IS A MECHANICAL DRIVETRAIN MORE RELIABLE THAN ELECTRONIC?
What’s more reliable? Are the more than a century old wound steel cables wrapped in steel helical housing more reliable than today’s modern CAN bus (Controller Area Network) electronic or Bluetooth wireless electronic drivetrains? While some findings may be subjective, undeniable reliability facts support both mechanical and electronic drivetrains. Which is better? That decision may be decided by what is available today or in the future.
The mechanical Bowden cable was invented near the end of the 19th century and beginning of the 20th century during an era of rapidly accelerated invention and scientific discovery. Yeah, cables have been around for a long while and for good reason: the Bowden cable is very reliable and functions well mechanically when adjusted properly. Modern light aircraft still use cable and housing systems for throttle and flap controls. That’s saying a lot, considering an aircraft is a flying machine with humans inside it at altitude! If it’s good enough for aircraft it should be just fine for bicycles, right?
The Bowden cable is used in a variety of applications: lawn mower throttles and deadman’s switches; piano pedals; WWI machine gun triggers; 3-D printers; power tools; motorcycle throttles; photographic shutter releases; hi-hat drum kits and even prosthetics. Electronics are everywhere in this modern world we ride in and, of course, you are likely very aware of how wonderful the current, new models of bikes are with regard to shifting, reliability, coolness factors, etc.
Over the decades, not much has changed when it comes to the technology involved in the manufacturing of current twisted wire rope (cables) and its protective flexible, hollow housing. Barrel adjusters, the inline hollow bolt, used to increase or decrease cable tension by shortening or lengthening the outer housing, have become (mechanically) more adjustable over the years due to adaptive cable ends, or cable nipples – a term which was once widely used in bicycles and isn’t so popular today. On that note: I’ve heard knowledgeable mechanics say, “spoke nuts” as opposed to “spoke nipples” and am still undecided on which is more controversial!
Contrary to popular bike shop jargon, cables don’t actually “stretch.” What does change, and requires adjustment over time, is the housing where the cable slides inside. The housing shortens or lengthens with the adjustment of the barrel and locking nuts and seats deeper in the housing ferrules fitted into frame cable stop, or cable boss for you old school wrenches. A simple turn in or out of the barrel adjuster increases or decreases the cable’s tension and actuates the mechanism, such as brakes and derailleurs, it is mechanically attached to – and viola!
As a high school kid, in the mid-1980’s, I was flying down a very rugged trail called Dead Man’s Gulch starting from the Forest Service lookout tower atop Blue Mountain bordering my hometown, Missoula, Montana. Then, every bike was adorned with cables, of course…and there were no dropper posts nor any suspension let alone lovely, lightweight carbon wheels and frames. Steel was real back in the day and aluminum bikes were few. Steel cables were what stopped us on steep, fast descents.
It has only happened to me once, but once was enough: my front brake cable, which was relatively new, snapped inside the housing while grabbing all the brake lever I possibly could and I wiped out terribly as a result. Now that was a rare occurrence but it happened and it forced me to question the reliability of, well, cables! I didn’t have an alternative then, however, and like everyone else who’d fallen in love with riding mountain bikes on gnarly trails, up or down, I replaced the cable at the bike shop later that day and kept riding with cables. I’ve never had a derailleur cable snap, or break, but I’ve been riding with others’ whose did snap which ultimately changed that particular ride entirely. To this day I still ride with a spare derailleur cable. I prefer riding Shimano Dura-Ace mechanical drivetrains on my road bikes for my own reasons even if they’re unjustifiable and, perhaps, debatable.
Today’s modern bicycles that shift electronically are, or can be, a thing of beauty. Elegant frame designs are changing how road bikes ride, entirely, and many manufacturers aren’t equipping some models with cable stops or bosses and are only available as wired, “wired-less,” or wireless versions for electronic shifters and derailleurs. There are a few high-end custom mountain bike frame builders building bikes without an option for mechanical shifters, derailleurs, or brakes but that hasn’t happened (yet) with production manufacturing of mountain bikes like it has with some road bike models. Arguably, bikes equipped with mechanical drivetrains are usually lighter than their electronic cousins. I find it odd that mechanical drivetrains are being phased out of the road bike category since one of the biggest factors in road bikes is their weight and the expense involved in ensuring they are as light as can be or as light as they need to be for racing. Without having weighed every mechanical drivetrain compared to similarly priced and categorized electronic drivetrains I may only be speculating because I appreciate the simplicity of cables and the mechanical tradition of the bicycle. I trust a wrench over a diode but my trust can be influenced by superior electronic performance.
WHAT CAN GO WRONG WITH YOUR ELECTRONIC DRIVETRAIN?
Barring lightning striking there really isn’t much that can go wrong with an electronic drivetrain other than, mostly, human error. No drivetrain is perfect. Well, almost – maybe – but probably not. I loved my electronic Shimano Di2 XTR I had on my 2016 Yeti ASRc which previously had mechanical XTR (before spurging for the electronic stuff). Although mechanical XTR performed flawlessly, I just HAD to get the Di2 version of that grouppo and within minutes on my first Di2 ride, on a mountain bike, I doubt I’d ever ridden any shifting system as innately intuitive. My fingers understood immediately and my brain knew which way the shifters functioned as if flying on autopilot.
Charging an electronic drivetrain varies per manufacturer just as actual battery use per charge, and battery life before needing to replace them, all vary. Without going into detailed specifics about electronics, we all know that without power the drivetrain won’t function. If you cannot shift your electronic drivetrain, you are, very unfortunately, now stuck pedaling in one gear and you will not be a happy rider – unless the ratio you last shifted to is desirable for the terrain or slope.
CARRYING CHARGED SPARE BATTERIES
If your eTAP AXS battery dies and you are not carrying a charged spare, or you didn’t fully charge your Di2 battery (if it was knowingly low on charge at the start of your ride), you are stuck in whatever gear in which you last shifted. Further, if you leave your battery in your AXS derailleur while driving across, let’s say, your entire state while on vacation or while driving to your next race, and then try to ride, you may find your battery is dead. The solenoid in the AXS derailleurs is active and leaves your SRAM electronic battery, or batteries, active. It is recommended that you remove your battery from your derailleur(s) if traveling by plane, train, or automobile.
One of the less mentioned differences between mechanical and electronic drivetrains is the hood size on different, or varying, road bike gruppos. Hand size matters and you will find manufacturers are integrating adjustable levers, to adjust the reach for smaller or larger hands, into new electronic shifters as they have with mechanical grouppos. Mountain biking components are always very adjustable whether or not they are mechanical or electronic and most seasoned riders, at least those I’m in cahoots with, all carry a spare cable and tools to fix their “broke-down” and “old-school” mechanical drivetrain – including yours truly.
FSA’s relatively new K-Force WE electronic gruppo and drivetrain tickle many cyclist’s fancies – I have read. My grimy, mechanically oriented hands haven’t had the pleasure of working on WE nor have I ridden that system but what I have been told and have read was positive. FSA, in my experience, has always made excellent components and dives deep as they are keen on what’s current and what works.
WHAT WOULD YOU BUY or BUILD TODAY: Mechanical or Electronic?
After a couple glasses of red and my riding buddies tipping their brewskis to loosen up our tongues, we all discussed what we would buy today: a mechanical drivetrain or an electronic drivetrain on a new, modern bike – most of which will only have disc brakes on road bikes. Across the board, we all agreed we would buy bikes equipped with electronic drivetrains or build framesets up with electronic gruppos regardless of whether it was WE, eTAP/ AXS, EPS, or Di2. Our preferred drivetrain of choice in the awesome world of mountain bikes our decisions varied based on whether the bike would be ridden on longer excursions in the middle of Nowheresville, or not. We agreed that modern electronic drivetrains shift incredibly and are very reliable if fully charged or while carrying a charged spare battery but that mechanical drivetrains remain light, reliable, and smooth when adjusted properly and kept clean.
Today’s cables and housings with their well made end caps and ferrules are impressive yet technology is winning the battle today. The automotive industry is shifting toward electronics or hybrids as well as automatic transmissions with paddle shifters instead of the once popular manual/standard transmission with a stick shift. The Bowden cable has become the stick shift it would seem.