From: mack@oakhill.sps.mot.com (Gregg Mack ( Sun ))
Subject: Re: new bike
Organization: Motorola Inc., Austin, Texas
Date: Thu, 24 Dec 1992 14:26:51 GMT

sbookey@ep.ieee.org (Seth Bookey) writes:


>I need some advice on how to replace a 15-year-old bike recently stolen.
>This is the last bike I bought, and I have no idea what to look for. I don't
>even know what is a reasonable price, or if I really need a 10-speed for
>just going through New York's Central Park, which is about the only place
>I ride.  Any ideas would be appreciated.

Seth, you might read rec.bicycles.marketplace and rec.bicycles.misc on the
USENET.  They are constantly covering this topic.  However, to save you
from wading through a few weeks of scanning them, here's the general run-
down on what you're looking for:

Currently there are basically three types of bikes available through bike
shops for adults today: road bikes, mountain bikes, and a relatively new
type of bike positioned in the market between the other two which is called
a "cross" or "hybrid" bike.

Although there are actually several types of road bikes (touring, racing,
sport, etc.), they all have the "curled-down" style of handlebars.  These
handlebars look imposing to a beginner, but they are the style that offers
the most choices of hand positions and allow you to "get down low" when
riding into a headwind.  Road bikes also have the narrowest tire of the
three types of bikes.  If you get a road bike, get one with the 700C
size wheels and get a tire about 25mm wide for a cushier, more comfortable
ride.  Road bikes usually weigh less and are much more agile than the other
two kinds of bikes.  A "good" road bike will cost you about $500 (or on
up to $2000).  Anything under $350 is not going to last more than a 
couple thousand miles before falling apart.

Mountain bikes are sturdy bikes with big fat knobby tires (although you
can put a more road-bike-like tire on it).  The handlebars are straight
across that leads to a more upright sitting position.  Shifting the gears
is done by simply moving a lever while keeping your hands on the bars.
Mountain bikes typically come with 21 speeds. Mountain bikes are usually
the heaviest of the three types of bikes.  A "good" mountain bike costs
about the same as a good road bike.

Cross, or hybrid, bikes fall in between road and mountain bikes.  They
have the same straight handlebar and shifting method as the mountain
bikes, but their frame usually weigh less, and the tires on the cross
bikes are usually around 32mm wide and have a slightly knobby tread
pattern.  A "good" hybrid usually costs a little less than the other
two, but this is mainly because the quality of the components is a
little below what is usually put on mountain and road bikes.  However,
$375 - $450 should get you a respectable cross bike that you could
put several thousand miles on.

I urge you to buy your bike through a real bike shop, and not a department
store.  There are several reasons for this.  First, the bike shop will
sell you the correct size of bike.  Second, it will be assembled correctly
at a bike shop, and third, a bike shop almost always gives you a free
30 day tune-up (readjust cables after initial stretching, readjusting
all of those gears, etc.). Some bike shops even give you 3 free tune-ups
for the first year that you own it.

I recently typed-up a procedure that I read in Greg LeMond's book on
bicycling that tell you how to buy the correct size of bike and then
how to make all of the adjustments to fine-tune it to your body once
you get it home.  I wrote it for another friend, so a comment or two
may not apply to you (he custom ordered a new pick-up truck).  Here
it is:

===============================================================================

  Even an expensive bike that doesn't fit you is about as valueable as a pair
of running shoes that are two sizes too big (or small).  It is inefficient
and uncomfortable.  Here's how to find the right size bike and then fine tune
it to your dimensions:

1. Measure your inseam.  Do this by standing on a solid (linoleum or concrete)
   floor.  Wear the same thin socks that you would to cycle in.  Put on your
   lycra shorts (or if you haven't got them yet - briefs) and stand with your
   toes very near the wall and feet spread about 6 inches apart.  Get a 1.5
   inch thick book (about the thickness of the nose of a bicycle seat) and
   have the front edge flush with the wall and the top edge "pushed" up into
   your crotch.  (Sounds funny, but this IS necessary.)  Make a mark on the
   wall where the top of the book meets with it.  Measure the distance from
   this mark to the floor; this is your actual inseam.

2. Multiply your inseam by 0.65.  This is the size of the bicycle frame that
   you should buy.  Measure the frame from the center of the bottom bracket to
   to the center of the top tube, measured in a line that parallels the seat
   tube.  Some manufacturers (such as Schwinn) mesure from the center of the
   bottom bracket to the TOP of the top tube.

3. If your calculated frame size falls midway between the sizes available,
   "round down" to the next smaller size.  This will be the lighter, stiffer
   frame. Some manufacturers make frames in two inch size increments, while
   many better models come in two centimeter increments.  

4. Buy the right size frame.  Stick to this no matter how sweet the deal seems
   to be otherwise.  Make no exceptions!

5. You would do well to know the gearing on the bike that you are considering.
   This will be even more important than the gearing on your truck (after all,
   YOU will be the 1/4 hp engine on this contraption)!  Count the number of
   teeth on the smallest chainring (front gears), divide it by the number of
   teeth on the largest freewheel cog (back gears) and then multiply this value
   by 27.  This tells you how far forward the bike will move from one complete
   revolution of the pedals. (Actually off by a factor of pi, but this is the
   way bicycle people know gears.)  A number greater than 45 will be pretty
   tough to pedal up a good hill.  My Crosscut has a number of 23, but it also
   has 3 chainrings.  Although I haven't used this low of a gear since I've
   gotten in shape, I do use the 27 and 31 gears occassionally.  Bikes with
   these low numbered gears are mountain, cross (hybrid), and touring bikes.
   Incidentally, the highest number gear I have is only a 92, but I have an-
   other set of freewheel cogs that will get me up to 106.  Racers go to 120.

6. Once you get the bike home, the first thing to do is to level the seat.
   First, loosen the bolt(s) that hold the seat to the seat post, and slide
   the seat back as far as it can go.  Tighten the bolts slightly.  Get out
   your carpenter's level and make the front of the nose of the seat level
   with the MIDDLE of the back of the seat.

7. Multiply your inseam value by 0.883.  This is the seat height.  Measure
   from the center of the bottom bracket along the line PARALLEL with the seat
   tube to the top of the seat.  Note that this is not the highest part of the
   seat, but more in the "cradle" of the seat.

8. Next adjust the fore/aft (front to back) position of the seat.  Put the bike
   near a wall and get on it.  Put the balls of your feet directly over the
   axles (centers) of the pedals.  Rotate the cranks until they are parallel
   with the ground (3 o'clock and 9 o'clock).  A plumb-bob hung from the
   "groove" between the kneecap and the shinbone of the forward leg should
   pass directly through the center of the pedal axle or up to 1/2 inch BEHIND
   it.

9. Recheck steps 7 and 8 until everything "settles" out and then check the
   level of the seat again.  This usually takes a couple of iterations.  Do
   it carefully, the muscles and joints in the legs and knees depend on it!

10. Now it's time to adjust the height of the handle bars.  The top of the
   handlebars should be 4 to 8 centimeters BELOW the nose of the seat.  If you
   have the drop style handlebars, make sure that the ends are parallel to the
   ground and that the bottoms of the brake levers are at the same height as
   the bottom of the handlebars.

11. Correct stem length:  Put your hands right inside the curves of the drops
   and then when the pedals pass through the one o'clock / seven o'clock pos-
   ition, there should be about 1/4" to 1" of clearance between the elbows and
   the knees.  (Elbows bent at 65 to 70 degrees.)  First time riding this way
   will feel extremely stretched-out, but will change in time.  AVOID being
   bunched up.  If the stem isn't right, replace the damn thing ($12).

12. The width of the handlebars should be the same as the outside edges of the
   protruding rotator of the shoulder blades.  Wider is better than narrow.
   typical sizes are 38 cm to about 44 cm.  Make sure the ends of the handle-
   bars are plugged; could be dangerous in a spill!

===============================================================================


-- 
Gregg Mack                  ---------- __o       __o       __o       __o
gmack@paceline.sps.mot.com  -------- _`\<,_    _`\<,_    _`\<,_    _`\<,_
Motorola RISC uProcessors   ------- (*)/ (*)  (*)/ (*)  (*)/ (*)  (*)/ (*)
Austin, Texas  USA          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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