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Bearing Systems Teacher Training

Bearing Systems

Objectives

  • Be able to recognize bearing problems
  • Be able to articulate the principal of an adjustable ball bearing with a locknut and adjustable bearing surface
  • Be able to adjust bearings
  • Teach EaB participants how to overhaul bearings


Materials/Tools typically needed

Bottom Bracket
  • Crank puller (3-pc. only)
  • Cartridge bottom bracket tool (3-pc. only)
  • Lockring spanner
  • Pin spanners
  • Fixed cup wrench
  • Pedal wrench (1-pc. only)
Hubs
  • Cone wrenches (usually 13, 15, 17 mm)
  • Appropriate combination wrenches (usually 15, 17 mm)
  • Freewheel remover or Cassette tool
  • Chain whip
  • Bench vice
  • Axle vice
  • 300 mm adjustable wrench
Headset
  • Headset wrenches (usually 32, 36 mm) (for threaded headsets only)
  • Channel locks (for threaded headsets only)
  • 300 mm adjustable wrench
  • Allen keys/hex wrenches (usually 5, 6 mm)


Activities

Go over the bottom bracket section of the Park Blue Book, demonstrate and have students experiment with this.

Take some time to talk about the particular pitfalls of the other bearing systems.

Things to emphasize

Definitions: Bearings allow the parts of the system to rotate and support weight. Given this definition, youth can be asked to figure out what parts of a bike are bearings. . Answers…Specific to bicycles, there are four major bearing systems: front and rear hubs, bottom bracket, headset, and both pedals. Hub bearings allow the wheel to rotate around the axle, and similarly, the bottom bracket bearings allow the cranks to rotate around the bottom bracket spindle. Pedal bearings allow for the pedal’s body to rotate around the pedal’s spindle.

Adjustable bearing systems have ball bearings which are sandwiched between two curved bearing surfaces: an adjusting cup or cone, and a cup or a race. There should always be grease as well between these bearing surfaces to minimize friction which in turn reduces wear on the bearings and the surfaces, which in turn, helps the bearing system last longer. Protecting the bearings and the bearing surfaces from dirt and weather also lengthens their lifespan.

With adjustable bearing systems, the opposing curved surfaces between which the bearings are sandwiched can be adjusted relative to each other, and that adjustment is held firmly in place with a locknut or lockring that tightens on top of the adjusting cup or cone. If the adjustment is too tight, there will be too much pressure on the bearing surfaces and the bearings and the surfaces will erode and become useless. Similarly, if the adjustment is too loose, the bearings will move around (this movement is called “play”) and rattle against the bearing surfaces, again causing erosion of both ball bearings and the curved surfaces they rest between. So, bearings should be adjusted as loosely as possible without play in the system.

Bottom Bracket

Bottom brackets get a great deal of wear and tear. They are the lowest part of the bicycle frame and so any water that gets into the frame tends to run down to the bottom bracket shell and get into the bearing system. The adjustable type bottom brackets use separate left and right side cups, a center spindle, and ball bearings (either loose or in a retainer), and all can be overhauled.

Overhauling any bearing system involves taking the system apart, cleaning out all the old grease and dirt, putting in new grease, and new bearings when necessary, re-assembling, and adjusting as necessary.

For Three Piece Bottom Brackets mount bike in repair stand. Remove the cranks – the cranks act as levers and connect the pedal to the bottom bracket spindle, and are pressed tightly onto the tapered bottom bracket spindle. They must be removed in order to effectively access the bottom bracket. Look for crank bolt or nut on the opposite end of the crank than the pedal – if no bolt or nut is visible, remove dust caps. Careful – some dust caps can be popped out with a flathead screwdriver, but some thread out. The Park Blue Book shows how to recognize and use a one-key release system. Turn best-fitting allen key/hex wrench, or bolt or nut head counter-clockwise and completely remove bolt or nut. Place bolt or nut on rag on workbench. Check for any washers inside the cranks and remove if they are there, and place them on rag on workbench. If you want to keep parts together, you can use an old spoke instead of a zip tie if you like—less wasteful and more solid. Thread nut of puller into arm several turns with fingers to make sure you don’t cross the treads and damage both the tool and your crank. This happens a lot!. Tighten the crank-puller nut the rest of the way into crank using a wrench. Thread internal driver into puller nut. Using handle or adjustable wrench, tighten driver (using crank as additional leverage) until crank is loose enough on spindle to come off. Be careful near the end; you don’t want it to just fall off! Remove crank from spindle and unthread both parts of crank puller tool from crank. Place the crank on your rag on your workbench. Repeat process for other crank.

Loosen lockring on non-drive side (left) by turning counter-clockwise using lockring spanner. Loosen adjusting cup on non-drive side by turning counter-clockwise using pin spanners – a half turn to adjust; remove completely to overhaul, and place adjusting cup on workbench. Hold fixed cup spanner firmly to drive-side (right) fixed cup and check its security by tightening counter-clockwise. If cup feels tight, then it is and leave it.

If overhauling, remove spindle; hold fixed cup wrench firmly to drive-side (right) fixed cup and loosen it by turning it clockwise. (If you are working on really old bikes, especially French and Italian, check a Sutherlands or other suitable manual for variations to this…) Remove completely and place spindle and fixed cup on rag on your workbench.

Clean all bearing surfaces with a rag and Simple Green: spindle, both cups, bearings. Do not spray Simple Green directly into bottom bracket shell.

Check for damage to bearings and bearing surfaces.

“Repack” both cups with new grease and either new or well-cleaned bearings

Reinstall bottom bracket

Lightly grease the threads of the fixed cup.

Carefully thread in the fixed cup to the drive-side (right) of the bottom bracket shell – thread in counter-clockwise several turns with fingers so as not to cross the threads, and seriously tighten the rest of the way with a fixed cup wrench.

Insert spindle – be careful to face the letters so they are readable from a rider’s position in the saddle.

Lightly grease the threads of the adjusting cup.

Carefully thread in the adjusting cup to the non-drive side (left) of the bottom bracket shell – thread in clockwise several turns with fingers so as not to cross the threads, and finger tighten the rest of the way – until you can feel it begin to touch the bearings.

Thread the lockring onto the threads of the adjusting cup on the non-drive side (left) until it stops.

Adjust adjusting cup to be a loose as possible without leaving any play.

Hold adjustment firmly in place with pin spanners on adjusting cup, and use lockring spanners to really tighten the lockring.

Double check your adjustment by checking for grinding or resistance (too tight), and for play (too loose). Check for resistance by rotating the spindle around and feeling for grinding. Check for play by grabbing both ends of the spindle and trying to rattle the spindle up and down – do this as you rotate the spindle all the way around.

Readjust as necessary in same fashion as described above.

Reinstall cranks

Cranks are pressed tight onto the spindle which has a tapered square spindle. The crank bolt or nut acts as a tool to press the cranks onto the spindle. When tightened down properly, the cranks will be pressed all the way onto the spindle and won’t move off of the spindle without another tool.

Wipe both sides of the spindle dry with a clean rag, as well as inside the cranks.

Install drive side crank onto the right side of the spindle.

Grease the threads of the crank bolts (or, if you have crank nuts, grease the threads on the spindle, but keep the spindle itself dry).

Use your fingers to thread the nut/bolt onto the spindle. Use appropriate wrench to tighten the nut/bolt (usually a 14 or 15 mm socket wrench) very tight using the crank as additional leverage.

Install drive side crank onto the right side of the spindle so that it is in a position 180 degrees (opposite) from the other crank. (Yes, people get this wrong often enough)

Grease the threads of the crank bolts (or, if you have crank nuts, grease the threads on the spindle, but keep the spindle itself dry).

Use your fingers to thread the nut/bolt onto the spindle. Use appropriate wrench to tighten the nut/bolt (usually a 14 or 15 mm socket wrench) very tight using the crank as additional leverage.

Reinstall any dust caps that you removed. If the dust cap has threads, grease them before threading snugly in place.

Return chain to the teeth by pedaling carefully forward. If chain gives resistance, reroute, and try again. Do not force the chain.

For One Piece Bottom Brackets

To check for proper adjustment, derail chain (if you need to, loosen axle nuts on rear wheel to release chain tension).

Grab both cranks down close to the pedals (but not by the pedals themselves) and try to shake laterally. If you feel a rattle – even slightly – that is called “play” and it means the adjustment is too loose. If no play is felt, rotate the cranks around and try to feel any resistance or grinding – like there is sand inside. If you feel any of this, it means your adjustment is too tight.

To adjust

Loosen locknut clockwise with a thin wrench or adjustable wriench quarter turn.

Loosen (clockwise) or tighten (counter-clockwise) adjusting cone as needed with appropriate pin spanners, so the adjustment is as loose as possible but has not play. You can sometimes use a screwdriver to do this

Hold adjustment tightly in place with pin spanners, and tighten (counter-clockwise) lockring tightly. Double check your work, and readjust as necessary.

To overhaul remove non-drive side (left) pedal.

Place pedal wrench (and pedal wrench only!) securely onto flats of spindle of pedal – take care to determine if flats take the 15 mm side or the 9/16th side of the pedal wrench – and loosen clockwise. Use the crank (or opposite crank) as additional leverage; for the proper mechanical advantage, orient wrench 90 degrees or less from crank, and then loosen. Once removed, place pedal on rag on workbench. Loosen locknut (clockwise) as above, and remove all the way. Place locknut on rag on workbench. Loosen (clockwise) adjusting cone with appropriate pin spanners and remove all the way. Be careful not to lose any ball bearings, so place your hand under the bottom bracket shell to catch any that may fall. Place adjusting cone and ball bearings on rag on workbench. Ease cranks out of bottom bracket shell from drive-side. Clean all bearings and bearing surfaces with a rag sprayed with Simple Green, as well as any threads that may need it. (Do not spray Simple Green or any other solvent inside the bottom bracket shell). Repack bottom bracket cups with new grease and clean bearings (new if possible). Ease cranks back through the bottom bracket shell, taking care not to disturb the new grease and bearings you have just put in. This is the hardest part—(you might want to practice this a couple of times without the new grease in there—just so you get the feel of it before you risk dirtying up the bearings you will install with new grease) Thread adjusting cone back on (counter-clockwise) with your fingers until you can feel the cone begin to touch the bearings. You will need to hold the crank in place while you do this. Install keyed washer. Thread locknut back on (counter-clockwise) until it hits the adjusting cone. Double check your adjustment – make the adjustment as free running as possible without play. Hold adjusting cone firmly in place with appropriate pin spanners, and tighten down locknut tightly with locknut spanners. Double check adjustment, and adjust as necessary ( Reinstall non-drive side (left) pedal. Grease the threads of the pedal, and thread in two or three turns by hand so you can make sure you are not crossing the threads. Place pedal wrench (and pedal wrench only!) securely onto flats of spindle of pedal – take care to determine if flats take the 15 mm side or the 9/16th side of the pedal wrench – and tighten counter-clockwise. Use the crank (or opposite crank) as additional leverage; for the proper mechanical advantage, orient wrench 90 degrees or less from crank, and then tighten. Really tighten.

Hubs

The wheel rotates around the hub bearings, which can be either adjustable or non-adjustable cartridge types. We will be working with the adjustable type. These bearing sets have a cup and an adjusting cone and can be adjusted to be as loose as possible with no play. All adjustable type front hubs are basically the same and can be adjusted from either side, but rear hubs can be either cassette hubs (freehub types), or thread-on free-wheel hubs. Both adjust form the non-drive (left) side.

To test if a hub is properly adjusted, ideally you should take the wheel out of the frame/fork. Grab the axle on either side and try to shake laterally. If you feel a rattle – even slightly – that is called “play” and it means the adjustment is too loose. If no play is felt, rotate the axle around and try to feel any resistance or grinding – like there is sand inside. If you feel any of this, it means your adjustment is too tight and/or something is broken or dirty in there.

Quick release hubs have hollow axles and the skewer flexes slightly inside the hub. Be sure to not confuse this play with a loose adjustment, by taking care to grab the axle and not the quick release skewer.

Overhauling any bearing system involves taking the system apart, cleaning out all the old grease and dirt, putting in new grease, and new bearings when necessary, re-assembling, and adjusting as necessary.

Front hub

To check for proper adjustment

Remove front wheel from bike. Remove any quick release skewer and springs and place on rag on work bench; remove any axle nuts and place on rag on work bench; remove any rubber dust coverings protecting the cones and locknuts and place on rag on work bench. Check bearings for play by holding either side of axle firmly and try to rock laterally. If you feel any looseness or knocking, the hub adjustment is too loose. Check bearings for any grinding by holding the axle and rotating it around within the hub. If you feel any grinding, that indicates that the adjustment is too tight. To adjust (adjust from one side, and one side only): Place axle in axle vice and tighten vice very securely. OR rest half of wheel on work bench with the hub off the edge, and using your knee or hip to balance it. Find appropriately sized cone wrench (usually 13 mm, 15 mm, or 17 mm) by starting to fit the smallest wrench to the flats of the adjusting cone. If the smallest doesn’t fit, then go one size bigger (1 mm bigger) until you find the appropriately sized wrench. Hold firmly with the arm of the wrench closest to your body. Find appropriately sized cone wrench (usually 13 mm, 15 mm, or 17 mm) by starting to fit the smallest wrench to the flats of the locknut. If the smallest doesn’t fit, then go one size bigger (1 mm bigger) until you find the appropriately sized wrench. Place at an angle that is 45 degrees or less to the cone wrench on the adjusting cone. Rotate the cone wrench on the locknut counter-clockwise (left) to loosen. Again, be sure to be holding the wrench on the adjusting cone still. If the locknut won’t budge, try squeezing the two wrenches together (making sure that you are turning the locknut counter-clockwise.)

To overhaul

Remove locknut and adjusting cone completely and place parts on your rag on your workbench. While you are removing adjusting cone and locknut, work over your rag on your work bench so as to be careful not to drop any bearings on the floor. Clean all bearings and bearing surfaces with a rag sprayed with Simple Green, as well as any threads that may need it. (Do not spray Simple Green or any other solvent inside the hub shell). Repack hub with new grease and clean bearings (new if possible). Ease axle back through the hub shell, taking care not to disturb the new grease and bearings you have just put in. Thread adjusting cone back on (counter-clockwise) with your fingers until you can feel the cone begin to touch the bearings. Thread locknut back on (counter-clockwise) until it hits the adjusting cone. Tighten or loosen adjusting cone as needed so that the adjustment is as loose as possible but has no play. Hold adjustment firmly in place by fitting appropriately sized cone wrench on adjusting cone (to help you hold it really steady, wrap hands around arm of wrench and around spokes at the same time), while you firmly tighten down locknut (clockwise).

Double check your work (if you have the wheel in the axle vice, you will need to remove the wheel from the vice to check if you adjusted the hub properly) by checking for play and/or grinding, and readjust as necessary. This is an area that students often find particularly hard. Adjusting the bearings is not a job that can be done once and gotten right first time. Even experts will often have to spend a few tries. The cheaper the equipment, the harder it is to get the adjustment as good as possible.

Rear hub

To check for proper adjustment

Remove rear wheel from bike as described in part I.Tires and Tubes section c.2. Remove any quick release skewer and springs and place on rag on work bench; remove any axle nuts and place on rag on work bench; remove any rubber dust coverings protecting the cones and locknuts and place on rag on work bench. Check bearings for play by holding either side of axle firmly and try to rock laterally. If you feel any looseness or knocking, the hub adjustment is too loose. Check bearings for any grinding by holding the axle and rotating it around within the hub. If you feel any grinding, that indicates that the adjustment is too tight.

To adjust, first of all you have to make sure that the cone and locknut are tight against each other on the drive side. Then adjust from the non drive side. (adjust from non-drive side, and non-drive side only):

Free Wheel type and Cassette/Freehub type

Place axle in axle vice and tighten vice very securely – drive side down. OR rest half of wheel on work bench with the hub off the edge, using your knee or hip to balance it – drive side down. Find appropriately sized cone wrench (usually 13 mm, 15 mm, or 17 mm) by starting to fit the smallest wrench to the flats of the adjusting cone. If the smallest doesn’t fit, then go one size bigger (1 mm bigger) until you find the appropriately sized wrench. Hold firmly with the arm of the wrench closest to your body. Find appropriately sized cone wrench (usually 13 mm, 15 mm, or 17 mm) by starting to fit the smallest wrench to the flats of the locknut. If the smallest doesn’t fit, then go one size bigger (1 mm bigger) until you find the appropriately sized wrench. Place at an angle that is 45 degrees or less to the cone wrench on the adjusting cone. Rotate the cone wrench on the locknut counter-clockwise (left) to loosen. Again, be sure to be holding the wrench on the adjusting cone still. If the locknut won’t budge, try squeezing the two wrenches together (making sure that you are turning the locknut counter-clockwise.) Tighten or loosen adjusting cone as needed so that the adjustment is as loose as possible but has no play (if you are using the axle vice, you need to remove the wheel from the vice to check the adjustment)

Return axle to the axle vice, drive side down, OR rest half of wheel on work bench with the hub off the edge, using your knee or hip to balance it – drive side down. Hold adjustment firmly in place by fitting appropriately sized cone wrench on adjusting cone (to help you hold it really steady, wrap hands around arm of wrench and around spokes at the same time), while you firmly tighten down locknut (clockwise).

Double check your work (if you have the wheel in the axle vice, you will need to remove the wheel from the vice to check if you adjusted the hub properly) by checking for play and/or grinding, and readjust as necessary.

To overhaul

Free wheel type

Remove Freewheel Find proper freewheel removing tool and fit into freewheel. If a quick release hub, reinstall quick release skewer to hold freewheel removing ool securely in place. If solid axle, thread axle nut back on (not tightly) to hold freewheel removing tool securely in place. Place wheel in bench vice freewheel side down, taking care to make sure the flat sides of the freewheel match up to the flat walls of the vice jaws. Tighten down vice very securely. Using the wheel itself for leverage, rotate the wheel counter-clockwise until you feel the freewheel loosen – usually no more than a quarter turn (90 degrees). Remove wheel from vice. Remove axle nut or quick release skewer and place back on rag on workbench. Make sure freewheel removing tool is still properly seated in freewheel. With your hands, continue to rotate the tool counter-clockwise until the freewheel comes completely off. Return freewheel removing tool to its proper storage place, and place freewheel on rag on workbench. Place non-drive side axle in axle vice and tighten vice very securely. OR rest half of wheel on work bench with the hub off the edge, using your knee or hip to balance it. Find appropriately sized cone wrench for the adjusting cone (usually 13 mm, 15 mm, or 17 mm) by starting to fit the smallest wrench to the flats of the adjusting cone. If the smallest doesn’t fit, then go one size bigger (1 mm bigger) until you find the appropriately sized wrench. Hold firmly, with the arm of the wrench positioned close to your body. Find appropriately sized cone wrench for the locknut (usually 13 mm, 15 mm, or 17 mm) by starting to fit the smallest wrench to the flats of the locknut. If the smallest doesn’t fit, then go one size bigger (1 mm bigger) until you find the appropriately sized wrench. Place at an angle that is 45 degrees or less to the cone wrench on the adjusting cone. Rotate the cone wrench on the locknut counter-clockwise to loosen. Again, be sure to be holding the wrench on the adjusting cone still. If the locknut won’t budge, try squeezing the two wrenches together (making sure that you are turning the locknut counter-clockwise.) Remove locknut and adjusting cone completely and place parts on your rag on your workbench. While you are removing adjusting cone and locknut, work over your rag on your work bench so as to be careful not to drop any bearings on the floor.

Clean all bearings and bearing surfaces with a rag sprayed with Simple Green, as well as any threads that may need it. (Do not spray Simple Green or any other solvent inside the hub shell). Repack hub with new grease and clean bearings (new if possible). Ease axle back through the hub shell, taking care not to disturb the new grease and bearings you have just put in. Also take care to put the axle back in the right direction – the drive side (the side you didn’t take apart) should be on the side of the hub that has the threads. Thread adjusting cone back on (clockwise) with your fingers until you can feel the cone begin to touch the bearings. Thread locknut back on (clockwise) until it hits the adjusting cone. Tighten or loosen adjusting cone as needed so that the adjustment is as loose as possible but has no play. Place non-drive side axle in axle vice (the side you are not working on) and tighten vice very securely. OR rest half of wheel on work bench with the hub off the edge, and using your knee or hip to balance it. Hold adjustment firmly in place by fitting appropriately sized cone wrench on adjusting cone (to help you hold it really steady, wrap hands around arm of wrench and around spokes at the same time), while you firmly tighten down locknut (clockwise). Double check your work (if you have the wheel in the axle vice, you will need to remove the wheel from the vice to check if you adjusted the hub properly) by checking for play and/or grinding, and readjust as necessary. Rethread freewheel onto hub taking care not to cross the threads. Tighten down very firmly using your hands (use a rag to protect your hands and to get a better grip if necessary) Reinstall rear wheel on bicycle.

Cassette/Freehub type

Remove Cassette Find proper freewheel/cassette removing tool and fit into grooves of cassette lockring. If a quick release hub, reinstall quick release skewer to hold freewheel removing tool securely in place. If solid axle, thread axle nut back on (not tightly) to hold freewheel removing tool securely in place. Place wheel upright on the floor leaning up against your knees - drive-side out. Rest chain whip on largest cog following the directional arrows on the tool. Take care to fit your 300 mm adjustable wrench onto the flats of the cassette removing tool, and adjust the wrench to fit snugly on the tool. Using the chain whip and the adjustable wrench against each other as leverage and to hold the wheel still, rotate the adjustable wrench counter-clockwise until you feel the cassette lockring loosen (it’ll make a funny noise, so don’t let it freak you out). Remove axle nut or quick release skewer and place back on rag on workbench. Make sure cassette removing tool still properly seated in lockring grooves. With your hands (or adjustable wrench if necessary), continue to rotate the tool counter-clockwise until the lockring comes completely off. Remove the cassette – it’ll come out in a stack. Place the stacked cassette and the lockring on your rag on your work bench. Place freewheel removing tool on rag on your work bench so it is accessible for you when you need to put the cassette back on. Place non-drive side axle in axle vice and tighten vice very securely. OR rest half of wheel on work bench with the hub off the edge, and using your knee or hip to balance it. Find appropriately sized cone wrench (usually 13 mm, 15 mm, or 17 mm) by starting to fit the smallest wrench to the flats of the adjusting cone. If the smallest doesn’t fit, then go one size bigger (1 mm bigger) until you find the appropriately sized wrench. Hold firmly with the arm of the wrench closest to your body. Find appropriately sized cone wrench (usually 13 mm, 15 mm, or 17 mm) by starting to fit the smallest wrench to the flats of the locknut. If the smallest doesn’t fit, then go one size bigger (1 mm bigger) until you find the appropriately sized wrench. Place at an angle that is 45 degrees or less to the cone wrench on the adjusting cone. Rotate the cone wrench on the locknut counter-clockwise (left) to loosen. Again, be sure to be holding the wrench on the adjusting cone perfectly still. If the locknut won’t budge, try squeezing the two wrenches together (making sure that you are turning the locknut counter-clockwise.) Remove locknut and adjusting cone completely and place parts on your rag on your workbench. While you are removing adjusting cone and locknut, work over your rag on your work bench so as to be careful not to drop any bearings on the floor. lean all bearings and bearing surfaces with a rag sprayed with Simple Green, as well as any threads that may need it. (Do not spray Simple Green or any other solvent inside the hub shell). Repack hub with new grease and clean bearings (new if possible). Ease axle back through the hub shell, taking care not to disturb the new grease and bearings you have just put in. Thread adjusting cone back on (clockwise) with your fingers until you can feel the cone begin to touch the bearings. Thread locknut back on (clockwise) until it hits the adjusting cone. Tighten or loosen adjusting cone as needed so that the adjustment is as loose as possible but has no play. Place non-drive side axle in axle vice (the side you are not working on) and tighten vice very securely. OR rest half of wheel on work bench with the hub off the edge, and using your knee or hip to balance it. Hold adjustment firmly in place by fitting appropriately sized cone wrench on adjusting cone (to help you hold it really steady, wrap hands around arm of wrench and around spokes at the same time), while you firmly tighten down locknut (clockwise). Double check your work (if you have the wheel in the axle vice, you will need to remove the wheel from the vice to check if you adjusted the hub properly) by checking for play and/or grinding, and readjust as necessary. Reinstall cassette. Slide the stacked cassette back onto the freehub body following the grooves, and making sure that the different sections and spacers are in their correct order. Thread lock ring back on taking care not to cross the threads. Grab the freewheel/cassette tool and fit into groves of cassette lockring. Place wheel upright on the floor leaning up against your knees - drive-side out. Using your 300 mm adjustable wrench (take care to fit wrench snugly to the flat sides of the tool), tighten locking well (turn clockwise). Reinstall rear wheel on bicycle. Refer to Tires and Tubes section i.ii. Headsets – the headset allows the fork to turn smoothly while riding. If the headset it pitted or worn, adjusted too tight or too loose, the handling of the bikes is affected. Very worn headsets tend to “index” when the front wheel is pointing straight . Pick up the bike and point the front wheel down; swing the handlebars back and forth from center – if the headset sticks in ‘notches’ as it swings, it is worn and should be replaced.

Headsets

Threaded headset /Quill stem

Adjustment

Threaded headsets are adjusted using the locknut and the adjusting cone/ race. The stem does not have to be removed to adjust the bearings. se an appropriately sized headset wrench to hold the adjusting cone/race still. se a second appropriately sized headset wrench (or a 300 adjustable wrench) to loosen (counter-clockwise) locknut. The adjusting cone/race is now free to turn. Adjust the cone/race as loose as possible without having play (check for play by grabbing the stem and pulling the fork back and forth – if you feel a knocking, the adjustment is too loose). Hold front wheel between your knees, keeping it parallel with the top tube of the bike. Hold your adjustment in place using the appropriately sized headset wrench on your adjusting cone/race and keep it still while tightening locknut down with appropriately sized headset wrench (or 300 mm adjustable wrench). Double check your adjustment – for play and for tightness (if it feels sticky). Readjust if necessary.

Threadless

Adjustment

Threadless headsets work on the same principle as threaded/quilled headsets. The bearing races press against the bearing. The bolt in the top cap puts pressure on the stem, which pushes on washers below the stem, which in turn, presses on the bearing races, which push on the bearings.

The cap and the bolt on the top of the stem do not hold the stem in place – the bolts on the side of the stem are what keeps the stem from moving once the adjustment is made. The cap is used for bearing adjustment only.

The stem must press down on the spacers in order to adjust the bearings. If the steering tube is level with the top of the stem, another spacer is needed below the stem. Remove the bolt and top cap to inspect the condition of the steer tube/column. Reinstall cap and bolt by hand but do NOT tighten. Do NOT lubricate inside stem or on steer tube surface. Loosen stem bolts that secure the stem to the steer tube and wiggle from side to side to make sure its loose. If the stem is jammed or rusted to the steer tube/steering column, no adjustment can be made. Line up the stem with the front wheel and gently thread in the top bolt until resistance is felt. Tighten stem bolts. Check for play by pulling back and forth on fork while holding on to stem. Rotate the bars to check for play in different positions. If the bearing system feels fine, double check that the stem bolts are tight and then tighten the top bolt securely. Double check adjustment and re-adjust if necessary. To adjust the bearing system, loosen the stem bolts. Turn the adjusting bolt in center/top cap clockwise to tighten adjustment, or counter-clockwise to loosen adjustment. Secure stem bolts and check for play and/or for tightness. Repeat steps g, h, and i until bearings are properly adjusted. Remember to loosen stem bolts before turning adjusting bolt in top cap.


Things to be sure that the Teachers are ready to explain:

  • The way a bearing works—like a sandwich

How to tell the difference between

    • Too tight
    • Too loose
    • Juuust right!
  • The three stage process of adjusting a bearing
    • Loosen locknut while holding adjusting component still
    • Move adjusting component
    • While holding adjusting component in its new position, tighten locknut
    • Check and do again if necessary
  • That you have to hold parts of the bearing still while you adjust some other part
    • The axle and the one cone/locknut combination in a hub
    • The fork and the crown race in a headset
    • The fixed cup (3-pc BB), fixed cone (1pc BB) and BB shell (frame) in a bottom bracket
  • That it is a trial and error process!