By Zack Vestal
Almost four years ago, someone handed me a set of synthetic brake and shifter cables, and said, “Check these out!” Until then, I’d never thought that traditional steel cables were heavy, but the feathery Power Cordz were dramatically lighter than any other cables I had used. Without any instructions (other than to wrap the cables 180 degrees around pinch bolts for the most secure attachment) I installed them on my road bike. Two years of virtually friction-free and flawless performance left me with a great impression.
Fast forward to February of this year, when I stumbled across a press release from the Io DuPont company describing its new 1.2 mm Power Cordz shifter cord (the previous version was 1.5mm). I decided to give the new version a try and ordered a complete kit of brake and shifter cables with housing.
When it comes to saving weight, the Power Cordz are unbeatable. And in my experience the performance is really slick — pun intended. But like any ultra-light, high-performance upgrade, they do require careful installation and some patience in final adjustment.
About Power Cordz
The structural element of Power Cordz is a synthetic fiber called Zylon HM or PBO. Around 10,000 individual PBO fibers are woven into a cord, which is enclosed by a slick nylon sheath to keep the fibers together and protect them from damage. Cable heads are anodized aluminum, bonded to the cord material. The materials will not rust or corrode, but the company advises replacement after three years due to degradation from UV exposure and other potential environmental factors.
Weights on these synthetic cables are staggeringly light: two 1.2 mm shifter Cordz weigh just 5 grams, while a pair of Shimano SIS cables of the same size weigh 32 grams. Road brake Power Cordz weigh 10 grams for a pair, compared to 46 grams for Shimano brake cables of the same length. Doing the math, the potential weight savings totals 60 grams. As for anything this light, the price is high: A pair of shifter or brake Cordz alone costs $37, and complete kits with housing cost $69.
I like the stealth colors available. Brake cords are black, and my shifter cords are white. Company rep John Burdekin says yellow cords are also available, with other colors soon to follow.
When it comes to installation, there’s no way around it: Power Cordz are not as quick to install as traditional steel cables. Like a carbon fiber handlebar or seatpost, Power Cordz must be installed with care.
I began my installation without reading the directions carefully, acting as though I were installing steel cables. It worked for me a few years ago, but this time around my haste and mistakes caused a few issues. My recommendations: read the directions, watch the YouTube tutorial on the Power Cordz website, and don’t attempt this installation unless you have a few years of mechanical experience.
For starters, Cordz don’t have the rigidity that steel cables have, and forcing them into too-tight housing or ferrules can cause damage. I tried to feed a brake cord through the lever and kinked it, cracking the sheath. Luckily, I was able to cut it short and use it on the front brake. Similarly, threading a brake cord through a top tube or other internal routing is a challenge, because it lacks the structure of a cable. It behaves more like a piece of rope or fishing line, so I had to feed it through a plastic cable liner, and then feed the liner through the frame.
As with any new cable installation, new housing will give the best results. Steel cables abrade the lining of brake or shifter housing, which impairs Power Cordz performance. I started my installation using the zero-compression housing that Power Cordz includes in its kit. But right away I found that the brake housing supplied was too tight for my set of brake cords, and I was getting more friction than normal. Simply using stock Shimano brake housing and Shimano SP-41 shifter housing gave great results.
Clamping the cords in place also requires care. Since they are not hard steel and have a slick nylon sheath, the pinch bolts and washers on most components don’t do the trick on their own — the cords can pull through. Securing shifter cords requires pulling the cord tight, then wrapping it 180 degrees around the pinch bolt before tightening in place.
For the brakes, I installed the front using the supplied Windsor clasp and followed company instructions, which provide ultra-secure clamping for the cord. For the rear brake, I simply wrapped the cord 180 degrees around the pinch bolt for more clamping area. Both methods worked well, but the Windsor clasp provides the most fail-safe method. My only nit-pick with the Windsor clasp is that the extra thickness of the clasp reduces the thread-in of the pinch bolt. It would be nice if longer pinch bolts were supplied along with the Windsor clasps.
Of note: Clamping Power Cordz pretty much crushes them flat, and damages the outer nylon sheath. Once clamped, it’s pretty tricky to re-clamp or readjust a cord. I made a few mistakes in my first installation and had to remove and reinstall the rear shifter cord. Not easy — again, use care in the initial installation, read the directions, and use barrel adjusters for final cable tensioning.
Correctly installed Power Cordz give almost friction-free brake and shift performance. Lever feel is fantastic, and shifting is accurate. My brakes and shifters have stayed in adjustment from the day I installed the new cords, and it seems as though they don’t pick up grime and contaminants from the road, either.
The brake Cordz have a springy feel, which I like. It’s possible that zero-compression housing would minimize this, but I like the way they feel with standard Shimano housing.
The shifter Cordz seem to have just a little “give” as well. Again, it doesn’t bother me, and I like how smooth and slick they feel at the lever. However, I found that they require very careful, perfect tension adjustment with barrel adjusters. With steel cables, it seems like I can get away with less-than-perfect tension adjustment. Not so with Power Cordz — cable tension must be dead-on for best performance.
While the initial cost for Power Cordz seems high, they do shave a lot of weight in percentage terms. Furthermore, they will not corrode and don’t abrade the cable housing liner, so they can last several years. Lifetime cost of ownership is similar to that of traditional steel cables, and performance (in my experience) is higher.
In my opinion, if you have some mechanical experience and are willing to take care during installation, they are a worthy upgrade. I would suggest the Power Cordz alone, and simply use some high-quality Shimano housing.