Bike Maintenance
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You can maintain your own bike!

A bicycle is a relatively simple machine and with commonsense most people can carry out the simple maintenance tasks needed to keep it in good running condition. This page details some of the common tasks which can be easily carried out with the minimum of tools. Sometimes specialist tools are required and they are mentioned in each section however a couple of shifting spanners, a set of allen keys and some ordinary metric spanners or sockets ranging from 8 mm to 17 mm, a screwdriver and pliers are handy to have.

Topics discussed are:

For most maintenance the bicycle needs to be held firmly with at least the rear wheel off the ground. There are purpose built stands which can be bought but personally I use a loop of rope hanging from the roof of my garage into which I hook the saddle - for most purposes this is all that is required but I also have a further piece of rope hanging which can be attached to the handlebar stem (the deluxe version) if the bike needs to be more firmly secured with both wheels off the ground.


Rear Derailleur

Most modern bikes use derailleur gears, originally the rider used a friction controlled lever which had to be positioned manually to select the required gear but modern gears are indexed and very easy to use. However for proper operation they must be accurately adjusted.

Travel Adjustment

If the travel stops are not correctly adjusted the chain will either jump off the outermost gears or those gears will be impossible to select. This adjustment is made using the two small travel limits screws usually found on the rear of the derailleur arm above the cable entry. Sometimes the screws are marked 'H' and 'L' but if you are not sure which screw is which just select the highest or lowest gear and look underneath to see which screw is touching or nearly touching a stop.

Top Gear Limit

Adjust the front derailleur to put the chain on the largest chainwheel then move the rear gear adjusting lever to select the smallest rear sprocket. Turn the high gear limit screw anti clockwise until there is little resistance then turn the screw clockwise until the small derailleur jockey wheels are in line with the small cog. Check by turning the pedals and ensure the chain runs true without clattering. Change gears up and down to see the top gear selects correctly.

Low Gear Limit

Adjust the front derailleur lever to put the chain on the smallest chainwheel then move the gear adjusting lever to select the largest rear sprocket. Turn the low gear limit screw anti clockwise until there is little resistance - make sure the jockey wheels don't hit the spokes - then turn the screw clockwise until the small derailleur wheels are in line with the largest cog. Check by turning the pedals and ensuring the chain runs true without clattering. Change gears up and down to see the gear selects correctly.

After adjusting both screws again check the gears select correctly.

Adjust Tension Screw

Not all derailleurs have this adjustment but it is usually a largish screw which pushes against the rear of the frame's derailleur hanger and positions the derailleur front to rear.

Put the chain on the largest chainwheel and the rear gear on the smallest sprocket and adjust this screw until the jockey wheel is close to but not touching the cog. Turn the pedals and run the chain onto the smallest chainwheel, then run through the gears to the largest sprocket checking that the jockey wheel does not touch any of the sprockets. Readjust if necessary

Adjusting Indexed gears

Indexed gears are great but they do need to be kept accurately adjusted.

If you are starting from scratch after changing a cable for example then put the chain on the middle chain wheel (large if there are only two) and position the rear on the smallest sprocket by selecting the top gear.

Now screw the barrel adjusters fully in - sometimes there is an adjuster at both ends of the cable sometimes just at the derailleur end - At the rear screw the adjuster out a couple of turns to allow for fine adjustments later. The new cable should now be adjusted so there is no slack by loosening the fixing nut, pulling the cable tight and retightening the nut (for normal adjustments this step shouldn't be necessary unless the cable is wildly out of adjustment).

Change the rear gear selector down one gear. Turn the pedals and start winding the barrel adjuster at the derailleur anti-clockwise until the jockey wheels line up with the second smallest sprocket and the chain runs quietly. Check by continuing to turn the barrel adjuster until the chain clatters as it tries to move to the third gear then wind clockwise until the clatter ceases and the chain runs true.

Run the rear derailleur through all the gears and ensure the mechanism works smoothly and the chain runs quietly in each gear. Fine tune if necessary - If I have problems I select the second from bottom rear gear, the small chainwheel on the front (my bike only has two) and try fine tuning there.

NB: The barrel adjuster may actually be a sleeve which needs to be pulled against a spring to engage with the threaded part, if you don't do this turning the adjuster does nothing - very frustrating!


Front Derailleur

Similar to rear derailleur but much simpler, the two adjustment screws are usually on the top of the derailleur arm and by looking at which is nearest the appropriate stop it is easy to work out which is which.

Positioning

The inner and outer cage plates should be parallel to the chainwheels when viewed from above. There should be a clearance of about 2 mm between the outer plate and the teeth of the outer chainwheel. Both these setting are adjusted by loosening the clamp or mounting bolt and moving the whole derailleur - once set this rarely needs readjusting.

Left Travel Adjustment

With the chain on the largest rear sprocket and the small chainwheel adjust the left travel screw until the inner cage plate is close to the chain without actually touching it.

Right Travel Adjustment

Put the chain on the smallest rear sprocket and largest chainwheel and adjust the right travel screw until the outer cage plate is close to but not touching the chain.

Check operation by changing from large to small chainwheel and back with the rear derailleur in various gears. Make fine adjustments as necessary.


Bearings

Bearings should be checked and adjusted regularly.

  • Wheel (hub) bearings
  • Bottom Bracket
  • Headset (steering)
  • Pedals

As a quick rule of thumb a bearing should be tightened finger tight then backed off about one eighth of a turn before being locked in that position. You will find that individual bearings need slightly more or less than the one eighth of a turn so that they run freely but without any end play but you will get to know what is required as you go. Don't be intimidated by this you will soon get a feel for it.

Wheel Bearings

Wheel bearings can be checked for play by attempting to move the rim sideways, if there is any play or clicking then the bearing needs adjustment, when the wheel is rotated there should be no roughness or tightness. This quick check should be carried out monthly, once a year the bearings should be striped down, inspected, greased and adjusted.

Most wheels use cone bearings and to dismantle this type of bearing you need a set of cone spanners - basically 'thin' spanners. These are not expensive and usually come as a set of two double ended spanners with 13/ 14 mm, 15/16 mm ends, ideally you need two of each but you can get away with one and a shifter or normal spanner of the right size.

Remove the wheel from the bike - if it is bolted on remove one of the securing nuts completely or, in the case of a quick release, remove the skewer.

You should be able to see the cone and lock nut - using two suitable spanners release the lock nut from the cone on one side and remove, then unscrew the cone. Most modern bearings use captured ball bearings but be sure to look as the bearing becomes visible. If they are not in a cage count them and continue removing the cone over an ice cream container to catch any that drop out.

Once the cone has been removed carefully slide the axle out of the hub. On some hubs the bearing seal is pressed onto the cone and comes away with it on others the seal is pressed into the hub. The latter type can usually be gently prised off - this should take little force to accomplish, the seals just pop out. Then remove the bearing cages and balls from each side (NB: note which way the cage sat).

Wipe the bearing surfaces clean, check they are shiny and unpitied, check the bearing cages are intact and all the balls in place. Use a little solvent to clean off the grease and dirt from the cones, ball bearings and hubs.

If all is well put a reasonable layer of grease over the bearing surface in the hubs, press the bearings into it and replace the seals. Smear grease over the bearing surface of the cone still attached to the axle (check the cone and lock nut are still tight) and carefully insert the axle into the hub.

Screw on the other cone after applying a little grease to the bearing surface and do up to the bearing finger tight. Screw on the lock nut until it is close to the cone.

Holding the axle still unscrew the cone about an eighth of a turn then, without moving it, screw the lock nut up to it.

Again without moving the cone or the axle use the cone spanners on the cone and lock nut to tighten them up together firmly.

Check the bearing for tightness - the wheel should spin freely but there should be no sideways movement. On your first attempt you may need to release the locknut and retry this a few times to get it exactly right but it comes with practice.

Once you are satisfied remount the wheel in the frame and test again - this is important especially with quick release hubs as the mounting device tends to tighten up the bearing very slightly. Again it is something you will soon get the feel of.

The rear wheel presents a slight difficulty because of the gears, a removing tool costs a few dollars or you can get your bike shop to remove the gears. If you have the more modern seven speed or above it is possible to remove and grease the bearings without removing the gears. Remove the cone and locknut from the opposite side to the gears and follow the instructions above - it might be a little fiddly but it is possible.

I only ever unlock and remove one cone and leave the other cone as is (unless the cone is damaged), it just makes reassembly easier, you don't have to worry about centring the axle etc.

The Bottom Bracket

Removing the Cranks

Yet another specialised tool required ($12ish).

Remove the dust cover from the centre of each crank and undo the nut or bolt revealed (often the extractor has a suitable socket built in).

Unscrew the centre piece of the crank remover so it well back inside the outer sleeve. Screw the outer sleeve into the crank - NB make sure it is screwed in as far as it will go and is not being restricted by the centre piece. If it is not fully screwed home there is a danger of stripping the thread on the crank - an expensive mistake.

Screw in the centre piece until some resistance is felt then tighten slightly, gently tap (ideally with a wooden mallet) on the centre of the extractor then tighten a bit more, again if necessary tap the extractor gently and tighten again. Usually this is sufficient to release the crank from the taper on which it is fixed. Be careful, especially with alloy cranks, don't just tighten until something gives.

Cassettes

More and more bikes these days use a cassette bottom bracket which is replaced in its entirety once worn. These require yet another special tool to remove and replace ($8 - $12) but are simple to remove and install. The only 'trick' is to remember the right hand side has a left hand thread so is undone by turning clockwise and tightened anti clockwise. The left hand side has a conventional thread.

The BSA Type Bottom Bracket

This consists of five parts:

  1. An axle
  2. Fixed cone (right hand side)
  3. Adjustable cone (left hand side)
  4. Lockring
  5. Two ball races

There are purpose built tools for dismantling this type of bottom bracket but a large shifting spanner, a small hammer and drift will usually get you by. The only special tool you will need is a crank remover.

Remove the cranks as previously described. On the left hand side you will see the lockring on the adjustable cone, loosen with the drift by tapping anti clockwise (or use the proper tool if you have it). If you are merely adjusting the bottom bracket there is no need to dismantle further.

Once the lockring has been released it should be possible to remove the adjustable cone by turning anti clockwise - all the ones I have removed have been so loose in the threads that it was easy to remove by hand but I guess there will be exceptions.

Usually the ball bearings are contained within a cage but if you are not sure it is wise to put an ice cream container underneath to catch any errand balls. If it has a cage note which way the cage is installed.

Withdraw the axle and note which way it fits - The chainwheel side is slightly longer than the left end (measured from the bearing ridge to the end) however sometimes this difference is hard to detect with the eye.

The fixed cone can usually be removed with a large shifting spanner or even gas pliers opened out to fit across the flats - take care there is not a lot of room and remember this has a left hand thread and is removed by turning clockwise.

Clean and inspect the components, replace the bearing(s) if the cage is damaged or balls missing (only costs a couple of dollars at most). Clean the threads on the cones and the frame.

Check the frame for corrosion -  any water getting in via the downtube can sit in here, on cheaper frames (which are those most likely to corrode) there is rarely a hole drilled to allow this water to escape, of course you can correct this yourself.

Put a good layer of grease on the bearing surface of the fixed cone and screw firmly into place (anti-clockwise). Personally I also smear a thin layer of grease onto the threads of both cones to reduce the chance of them corroding to the frame.

Smear a layer of grease on the axle bearing surfaces and those of the adjustable cone, place the bearings on the axle followed by the adjustable cone. Insert the axle (the right way round) into the frame and out through the fixed cone then screw in the adjustable cone until it is finger tight against the bearings. Screw on the lockring until it just touches the frame.

Unscrew the adjustable cone about an eight of a turn and tighten the lockring either with the special tool or tapping gently with the drift (do this at several places around its circumference) - ensure the adjustable cone doesn't move during this.

Check the axle moves freely without any side play. Readjust if necessary.

Make sure the chain is looped over the frame's bottom bracket casing then replace the cranks - personally I  smear a little grease on the tapers - replace and tighten the bolts/nuts and replace the dust covers. Finally lift the chain onto the chainwheel.

Check the cranks are fitted firmly by setting them horizontal and pressing firmly down on both pedals. Turn the cranks through 180 and press down firmly again, there should be no movement at all.


Getting the Right 'Fit'

Making your bike fit you makes all the difference to the pleasure that is cycling. It is worth spending a bit of time getting it right.

Choosing the frame size

There are many different methods of determining the correct frame size involving inside leg measurements etc. But the one which seems to work for me is to stand over the bike with both feet on the ground each side and ensure there is between 2.5 and 5 cm clearance between the top tube and the crutch. This works well for racing or touring bikes but most books recommend you allow an additional 5 to 10 cm for a mountain bike - I have never bought one but it sounds right to me - the extra space is to allow the bike to move more beneath you.

Having found a bike which seems right according to the above get the shop to adjust the saddle roughly to suit and try the riding position because it does vary from make to make.

Be warned: frame sizes are measured up the down tube but some manufacturers measure from the centre of the bottom bracket to the top of the downtube others measure to where the centre of the top tube joins the downtube. As you can imagine the difference is several centimetres.

Getting the Saddle Level

To set the saddle level check using a spirit level from front to back and adjust until true - this is the best position to start with, if this is not the best for you then the nose of the saddle can be dropped very slightly until you are comfortable - the saddle should never slope backwards.

Adjusting the Saddle Height

When the crank is at the lowest point of its travel your leg should be very slightly bent. If the leg is completely straight you will hurt the back of your knee and your hips will tend to swivel on the saddle. If it is too bent you will not get maximum power from your leg. A centimetre either way can make all the difference. One method of checking your saddle height is to put your heels on the pedal (in your normal cycle shoes), at the lowest point your leg should be just straight, pedal backwards to check that your hips don't bob - if they do, lower the saddle slightly and try again.

Adjusting the Saddle Position

Once the height is right the saddle needs to be adjusted so that when the crank is horizontal the bony part of your leg just below the knee cap is vertically aligned with the axle of the pedal (and the ball of your foot). I use a piece of cotton with a small nut attached as a bob to check this measurement.

If the alignment is wrong then the saddle needs to be loosened slightly and slid forward or backward to suit.


Disclaimer: These instructions are compiled with great care and work for me, however I can take no responsibility for your actions and only guarantee that if you break something you get to keep the bits.
Copyright © Bruce Lloyd 2005

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