear you can climb in, and settle in. If the hill is long enough, it's OK, to attack some at intervals to make time, but make sure you leave enough in your legs to make the top without being too dead to ride fast after.

Interestingly, over the years I find that my fastest average speeds are on stretches of bite size roller coaster hills. It seems that the attack psychology motivates me to exert more effort than I will on long flat stretches, and I can use gravity and my higher gears to gain speed on the descents.

I hope this helps.


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