Bish Bash Bosh Part 4: Building wheels

Now one of the most important elements of the bike are the wheels, particularly if they are handbuilt they can be one of the most single time consuming tasks.  I've build about 6 sets of wheels at this point, all without a spoke tension meter.  I however spotted the Park TM-1 Tension meter on special for £35 which is about 1/2 price so I just went ahead and got it.  Also for good measure I bought a torque wrench as well as the Bish Bash Bosh frame is carbon and you should be very careful not to overtighten fasteners or risk damaging it.

Spokes

Previously I discussed the hub and rim choice for the build, the missing part from this was the spoke choice.  This is one reason why I like building my own wheels, you get to chose every single part of the build to perfectly suit your needs.  Previously I have used double butted spokes.  Double butted spokes are thicker at the ends and thinner in the middle to put material where it is needed.  Not only are they typically lighter but they also have a bit more give so can actually build a more resilient wheel. Previously I have used DT Swiss competition which are a double butted 2.0/1.8mm spoke.  These are readily available, reasonably light and strong.  They are an almost standard spoke to use.  However this time, as I was hell bent on a sub 9kg bike I had to go that little bit further...

I looked into the DT Revolution spokes, however at 1.5mm thick at the centres I've read that they aren't the strongest or stiffest spokes, also their price is significantly more.  Alternatively I looked at Sapim spokes, the CX-Ray is a popular high performance spoke which is both light and aerodynamic, however they are also extremely expensive.  The Laser is also a similar price but similar to the DT Revolution.  However there was the Sapim D-Light which is somewhere in between these, it's a double butted spoke which is 2.0/1.65mm.  What kind of weight difference is there?  Well compared to a standard 2.0/1.8mm spoke the Sapim D-Lights would save about 80g on the wheelset which isn't insignificant.  Also importantly, they aren't much more expensive either so why not?  I'd never used Sapim spokes either, I'd always used DT Swiss in the past.  I did however use the Sapim Race 2.0/1.8mm spokes on the drive side rear with the D-Lights 

 Spoke nipples form the crucial function of not only connecting the end of the spoke with the rim but also facilitating the truing and tensioning of the wheel during the build and in the future.  Alloy nipples have a reputation for rounding out more easily as well as tending to seize due to corrosion.  They are marginally lighter however I generally prefer brass nipples for the serviciability and durability.  Luckily the D-Lights shipped with Sapim brass nipples.   One note though, was that compared to DT Swiss nipples, I found there was noticeable variation in their fit.  I had trouble fitting the Park Tool spoke wrench I had over some of the Sapim nipples, some were perfectly fine.  The same spoke wrench never had any problems with the DT Swiss nipples I used in the past.

The build

The great thing about the rims I discussed previously is that they are asymmetric, this helps a lot with both disc braked front wheels and 11-speed rear wheels.  A strong wheel is built not by strong components alone, but by a careful build as well as a good balanced, even tension in the spokes.  Over the decades as wheels have gained more speeds, the amount of uneven offset from drive side to non-drive side has increased significantly.  Enough so that it isn't unusual to see a rear wheel have 50% less tension on the non-drive side to balance it.

You can see in the picture above the difference an asymmetric rim makes, essentially the bracing angle of the spoke is closer to being symmetrical which means spoke tensions can be closer to even on either side of the wheel. The BOR XMD-366 rims I am using have a 1.4mm offset, on the rear it will be offset to the non-drive side and on the front disc wheel it will be offset to the drive side.

Before ordering my spokes I have to plug the dimensions of my rims and hubs to figure out what length I have to order, the calculator I use also gives you the theoretical spoke tension difference between drive and non-drive.  Using the dimensions I input, the front wheel has drive side spokes at 88% of the non-drive and the rear has non-drive side spokes at 62%.  If I had used a symmetric rim the figures would be 80% and 56% respectively.

I laced the wheels 3x front and back which is pretty standard for disc brake builds.  For those with a keen eye, I've laced the wheels with the leading spokes on the inside, which I realised after and reversed so they were on the outside.  This doesn't make a huge difference in reality, however having the leading spokes on the outside for a disc brake wheel means that under braking, the spokes being loaded are also the ones with the elbows on the outside and are thus stronger.

Weight including quick release and adaptor is 1,103g, without it is 1,009g which is pretty good for a 32h dynamo disc braked hub.

The rear came in at 867g for a total weight of 1,876g which is about 330g lighter than the set I built for Phil which is a similar build.

Tubeless install and final tensioning

The next step after tensioning was installing the tubeless tape.  Initially I used a 5m roll of BOR branded tubeless tape, pressing it down into the channel making sure there were no bubbles, overlapping the tape around the valve hole about 15cm either side.  I managed to install the Maxxis Ramblers on quite easily with a little soap and water, the beads popped into the rim hook very quickly with just a track pump.  The rear wheel sealed quite nicely only losing a few psi over night with no sealant.  The front wheel however would not seal properly, I ended up retaping this one with Stans tape and it was fine.  A trick I found was to put a little bit of sealant around the valve when inserting it in the valve hole.

One thing I did read about was that tubeless road tyres with carbon beads like the Maxxis Ramblers have a noticeable effect on spoke tension.  Apparently the carbon beads are so tight they compress the rim and reduce the spoke tension, requiring a tightening up to get it back up to normal.  I measured it using my Park TM-1 and found it dropped about 20kgf.

Speaking of the Park TM-1 Tension meter, I've found this tool almost invaluable.  The ability to systematically sample and record the tension of every spoke means you can straight away get an overall picture of the tension in the wheel.  The TM-1 is a very simple tool which has three pins which push against a spring giving a readout from which you convert on a chart.   It's likely not the most accurate tool, however it is still much better than just guessing from tones.  Also Park Tool has a web app called Wheel Tension App which you can put your readings into, it then converts the readings into kgf and gives you an illustration of the whole wheel tension.

I found this extremely useful as you can be extremely systematic about the wheelbuild, previously I would obsess about getting the wheel straight, however with this tension meter and the app I was able to both balance the tension as well as straighten the wheel. 

In the end the spoke tension I eventually reached was 117/102kgf on the front and 81/127kgf on the rear wheel non-drive/drive respectively.  The tension differences were pretty much spot on from what I had calculated beforehand.

Now the wheels are done there are still the brakes, drivetrain and other bits and bobs to do.  Thanks for reading.

Continued in Part 5