What Are Drivetrains On Road Bikes?
Road bike drivetrain technology is under the constant scrutiny of the entire cycling industry.
There are some very promising options out there so Cycling Weekly's Sam Gupta runs through what he believes could be the tech of future for road bike drivetrains.
There are some very promising options out there so Cycling Weekly's Sam Gupta runs through what he believes could be the tech of future for road bike drivetrains.
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00:00The drivetrain as we know it with two derailleurs and a chain has been the
00:04favoured method of converting spinning legs into speed for nearly 100 years. As
00:10we all know over this time we have seen countless improvements to the system
00:15which has landed us with where we're at today which by all accounts is a pretty
00:20refined and efficient system. However as we reach what may be a plateau of
00:26innovation in this space suggesting we may actually have the best version of
00:30the system it's only natural to wonder what the next generation of drivetrains
00:34will be. While the current system serves the masses really well for some there
00:39are some potentially huge gains to be had in other technologies.
00:48CeramicSpeed debuted its wacky looking system back in 2018 much to the intrigue
00:54of anybody who set eyes on it. It works by using sculpted plates rather than
01:00chain rings and sprockets with an electronically controlled drive shaft
01:03which can shift between different diameters of the plate to engage a
01:08different gear. As yet it's still very much in the testing and development phase
01:13however CeramicSpeed claims that it was able to achieve a speed of 45
01:17kilometers per hour on the track on a single speed prototype during part of
01:23its load testing phase. If this drivetrain ever does hit the market in
01:29the first instance it will undoubtedly be incredibly expensive but of course
01:34that's the same for any brand new and truly revolutionary tech. It always takes
01:39a bit of time for it to trickle down to those lower echelons. If CeramicSpeed
01:44really are successful in creating a drivetrain that is 99% efficient it will
01:50of course attract the attention of those chasing every single want.
01:55Drivetrains like this could find a home on top NTT and triathlon bikes maybe
02:01even aero bikes optimized for flat races that will end in a sprint. The
02:06drivetrain efficiency is one thing but the other benefits that come along with
02:10a setup like this is that there's no chain to come off. The system is more
02:14compact and therefore more aero. CeramicSpeed are claiming that they have
02:20recorded an advantage in specialized wind tunnel. But finally since there are
02:25no delicate components hanging off of the frame if a rider is to have a crash
02:29they should just be able to jump on the bike and carry on. Snapped mech hangers
02:34will become a thing of the past although SRAM's direct mount rear derailleur also
02:39seems to be doing a pretty good job of this.
02:44From one direct drive system to another but one is actually in existence and is
02:50available to purchase is the driveshaft tech from Honbike. They have done away
02:55with convention and constructed a pretty sturdy and utilitarian version of a
03:00similar concept. In Honbike's case they have also made the housing for the
03:05driveshaft integral to the frame and it doubles as the chainstay which holds the
03:11rear wheel in place. Honbike has offered the system within their e-bike range and
03:16given the system weight it's unlikely something similar would make it over to
03:20the world of road bikes. However it's not impossible. There are a lot of
03:25engineers in the world all of whom are much smarter than me so perhaps there
03:29could be a middle ground between what Honbike has created and what Ceramic
03:33Speed are working on and perhaps that's where we'll see more of an affordable
03:38direct drive system emerge from.
03:44One of my favorite drivetrains and one which I feel is often overlooked is the
03:50humble belt drive. Commonly found on urban and commuter bikes the belt drive
03:54is just that. A belt very similar to the one that you might find in your car but
03:59also has humps or teeth that engage with a similarly shaped front chainring and
04:04rear sprocket. Unsurprisingly the belt itself can't be shifted so to work
04:10around that limitation belt drive bikes are often ones that instead incorporate
04:15a hub gear. For riders who demand bomb-proof simplicity I don't think you
04:20can get much better than this. There's no oily chain to make your legs or clothes
04:24dirty, it doesn't need lubing and it cannot rust. The hub gear is completely
04:30sealed from the elements and often only ever need servicing once every few
04:34thousand miles and even then it's just a case of topping up any oil that might
04:39have escaped. Hub shifting is notoriously smooth, it's very much a fit and forget
04:45type of system. Perhaps it's down to a lack of awareness or education but I
04:51think that this tech on a flat bar hybrid is quite possibly the best option
04:56out there. There are minimal downsides for the intended user but there is so
05:01much to be gained.
05:07E-bikes have actually played host to quite a few innovations years before
05:11they've made their way onto road bikes. Let's not forget that Shimano Di2 was
05:16first found on an e-bike nearly five years before it showed up as an option
05:21for road bikes. So I think it's prudent to keep a keen eye on the latest
05:26innovations that pop up in that sphere as one day it would not be a surprise to
05:30see it become the new normal for road bikes. One innovation that has come from
05:35the behemoth that is Shimano is their automatic stepless shifting. You may be
05:41thinking what does it do? Well quite what it says on the tin. You start pedaling
05:47and when you do you'll be in a nice easy gear to get you going. Then as you build
05:52up speed and work up to a faster cadence the auto box will move up the gears to
05:57allow you to increase your speed while keeping you at a comfortable cadence. But
06:02the really remarkable part about this is the ease at which it changes gear. You
06:08barely feel a change, it's more of an audible click quickly followed by a
06:12change of cadence. Perhaps this could be a great option for those who just want
06:17to focus on riding and let the bike take care of the rest.
06:23Lastly and potentially most importantly Classified seems to be leading the
06:29charge in terms of the next best alternative to the conventional drivetrain.
06:34Perhaps this is because it's not too far removed from what we already have. As the
06:40brand seeks to ditch the front derailleur and replace it with a wireless
06:43two-speed hub gear we're still left with a conventional chain and rear derailleur
06:48setup. But the new tech does mean that front shifts can be conducted under
06:53extreme load without the risk of misshifting or dropping a chain and
06:57chain lines can be optimized for an even more efficient setup. The last hurdle
07:03that the brand has to overcome is the integration with the shifters themselves.
07:09At the moment the hub is operated by a wireless button that mounts to your
07:14handlebars but hopefully one day in the future the tech can be integrated into
07:19the OEM shifters without voiding any warranties. My hope is that SRAM decide
07:25to acquire Classified and then build it into their entire ecosystem. Imagine this
07:31a pair of zip wheels with a classified hub that also makes use of the brand's
07:37ownership of Powertap to create a zip classified Powertap set of wheels and
07:43then perfectly integrates with SRAM's already wireless group sets. What a dream
07:49that would be. One for the future I'm sure and perhaps I'm being a little
07:54optimistic that such a thing could ever exist but it's not outside the realms of
07:59possibility. Let me know what do you think the future is for the humble
08:04drivetrain? Do you think it will ever develop beyond the conventional two
08:09derailleur system we already have? Do you think Classified or Ceramic Speed have
08:13the answer? If you enjoyed the video then please do drop it a like, subscribe to
08:18the channel for more content and I will see you again very soon.