Quick Bike Fit and Function Checkup

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Quick Bike Fit and Function Checkup for Scout Troops
Getting the best results with what you’ve got!

Author's Note: This page describes an efficient system for fitting and trouble-shooting the bikes of any large riding group such as a Boy Scout troop. It assumes you won't be upgrading parts or sawing off pieces of bicycle. Fitting and checkup should take less than 5 minutes per bike. Full details for fitting a bike are found on the Fitting a Bike page, where you'll also find photos that illustrate the process. I suggest you print the single-page reference for the group bike checkup (a condensed version of this web page in MS Word format) for your assistants to use during "bike checkout night." The Troubleshooting Guide may be useful to quickly diagnose problems you discover during this Fit and Function checkup, and is also available as a single-page troubleshooting quick reference in MS Word format for on-trail use. A laptop with the web browser set to the Fix-it section of UtahMountainBiking.com will help your Repair and Tuneup team. - Bruce Argyle

You will need:

Trainer (24 and 29-inch wheeled bikes may not fit)
Carpenter's level to check handlebar height, seat level
Large thin hard-cover book to check seat leveling
4-foot straight board (1x2 OK) to check handlebar height, and as vertical marker for derailleur hanger check
Measuring tape for inseam measurement, starting position for seat
Metal measuring ruler for chain-stretch checkup
Plumb line to check seat front-to-back position
Set of bike tools
Repair stand (consider also: wheel-truing stand)
Recommended supplies: degreaser and buckets/brushes, chain lube, paper towels, tubes, high-capacity patch kit, extra tire, rim-brake pads (V-brake and cantilever), derailleur cables and cable housing, brake cables and housing, 7-speed and 8/9-speed chain, extra threadless-headset spacing rings, and maybe a broken bike or two to cannibalize.
Repair manual, or laptop with internet access

Personnel (4 persons, 2 of whom have bike-repair expertise):

Coordinator/Recorder (Wrangler) - coordinates movement of bikes and scouts, records required parts, supplies, and repairs
Fit and Function specialist (Fitter) - does an efficient bike checkup on the trainer as listed below
Repair specialist (Wrench) - expert half of two-person team with a full set of tools, repair stand, and spare parts
Repair helper - assists Wrench

Procedure:

Each rider brings his clean bicycle and supplies, including helmet, backpack, bottles, and riding clothing to "checkout night."
Wrangler checks scout's helmet, clothing, and supplies. Is he ready for the trip?
Wrangler brings scout and bike to Fitter.
Scout pedals bike in trainer, gets off and on again as Fitter makes adjustments. Wrangler records any required repairs.
If problems are found, Wrangler takes bike and owner to Wrench, while Fitter continues with another scout.
After all problems are repaired, Wrangler routes scout back to Fitter where the Fit and Function process starts anew.

Supply checkout!

Does the rider have a helmet, and is it fitted properly?
Are the rider's shoes appropriate to the activity? Is the clothing appropriate? (Trouser "cutoff" shorts have a seam that will chafe the upper thighs.) Riding gloves highly recommended.
Each rider should have a backpack. If the backpack doesn't have a hydration bladder, the rider must have water bottles (and bottle cages on the bike frame)!
The underseat pack or backpack should contain: spare tube of correct size, patch kit with glue that's still liquid, multi-tool, plastic rain slicker. Consider also: individual sunscreen/insect repellant packet, chain "quick-link".
Rider should have individual mini-pump, either attached to bike frame or in the backpack.
For multi-day rides: add mini-flashlight, small first aid kit, and small lube bottle to backpack. Extra set of bike-specific brake pads and any supplies that are unique to the individual's bike (tubeless setups, 24-inch or 29-inch tubes and tires, etc) are labeled with the scout's name and added to the main supply cache (to go in the support vehicle).
If it's a multi-day ride, confirm adequate group supplies: Full tool kit, chain lube, paper towels, floor pump, shock pump, 7 and 8/9-speed chains, quick-link for 7 and 9-speed chains, tubes, spare tire, large tube-and-tire patch kit, rim-brake pads (V-brake and cantilever), derailleur cables and cable housing, brake cables and housing, full first aid kit, big bottle of sunscreen. Consider: bleed kit for hydraulic disc brakes, tire liners, Flat Attack or other sealant, repair stand (a trunk or hitch bike rack that lets the bicycle hang down can function as a field repair stand). Add individual supplies purchased by riders with unique bicycle setups (for example Stan's sealant and extra tubeless valve, 29-inch tubes and tire).

Bike Fit!

Assess overall bike size: (Does it look like a "borrowed bike?") Frame = 2/3 x inseam. (example, 24x30-inch trouser size = 2/3 x 30 = 20 inches, which would usually be a medium (19 inch) frame size, but could get by with a large (21). Consider bike swaps for gross mismatches.
Clamp bike in trainer. Use front wheel block to make bike level.
Seat tilt: Horizontal to trace upslope. Use book and level.
Seat height: Starting point = middle of crank bolt to top of seat, directly along seat post = 0.88 x inseam length. Knee angle should be 155 degrees when the pedal is extended. Rules of thumb: Put seat about an inch lower than where you begin to see tilting of hips with pedaling; Scout can barely touch ball of ONE foot to ground while sitting on seat (while starting to ride -- not while bike is in trainer). Most scout will arrive with bike seats that are way too low for efficient pedaling.
Seat fore-aft: Pedal until comfortable. Have scout stop pedaling with cranks horizontal. Use your plumb line. Move the seat forward or back until the bump just below the knee tendon (tibial tubercle) on the forward leg falls directly over the pedal axle.
Handlebar height: Starting position = handlebar grip height is 2 inches lower than top of seat (use board and level). Put scout on bike, pedal briefly to get into riding position. Raise or lower the handlebar so the scout's view of the front axle is blocked. (You may need extra spacing rings for threadless headsets.)
Handlebar sweep (rotation that controls the angle of the grips on curved handlebars): Rotate so the grip is comfortable with the elbows hanging slightly away from body, forearms straight forward, wrists straight (not bent side-to-side).
Brake lever position: Scout grasps handlebar grip so that the middle of the handlebar, the space between thumb and index finger, the middle of the wrist, and middle of the elbow are all in a straight line. Scout now loosens thumb and index finger. The outer two fingers maintain grip on handlebar. Loosen attachment of brake lever. Slide and rotate brake lever so that the crook in the curve of the lever falls under last joint of index finger. If the lever is beyond the finger's reach, use the small adjusting screw to move the lever closer to the handlebar.
Index shifter position: While maintaining the grip and with the index finger on the brake lever, loosen the shifter attachment. Move the shifters so the thumb/finger can contact the shifting paddles without releasing the grip on the handlebar.

Quick part checkup!

Chain: 1 foot = exactly 12 links. Lubed. No twisted links. No rust. Rolls around rings and derailleur pulleys smoothly.
Front rings: Spaces between teeth perfectly round semi-circles, no bent or missing teeth, no “dolphin fin” teeth. (Note: chainring teeth are NOT normally perfectly in line; the slight side-to-side wandering of the teeth assists in chain take-up).
Cassette: Teeth of cogs in good condition as above. Cassette doesn't tilt back and forth on freewheel mechanism.
Derailleur hanger: Quick visual = straight with vertical axis of bike frame (not bent inward) and straight along forward axis of bike (not twisted). Put board onto frame for vertical axis, sight on cage between pulleys to see if it lines up with edge of board.
Rear derailleur: Cage straight, both pulley wheels turn easily, teeth intact? No excess “play?” Moves when cable pulled.
Front derailleur: Cage intact and unbent? No excess "play" in mechanism? Firmly attached to frame? Moves when cable pulled.
Cables: Cable caps in place. No fraying. No obvious sharp bends in cable housing. No "floppy" connections of cable housing to receiver in shifter or derailleur.
Wheels: Any broken spokes or cracks in the rim? Any bulges, exposed cord, or obvious problems with the tires?
Brake pads: Enough left for a long, long brake-intensive downhill ride?

Bike Function!

Front shifter: Have scout shift rear derailleur into the middle cog of cassette. While pedaling, shift up and down through all rings on the front. Chain should drop into smaller ring quickly. Should take up on large ring without hitting derailleur cage. Make sure it's not possible to drop chain rightward off of the biggest ring onto the pedal when over-pushing shifter.
Rear shifter: Shift the front into the middle ring. Have the scout shift the rear (right hand) as follows. Drop all the way to the smallest cog. Now shift up 1 and back down. Now shift up 2, then back 1. Repeat the up-2, back-1 up to the biggest cog. Make sure it's impossible to drop the chain leftward off the biggest cog into the spokes when over-pushing the shifter. Walk back down to small cog. Refer problems to the repair team.
Wheels: Any wobble?
Brakes: Levers shouldn't hit fingers when pulled hard. (Use barrel-adjuster to adjust.) Cables slide easily without noise? Rim brakes pads hit rim and ONLY rim. No rubbing of pads (lift front of bike and spin wheel; disengage roller in trailer to spin rear wheel).

Acid test! Pedal bike hard uphill in different gears. This will bring out any problems with shifting, chain, and rings. Make quick stop with brakes.

Now. Where do you take your boys to ride? See our arbitrary Scout Trail Recommendations.