Removing tubular tires should be easy. Getting the tire off the rim should not require gorilla strength.

Over the past few years a new issue has arisen. Pulling tubular tires from carbon fiber rims can cause delamination of the rim bed. Creepy, to say the least. Is this normal? What is going on? What to do?

Key points:

Carbon delamination – please, no!
No carbon rim maker wants to hear about structural delamination during tire removal. Every design effort is made so it cannot happen, as it is impossible with aluminum rims. We all have the same objectives. Under normal circumstances, the inter-laminar carbon layup strength is greater than contact cement on the surface.

Is the delamination important?
Plies (layers) of carbon cloth are extremely thin. Departure of several plies is visually dramatic but may not be a structural problem. It all depends on the design. The rim maker is your only reference. Hopefully, the departed plies are sacrificial, intended to be rugged and expendable.

Gluing is improving
We are seeing a growing appreciation for tire gluing integrity. More than ever, mechanics are using best practice for achieving strong bonds. In the past, when glue integrity was mainly a concern for high level road racing, technique could be less rigorous. Cyclocross, in particular, sees weird rim-to-tire combinations (where bed and tire form do not closely match), suffers water contamination (weakening bonds), and uses very low tire pressure (lower pressure = less tire grip to assist the glue). CX gluers are doing really good bonding.

How to minimize risk when removing a tubular
First, deflate the tire. Air pressure makes the tire grip the rim. Not enough grip to ride without glue but enough to interfere with removal.

Next, try and pry a small section of tire free. Use all your thumb and grip strength. If the tire is properly glued, you will fail. Well glued tires cannot be removed by hands alone. Still, give it a try. After working a 10cm section on one side, flip the wheel over and try opposite. With luck, some of the tire base tape will begin releasing from the rim.

Even strong hands may fail.

You’ll then need a narrow pry tool, such as a slotted end screwdriver, to push into the glue and separate the tire from the rim. Your goal is to push the screwdriver (or equivalent) all the way through between tire and rim, from one side to the other. A steel tool like this can damage the rim or the tire. Use it gently, pushing carefully, wriggling small amounts, separating the tire from the rim in tiny bites.

Careful screwdriver use.

Hurry, the driver is through.

Once you achieve tool insertion, replace the slotted (sharp end) screwdriver with a round, Phillips type. My best luck is with a blade about 6mm (1/4″) in diameter. A larger diameter dowel works but the rim and tire prefer the small steel shape. While seated, place the wheel between your legs, with the screwdriver handle in your dominant hand. I am right handed, so here the screwdriver handle is on the right.

Rotate the handle clockwise while you pull the driver towards you.

Orient the wheel so the screwdriver is at the top. Pull the driver towards you with both hands while you rotate it clockwise (viewed from the right side). Pulling while rotating advances the blade towards you, rolling against the sticky tire bed and skidding against the smoother rim.

This rolling requires a strong turning hand (right for right handers) and a firm pull on both sides. The tire bond is no equal for this rotation. The tire will begin to separate from the rim as you pull and rotate.

You can also use a dowel but the screwdriver blade offers less resistance and a better separation angle. The glue joint is more susceptible to the small radius of the metal driver.

You’re inducing a glue joint failure and the angle of separation is better for the small rotating blade than a larger rotating dowel. We’re inducing a cohesive failure with glue remnant on both rim and tire, handy for future gluing.

As soon as enough tire is separated, pull the tire from the rim. Pull in the plane of the wheel so the tire is doubled over as it leaves the rim. This minimizes base tape separation as you pull it from the rim.

Back to our carbon rim problem, Using the small diameter metal rod induces cohesive failure and minimizes the chance of rim delamination. The final tire removal (over 50% of the circumference) is done without the metal rod, just arm strength. Doubling back the tire as it peels reduces delamination forces.

More than a few mechanics note that heat aids tire removal. At 70C (160F) rim cement is liquified. At 40C (100F) cement is substantially weaker than on a cool day. Using a heat gun to warm is impractical. A wheel is large and sheds heat. At least appreciate this principle and let wheels come to the highest available temperature before pulling tires.

Throughout tire removal, proceed slowly and watch the tire carefully. Stop if anything does not proceed smoothly. Some tires will disintegrate upon removal but it’s rare except for limited use track tires.

There is much to tire mounting that you must know. Demounting is not the opposite of mounting. Great instructions are available in many places: mine (here and here), Calvin’s, and Chip Howat’s scholarly works, among others. Gluing tires is done thousands of times a day and each job carries immense responsibility for rider safety. Learn your stuff and be part of the reason cycling is known as a healthy sport.

As ever, practice is the best teacher. Try different techniques, pester experts with questions, listen to all opinions, and develop dependable techniques. There are too few tubular gluing guru’s. Please join this club!

This piece is only of interest to a minority of professional bicycle mechanics. That’s my excuse for such a lengthy exposition and references mechanics will catch but others may not. The time for this story is now, mechanics are networking and organizing as never before.

A can-do mechanic.

Starting with a cadre of race mechanics, acquainted through events and programs like the USAC Mechanics Program, there is now a professional mechanics FB site that has grown to 3000 members in a matter of weeks. If you are a mechanic and not a member, please check it out. Many important discussions are occurring around shared goals of improved standards, wages, accountability, diversity, technique, and advancement. My two bits are related to those topics.

The following concepts are big but simple, so I’ll tell it like a story. The story is true in message but not every detail is exact. Please follow along and see if the points make sense.

Service in today’s economy
Service is one of the most secure, best paid, and fastest growing employment sectors in the developed world. Fixing and maintaining copiers, plumbing, computers, vehicles, elevators, espresso makers, etc. is in increasing demand.

Cheer up, it’s going to get better.

Yet bicycle service is plagued by low wages and high turnover. There are few paths to advancement, little diversity, working conditions are often primitive, and access to training is scarce. At the same time, employers (shops, teams, companies, riders) complain of a small pool of effective technicians, widespread low standards, unprofessional attitudes, and lack of accreditation.

Why the contradiction?
When I left retail in 1999, my shop was trying some novel service ideas. That experiment was interrupted but interesting points were raised. I dove into cycle manufacturing, particularly large scale wheel building. I found the economics of manufacturing surprisingly similar to shop service departments. Yet, in shops, service is usually managed like a subdivision of commodity retail.

Seeking answers for the mechanics’ dilemma, I interviewed service operations in motorcycle, auto, marine, and aviation. Perhaps their practices would help explain the contradiction. A telling experience in my quest was a visit with Cal BMW’s owner, Kari Prager (much admired and since passed). His Mountain View, CA business was among the premier BMW motorcycle dealerships in the US. I explained my quest and he asked a few questions.

“What’s your shop rate?”
I said “$95/hr.” My shop was 20yrs old and regionally well known. We had mechanics with high level experience and an impressive service department. Other shop rates went from $50 to $85, so we thought it wise to stake out $95 for ourselves. That’s the way most shops do it: we select a rate rather than generate it from our costs.

Kari said, “Great, I’m impressed. So you pay your mechanics $45/hr? I wish I could do that. Our starting wage is over $60/hr and still we have turnover trouble. They’re poached by auto performance shops that pay better.”

I said, “Whoa, we pay around $20/hr and are locally famous for such a high rate. I couldn’t pay more if I wanted.” Kari said, “That’s incredible. You charge $95/hr and only pay $20? What a clever guy you are. What do you do with all that money?”

I said, “No way. I’m always broke and challenged to make payroll. I can’t buy a new car. There’s no gold mine at my shop.”

He said, “Something is wrong. If you charge $95, where is the money going?” This led to a simple experiment: determine the ACTUAL labor rate. It’s simple: pick a period, divide all receipts for labor by all hours devoted to those jobs. Exclude phone calls, customer consults, and parts chases. Count only hours for jobs. This will identify the ACTUAL labor rate as opposed to the ADVERTISED rate.

We did this and found our ACTUAL rate was 1/2 our ADVERTISED. I have since done this calculation at a number of shops and never found an ACTUAL rate that was more than 1/2 the ADVERTISED rate.

Huh? Customers are asked to pay a labor rate, they agree and, without being told, are charged half. Mechanics are told their work is being charged out at a specific rate but then paid less than 1/4 in wages. Service business in the larger world doesn’t do this. This is broken thinking and everyone loses.

What do other service sectors do?
In auto, marine, and aviation service operations, I found similarities to each other but little resembled bicycle practice.

One way to make it easier.

The point is to know more precisely how service makes money, which usually leads to higher wages for mechanics. Here is how it is done: each task is assigned a flat rate that represents expectations (not necessarily outcomes) for each job. Mechanics record (with a time clock) the beginning and end of every task. Answering phones, service writing, selling, unpacking orders, these are clocked accordingly, NOT as service labor. This record keeping must be diligent, it’s nearly impossible to track without time clocks.

Time clocks are unwelcome in most bike shops, seeming impersonal and authoritarian. However, service is more like manufacturing than commodity retail. In manufacturing, time clocks are the worker’s best friend. They defend proper compensation. Management must prove that all clocked hours are paid. Time clocks are not exploitative but empowering evidence on behalf of mechanics. Likewise, if your efficiency as a mechanic is brought down by interruptions, the evidence should be available.

Using a time clock does not mean piece work pay. That is another discussion. The time clock gives the shop data to become smarter and, in turn, mechanics are usually winners.

Each week, data must be analyzed. Every job type (overhaul, tire install, etc.) is checked against hours to see how close it comes to expectations (flat rate). Each mechanic is measured for efficiency. Some are fast, some are slow. We know whose work is better (compliments, come-backs…) but who is consistently faster is often barely known.

What to do with this insight?
Some jobs need re-pricing, up or down; others require better specs so time spent matches time expected.

Mechanic productivity varies more than most think. Interruptions are extremely expensive. Mechanics who are best paid are too often slow. No other service scene employs so many that are not particularly mechanical. Intuitive mechanics solve problems while they move forward, anticipating parts and tool needs, and try and work as quickly as possible. It seems programmed into the very core of a gifted mechanic. Like commercial chefs, they do not work like home cooking aficionados. Many bike mechanics are enthusiastic riders. Some should be service writers, not mechanics.

Shops are like race teams. In general, the quickest rider is the best paid. Many shops do not know enough about speed. Faster mechanic numbers jump off the page. They can be 2-4X faster, may lack an interest in chit chat, may not ride so much, may prefer mechanical hobbies.

Our industry does a poor job of retaining them because they are not paid according to their productivity and drift to industries where they are. Too many cycling mechanics are not mechanically intuitive. Service businesses outside cycling normally pay at least 1/2 of their labor rate to the mechanic. If paid less, the shop rate may be bogus.

There is no correct response to this collected data. Anyone with it will have ideas. Slow mechanics are welcome but shouldn’t be paid too much. For tiny shops, time clocks may not be an option. The point is: too few in the service end of cycling seek or have these numbers. We’re not trying to make shops like factories. We want to be as smart as possible and not suffer any avoidable handicaps.

Until more shops measure service the way successful operations outside cycling do, gifted mechanics will have trouble being paid and the career will remain backward. Many improvements in the profession are needed but if the engine that pays is busted, progress will be slow!

Spline’s Advantages
• Lighter than square drive
• Cannot strip (spoke breaks first)
• Aerospace aluminum (2024-T6)
• Nearly impossible to scratch color
• A wrench fit every 60° rather than 90°
• Sleek, distinctive, better, available now

Why Not Square?
Fastener interfaces have evolved since the dawn of mechanics. Square was the first shape for fastener heads and matching wrenches. Square steel nuts were common on machinery of the late 19th through mid 20th century but today hex drive shapes have displaced them. One reason is that a hex pattern offers wrenching access every 60°, while square offers only at every 90°.

Square headed nuts were also known as cut nuts, made by drilling/punching a sheet of steel with holes in rows and columns. Then the sheet was cut in a shear creating strips each with a single row of holes. These holes were threaded and then a second shear cut across the strip making square nuts. The cutting process was often inaccurate and cut nuts were often not square nor the hole centered.

1949 agreements to standardize threads into ISO inch and metric spelled the end of square headed bolts/nuts (except for cycling!) since new and better machinery to make them would have been required. As machine design advances, nuts and bolts must fit in smaller spaces, meaning less room to swing wrenches through a useful angle. The more faces on a nut, the better.

Rainbow without weakness!

No more of these.

Why Spline Now?
For bicycle nipples, we have a work in process. Square drive has been unchallenged for 1-1/2 centuries. With steel and brass as dominant nipple materials, enough torque can be delivered to build and repair worst case wheels. However, aluminum is fast replacing brass on higher performance wheels, reducing rotating weight and offering a range of decorative colors. Square is wrong for aluminum which is softer than brass. At the very least, decorative anodizing is too easily scratched, even during careful builds.

Stripped and deformed aluminum nipples are common, driving a backlash back to brass. With a spline drive, an aluminum nipple can resist more twist force than ever needed. In fact, a spline nipple  fails only after its spoke snaps from the torque. You will never see a spline nipple torque failure. No wonder both Mavic and DT regularly use splined nipples of their own design.

Technically Speaking
To be precise, the drive standard on our nipples is compatible with Spline Drive of the 1990’s. An attempt was made to commercialize splined nipples by entrepreneurs in Southern California. Perhaps their approach was flawed, certainly the industry was not yet ready. They closed up but not before thousands of builders used them with many considering it superior.

Our standard is described in US Patent 5673976. Technically speaking, it’s not a spline but, instead a ribe drive. There is no wavy curve to the contour (like Torx). It resembles a freehub body with all driving surfaces meeting squarely. Enormous amounts of metal need to move in order for the drive to strip.

About Wrenches
Available now:

7 wrenches.

The detail, below, shows the wrench shape. Notice the convex curve on its bottom surface  to maximize rim clearance.

This wrench delivers more torque, engages every 60°, and won’t slip off the nipple by tipping away (fewer wrench drops). We offer one model in the familiar chromed wire loop, Park-type shape. Other styles will become available during the year. Though we are currently the World’s only source of 12mm aluminum spline nipples, this won’t last for long!

Now is a great time to dive in and enjoy this building option. Sleek, light, smart, and faster to build!

The Golden Nipple
At NAHBS 2016, we made a huge gold nipple from poplar. Below, it takes shape in Jon’s MT shop. By now it has been seen Worldwide thanks to journalists and other fans of the unexpected!

If your tensiometer grabs a spoke but the spoke thickness is not what’s expected, what happens? No surprise, the tension reading is WRONG. The news is how huge these errors can be.

Why?
All commercial spoke tensiometers read spoke thickness as well as deflection. The ONLY exception is the Wheel Fanatyk (Jobst Brandt) design. For all others (DT, Sapim, Park, Wheelsmith, Pillar, CN, Icetoolz, Hozan, Union, Centrimaster, etc.) spoke thickness is a major part of the reading.

Drawn wire is not as precise as one might assume. 14 gauge, for example, varies commonly from 1.96 – 2.02mm. Swaging (for butting) and forging (for blades) is also imprecise for dimension. Sapim publishes the CX-Ray thickness as 0.9mm. Many would admit this is often 0.95mm. Such variation is within normal spec but wreaks havoc on tensiometer accuracy.

© DTSwiss

Painted spokes are popular. Paint thickness varies all over the map, even within small batches. The chart below shows some careful (but limited quantity) measurements and the reading errors they induce.

For white CX-Rays, batch 1 and 2 were far apart but similar within the batch. Perhaps batch 2 was double coated? This would make for an extra rugged finish, hardly a spoke company error. But attempts to read tension go haywire.

Do not over-analyze this chart
These specific predictions are not the point. It is the principle that needs addressing. Spoke thickness (at the location the tensiometer is working) can be all over the map these days. To avoid huge tension measurement errors you have limited options.

Three options
(1) Rely on your trained sense of appropriate tension (comes with practice) to avoid big mistakes. This is especially effective if you have years of experience, have made many learning mistakes, and are familiar with the components in hand.

(2) Measure the spokes in your wheel before you use your tensiometer. The best way to determine thickness is not a basic vernier caliper. You want 0.01mm accuracy which can be consistently delivered by a micrometer. You need to know average thickness and approximate range.

Inferring correct tension from a measured thickness discrepancy is not so simple. Common sense leads in the right direction but tension vs reading is not linear and knowing the shape of the underlying curve requires a fair bit of math. A simple engineer’s task but daunting for so many tools, spokes, paint, and for each wheel. Certainly limited insight is better than blindness!

(3) Switch to Jobst’s design where NONE of this has ANY effect. Thirty years ago he wanted tension reading free of spoke thickness. With this priority in mind, many possible tensiometer designs are useless. The position of a deflection load, points of contact, and indicator location make a design vulnerable or immune to spoke thickness variation.

It is not a stretch to assume tensiometers of the future, whatever their appearance, will take care to isolate the deflection from thickness. Errors like builders are now suffering are entirely avoidable. There is no associated cost to a correctly designed tension measuring tool.

Anecdote
During NAHBS (2016) I was fortunate to learn about wheel building at Edco in Switzerland from Randy Kilgerman and Rob van Hoek. They use Hozan tools and painted spokes in some wheels and I worried about the possible tension errors as Hozan is vulnerable (like nearly all others) to spoke micro thickness variation.

They assured me, good engineers that they are, this is well understood and they calibrate their tensiometers to the spokes used. Their own calibration “chart” accounts for the painted spokes additional thickness (assuming it is consistent).

How many of you make your own calibration charts for particular examples of painted (and bladed) spokes? Spoke tension is not the end-all in wheel building but it is beyond silly to spend time measuring or discussing spoke tension if accuracy is absent!

Our Spoke Cutting & Threading (SCT) machine has undergone some pretty nifty improvements. All the tweaks below are found on SCT’s we currently (2016) ship. If you plan to attend NAHBS in Sacramento, please pay us a visit in booth 85 to see this marvel in person.

The design’s inventor is Morizumi Masakazu who made them by himself and, since 2007, is represented worldwide by us. In 2014 Mr Morizumi stepped back from production and a new team took over. Mr Morizumi stays closely involved with the project and we continue to add clever details.

Read more →

For years we’ve needed a dedicated wheelbuilding oil for spoke threads and nipple-rim contact. Builders succeed with oils intended for other uses: linseed oil (for paints), chain lubes, and oil for derailleurs and brakes. However, wheel building is a very specific task and deserves a dedicated lube.

As builders, we have particular needs: our task can be quickened or hindered by tool and lubricant choice; the wheel itself has specific performance objectives and hazards to endure; and the builder has aesthetic, economic, and health concerns.

At last, Wheel Fanatyk announces CLEAR, oil for wheel building.

4oz and 16oz sizes, each with cap and spout.

FEATURES
(1) Amazing friction reduction, a truly slick feel between fingers. Equivalent load capacity and wear reduction to the highest grade motor oils.

(2) High viscosity but easy to pour. Adheres to and compatible with all materials. Excellent corrosion resistance.

(3) Food safe (Kosher Pareve and HALAL registered) and biodegradable. No known symptoms from eye or skin contact or ingestion.

(4) 100% synthetic, extremely temperature stable. Over 100°F higher flash point than most petroleum or mineral based oils.

(5) Economical, available in 4oz (118ml) and 16oz (473ml) bottles with caps and Yorker spouts.

Convenient pour tips.

TOXICITY
We rarely discuss toxicity in bike mechanics. Maybe because the sporting goods industry is full of health, fresh air, and fun. Besides manufacturing, the industry seems clean and benign as a public park. We also face more obvious risks: losing it on a steep section; a distracted driver in your right of way; or oil, slimy leaves, or ice where you least expect it.

Wheel Fanatyk CLEAR meets high performance standards but takes toxicity very seriously. To understand means seeing through over-simplified labels like “environmental,” “biodegradable,” “green,” “natural,” etc. Unfortunately, that means most prospective customers won’t make it through the story. For those of you who do, you are a lucky lot. Choices like the one I’m offering are key to living well in the 21st century.

Nice image that stands for no particular standard. Used for dry cleaning, diapers, and produce.

Green for the biosphere can be toxic to humans. We often miss this detail and chain lubes are a good example as many go the extra mile to be environmentally friendly. However, how many are truly non-toxic? A bit of anything you breathe or contacts your skin ends up in your blood. We are protected from many contaminants but our bodies are permeable.

ECB (European Chemical Bureau) hazard symbol.

FOOD SAFE
What is the standard for safe use? That is a complicated question so I, as a potential user, suggest “Food Safe.” Most bicycle lubes and cleaners fail this test. Sometimes there’s no choice for the task at hand, but there is often an alternative.

After decades of covering my hands with lubes, fuels, and cleaners as a mechanic, I am determined to offer a Food Safe wheel building oil. This quest seemed hopeless until entering the food processing world, a huge scene with many products that never see retail commercialization. Long story short, I found lubricants with astounding performance including being food safe!

No surprise, just think of the massive horsepower, speed, temperatures and loads in food processing. I found a gear lubricant that outperforms synthetic automotive racing oils yet is Food Safe. Why aren’t these in our cars? Price, of course. Secondly, “Food Safe” isn’t required of many chemicals not meant for bare hands. Paints, for example, are used with gloves by those with chronic exposure. Same with automotive oils. Bicycles, however, are hands-on machines both for riders and mechanics, and nearly impossible to work on with gloves.

CLEAR WHEELBUILDING OIL
It’s called CLEAR because it is almost completely transparent. In actuality, there is a faint amber tint but in a tablespoon it appears transparent. Let your components shine through. It is also nearly odorless.

Question: what about linseed oil?
(1) It must be industrially boiled so that it will eventually dry. Boiled linseed oil retains the label “boiled” but no longer is. The equivalent chemistry is done today with additives that are usually not specified. Toxics in these additives (heavy metals) are in very low quantity and, besides, boiled linseed oil is intended as a paint or paint ingredient. Why risk if there’s an alternative?

(2) “Boiled” linseed oil dries by oxidizing. In a warm and humid atmosphere drying can take two weeks; too long for an event in process. Oxidation releases heat and anything flammable (textiles, paper towels, wood chips) containing “boiled” linseed oil will catch fire, with near certainty. Closing the container limits oxygen so the fire may be delayed. This tendency to burst into flames makes “boiled” linseed oil a substance to handle with care.

Question: how best to apply CLEAR?
(1) Apply as you presently use oil. Many add to a freshly laced wheel, dripping into the partly occupied nipple bore and around the nipple head to wet the nipple-to-rim seat.

(2) Others prefer dipping nipples in oil, draining, and then sorting. Wheel Fanatyk’s Nipple Bath and Nipple Shuffler support this approach. Pick up each pre-oiled nipple from the Shuffler with a pointed tool like EVT’s Mulfinger or our Nipple Inserter. Then start the nipple on a spoke. CLEAR’s high viscosity means plenty is on the nipple even weeks after a soak-drain.

(3) To secure threads, use a post-assembly Loctite™ (222 or 290) or DT Spoke Freeze™, or coat spokes with a compound like Spoke Prep™ prior to lacing. I prefer the last since Prep dramatically reduces friction so truing is less strenuous and more accurate. For me, this is fastest.

MORE DETAILS
• CLEAR oil is a synthetic, PAO based material. This accounts for the astounding load capacity, thermal stability, and surface tenacity.
• Actual viscosity: ISO-320, SAE 60 (engine), SAE 125 (gear), AGMA 6. Easy to pour and apply.
• CLEAR has no food value, do not drink! If ingested, stay calm and drink small amounts of water.
• Exceptional water resistance, high demulsibility, superb corrosion resistance.
• Outstanding film strength, ASTM D-4172 (4-Ball Wear Test) = 0.31mm. Here (pg 4) is a 2013 test of ten high end synthetic oils that CLEAR would have won.
• CLEAR bottles are HDPE (plastic #2), durable, squeezable, most recycled plastic in the US.

A responsible choice.

• Biodegradable is good but we don’t want this oil degrading quickly. Technically, CLEAR is “ultimately biodegradable.” Like steel, returning to the environment through natural processes, but not quickly.
• Food safety is not new but programs to ensure it are fairly recent. The worldwide standard, HACCP, was developed as a microbiological safety system in early days of the US manned space program to assure the safety of astronaut food. Prior, most safety was based on end product testing that didn’t fully guarantee safe products as 100% testing was impossible. Consequently the pro-active, process-focused HACCP concept was born. CLEAR is in compliance, meets FDA regulations 21 CFR 178.3570 and CFR 172.882, and certified NSF H1.
• Wheel Fanatyk sells direct so an important margin is missing, hence more value.
• MSDS is available on our site.

TRY IT!
The 4oz squeeze bottle is a generous amount for a busy wheelbuilder and enough to form your own opinion. You may resupply with the 16oz bottle but the 4oz container is still the most convenient to use if you apply at each nipple.

If you’ve made it this far, you are definitely someone who should try CLEAR!

My fellow spoke nerds deserve something to chew on, even at the risk of boring other worthy readers.

Disclaimer: I’m going to share some magnified images of threads. Some of you may find these unexpectedly ugly and not representative of the named brands. Mind you, none of this post is intended to evaluate brands. Let’s just explore the details.
Read more →

Part 4 closes our ball bearing series with a visit into how these little mechanisms impact our wheel building.

Bearings make wheel building possible. However, their effect is exaggerated. What happens at the hub is magnified ten-fold at the rim (where we work). This is owed to wheel geometry and must be appreciated throughout the build process. Bearing play has a disproportionate effect on trueness but it’s there for an important reason.

Play is good
For anything to run freely there must be play, a bit of extra space between moving parts so they never suffer self-inflicted friction and wear. The loads of cycling are quite enough. Internal, avoidable loads are unacceptable. Play can be small if rolling parts are made and aligned with great precision. While grease prevents easy feel of this play, it is present none the less. If a hub is built too tight, without such play, wear will create it. Running in a tight hub makes needless wear that eventually creates the missing play.

Work without play is dull.

A wheel builder wants a hub with no play so the rim is not subject to movements generated by bearings rather than spokes. Trouble is, 0.002” of hub play (less than the thickness of paper) creates 10X the rim play. Most riders consider 0.02” rim play excessive. If a rim jumps around on bearing looseness, truing becomes a moving target. In the past, most hubs could be tightened to excess (bad for riding) so they are free from play (good for building), then loosened for use. Today’s hubs are more often equipped with cartridge bearings that can’t be adjusted (magneto bearings as used in Odom hubs, an exception). Many riders perceive hubs that have no play to be superior but more often the absence of play is evidence of friction under load.

A builder can do little to fix a hub’s play/friction situation. We need to notice if untrueness seems to change from rotation to rotation. If the pattern of rim wobble is not exactly the same on each wheel rotation, you can be sure something in the bearings is responsible. You might worry you’ll be blamed for untrueness owed to bearing play but rarely will you. While truing, keep a finger on one side of the rim, applying a small side load to dampen bearing play. This way you can see actual wobble more clearly and true in spite of play.

It’s important you appreciate bearing play because it is a guarantee of smoother running and longer lasting mechanisms. All small cartridge bearings, made for modest (not engine) loads contain play. If handled individually, the play is easy to detect. Manufacturers specify the exact amount for each product. Hub bearings are used in pairs so play is nearly cancelled, but the cost is microscopic friction. Cartridge hubs that claim to be adjustable without using the historic cup-cone (as with magneto) approach, are simply side loading. Play disappears but only thanks to friction.

Play is unavoidable
Up to 0.008” of play (measured at the rim) is generally acceptable in a bicycle wheel. Such a small amount cannot contribute to handling trouble, generate high speed wobbles, or cause premature hub wear. To measure, put a dial indicator on the rim and push and pull using only ultra-low force, just a feather touch, or you’ll be watching the wheel flex. Good proof that bearing play is not a factor compared with regular flexing of the spoked structure.

Bearing play (and untrueness) impacts dishing (centering) measurement. A dishing tool applied to both sides of a wheel is very accurate. Small untrueness and bearing play will reverse dishing measurements if they are taken several times around the wheel. No worry, just don’t be a slave to dishing.

To work with modern hubs and their cartridge bearings, bear a couple of principles in mind:

(1) Spoke tension is a huge force on hubs. Most hubs expand with spoke tension so cartridge bearings no longer fit snug in the hub shell. The solution is to make hubs too tight for bearings but, after spoke tension expansion, the bearing is held with appropriate light force. This is a universal feature among hubs but hard to navigate. Who knows exactly how much spoke tension a hub will see? How can you compensate for an unknown load? As an industry, this problem is handled well. Just be aware that it underlies bearing play issues. No free running cartridge bearing would ever be made to endure the press fits of bike hubs. The expansion of hub shells with spoke tension is supposed to reduce friction-causing compression. The bearing press you use to service the hub would be a bearing engineer’s nightmare if she didn’t know the fit will become looser with spoke tension.

(2) Individual cartridge bearing hubs are built with play both in radial and angular movement of the axle. Since bearings are generally used in pairs in bicycles and electric motors, that movement tends to cancel out between pairs. Hubs that seem free of play actually have excess grease, hiding the play from detection, or friction .Thankfully, such low friction and premature wear are small factors and most hubs give good longevity in spite of it. In practice, more hubs die from contamination and corrosion than pure wear.

Going to extremes

Hub shell in titanium.                               © Gokiso

(3) To have cartridge bearings run perfectly requires unreal attention to alignment. One Japanese hub maker has gone the distance on this topic: Gokiso. Take a look at their elaborate designs. Here is a hub designed by bearings! Not inexpensive but legendary. While 700g and $5000USD may seem high for hubs, these have a strong following. Some models are guaranteed for 29 years and you can watch wear tests of 100,000km at 300kph! Takeaway: all the hubs on the market are all compromises for economy and weight. We use them to take terrific rides but judge accordingly.

Flexing Ti fingers spare bearings shock.                © Gokiso

Get out the Q-tips, this beauty will take some maintenance!             © Gokiso

(4) Resist the temptation to spin your wheel fast in the truing stand. If you do, no worry, but realize it slows you down and makes trueness harder to isolate and address. Short, half turns are mostly what is needed. Adjust an area but don’t throw everything back and begin again from zero. I did this for years. You can become quite quick in spite of such a style but, in the end, it will limit your speed. Contact indicators will bounce, confusing the picture and your eye, while it perceives a pattern, is handicapped for devising corrections. Few can retain the 3D mental image of a full wheel with precision enough to act effectively. It’s just a recess. Spin fast for relaxation but not to nail the target.

(5) Avoid building around a hub with blown bearings. Not only is the task made harder but once new bearings are installed, the wheel may show untrueness or asymmetry. The builder gets the blame or at least the unpaid task of retruing. We build wheels around bearings. Minute changes that arise from bearing replacement will cause effects at the rim. Of course, field conditions may give you no option.

Wheel builders, don’t be overly critical about components like hubs. They’re an easy target. Be a guru so the wheels you create balance cost and performance in your riders’ best interests. That wisdom is too rare. Don’t let marketing define your work. Today’s great products will soon enough be obsolete. The “no free lunch” rule is in play: a perfect running hub is heavy and expensive. Be grateful for the hubs we have and work with the consequences!

Yup, it’s spoke tension time again. I hear too many builders saying “I don’t really know if my tension gauge is accurate but it’s easy to use and we do OK.” Ask yourself, what is a measuring instrument without a scale? Or with a scale that is wrong? Not much. Perhaps a waste of time.

If you use a tensiometer, and not everyone does, be sure of its accuracy. A simple in-shop weight test is better than nothing. Hang a bucket of known weight from a spoke and see what your tools say. Mass doesn’t lie. DT, Park, and we offer calibration tests. There is no specified amount of use that recommends you have a tool checked. Under ideal conditions, a simple articulating, spring loaded tool should go forever. However, the world is full of dirt, accidents, and mischief that puts tools into doubt. Read more →

Here’s a post just for wheel builders. Some topics are best shared with those who understand (not necessarily agree) with what I am saying. If you are not a builder, proceed at your risk. If you find content disturbing, please know that it takes a builder’s perspective. If you don’t have it, don’t blame us.

I’m weary of builders on the spot for spoke breakage. That was true in my youth, an age of much greater wheel building ignorance. Such worry plagued my early career and those of peers. It’s likely some aspiring builders ditched the trade rather than face ever present guilt over spoke breakage.
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