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Old 10-24-2014, 10:43 PM   #21 (permalink)
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Originally Posted by Grant-53 View Post
Picking the right bike is a bit more complicated than going to a store and picking the one that looks nice. Weather, terrain, and traffic density affect the type of bike whether hybrid, commuter, or road bike. Next is getting the frame sized properly for your body dimensions. I use Zinn Cycles online program for recommendations on frame, stem, and crank arm sizes. Gearing is a matter of plotting the steps between a suitable low and high. If you are in stop and go traffic without steep hills, an internal gear hub is easier to shift when stopped. I have a 24 spd Jamis Aragon 700C and a Huffy 3 spd 26" as favorites. The aluminum Jamis is great on hills and towing a trailer. The Huffy is slick in traffic. I have fairings and bags for both.
Zinn's calculator is not too far off overall, but I disagree with the longer crankarm length (theory) that is a theme with Zinn. I still have a variety of crankarms here with some longer Bullseye 190's and then down to 152's. Over two years of using a variety of length adjustments on the powercranks and data from the Computrainer, I repeatedly found VO2max through the roof with longer cranks not to mention the aero disadvantage that accompanies them via poorer aero profile due to lower seat height. (This was also the experience of a few of my competitors at the time). My best years racing started as soon as I switched to the shorter cranks and making better use of the gears and decreased shorter crank circumference. With the powercranks and additional pedal weights, it was possible to actually pedal around the entire 360 circle, even in the full aero position. Not possible with the long cranks unless the front bars were raised. Almost 15 years later, the industry started gravitating that way (beyond the stock 175mm) and you could see the shorter ones being more readily available as opposed to the stock 175-ish ones.

Interestingly, like engines (with their bore/stroke ratio), people (with their leg length ratio) have a relationship when it comes to power output in cycling. When a longer crankarm is used and a higher cadence is desired, the footspeed is also considerably higher and the lower leg (and knee) get to deal with this increased speed as a result.....

On a downhill, "spinning out" was nearly impossible with the short cranks, no bounce either like with the long cranks..

Ok, sorry for all the blabbity, blab but I'm not convinced an optimal crankarm length can be based on a formula. There's way too many variables to include fast-twitch/slow-twitch as well as the actual event itself (distance/sprint/mountain/etc..)..... And then there's the rabbit trail of the KNOPS (knee over pedal spindle). It never ends!

~CrazyJerry

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Old 10-25-2014, 06:52 PM   #22 (permalink)
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I agree. The bike needs to fit the person, the terrain, and gearing. Some people ride around town at 60 rpm. I gear for 90 rpm and those who road race will spin higher. There is a great range of options in sizing a bike. That is what makes a bicycle different from a scooter or motorcycle. So how long is your femur
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Old 10-25-2014, 09:29 PM   #23 (permalink)
Changfa diesel + Suzuki
 
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Centurion - '74 FIAT X1/9 Centurion Full Race DNA
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Quote:
Originally Posted by Grant-53 View Post
I agree. The bike needs to fit the person, the terrain, and gearing. Some people ride around town at 60 rpm. I gear for 90 rpm and those who road race will spin higher. There is a great range of options in sizing a bike. That is what makes a bicycle different from a scooter or motorcycle. So how long is your femur
Agreed! At the time I had a Softride (for fitment and training) and used Powercranks, so I was able to see every adjustment's affect on heartrate and power output. After switching focus away from racing, I used that same setup again when generating electricity from the bike for the house. The goal was to get as many watts possible from these getaway sticks. This resulted in yet another extended study of the longer lever idea with crankarms....

On the Vengeance (diamond frame) for speed there is a 56 tooth front ring and an 11 tooth rear.
On the Challenge (recumbent) for speed there is a 60 tooth front ring, then a mid-drive, and an 11 tooth rear. If I need more on a downhill a Schlumph is my Hail-Mary! YeeHaww!

Femur-wise is around 22.5 inches. I used to stumble over all that info at one time, now it's all buried somewhere!

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Old 10-27-2014, 11:19 AM   #24 (permalink)
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Blackfly - '98 Geo Metro
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90 day: 52.71 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
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spotted another one...

So, you know how when you get a new car, all of a sudden you start seeing them everywhere?

This is not exactly the same.

And you know how some people like to decorate their properties with old bikes painted in bright colours?

Yesterday I spotted an old CCM just like my '62 (the "kinked" top tube is a dead giveaway), but painted bright red -- a bauble on a farmer's fence. I'm tempted to stop in next time to check the serial number to see what year it is. Possible trade up/down?

Is this how it starts?
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Project MPGiata! Mods for getting 50+ MPG from a 1990 Miata
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: 70 MPG in my ecomodded, dirt cheap, 3-cylinder Mirage.
Ecodriving test: Manual vs. automatic transmission MPG showdown



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Old 10-27-2014, 12:25 PM   #25 (permalink)
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Yes, this is how it starts.
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Old 05-06-2015, 05:33 PM   #26 (permalink)
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Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 52.71 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)

Appliance car - '14 Mitsubishi Mirage ES (base)
90 day: 52.48 mpg (US)
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CCM out of hibernation; first mod!

The old machine wintered well! It still had 30 PSI in both tires! (Seems the tires on my cars aren't even that good.)

First mod: CCM pickup truck. AKA wicker basket on the rat trap. 100% more useful!

However the singlespeed made it -100% useful to start with, so we're really just getting back to zero on the utility scale.

But now I have an inexplicable desire to pedal to a market and buy some French bread.

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Project MPGiata! Mods for getting 50+ MPG from a 1990 Miata
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: 70 MPG in my ecomodded, dirt cheap, 3-cylinder Mirage.
Ecodriving test: Manual vs. automatic transmission MPG showdown



EcoModder
has launched a forum for the efficient new Mitsubishi Mirage
www.MetroMPG.com - fuel efficiency info for Geo Metro owners
www.ForkenSwift.com - electric car conversion on a beer budget
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Old 05-06-2015, 08:23 PM   #27 (permalink)
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"And your little dog too." I keep a selection of chain rings front and rear to adjust gearing.
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Old 05-06-2015, 09:07 PM   #28 (permalink)
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Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 52.71 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)

Appliance car - '14 Mitsubishi Mirage ES (base)
90 day: 52.48 mpg (US)
Thanks: 4,062
Thanked 6,960 Times in 3,604 Posts
Makes sense. This old bike's chain & rings don't look like standard (modern) sizes, so maybe not easy to find alternative gearing?

I'm content to just complain about it.
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Project MPGiata! Mods for getting 50+ MPG from a 1990 Miata
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: 70 MPG in my ecomodded, dirt cheap, 3-cylinder Mirage.
Ecodriving test: Manual vs. automatic transmission MPG showdown



EcoModder
has launched a forum for the efficient new Mitsubishi Mirage
www.MetroMPG.com - fuel efficiency info for Geo Metro owners
www.ForkenSwift.com - electric car conversion on a beer budget
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Old 05-06-2015, 09:52 PM   #29 (permalink)
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old ccms

Nice ride metro, looks pretty good in that color. Cool old seat too. My 48 on 28s is my favourite bike by far. Rolls so fast. Its made from at least 2 dump scores. And some old bars.
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Old 05-06-2015, 10:03 PM   #30 (permalink)
Batman Junior
 
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Join Date: Nov 2007
Location: 1000 Islands, Ontario, Canada
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Blackfly - '98 Geo Metro
Team Metro
Last 3: 70.09 mpg (US)

MPGiata - '90 Mazda Miata
90 day: 52.71 mpg (US)

Even Fancier Metro - '14 Mitsubishi Mirage top spec
90 day: 70.75 mpg (US)

Appliance car - '14 Mitsubishi Mirage ES (base)
90 day: 52.48 mpg (US)
Thanks: 4,062
Thanked 6,960 Times in 3,604 Posts
Wait - yours is a 1948 frame?

And is that the rumdog?

__________________
Project MPGiata! Mods for getting 50+ MPG from a 1990 Miata
Honda mods: Ecomodding my $800 Honda Fit 5-speed beater
Mitsu mods: 70 MPG in my ecomodded, dirt cheap, 3-cylinder Mirage.
Ecodriving test: Manual vs. automatic transmission MPG showdown



EcoModder
has launched a forum for the efficient new Mitsubishi Mirage
www.MetroMPG.com - fuel efficiency info for Geo Metro owners
www.ForkenSwift.com - electric car conversion on a beer budget
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