[TheThinkTank] Step-by-step Mechanic Lessons Request

Ron Kellis ron.kellis at velocitycoop.org
Thu May 26 10:50:17 PDT 2011


Thanks much Ryan! Just this week I started expanding our one page class
topic sheet into an instructor crib sheet. With a bit of triva for
conversation. 1st rough draft, LOTS missing and the citations need to be
tightened up.

Ron

 Overview

Rider/owner bike maintenance generally involves *inspection*, *adjustment*,
and *lubrication*. Sometimes cleaning and lubrication must precede
adjustment.
1.  Major Bike Parts 1.1.  Groupset

Gruppo; from Italian for "group" (often misspelled grouppo) is a bicycle
component manufacturer's organized collection of mechanical parts.

2 gear levers or shifters and

2 brake levers or

2 integrated brake levers/shifters

2 brakes, front and rear

2 derailleurs, front and rear

1 bottom bracket

1 crankset

1 chain

1 cogset, freewheel or cassette
1.2.  Everything else

Frame

Forks

Handlebar stem

Seat post

Seat

Wheels (hubs, spokes, rim)

Tires
2.  Tubes & Tires 2.1.  Tubes

Show one of each
2.1.1.  Schrader - Larger and have springs that hold the valve shut. Will
lose some air when air-chuck is removed. 2.1.2.  Presta - Smaller. Air
pressure holds the valve shut. Adapter used for a Schrader air chuck. 2.2.
Tires 2.2.1.  Removing Tires      (Tool: Tire Lever) 2.2.2.  Checking
Tubes
(Tool: Bucket of Water) 2.2.3.  Puncture Repair      (Tool: Patch Kit) 2.2.4.
 Re-inflation   (Tool: Bicycle Pump) 3.  Groupset Inspection, Lubrication &
Adjustments 3.1.  Bowden cables and housings

Date from late 19th century, first used by Raleigh Bicycles in England.
3.1.1.  Barrel adjuster for adjusting the cable tension using an inline
hollow bolt. Lengthens or shortens the cable housing relative to a fixed
anchor point (brakes or derailleur). Lengthening the housing (turning the
barrel adjuster out) tightens the cable; shortening the housing (turning the
barrel adjuster in) loosens the cable. Start cable end adjustments with
barrel all the way in. 3.1.2.  Use spray dry-lubricant if available or else
Tri-Flow because of Teflon 3.1.3.  Cables may have to be removed from the
anchor point (brake or derailleur) to get enough cable slack to apply
lubricants. 3.1.4.  Rubber tori, called donuts, can be threaded onto a bare
run of the inner cable to prevent it from striking the bicycle frame causing
rattles or abrasion (Rarely replaced). 3.2.  Brakes & Brake Maintenance 3.2.1.
 Common Types 3.2.1.1. Rim brakes (Wikipedia citation needed) · Rod-actuated
brakes · Caliper - The caliper brake is a class of cable-actuated brake in
which the brake mounts to a single point above the wheel, theoretically
allowing the arms to auto-center on the rim. · Rarely found on modern
mountain bikes. But they are almost ubiquitous on road bikes, particularly
the dual-pivot side-pull caliper brake. · Side-pull caliper brakes Single
pivot side-pull caliper brake. Single-pivot side-pull caliper brakes consist
of two curved arms that cross at a pivot above the wheel and hold the brake
pads on opposite sides of the rim. These arms have extensions on one side,
one attached to the cable, the other to the cable housing. When the brake
lever is squeezed, the arms move together and the brake pads squeeze the
rim.  Dual-pivot caliper brake. Dual-pivot side-pull caliper brakes are used
on most modern racing bicycles. One arm pivots at the center, like a
side-pull; and the other pivots at the side, like a center-pull. The cable
housing attaches like that of a side-pull brake. · Centre-pull caliper
brakes  Centre-pull calliper brakes have symmetrical arms and as such center
more effectively. The cable housing attaches to a fixed cable stop attached
to the frame, and the inner cable bolts to a sliding piece (called a
"braking delta" or "braking triangle") or a small pulley, over which runs a
straddle cable connecting the two brake arms. Tension on the cable is evenly
distributed to the two arms, preventing the brake from taking a "set" to one
side or the other. · U-brakes  U-brakes (also known by the trademarked term
"990-style") are essentially the same design as the center-pull caliper
brake. The difference is that the two arm pivots attach directly to the
frame or fork while those of the center-pull caliper brake attach to an
integral bridge frame that mounts to the frame or fork by a single
bolt. · Cantilever
 The brake shoe is mounted above the pivot and is pressed against the rim as
the two arms are drawn together. In the first-class lever design, the arm
pivots above the rim. The brake shoe is mounted below the pivot and is
pressed against the rim as the two arms are forced apart.  Low profile
'traditional' cantilever brake. The traditional cantilever brake, or
commonly cantilever brake, pre-dates the direct-pull brake. It is a
center-pull cantilever design with an outwardly-angled arm protruding on
each side, a cable stop on the frame or fork to terminate the cable housing,
and a straddle cable between the arms similar to center-pull caliper brakes.
The cable from the brake lever pulls upwards on the straddle cable, causing
the brake arms to rotate up and inward thus squeezing the rim between the
brake pads. · V-brakes  Linear-pull brakes or direct-pull brakes, commonly
referred to by Shimano's trademark V-brakes, are a side-pull version of
cantilever brakes and mount on the same frame bosses. However, the arms are
longer, with the cable housing attached to one arm and the cable to the
other. As the cable pulls against the housing the arms are drawn together.
Because the housing enters from vertically above one arm yet force must be
transmitted laterally between arms, the flexible housing is extended by a
rigid tube with a 90° bend known as the "noodle". The noodle seats in a
stirrup attached to the arm. A flexible bellows often covers the exposed
cable.  Because of the higher mechanical advantage of V-brakes, they require
brake levers with longer cable travel than levers intended for other types
of brakes. Cheap or poorly-specified V-brakes can suffer from a sudden
failure when the noodle end pulls through the metal stirrup, leaving that
wheel with no braking power whatsoever. Although the noodle can be regarded
as a service item and changed regularly, the hole in the stirrup may enlarge
through wear. The stirrup cannot normally be replaced, so good quality
V-brakes use a hard and tough steel for the stirrup.[14] 3.2.1.2. Disk 3.2.1.3.
Drum brakes 3.2.1.4. Coaster brakes 3.2.1.5. First invented in 1898, the
coaster brake, also known as a back pedal brake or foot brake (or torpedo in
some countries), is a type of drum brake integrated into hubs with an
internal freewheel. Freewheeling functions as with other systems, but when
back pedaled, the brake engages after a fraction of a revolution. The
coaster brake can be found in both single-speed and internally geared
hubs. 3.2.1.6.
When such a hub is pedaled forwards, the sprocket drives a screw which
forces a clutch to move along the axle, driving the hub shell or gear
assembly. When pedaling is reversed, the screw drives the clutch in the
opposite direction, forcing it either between two brake pads and pressing
them against the shell, or into a split collar and expanding it against the
shell.[1]<https://mail.google.com/mail/u/0/html/compose/static_files/blank_quirks.html#_ftn1>
3.2.2.
 Evaluating Wear

Pad wear groove.
3.2.3.  Alignment & Adjustment (Tool: Third-hand Tool, Fourth-hand
Tool) 3.2.3.1.
Pads 3.3.  Chains & Chain Maintenance 3.3.1.  Evaluating Wear (Tool: Chain
Wear Indicator) If worn don’t bother cleaning, replace and check chain-ring
and cogs for wear.

3.3.2.  Check for tight chain links. They may affect shifting.
3.3.3.  Cleaning & Lubricating (Tool: Chain Cleaner, Lubricant) 3.3.4.
 Removing
& Replacing (Tool: Chain Breaker) 4.  Shifters & Dérailleurs

Shifters and derailleurs and part of a system that relies on cables,
springs, alignment, and a maintained chain. Best if everything is clean and
lubricated.



Troubleshooting:

Some information copyright of www.bikebooboos.com.



Check the easy things 1st. While spinning the chain-ring check for proper
shifting.  Make sure cables are free and when the derailleur is at the
highest gear setting (smallest cog) the cable is loose enough to deflect but
not so loose that moving the shifter doesn’t do anything.  Adjust if
necessary and

Before adjusting the derailleur screw settings, consider other potential
sources of your poor shifting problem.

   - If the rear shifter works properly when using the large chain ring but
   not the small chain ring, or vice-versa, then the rear derailleur hanger
   might be bent.
   - If the shifting skips when you apply pressure, check that your chain
   and cassette are not worn.
   - If the shifting skips every third or fourth pedal revolution, check for
   a tight chain link.
   - If the shifting skips when you go over a bump, and you are riding a
   full suspension bike, check that your cable housing is long enough. It may
   be stretching as the suspension flexes, causing the gears to ghost shift at
   that time.
   - Dirty, rusty, kinked or damaged cables and cable housing will also make
   shifting a problem. Index shifting is very sensitive to excessive friction
   in the cable.

Having ruled out these sources of concern, follow this procedure to adjust
your shifting.



First check the derailleur’s range of motion.

The high and low gear limit screws determine how far the derailleur can
shift to the left and right. Too far to the left, and your chain ends up in
the spokes. Too far to the right, and it ends up grinding away your dropout.




Usually the screws are labeled H and L, but if not, high is typically on
top, low is on the bottom. I once had a derailleur labeled I and J … until I
turned it clockwise 90 degrees!



To check the leftmost range of motion, put the bike into the smallest front
chain ring and the lowest rear gear (largest cog). Looking from behind the
bike, the pulley wheels should be directly beneath the largest rear cog.



Now move to the largest front chain ring, and the highest rear gear
(smallest cog). Looking from behind, the pulley wheels should line up just
slightly to the right of the smallest rear cog.



If the chain isn’t on the bike at this point, just push the derailleur as
far as it will go in each direction to perform this check.



If the pulley wheels don’t line up, use the appropriate gear limit screw (H
= High = highest rear gear = smallest cog) to move the derailleur. You will
see the pulley wheels move when you turn the screw. For both adjustments,
counterclockwise turns typically let the pulley move further; clockwise
turns limit its movement.



Two screws to move the derailleur.

H = High = highest rear gear = smallest cog

L = Low = Lowest rear gear = biggest cog)

You will see the pulley wheels move when you turn the screw. For both
adjustments, counterclockwise turns typically let the pulley move further;
clockwise turns limit its movement.


4.1.  Types, Components 4.2.  Alignment & Adjustment 4.3.  Slack cable 4.4.
 Low end 4.5.  High end 5.
Gears/Cogs/Sprockets/Freewheels/Cassettes/Chain-rings 6.  The Variables of
Bike Fit 6.1.  Frame Size, Crank Length 6.2.  Stem Length & Height 6.3.  Saddle
& Seat post Height 6.4.  Handlebars 7.  Bonus: Basics of Wheel Truing

Right hand threads, nipple is in from back so thread acts reversed.



------------------------------

[1]<https://mail.google.com/mail/u/0/html/compose/static_files/blank_quirks.html#_ftnref1>
http://en.wikipedia.org/wiki/Bicycle_brake#Types_of_rim_brakes accessed May
24, 2011


On Thu, May 26, 2011 at 1:26 PM, <ryanguzy at gmail.com> wrote:

> We've got step by step handouts for our maintenance classes. I'll send
> links to the google docs later today or tonight. These could also go up on
> the Wiki, I haven't looked into it yet though.
>
> Ryan Guzy
> Bike Saviours Collective
> Tempe, AZ
>
>
> On , John Barrett <Jonny at goodlifebikes.ca> wrote:
> > Hi,
> >
> >
> >
> > Does anyone have documents for step-by-step individual mechanical
> >
> > tasks (IE rear derailleur adjustment).  We want to make individual
> >
> > instruction sheets to have available in the shop so that it's really
> >
> > simple for folks to learn on their own.
> >
> >
> >
> > I realize this sort of thing is widely available through many books
> >
> > and the Internet, but it would be great if there's an already
> >
> > formatted doc available.
> >
> >
> >
> > Thanks!
> >
> >
> >
> > --
> >
> > John Barrett
> >
> > The Good Life Community Bicycle Shop / Two Wheel View - Calgary / The
> >
> > Organic Saskatoon & Iron Orchard
> >
> > jonny at goodlifebikes.ca
> >
> > 403.619.2648
> >
> > _______________________________________________
> >
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> >
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> >
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> >
>
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