The #1 Bicycle Mechanic Website in the World!

OFFICIAL SPONSORS

Cardio Trek Personal Trainer
Cardio Trek
Sports Trainer
East York, Toronto, ON
Email: cardiotrek@gmail.com
Hours: Tues-Thurs 10-5:30, Sat-Sun 10-3:30
Cardio Trek is best known for teaching archery lessons.

Sunday, April 19, 2009

Wheel Truing and Repair

When are wheels not true? No, its not when they're lying to you... its when they're not straight. A true wheel is rounder, centered, easier to pedal and they wobble less.

Thus knowing how to make a wheel perfectly round, replacing broken spokes and damaged nipples and fixing damaged rims can be quite important for keeping a bicycle in tip-top shape.

A lot of the tasks required to true a wheel require tools only found in a well-equipped bicycle shop (like a truing stand), so you will likely need to contact a local bicycle mechanic.

WHEEL TERMINOLOGY

Cross Pattern - The pattern created by spokes laid in opposite directions.

Dish - The centering of the rim to the hub locknuts. The flanges are sometimes different distances, so the goal is to make the wheel look like a dish when viewed from the side.

Eyelet - A metal reinforcement in the nipple hole.

Hub - The mechanism at the center of the wheel, that the axle rotates inside of.

Hub Flange - The metal discs on opposite sides of the wheel hub, to which the spokes attach.

Interlace - This is when the last spoke of a set goes under the spoke instead of over it.

Kgf - Kilograms of Force, a measurement of spoke tension.

Nipple - The long nut that attaches to the rim and holds a spoke in place with threads. Tightening the spoke nipples controls the spoke tension.

Truing Stand - A special stand specifically for truing wheels. Anyone who doesn't use one of these is an amateur.

Radial Bump - This is a bump in the rim, going outwards.

Radial Dip - This is a dent in the rim, going inwards.

Radial Error - An error in the roundness of the rim, either a dip or a bump.

Reading Unit - A number used to measure spoke tension, which is then converted to kgf.

Rim - The metal hoop attached to the spokes, on which the rubber tire is attached.

Rim Beads - The two edges of the rim on the outer sides.

Rim Sidewall - The sides of the rim, to which the brake pads press.

Spokes - The wires that go between the wheel hub and the rim.

Spoke Elbow - The 90 degree hooks that attach to the hub flange's holes and hold the spokes in place.

Spoke Head - The flattened end of a spoke that at the end of the spoke elbow, which holds the spokes inside the hub flange.

Spoke Nipple Holes - The holes in the rim to which the spoke nipples attach.

HOW DO YOU KNOW YOUR WHEEL IS CROOKED OR NOT TRUE?

If your wheels wobble from side to side (lateral error), your wheel might not be true.

If you have difficulty adjusting the brakes (its too high or too low), your wheel might not be true.

If you are experiencing brake pad rubbing, your wheel might not be true.

If your bike has a tendency to go to one side, your wheel might not be true.

If your wheel won't center between the fork, your wheel might not be true.

There might be other issues causing the problem, but this is also an easy one to check and fix.

You will also need to true your wheels whenever a spoke breaks. A broken spokes suggests there might be tension problems with the wheel spokes. If they keep breaking, its an indicator that spokes are just old and need to be replaced.

Minor rim damage can be easily repaired, but major damage should result in either replacing the rim or the whole wheel.

HOW DO I KNOW I SHOULD REPLACE MY WHEEL OR RIM?

Indicators include: Multiple broken spokes, multiple damaged or corroded nipples that won't turn, dents in the rim that can't be straightened out, cracks in the rim, severe sidewall wear or rust.

WHEEL TRUING MAINTENANCE

Spoke tension should be checked when the bicycle is first purchased, because manufacturers rarely check for true wheels.

Spoke nipples should also be lubricated so that they don't rust or corrode, once or twice a year. Put a drop of light oil at the top of each nipple so it can soak downwards. Alternatively you could treat it with Wheelsmith Spoke Prep (a lifetime corrosion preventative) which will last a lot longer.

BICYCLE SPOKE TENSION - WHAT TO WATCH FOR

#1. Make sure the wheel hub is tight and doesn't jiggle. If it jiggles you won't be able to true the wheels properly. Tighten the wheel hub so the axle still moves freely, but doesn't jiggle any more.

#2. Check for rounded/damaged nipples using a Park SW-10 nipple wrench. If one is found, check all the others. A wheel with many damaged nipples are not cost effective to repair and you'd be better off just replacing the entire wheel.

#3. Check for stuck or frozen nipples. If you can't move them using a Park SW-10 nipple wrench. If many frozen nipples are found the wheel should be replaced because it won't be cost effective trying to remove and replace them.

#4. Replace any broken or bent spokes, but calculate first how much it will cost and determine whether its cost effective to replace the wheel. If spokes break during the truing of the wheel, or if there are many signs of previously broken/replaced spokes, it may be time to replace the wheel. Depending on the wheel type it may be worth it to replace ALL the spokes and rebuild the wheel.

#5. Check for a loose chain. Spokes sometimes get damaged or bent by a chain bumping and catching the spokes. If the chain is really loose, it should be replaced.

#6. Check to see if you have replacements for spokes of unusual length. You can sometimes use a Hozan spoke threader tool (if you have one) to cut and replace spokes with weird lengths.

#7. Check for spokes that are too long and may puncture the tire tube or won't thread properly. Too long spokes should be ground down using a file or rotary tool (and possibly rethreaded if the nipples are running out of usable thread).

#8. Check for bent rims, either radial flat spots, lateral bends, bent rim beads, and collapsed rims.

Radial flat spots are usually caused by hitting curbs or landing too hard.

Lateral bends are caused by impact to the side of the rim.

Bent rim beads is usually a ding inwards or outwards. This is a minor problem that can be hammered out before truing the wheel.

Collapsed rims (aka Potato Chip syndrome) is when the wheel is bent so out of shape it looks like a potato chip. If so then its time to toss the rim in the recycling bin and get a new one.

#9. Cracked rims are useless. Toss it in the recycling bin and get a new rim or a new wheel.

#10. If the sidewalls of the rim are worn-out or have severe brinelling (caused by too tight brakes) its time to replace the rim/wheel.

#11. Cheap rims are very difficult to be made true because the sidewalls cannot be made true at the same time. Some of them can just be a waste of time and it would be cheaper to replace the rim or wheel.

#12. Check to see if the tire is glued to the rim. Removing and re-gluing a tubular tire is expensive and not recommended. Gluing a tire is also potentially bad because if an accident happens the bike shop can be sued for faulty work. The best solution is to deflate the tire and try to work around it. You may need to put fresh glue under any sections that has been lifted.

#13. Mislaced spokes can be spotted by looking for spokes that cross other spokes 3 or 4 times. Depending on how badly the spokes were laced onto the wheel you may need to pull them all out and start afresh by cross lacing the spokes, each one at least one hole off from where they should be in the flange.

TIPS WHEN TRUING WHEELS

#1. Don't turn the nipple the wrong way when you meant to go the other way. Pay attention to which way you're turning and whether it is tightening or loosening the nipple: Righty tighty, lefty loosey.

#2. Don't over-tighten the nipples. That could break the spokes or bend the rim.

#3. Set the truing stand so it just barely touches the wheel rim. After you tighten the nipple closest to the stand, the wheel rim will move a fraction away from the stand. If it doesn't you've turned it the wrong way.

#4. Don't turn the nipple a full turn when adjusting. Quarter turns are better. It is better to tighten everything slowly and one nipple at a time than doing full turns and overtightening sections of the wheel.

#5. Follow procedure, not instinct. Some people seem to think they have an innate ability to know when a wheel is true. WRONG! Often they worsen the situation by ignoring procedure.

#6. Double and triple check things. Once section is trued that doesn't mean it won't be made out of whack later. When you tighten one section of the wheel you have to go back and double check all the other sections because they've just been made looser in comparison.

#7. Always correct the lateral true before checking the dish or using a dish gauge.

#8. Keep track of both sides of the wheel, especially when making lateral and dish corrections. Mark the right side of the wheel axle with tape or a rubber band so you can remember which side is the right side.

#9. Try to do the right side first with everything, so you get in the habit of it and won't make mistakes by losing track of which sides you've already fixed. Its also because the ride side tends to be the side that naturally needs to be fixed more (don't ask why, it just is).

#10. The lateral alignment will not stay constant, especially when fixing radial dips and bumps. You will need to recheck for lateral errors constantly. (A good trick is to check after every 3 corrections.)

#11. Remember for every nipple you tighten there are 27 to 35 (depending on whether you have 28, 32 or 36 spokes) other nipples that have just been slightly loosened.

#12. If you don't backtrack while working on lateral errors you will end up creating more lateral errors and end up in vicious cycle (haha, cycling pun).

#13. When correcting a round error, remember to balance both left and right sides. Its better to tighten two spokes at the same time so you maintain lateral balance.

#14. Be very careful using math when dealing with spoke tension. Spoke tension meters can be confusing for amateurs so be careful about your measurements. Some people like to ignore measurements and pluck the spoke like you would a guitar string. If you get a sound then you are on the right track. If its so loose you don't get a sound then its really loose. DO NOT TRY TO MEASURE SPOKE TENSION BY SOUND. Some amateurs claim they can true a wheel by plucking the spokes, but that is a myth because the tension will be off by 20 kgf or more and would be dangerous if the wheel has catastrophic wheel failure. An amateur who does so also places themselves at risk for being sued if someone gets injured or killed because they didn't true the wheel properly.

#15. Measure the right side first, because if you measure the left side first and correct it you will over-tighten the right side.

#16. When measuring tension readings, keep track of every reading on paper and divide by the appropriate number to get the average. A common mistake is to divide by the wrong number and get a result that is horribly wrong. Another common mistake is adding the same number multiple times before dividing. Watch out for numbers that look suspiciously high or low.

#17. There will be lots of little errors. Don't stress it out, just be patient and you will correct it by following procedure.

PROCEDURAL STEPS WHEN TRUING A WHEEL

1. REMOVE THE WHEEL FROM THE BIKE.

2. REMOVE THE TIRE FROM THE WHEEL.

3. MARK THE RIGHT AXLE.

4. JERK AND JIGGLE AXLE TO MAKE SURE IT ISN'T LOOSE, TIGHTEN IF NECESSARY.

5. INSTALL WHEEL SECURELY TO TRUING STAND, RIGHT AXLE ON RIGHT SIDE.

6. CHECK THE DISHING USING AN ADJUSTABLE DISHING TOOL (see below).

7. PUT A DROP OF OIL ON THE TOP AND BASE OF EACH NIPPLE.

8. MEASURE SPOKE AT ITS MIDPOINT TO GAUGE SPOKE SIZES. WRITE DOWN RESULTS IN MM, INCLUDE FRACTIONS (common sizes: 2.0 mm, 1.8, 1.7, 1.6, 1.55, 1.5...). SOME TRUING SETS COME WITH A SPECIAL SPOKE GAUGE YOU CAN USE.

9. FIND YOUR SPOKE WRENCH FOR THE APPROPRIATE GAUGE SIZE.

10. USING A TENSION METER, CHECK THE TENSION OF THE SPOKES ON BOTH SIDES OF THE WHEEL AND COME UP WITH AN AVERAGE TO DETERMINE YOUR AVERAGE STARTING TENSION. YOU CAN CHECK JUST 10 SPOKES, OR YOU CAN CHECK'EM ALL DEPENDING ON HOW ANAL YOU WANT TO BE.

11. ADJUST THE TRUING STAND CALIPERS TO A POSITION WHERE THEY BARELY TOUCH THE SIDES OF THE RIM.

12. SPIN THE WHEEL WITH YOUR LEFT HAND AND WHEREVER A BUMP TOUCHES CALIPERS (USING YOUR EYES AND EARS) STOP THE WHEEL AT THAT SPOT OR SECTION AND ADJUST THE SPOKES USING A SPOKE WRENCH IN YOUR RIGHT HAND. IF YOU WANT THE LATERAL ALIGNMENT TO GO RIGHT, PUSH THE WRENCH FORWARD ON RIGHT SPOKES AND PULL LEFT SPOKES TOWARDS YOU (AND VICE VERSA). ALWAYS ADJUST THE SPOKES ON EACH SIDE EQUALLY, IN GROUPS OF 2 OR 3. (IF YOU ADJUST 2 RIGHT AND 1 LEFT, USE HALF FRACTIONS ON THE TWO RIGHT SPOKES.) ADJUST THE SPOKES WITH QUARTER, ONE-EIGHTH OR ONE-SIXTEENTH TURNS. DO not USE HALF OR FULL TURNS (THIS COULD OVER TENSION YOUR SPOKES AND BREAK THEM, AND IT COULD CREATE TENSION PROBLEMS THAT WILL WARP THE WHEEL IN OTHER SECTIONS.)

13. REPEAT STEP 12 AGAIN AND AGAIN UNTIL MOST OF THE LATERAL BUMPS ARE GONE, TIGHTENING THE CALIPERS EVERY TIME THE BUMPS BECOME TOO SMALL TO TOUCH THE CALIPERS.

14. YOUR END GOAL IS TO GET THE LATERAL ALIGNMENT WITHIN 0.5 mm OF TOLERANCE. PROFESSIONAL CYCLISTS LIKE TO HAVE IT WITHIN A RANGE OF 0.1 mm or 0.2 mm, BUT THIS IS NOT NECESSARY FOR MOST CYCLISTS.

15. ONCE THE LATERAL ALIGNMENT IS DONE, ADJUST THE CALIPERS AND CHECK THE RADIAL ALIGNMENT (THE OUTER EDGE OF THE RIM). LOOK FOR BUMPS AND DIPS. TIGHTEN BOTH LEFT AND RIGHT SPOKES WHERE YOU FIND BUMPS, OR IF THE BUMPS SEEM TO BE MANUFACTURING ERRORS, USE SANDPAPER & STEELWOOL TO SMOOTH DOWN THOSE BUMPS.

16. CHECK THE SPOKE TENSIONS. GENERALLY SPEAKING YOU WANT TO ADJUST FRONT WHEELS TO 80 - 100 kgf AND REAR WHEELS TO 100 - 120 kgf. THIS MAY VARY DEPENDING ON THE SPECIFIC WHEEL SPECIFICATIONS (ie. expensive titanium wheels). IF THE RIDER IS EXTRA HEAVY OR THE BICYCLE IS BEING USED FOR EXTREME RIDING YOU WILL WANT MORE kgf. A LIGHT RIDER OR AN OLDER WHEEL SHOULD BE ADJUSTED SO THE TENSION IS LIGHTER.

17. TAKE THE WHEEL OFF THE STAND, PLACE THE AXLE ON THE GROUND AND PLACE YOUR HANDS ON THE RIM AT 180 DEGREE ANGLES AND PRESS DOWN GENTLY BUT FIRMLY. YOU MAY HEAR TINY POPPING SOUNDS. REPEAT THIS ON BOTH SIDES AT DIFFERENT ANGLES.

19. RECHECK THE DISHING AND LATERAL ALIGNMENTS FOR ANY ERRORS. REPEAT STEPS 12-17 AGAIN IF NECESSARY.

20. RE-ATTACH YOUR TIRE TUBE AND TREADS, AND PUT YOUR WHEEL BACK ON YOUR BICYCLE.

USING A DISHING TOOL

When using a dishing tool you want to check to see how well the hub is centered compared to the rim. Start from the hub and push the tool into place so the sides are touching the rim. (If both sides of the rim don't touch then its a sign you have some major lateral errors.) Lock the center piece of the dishing pool in place and turn the wheel 90 degrees and check to see if both sides of the rim touch the tool. Some people like to spin the wheel a bit to see if there are any majors gaps.

Then take the tool (with the center piece locked in) and compare it to the other side. If the middle or rims don't all touch at the same time it means you have some lateral dishing errors that need to be fixed. Determine which side needs to be adjusted and remember that when you are fixing the laterals (see below).

USING THE TENSION METER

Squeeze the hand levers on the tension meter and place the three prongs around a spoke. Release your hand gently and that spring-loaded lever will indicate a degree on the side of the meter. Using that degree you can compare it on the kgf chart for the approx. tension value in kilograms of force (kgf). In the early stages of wheel truing you will want the spoke tension to be about 70 kgf, but as you get closer to the end of the process you will want to adjust all the spokes to the desired kgf range (approx. 80 - 100 kgf for front wheels and 100 - 120 kgf for rear wheels).

FINAL NOTES

Truing a wheel, especially if you've never done it before, is a difficult task. If you're still unsure I recommend reading BARNETT'S MANUAL, chapter 17. It is the ultimate guide to bicycle mechanics (he's very anal and scientific about it). Truing a wheel is NOT an art form, no matter what amateur mechanics may tell you. Its a science that requires a lot of measuring, careful tracking and adjustments, the proper tools and patience in order to get a perfectly round and safely tightened wheel.

If you decide to hire a professional, ask the bicycle mechanic if they have a tension meter, a truing stand and a dishing tool. If they are missing ANY of these three, they're not a professional. Don't trust your wheels (or your life) with an amateur.

3 comments:

  1. Interesting article on truing, with a number of useful comments. Way too arrogant for me, though. I have put in 30 professional years behind the wrench, including successfully and professionally building and truing wheels without a tension metre. Using a tension metre without knowing first how to properly judge tension by feel and sound, is akin to giving a four wheel drive car to someone who can not drive in winter on the assumption that the car will cover for the drivers ignorance, and as a result give the driver false confidence in the car, leading to "catastrophic failure". What about the extra hour it adds on to the build? If a mechanic is unable to do what she or he says with or without toys, it has nothing to do with amateurism or professionalism; it comes down to spending more time on the truing stand and learning and experiencing the true nature of the beast. There are wrenches here in Victoria whom I trust. I have not noticed the use of tension metres, nor has their absence appeared to affect the work done by these professionals. Nice try.

    ReplyDelete
  2. I just built a set of Velocity Dyads. They were my first wheel build so I bought a Park Home Mechanics truing stand and tension meter as well as 3 different Park tool spoke wrenches. I spent the better part of 3 evenings reading articles on the internet and doing and undoing the nipples in an attempt to build the perfect wheel.

    I have to disagree with Danna on one small point. Before I purchased the tension meter I used the "flick and listen method". But when I squeezed the spokes they seemd soft. I went ahead and purchased the same tool pictured in the article and found that most of them were less than 70kgf. Velocity suggests 110-115. And since I am building a 5 speed steel framed touring bike, this would have been totally unaceptable for the weights and road conditions I may encounter.

    So as I respect that fact that you have been doing this much longer than I have been riding bikes, I do believe that if it wasnt important, the manufacturer wouldnt suggest it. In fact had I bought the wheels already built by them.....(I added a sturmey archer 5 speed internal hub so this wasn't an option), then they would have been built to those tolerances.

    ReplyDelete
  3. Oh, and great article! very informative and thoughtfully written.

    ReplyDelete

NOTE

Spam comments will not be approved. If you want to advertise your product or service (or want to sponsor this blog) please contact charlesmoffat@charlesmoffat.com.

Recent Posts

Popular Posts

Looking for a bicycle mechanic school in Canada? The Quadra Island Bike School in British Columbia is a Canadian bicycle mechanic school that trains professional bicycle mechanics against the backdrop of the beautiful Quadra Island.