Micro-Truing Wheels - FINALLY!

GSAstuto

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Oct 11, 2009
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tokyo
www.roadfixie.com
#1
After a long and anticipated wait I finally got our first P&K Lie truing stand delviered. Actually I ordered a couple of them - but only one has arrived (another story). But this is enough to get me ranting and raving all over again!

One of the biggest hassles I have as a wheel builder is getting a wheel perfectly round AND perfectly in tension. Especially for carbon rims, where a few kgf either way on a spoke means you either start delaminating the rim, or start breaking spokes. So - there is minimal room for tolerance in building super tight and true wheels with carbon.

The P&K addresses these issues by allowing for wheel calibration + lateral and radial truing instructions within the same unit.

Step 1: Calibrate the wheel - including axle runout. This means to set the gauges (regardless of current wheel state) to absolute center - including the axle! From this absolute center - you can begin all truing steps.

Step 2: Run the wheel through a complete revolution to acquire maximum runout laterally and radially.

Step 3: Adjust ONLY the spokes at the max runout points to bring the wheel into perfect true.

Step 4: Cross check tension and repeat above (if required).

Since wheel runout is determined primarily by spoke tension and then secondarily by several other factors (including hub runout) , this method allows for very fast and super accurate of truing and then any post-truing compensation required to make the wheel 'perfect'. In essence, the builder knows exactly what's going on with the wheel from the absolute center point on out. So the wheel is trued as a 'whole' rather than simply lateral OR radial measurement at the end of the circle.

Of course you can mimick this with a standard truing stand (we do that all the time) , but it takes an exceedingly longer time to get it right - and too much 'feel' . With the P&K , I can teach a junior wheelbuilder exactly HOW to build a perfect wheel - and pretty much guarantee they'll get it right every time. I just set the recipe based on spoke tension and the truing happens 100% according to a known, numerical process that the builder can easily follow.

Very cool stuff. I have one of these now in our shop and will add more as they arrive. Once we get everything (and everyone) trained up , then we'll start offering micro-truing for wheels. I can get most alloy wheels within +/- .1mm and carbons +/- .25mm very quickly. If you followed the British Cycling Team at the Olympics - you may have caught the gist of a jab by the French questioning why the Brits immediately put their wheels in bags after each event suggesting that somehow the Brits were using 'non-standard' wheels.

The response by British Cycling was - 'well, yes we are --- they are round!' 'And we like to keep them that way!. Haha! Well, there's alot to this comment - because , a perfectly round wheel loses less energy in rotation than it's egg shaped counterpart. And, when milliseconds count on the track the last thing you want is to be rolling on a wobbly wheel!

From the road perspective - what this means is that having an evenly trued and round wheel lessens the effects of harmonic imbalance causing similar issues such as energy loss, high speed wobble and even spoke or hub failure with high tensioned wheels.

For the ultimate OCD wheel experience we could even true the wheel and tire as a unit! (This is in fact what the Olympic's Teams do) I don't have the nifty tire shaver yet - but that will be coming! :)
 

GSAstuto

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Oct 11, 2009
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#4
Well, I've been getting up to speed with this unit and it is really great! I can get a wheel into perfect true within 15min or so - and even faster if I'm just doing a lateral run-out adjustment (perfect for pre-race checkup). P&K have done an excellent job of building a superb wheel building and truing stand - really looking forward to seeing this product evolve and mature.

Like any truing stand, though, the builder must still take in consideration spoke tension. Even if the wheel is true - it is possible to have spoke tensions that are not consistent, so you need to watch that too! By combining both tension-based and origin-based truing the wheel will come out the best. What I currently do:

1) Lace up and pre-tension the wheel in several steps (usually 3 or 4).

2) Initial tensioning steps set all the spokes at the desired 'pre-true' tension. So, regardless of the actual lateral and radial run-out, I make a wheel that has perfectly even spoke tension. If it's a new wheel, the run-out will generally be pretty small at this point - maybe 2-3mm.

3) Then put in the P&K for run-out adjustment and centering. Since the P&K works from an origin point, once the wheel is calibrated, you don't need to use a dishing tool and all adjustments serve to correct the wheel back to it's real centerline.

4) By using the dial readings you determine whether a single spoke or it's 'neighbors' require adjustment - and in which direction. So - you just move around the wheel literally spoke by spoke and make the adjustment. For each spoke this takes maybe 15-30s, so you can see that within a few minutes, the whole wheel is completed.

5) Taking a quick tension measurement and applying that to how you adjust the spoke (or it's neighbors) and you guarantee that consistent spoke tension is maintained.

The result is a wheel that can be trued within a few hundreths of a mm AND a couple kgf spoke tension - especially if you're using a digital tensionometer like we do.

I went through a few sets of wheels and touched them up for fun. Amazing! Almost feels like you're riding a different set of wheels! I used this on some new, out of the box wheels, as well. Shimano makes really great wheels - but by touching them up on the P&K , I can make 100% for sure they are correctly tensioned AND true - especially after a short ride to de-stress the new wheel.
 

Doug3

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Jun 24, 2010
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www.tokyocyclingcoach.com
#5
Hey Tim, Looks like a nice tool to have in the workshop.

I would like to hear your opinion on radial truing of carbon rims, especially deeper profile like 50mm or more. To me it seems that the radial shape of these rims would be difficult to change, relative to alloy wheels, and the radial shape is somewhat determined my the mold.

My image would be that if you try to change the radial shape of a carbon rim, you would quickly end up with a bunch of spokes that are at a considerably higher tension than others.

Basically I am wondering is it possible to radially true carbon rims, or are you "stuck with what you got"?
 

GSAstuto

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#6
@Doug - depends on the rim was laid up - but generally speaking the region around the valve hole tends to be a little different than the rest of the rim - meaning - it may take 1-3kgf more as a group to adjut for perfect radial runout. And, yes, carbon or other composite rims tend to vary more than an alloy rim becuase the material is not perfectly consistent. But, so far I'm getting (at least our blanks) within 1-2% range for all the spokes. They are laid up with a 3 piece mold and have very high wall consistency - so that does help.

Also - carbon rims may have some small imperfections along the surface - so you need to make sure you are truing against a spoke location and not compensating for a bump in the carbon. With the P&K this is really easy to see as you follow the needle motion and line it up exactly at the spoke to make the adjustments - then check tension and you'll know instantly whether its a material inconsistency or run-out issue.

For mounted wheel truing, I generally drop the radial measurement - as long as the wheel was / is round to begin with - most tires will have more radial runout than a well trued rim - so we can assume the tire is the culprit more than the rim. However - lateral run out can be optimized, and should be as it will change quite a bit with an inflated tire. So - in this case, you are making small adjustment for the wheel+rim together, which results in a straighter wheel system.

Always remember to check tension throughout the process (even for alloy) as this gives you information regarding the consistency (or potential damage) of the rim. Say a typical front wheel should be at about 70-90kgf , then your tension should not vary more than 5% of that. Higher tensions and you have a little more to play with - lower tensions and you must be very close - otherwise you risk 'unloading' the wheel under load which can result in catastrophic or partial failure (tacos, broken spokes, etc).
 

GSAstuto

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Oct 11, 2009
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#7
Check this out ..

http://instagram.com/p/PL5Qfmo9pd/


Hey Tim, Looks like a nice tool to have in the workshop.

I would like to hear your opinion on radial truing of carbon rims, especially deeper profile like 50mm or more. To me it seems that the radial shape of these rims would be difficult to change, relative to alloy wheels, and the radial shape is somewhat determined my the mold.

My image would be that if you try to change the radial shape of a carbon rim, you would quickly end up with a bunch of spokes that are at a considerably higher tension than others.

Basically I am wondering is it possible to radially true carbon rims, or are you "stuck with what you got"?
 

GSAstuto

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Oct 11, 2009
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#9
Well, the difference is that I'm not a comparison to Karl Lagerfeld and more interested in bringing DOWN the cost of entry to riders, rather than RAISING it as a means of creating false value based on what should be common sense and good mechanical skills.

Nice to see he's using a P&K - which is something I can get excited about as it's a really good tool! And wheel building , in general, is 50% skill and 50% 'feel'. So the more we can work on a process based on using a good tool that ANYONE could do - it's going to be better overall for the riders (and the shops that have a hard time getting super skilled staff).

maybe a bit OT - Spiegel Online article about the German version of Tim (sorry only in German).
 

joewein

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Oct 25, 2011
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#10
It says this guy builds only 2-3 wheel sets a day, about 10 sets per week. He talks about moneyed customers who only ride their 8000 euro titanium bikes three times a year.

That's really small volume, high margin, for people seeking bikes primarily as status symbols (what a waste!) -- indeed very different from Tim, who is trying to make good quality affordable.

I'm very happy with my dynamo hub wheel built by Tim at a good price :)
 

FarEast

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May 25, 2009
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#11
in general, is 50% skill and 50% 'feel'. So the more we can work on a process based on using a good tool that ANYONE could do - it's going to be better overall for the riders (and the shops that have a hard time getting super skilled staff).
So true! Some of the best wheel builders I know will always touch the wheel up before even putting it in the jig.
 

GSAstuto

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Oct 11, 2009
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#12
See, I come from a fairly utilitarian training. The biggest eye opener for me was when I was working as a mechanic in Italy for a small team and basically this meant pumping out as many rideable machines as possible within very short period of time. Now, in my home town (Seattle) these machines would be regarded as works of art to be ridden maybe 3x / yr (like Joe's reference) and handcrafted by snooty 'craftsmen' with a penchant for carving and engraving lugs over the evening fire. But in our team these were rider's tools - nothing more or less. Build-Ride-Race-Recycle! So, I take similar approach with the wheels - same as then - and now. How can we build these better, faster and more consistent. So that simply a rider can use a better tool to get the job done without thinking about it. A good mechanic will spot deficiencies in the process and try to correct by using different tools or modifying the process. Again, it's just really nice to see companies like P&K putting such effort into one of the tools that is really important in this process. There are lots of hacked together solutions , but the P&K folks just 'built it right'. Sure there's more room for improvement - but the process is simpler, more consistent and accurate - so it lets me do a better job, faster - and most importantly - pass that experience onto other mechanics so they can do the same.

By integrating this with access to the economical and mass production components available from our neighbors, we'll be able to provide really nice wheelsets at even more economical prices and wider variety of selections.

I guess wheels are intriguing especially to me cause they are the user interface to the road - or at least a pretty major one. And small changes in that interface result in pretty noticable effects in the riding experience. And even within a wheelset, changes can affect the results - that's pretty cool and fun to play with. And when you get a set of wheels that can really 'sing' you know it.