The Ultimate Efficiency - Fuel Economy, Hypermiling, EcoModding News and Forum

bmwboarder · 10-05-2010, 04:50 PM

Its fairly well established that a bike is one of the most efficient forms of transportation. However, I would like to take that a little further. Bikes come in a huge range of forms, from full suspension mountain bikes (Full sized trucks) to hybrids (compact SUV's) to decent road bikes (fwd basic everyday car) to really good road bikes (diesels) to fixed gears (Insight).

What, a fixed gear? Yes, a fixed gear bicycle is the most efficient form of transportation in my mind, so let me explain why.

One of the best things about a fixed gear is that it is a direct drive. The chain goes from your crank, where your power is generated, straight to the wheel. There is no derailleur interfering, no tension on cables, no alignment issues. It is a straight and pure lever pulling a gear. But does this matter? Oh yes.

On the bike below, I can get up a rather large hill in Seattle riding a 3.0 gear ratio on normal road wheels (48t x 16t). Riding a high-end road bike I would be in one of the lowest gears, usually a 39t x 20-23t, which is a gear ratio under 2.0. I would have to gear down to 2/3 of the fixed gear ratio in order to make it up the hill, due mostly to the derailleur's added stress, the non-straight line of the chain, and slightly more weight of added parts (gears and gear changers). Amazing.

15lb fixed gear

One big problem with fixed gears is that they are often made for "tricks," or made out of older road bikes as a "fun" project, so they don't reach their optimum in efficiency.

For this one we chose to spend a little extra money on the key parts, wheels, crank and fork. The result is that it is extremely fast. By making the bike so light, one gear is not a problem. I can make it up almost any hill that a person on a good high-end bike could (even on a $3000 road bike). I could accelerate to 20mph just as fast if not faster than someone with gears, and I could steadily hold 25mph, with bursts up close to 35mph.

I helped build the bike above for a friend, so it is not my own, but even at 15lbs, it still uses an old Peugeot frame (5lbs). Someday we'll swap that out for some nice 3lb frame so that we can glean an even bigger smile as we effortlessly ride around

My bike isn't quite as fast, but hopefully I'll get there:
Leader 735tr

If you ever have a chance to ride a good quality fixed gear, its worth your time as you can immediately feel the efficiency gain. Maybe its not for everyone, but as far as efficiency, I believe it is the purest form of transportation available.

RobertSmalls · 10-05-2010, 05:53 PM

No brakes, only one gear ratio, no cupholders, no cargo space. You're crazy, you know. Those features more than pull their own weight through added safety, comfort, and versatility. Your bike is faster than my 24-speed road/utility bike, but only in a narrow range of speed and loads. I can turn at 100-120RPM at 5mph, up a hill, in traffic, whenever. I feel sorry for your knees.

How much weight do you save by going fixie, anyway?

bmwboarder · 10-05-2010, 06:10 PM

I would agree, a fixed gear isn't for everyone, just as a Honda Insight isn't either.

You only loose about 2lbs by "converting" to fixed, but its more about the efficiency gained through running your chain through fewer parts.

I wouldn't feel too sorry for my knees. There is a vast difference between a good fixed gear and a cheaply built one, and I think that idea mostly comes from heavier cheaper fixed gears, as a lighter bike with light wheels isn't very harsh. I will get flogged if the fixed gear community sees this statement, but I ride with two brakes too, so I don't have to use my knees to brake if I don't want...

I rode for 2 years on a fixed/singlespeed through Seattle, and I could make it up all the hills just fine, and I carried a change of clothes and shoes with me in a backpack. I also have a singlespeed cyclocross bike that would be considered my utility bike if I don't need to go quite as fast

Lokalazeros · 10-05-2010, 06:42 PM

IMHO, a singlespeed bike would suit most people wanting to travel relatively short distance (commuting, in-town transportation). You'd get the advantages of a straight chain line, teh ability to coast, and the safety of having brake(s) when needed.

BMWBaorder, is your bike a fixie ? I see you have one speed, and brakes, and I was wondering if it was singlespeed, or fixed.

bmwboarder · 10-05-2010, 07:23 PM

I have a flip/flop hub, so I can run it either way. In the picture it is fixed, but I ride it both ways now and then. A fixed gear doesn't have to have no brakes, that is just the status-quo (unless you are riding on a track.) I like both singlespeed and fixed, though really I just like nice bikes that are super efficient (aka fast!).

discovery · 10-05-2010, 11:07 PM

Quote:

Originally Posted by bmwboarder

I have a flip/flop hub, so I can run it either way. In the picture it is fixed, but I ride it both ways now and then. A fixed gear doesn't have to have no brakes, that is just the status-quo (unless you are riding on a track.) I like both singlespeed and fixed, though really I just like nice bikes that are super efficient (aka fast!).

I have one bike for more than 10 years. Bought mine from Wall Mart for $90. It was on the back of my car and traveled across the country twice with it. Been trough hurricanes outside my house (it was under water for two week during Katrina) still runs and serves me well.

BTW that site for the bikes is cool, I like it.

bmwboarder · 10-05-2010, 11:34 PM

Thanks Discovery

Bikes that last are definitely a good thing. Sounds like your bike has seen more of the country than my bike has too.

Frank Lee · 10-06-2010, 01:36 AM

I wanted to go penny-farthing for ultimate efficiency but the wheel can't get big enough.

I think the weight difference in fixie vs multi-speed is inconsequential; emptying out your colon before departing would have a larger effect.

I wonder about the drivetrain efficiency difference. I've seen derailleur systems credited with 92.5-98.5% efficiency, depending on gearset and tension. Fixed ratio couldn't be 100% and assuming there's no reason it wouldn't be worse than the best derailleur scenario means we'd be comparing 98.5% to 99% or 99.5%? Either way I wouldn't think that's detectable to the rider.

I bought my 27" framed Fuji in 1983 and for quite a long while put 25+ miles on it daily. Sure wish it had an odometer- am curious how many miles are on it!

bmwboarder · 10-06-2010, 01:55 AM

I would disagree with the bike weight importance. 2lbs is huge when you are talking about a bike that only weighs 18lbs. I'm not sure why, but it makes a bigger difference then losing two pounds of weight off the body. (I would absolutely trade 2lbs off my bike and put in a backpack on my back anytime!). I can't say why this is scientifically, but I can definitely feel it.

Do you know which derailleurs these super efficient ones might be? I had a bike with top of the line full Dura-ace, which is the bike I used for comparing to the fixed gear.

Either way, if you can get a bike with derailleurs like those, you will be putting much less effort into moving than the vast majority of cyclists.

Frank Lee · 10-06-2010, 02:36 AM

I have a mountain of bikes to choose from. Which one have I been riding almost exclusively the last two years? A 50 lb behemoth with dual suspension- just on the street. Were two pounds to be subtracted or added, I wouldn't even know. The weight of it definitely is a lesser factor than the comfort and utility of it.

That would be, any ordinary old derailleurs.