Wednesday, 22 April 2020

Schmolke carbon rims - how much premium is in the premium?

Schmolke carbon wheels, a dream for most of us, the road cyclists. Top premium brand, known for lightweight, and beautiful carbon components.

I remember, when I was starting my wheel building business, I was dreaming about such top projects. Today, a few years later, such builds became reality and thus I wanted to share with you some wheel building insights about Schmolke rims. 




First things first, Schmolke rims are made by Munich composites,  company based in Germany, specialized in the innovative "Braiding carbon fiber" technology.


The coils feed carbon fibers into the machine, which braids them into a strong strand.

This technology allows to make significantly lighter and yet very stiff carbon components like handlebars, seat posts, rims, and automotive elements. 


The top Schmolke's rims, called TLO (The lightest one) come with an impressive weight of 430 g for 45mm tubeless rim profile, and such rims I had in my two builds described in this post.


One wheelset was made for a pretty light rider, so with 24/24h spokes and the other one went for a heavier rider, and thus 28/28h spokes.


In both cases, I went with Industry 9 hubs. Absolutely my number one hubs for long-lasting, stiff and good looking wheels. You can't go wrong with those hubs. They work very well with symmetric rims, and that's the case with Schmolke rims. They come only in symmetric version.




Spokes used in those projects were from Pillar. The combination of Wing 21 and 22 versions in order to make stiff, but at the same light wheels.


Rims came for disc setup, however, the same finish goes for rim brakes. Honestly, looking at the braking surface I have my doubts if those will brake well in the rainy conditions...


All Schmolke rims/wheels come with internal nipples. I'll be open here - I'm not a fan of internal nipples at all. I know that they save some watts and make wheels faster, however from the wheel building perspective I can only see disadvantages. More about them in a second....


You can choose between black, white, red, or no decals options. All of them look really nice. Visible carbon fibers provide a really unique look which I liked a lot.


All in all, the wheels came out pretty nice. Good weight, solid hubs, fast spokes, and light rims. They were very stiff too. I could feel that during stress relief when I push the wheel with both hands applying all my body weight.

That was also confirmed by the first feedback from the customer. He was very pleased with the acceleration, side wind handling, and high stiffness. 


Now, let's talk about wheel building of those...

How should I start? Honestly, I thought about that for a bit of time. Don't get me wrong here, it's not my point to discourage potential clients, but at the same time, I think it's important to highlight few points, which might be useful for other builders. In the end, that's one of the reasons why I maintain this blog...

So... how should I start? Let's put it this way - I was expecting much more from those rims. In the end we are talking about one of the most expensive rims on the market.

1. Drilling
Rims come pre-drilled. They are not fully drilled. Before the build, what you need to do is to fix every single spoke rim hole. I simply used an old spoke with sharped ending to fix the original drilling.



I never came across such thing before. It wasn't a big deal but still... 

2. Washers
In those rims, nipple washers are a must. Using external nipples, installation of nipple+washer is not a problem, even for deep rims, but here we have internal nipples, washers, and deep rims. 

The trick which works in such cases is the following:


What you want to do is:
- lace the spoke and put it through the rim hole
- use peace of old spoke, put washer through it and hold it with your finger
- put the old spoke with nipple through the rim and touch the laced spoke
- release the washer so it falls through the spoke and lands in the rim and laced spoke
- install the internal nipple

In this way you won't drop any washers. I had 100% successful ratio on both wheels, no single washer dropped!

Due to internal nipples and washers, I strongly recommend using boiled linseed oil. Such oil will lube rim/washer/nipple during the build and will dry after a few days holding everything together very well. This is really important as most of the wheels with internal nipples and washers suffer from nipple self unwinding. This is caused by a lack of contact points between rim and nipple, even at high tension.

In my case, I made a solid nipples bath in linseed oil before the build. It's not the first time I'm using this method and it always worked very well. You can also use standard thread locker, however remember that it won't give any protection from galvanic corrosion, which is very often the case with internal alloy nipples and carbon rims.

3. The build
Not easy at all. The first issue I came across was the drilling again. this time the external rim holes were not aligned with nipple holes and as a result, I could not reach to some nipples:


This one is a 100% manufacturing issue. Shame, because this was reported many times already and nothing was done to improve that.

The trick to overcome this problem is to flip the rim in case you can't reach the nipple. Because drilling is done at specific angle, you need to insert the nipple driver at the exact same angle as drilling machine and then, barely, but you'll be able to turn the nipple. I was also lucky here that I used brass nipples. They are much harder so I had no risk of damaging the nipple itself.

4. Truing 
At the time when I write this post, I'm at about 120-150 yearly wheelsets level. All those come through my hands so I already have a pretty good feeling how the build will go. I think I can classify the rims into:
- easy, when the wheel comes true almost out of the box
- medium, almost out of the box, need some extra tweaks here and there
- bitchy ones, long hours on truing stand trying to make them perfect

Unfortunately, those rims come under the third category. Seriously, don't think you can make a complete wheelset in 2-3 hours. If you really want to do it well with equal spoke tension, you will need a lot of patience and spare time. 

I'm not the engineer but I think it's related to the technology used to produce them. Those rims are super sensitive for spoke tension. Even 1/4 of nipple turn will cause a large effect. The worst thing is, that by touching one spoke, you'll cause a change 4-5 spokes after. It's a bit like chasing your own tail...

One thing which I recommend - use the best wheel-building practices to build those:

- if you want to dish the wheel, first loosen spokes on one side (one turn max) and then tension up on the other side
- if you want to equalize the tension, try to find three spokes next to each other where the middle one has higher tension than two neighbors. In this case, you lose first the middle one and you tension up the other two
- small incremental steps
- always first loose and then tension up. If you'll start only tensioning up, the rim will start deforming and you're doomed
- constantly keep an eye on truing stand gauges and don't let the wheel to escape from lateral and radial trueness 

Make sure you have calibrated tension meter for the specific spokes you'll be using. Those rims won't accept too high tension.


110kgf is the limit for those, I mean really max. I built mine with 105kgf and that was more than sufficient.

Last but not least, take your time and do the job well. Remember that those rims come with internal nipples so when the tire is mounted you have no way to correct trueness... well there is a way but it's painful. More details on Melodywheels Instagram profile:



P.S. The Above trick won't work on tubular tires...

To sum up, if the job is one well, those wheels will pay back with excellent handling, lightweight, nice acceleration, and top look. Just make sure you have enough experience and skills before offering them to your customers.


Thanks for reading, hope it was useful.
Tomasz
blog-wheelbuilding

2 comments:

  1. Fantastic post. Thanks for sharing all these technical details. After experimenting with many new thread lockers, I ended up going back to boiled linseed oil. No carbon issues, great all weather performance, good long term serviceability, and cheap!

    I found a local furniture company selling food grade boiled linseed with no added drying chemicals. I'll be experimenting with that for my next two personal wheelsets (before I offer it to customers). I think it will take a bit longer to cure, but I'm keen to avoid any toxic chemicals.

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    1. Cheers Andrew! Old school with linseed oil :) Happy that the post was useful. Stay tuned for more, interesting stuff is on the way!

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