Hooey. If you will go get a ruler with metric markings on it and look at how much difference we're talking about, you'll see these are insignificant variations in crank length. If you happen to be an individual of nearly average size, you can find what you need; but if you are tall or short, these variations are simply a joke.
If you are very tall or very short, you have probably
the length crank called for by this formula. My own 34-inch
calls for a 186 mm crankset, and I'm not exactly NBA
if you understand why such sizes are needed, just where would
a critter? Good question.
The chainrings that were fitted to Viscount bicycles back in the 70's will also fit the TA crank, and are durable -- but the design is heavy to the point of being wasteful.
If you need longer than 185 mm, the options are even
Check out the High Sierra Cycle Center at http://www.hscycle.com.
also offer a variety of products for people with unusual
such as one leg longer than the other.
offers cranks from 150mm to 200mm. They specialize in
tandem bicycles, but their cranks will work on any bike.
They even offer a 3-hole crank that'll give you three lengths
in one, just choose which hole to screw the pedals into.
That's primarily to fit children, since the difference from
one hole to the next is waaay too far for any sort of minor
Another source is Heiko Brechtel's custom crank
in Germany; you can visit it at http://www.customcranks.de.
claims that my web site was an inspiration to start his
You can also visit Zinn Cycles, Inc., at http://www.zinncycles.com;
Lennard Zinn offers CNC machined cranks in any desired
fact, Zinn offers entire bikes designed specifically for the
rider (Zinn himself is 6'6" and a national champion, so he
he's doing). Kieran Cox ordered a bike from Zinn and
report: "Zinn's work is flawless. The bike came
than I thought it would. I questioned the expenditure a
months into it, but after seeing the finished product it was
The advent of ATB has provided a better selection of long cranks than there used to be. Many of these long cranks are inordinately expensive, unfortunately. They also look like ATB cranks, and that may be objectionable when mounted on a road bike. However, they generally can be mounted on a road bike, possibly requiring the omission of an inner triple sprocket.
Profile Racing offers aluminum cranks (look like road cranks) in 160 mm to 180 mm lengths, but they also offer 4130 Chro-Moly (industrial-looking) cranks in 160 mm to 190 mm lengths plus the option of "custom lengths".
Azonic offers 4130 Chro-Moly cranks in 165 mm to 185 mm lengths.
cranks in 160 mm to 210 mm lengths. Unfortunately,
site is only viewable in German, so you may need a translator
The trick is to choose the right crank to modify. You want one with broad arms, not arms that are necked down a lot just inward of the pedal. If they are broad enough in this area, you can drill new pedal holes without weakening the crank; if the arm is narrow where the new pedal hole is drilled, it may end up with very little metal on either side of the new pedal hole.
The crank must also be long enough. Since the new pedal holes must be far enough inward of the original pedal holes to leave enough metal to surround the new holes, a crankset cannot be shortened by less than 19 mm or so. If you start with a 170 mm crank, the longest crank you can create will be a 151 mm. For this reason, if you need something in the 155 mm area, you need to start with a 175 mm or longer. If you are trying to make a 160 mm, you will need to start with a 180 mm. Fortunately, since 165-180 mm cranksets are commonly available, this shortening process means that any length up to 180 mm is available.
The last remaining challenge is finding a 9/16" tap in left-hand thread. They are available from outfits that sell bicycle tools.
Once you have taps, cutting off the crank arms, drilling and tapping new pedal holes, and grinding and smoothing the ends of the arms is all relatively easy. You can have a machine shop do it to get the pedal holes perfectly straight and true, or you can do it by hand; if done by hand and the pedal axles don't come out perfectly parallel to the BB axle, it's possible to mount one end of an arm in a large vise and forcibly bend or twist the arm a little to align the pedals.
Engineering in Wales provides a crank shortening service
most sizes available.
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