5mm Tune plastic housing, 18.4g/m

There's not much literature on these, so I decided to write a preview about them.

5mm Tune plastic housing

General features

Firstly, Nino weighed exactly 2 pieces + 2cm of these once (100cm), and found them to weigh 17.0g/m. They come in 5mm (derailleur) and 6mm (brake) sizes. I was told that the 6mm size is REALLY stiff (you already have to heat 5mm housings to get them to shape) and that brake cables fit in the derailleur housing anyway.

Weight

A breakdown of their weights show that they're produced very precisely. (8.8/8.8/9.0/8.8/8.9/8.8) Overall, they weigh 18.4g, averaged over 288cm.

8.8g for 48cm.

Weight of 6 pieces of housing.

Performance (friction, stiffness)

I was told that these "feel very slick", so I expected these to have some sort of smooth inner coat, but that doesn't seem to be the case. There had to be some explanation, so I took a better look at the inner core and as far as I can tell, they were made out of some type of nylon, if not a high density polyethylene but I doubt it.

The white inner core is made of nylon.

Compare to the nylon bolts I use for my bottle cage, pictured with a filled bottle here. It's a strong material. Dismantle your toilet seats and you'll know.

I referred to Hamrock et al, (2004). Fundamentals of Machine Elements. Ch 8, p. 395... And confirmed that nylon has lower coefficients of friction with steel (kinetic: 0.35) than polyethylene with steel (kinetic: 0.50). Polyethylene is most commonly used in your regular plastic inner liners (for example, Nokon, Alligator etc.)

So it does feel very smooth. Moreover, smoother with Powercordz (say, the derailleur cordz with nylon outers) (kinetic: 0.15).

The material explains why these are VERY, VERY stiff. I could knot Shimano SIS housings (which are stiffer than Jagwire regular housings) with a shorter length, whereas a longer length of Tune plastic can't be knotted at all. But it stays in shape after you've installed them - and will feel extraordinarily 'compressionless'.

Installation, servicing, compatibility
Because these are very stiff, Nino is right - you need heat from a hair dryer to pre-form these. Because they aren't run with a continuous inner liner, or coated inners, I'd guess it's necessary to lubricate these more frequently than the regular Shimano SIS setup. They should be smoother than housings with lubricated polyethylene liners after that, though, by virtue of the material.

Now, my only worry was if these are compatible with the thick Powercordz brake cables (1.71mm diameter). If those fitted, I wouldn't worry about anything else.

I can't get a clear picture of 1.71 - but you get my point.

In contrast, the standard steel cable that is meant to be run inside these housings has a 1.36mm diameter.

I can't get a clear picture again, but you get my point.

I found a length of old Powercordz brake cable and lubricated it with cable lube - then slotted it in and pulled around. Very smooth.

The picture doesn't look convincing though, but it really is.

Price

I was considering getting the highly recommended Alligator with Powercordz brake/derailleur cables. What I didn't like about that setup was that it would cost me S$65 (Alligator brake set) + S$65 (Alligator derailleur set) + US$36.95 x 2 (Powercordz) + US$11.25 (Nokon liner) = US$92.82 + US$85.15 = US$177.97! Excluding shipping! And S$65 is extremely cheap for an Alligator cable set: US$46.41.

(The other thing that I didn't like about Alligator was that it looked very cheap. Nokon looks prettier to me when set up without kinks. But it has its functional issues too.)

How much did I pay for the full Tune housings + Powercordz setup? US$144.54 including shipping. If you opt for Powercordz, it seems that this is the best option. It's also true that going for Alligator with the original steel cables presents the better value-for-money option. Then there's also the generic Shimano SIS setup which is really light, and effectively free.

Conclusion

There's really nothing much I want to say, because they're just housings. I've heard a number of negative reviews (I note that I heard them from people who claimed to hear them from some other source and so on) about these, and stories of incompatibility with Powercordz - none of which turned out to be true.

To be fair, I can't comment on the brake feel in actual use. I haven't set up my bike. I also can't comment on long term wear and tear. I recall Madcow mentioning that the Powercordz coating would wear and clog the housing. Sounds viable. I'd see if more careful maintenance eradicates this potential problem.

Now, something that's true: these aren't 17.0g/m, and don't buy the 6mm housings.

Lastly, a preview of my crankset. I'll show the final weights etc. when I've found the bearings that I wanted.