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TiresAndFlats

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(note: minor changes in later Word file in Training folder)

text in italics might be omitted to keep this under 3 hours! (JS 2009/11/04

Bicycle Basics is the first class in the series and covers how to change a flat, diagnosis of causes of flats, flat "prevention," parts of the bike vocabulary, some useful mechanical principles, the Safety Check, seat and handlebar adjustment for basic bike fit, chain lubing and the purpose of gears, basic tools to carry, and wheel removal and replacement.


This class is free with a bike bought from OCBC, and is the mechanical prerequisite to Traffic Skills 101 (held on the first Sunday after this class). Bike purchasers also get free Intro to Traffic Skills ($25 otherwise), held on the 2nd Saturday, same material, no test or certificate.

This class covers the essentials to use a bike — in order of importance — Safely, Reliably, Economically, and Efficiently (SREE: our goals are to help students avoid:

1. getting hurt (from mechanical failure, but also from poor bike size or fit),
2. walking home (by having a roadside repair they can't fix),
3. spending too much at the bike shop (by wearing parts out prematurely or allowing cascading failures), or
4. being late (to work, or to the finish line; efficient cycling is faster and more fun, but is less important for practical cycling than safety, reliability, and economy)
NOTE: ''each rider's priorities may move lower priorities up, but only the last two (EE) should be re-ordered for practical cycling). Fashion also plays a role, and is important for some cyclists' satisfaction..."

Taking the whole course of 4 repair classes includes a year's co-op membership and two hours of shop use. Series covers general concepts of regular maintenance (beyond air in the tires and oil on the chain), following all the steps done in a tune-up, which is ~$50 at a bike shop, (Overhaul is ~$150 at a shop, and can be done at OCBC after taking these classes: $5/hr shop use includes advice on stuff not covered here. Course also covers some parts replacement concepts, and, especially, common emergency repairs.

There is some hands-on practice of needed skills in class, but for students to really practice and remember what they have learned, they should use the course "lab time" by volunteering (for credits) on Apprentice Wednesdays (5 - 9pm) — to do a tune up all at once, with an expert mentor. For specific procedures they should use the included 2 hours of credits to work on their own bikes on Members' Mondays (noon - 9pm). All current members may re-take any classes for free. Refer them to the website for details, and note this page on the wiki. Also, OCBC is a Park Tool School, so we have their book for $20, or for loan (along with many others). this info is changing for 2010 — refer to website

Explain that this course (and especially this first class) covers basics that some may know already, but we hope they may learn the best ways to explain these concepts to others (like their kids, or less-skilled folks at the co-op), and we are looking for instructors, so taking the course twice is useful.

Ask for a show of hands: who has fixed a flat? knows what a cam or left-hand threading is? (all in this class) Adjusted a bearing, trued a wheel, used a chain tool? (all in class series)

Show of hands — anyone NOT signed in on computer (can do this during break). Make sure you have all names on paper roster, with payment types (correct at break).

Instructor notes for class sign up procedure: Everyone log in under their own name, and choose "take a class", but DON'T log off: instructor will do that to credit class properly. ALSO put student's names and emergency phone # and payment type (check paypal emails to ) and put a "1" in the column for each class attended, and a "-" for each absent. To "teach a class" in the computer: you log in (don't need to, but can be logged in as "volunteer" or Staff" first) and choose "teach a class"


Be sure to check the right class, date ("today" is check box) and check each present student's name, and enter payment in dolar value for that class (this is screwed up, we need to standardize notation, so do what you have sritten on the paper roster).

If you leave a student unchecked, they won't get credit. If you leave class or date undone, you'll have to re-enter it all.!!

Outline

Bike Basics

[T]Above intro
[A] Hands-on Tire removal / replacement
[T] Demo Fixing a flat
[A] pass around punctured tube to diagnose.
[T] Causes of flats, diagnosis
[A] pass around tire failures, flat "preventions", valve and rimstrip demo parts.
[T] Demo mechanical concepts
[A] pass around barrel adjusters, stem and s/post, but just show others around (passing stuff seems to detract from attention to subsequent information: ultimate goal is for students to each have their own board of demo parts, but this may be even more distracting).
mechanical principals, etc.
break, put away chairs
[T] parts of the bike
[T] safety check
[A] feel tire pressure, spoke tension on yellow demo bike
[T] lube chain on "good" bike
[T] Wheel removal on "good" bike
[T] Students' wheel removal (if time) from demo bikes, NOT their own

LIST CONTENTS OF BOXES HERE — JM notes from Mentor Rec. classes
Tool kits for sale see notes on Curriculum page

Tire removal / replacement

This starts the class with hands-on practice of this very important skill. Concentrate on the abstract actions this time - using the lever, not catching the tube between the tire and the lever, not pushing too hard at the beginning and running your knuckles into the spokes, getting the bead off, removing the tube, putting the tube back in from the side of the tire that is not on the rim. Stress the two crucial steps of using the lever when removing, and using your thumbs where the bead has already crossed the rim to get leverage when replacing.

Use the highlighted steps in the "how to fix a flat" page (should be in the demo parts box) to demonstrate all the steps first, then have students do it themselves. Students remove and replace tires from the 16 inch wheels in the trunk, and get to keep the tire lever they are given (be sure there is a stock of new ones in the pouch of the wheel box). Explain the original purpose of the hook end of the lever (and how it can also be used to open Schraeder valves), but show tire removal technique with ONE lever (get it moving while perpendicular to the plane of rim, then lever it down, to "catch the tire by surprise"). Help those who are having trouble, and those done early can take a short break.

This is just for students to practice using tire levers, and understand how the tube, tire and rim work together. Save the practical concerns such as unsticking the bead from the sides before removal, putting a little air in the tube before replacing, and making sure the tube isn't under the bead (and the bead is seated) for the find-the-cause demo, next.

Fixing flats

Explain that fixing flats is a matter of removing the wheel, getting the tire off, inspecting the tube to find out what caused the flat, either patching or replacing it, and replacing the tire and the wheel.

Demonstrate all the steps in "how to fix a flat" (except wheel removal and replace, which will be done at the end of the class) using the the 16" wheel in the box with the black tire, silver rim (with "demo" written on it) and pink spokey-dokey. This wheel has a tube with a puncture covered with red duct tape, to show how to feel with your lips and listen for air escaping, and a bulge in the tube to show that is not a defect. Pass it around with a pump attached, and students listen and pump before passing it on. Discuss PSI (wide tire/narrow tube & wide tire/narrow rim (and reverse of both), range of tube widths, rolling resistance and pinch-flat protection vs. comfort.

Before replacing the tube, briefly cover patching, including an emphasis on sanding the area, letting the glue dry, and which side of the patch to put down (foil).

This demo allows you to repeat the steps of tire removal while you show how to find the cause of the flat, and how to pump the tire at the end (with special attention to not stressing the valve, and proper bead seating ).


Types of flats, from most-to-least common.


The types of flats are taught in the context of fixing and avoiding them.
  • Foreign object flat: Caused by riding over something sharp, such as a shard of glass, creating one hole on the outside of the tube. When fixing, be sure to find the object before you put the new tube in. Using the label/valve stem alignment can help, as can running your finger inside the tire until the object cuts you. Avoid these flats by riding in the right car tire track instead of the gutter, and by paying attention. Tires with flat-protective belts also help. If the object was very large and the new tube starts to bubble out through the hole in the tire, the tires needs to be replaced as well.
  • Pinch flat: Also known as snakebite flats, these are caused by hitting something such as a pothole hard enough that the tire is flattened against the rim and pinches the tube, usually causing two holes. There is no special technique needed for fixing these, but check to make sure the wheel is still true and the rim and tire are not damaged. Especially check that the rim is not dented, creating a spot where the brake pad may contact the tire and cause a future blowout (see below). Avoid these by riding more delicately, (weight on the feet, using knees as suspension) keeping more air in your tires, or if they happen with the tires inflated fully, riding tires with more volume.
  • Valve stem failure: This mostly happens with Schrader valves, and can be hard to diagnose. If you can't find any problems with your tube, try bending the valve stem with the tube somewhat inflated and listen for air coming from the base of the valve, on presta, or from a cut in the rubber around the base on a schraeder valve. This this problem is caused by riding with very under-inflated tires, or careless pumping, especially with a hand pump. It is not patchable and requires a new tube. However, if the air is coming out of the end of a schraeder valve, removing and re-tightening the core will usually solve the problem.
  • Rim strip failure: If there is one hole which is on the inside of the tube (facing the rim), check the rim to be sure a nipple hasn't been exposed.

Tire failures (see hand written notes on JM,s copy, with code to demo parts)

  • Brake pad misalignment: If a brake pad is too high and comes over the rim, it will develop a lip that reaches over and eventually cuts the sidewall of the tire, which will cause the tube to blow out. This type of flat will require a new tire and tube, but is easy to avoid with careful brake maintenance.

Tire boot, etc.

Flat "prevention" methods

BRIEFLY cover efficiency and rolling resistance.
Transition to safety check: ABC Quick check before every ride, but for any bike you are unsure of, Steerin Stopping and Security is more thorough — e.g. front tire failure is dangerous , so steering is 1st (why spend all this time on tire failure? Contact patch/tire width, tread vs. slick, "any other questions," etc.)

But first: mechanical principals: .

Three Ls - basic principles of bicycle maintence

  • Lubrication - To make things turn smoothly and not rust.
  • Leverage - Not just getting more power, but using the right tool generally - makes the job easier and reduces the chance of damaging parts
  • Love - Pay attention and understand what is going on, do the right thing now so you don't have to apologize and buy the bike flowers later (yes, I really say that)

clockwise, Left hand threads, locknut, Lube on threads, Cam (Q/R) seatpost and stem... this needs developed : show of hands re: cam, LH threads, etc(?) to assess student levels first...

FIT
"cockpit dimensions. Stem height, relation to bike size. (level seat/grips)

Seatpost height

Explain why seatpost height is important and that people often ride with their seats too low. Correct seatpost height allows more efficient pedalling, with the leg operating in the range where it is stronger, and lowers stress on the knees, greatly reducing the damage done to the joint. Hand and seat pain.

Seatpost height adjust

Explain the process of getting the seatpost loose, that greasing the seatpost is done to prevent corrosion, and how to find the proper seat height. Mention the max height line. A good starting rule is to make the rider tiptoe to the ground when sitting on the seat, and another method is to raise the seat 5mm at a time until it's a little too high, then coming down a notch. The "too high" feeling is easily recognigzed as a feeling of rocking back and forth on the saddle and stretching for the pedals. This is as opposed to some riders' feeling that they should be able to keep the bike stable at rest without coming off of the seat.

Mounting and dismounting

Since some students will not be used to riding with proper seat heat, demonstrate proper mounting and dismounting technique and mention Traffic Skills class where this is practiced.

General Fit

Explain the primary dimensions of bicycle fit: the distance from the bottom bracket spindle to the saddle, and the distance from the saddle to the handlebars, and how these can be varied: frame size, stem length, seatpost adjustment. Also discuss fitting the type of bike to the type of riding, which includes gearing concerns, handlebar type, and tire size.

''I generally tailor fit to the type of riders in the class. I always explain the difference between flat-bar bikes and drop-bar bikes. (Flat bar are generally more upright, more casual, for shorter distances - fit is more of an approximation. Drop bar are more stretched out, requires conditioning to be comfortable, fit more precisely) I don't personally dwell on fit methods that fit a person exactly using measurements and tools, specifically because these are tailored toward racer needs and are not optimized for comfort (and I say so). -PG (this removed on Mentor Rec. printed Word file)

NO — discuss range of frame sizes one can fit, and advantages (aerodynamics vs. comfort and rear scanning ability).''

Threaded stem adjust

Explain the way threaded stems are secured into steerer tubes, and show how to remove stems and grease them for corrosion prevention and to reduce friction on wedge "ramp" and threads (which are also "ramps" i.e. inclined plane). Mention the max height line, as with the seatpost.

threadless stems

Show the difference and explain how to tighten, adjust height with spacers, adjust bearing with top cap (more in next class on bearings).__

Quick release theory

Explain how quick releases work, using the demo quick release where the cam shape is easy to see. Emphasize correct tightness, where the skewer is adjusted so that friction is felt halfway between open and closed, and so that it leaves a mark on the hand. Also mention that it is important to make sure the skewer is completely closed, since the cam is designed so that tension actually decreases at that point, making it harder to open accidentally.

!!Parts of the bike

diamond frame, bike size vs fit

Safety check


derailer limit screws and replacing dropped chain (very bad if in spokes, loosen axle if against frame; use stick instead of fingers if off on front (demo); low is left, shift before climbing a hill, when chain is under tension.

oiling a chain — how often? by sound ("wooshing" from dry chain — waiting for squeaky is way too late); by feel: should leave streak on finger; by sight: should look shiny (though inside is where oil is really needed)


Wheel removal/replacement

Describe the process of wheel removal, demonstrating the steps. Loosen the nuts/skewer, show lawyer tabs and describe their purpose and use, quick release the brakes if needed (and if possible), and loosen Q/R on the front wheel by reaching through the frame from behind (easier than trying to hold wheel between knees crouched in front) — or holding q/r lever with right foot instep while unscrewing nut with left hand (difficult).

laying the bike down on the non-drive side while (either) wheel is off.

Hold the bike by the stem and remove the front wheel, then replace. (bikes with no brake release, put wheel in while tire is still soft: don't remove brake pad). For the rear, explain shifting to both small gears to maximize chain slack. For replacement, emphasize getting the front axle all the way up into the dropouts and aligning it correctly, and remind of proper quick release use. For the rear, vertical dropouts are similar to the front, but horizontal dropouts require advice on centering the tire between the stays. For nutted axles, explain the process of centering by tightening the nuts separately.



Created by: pgarver. Last Modification: Tuesday 05 of January, 2010 08:56:23 UTC by JSheehan.