Jim’s Tech Talk
By Jim Langley
After last week’s column on Dropped Chains with Chain Keepers a reader named “Phil” and Harvey Miller recommended other ways to deal with the problem of dropped chains, front derailleurs and chain keepers. Which is to do away with the double chainring and front derailleur by going to an alternative system.
Front Derailleurs in the Crosshairs
It isn’t a new idea to nix front shifting. I was the new products editor for Bicycling Magazine for 10 years during which I saw thousands of inventions. One came from the Swiss engineer Florian Schlumpf. He came into our office with a very unique single chainring crankset and bottom bracket.
Instead of dust caps covering the bolt holes on the crankarms, his crank had what looked like a raised dust cap on one side and an inset one on the other. But, they were actually buttons that you activated by swinging your ankle in to strike and press in the button. When you did this, you changed the gearing from high to low or vice versa. It sounds difficult but we editors in the office test rode it and it was actually easy to operate and shifted well too. Florian’s invention is still online if you’d like to see it: https://www.florianschlumpf.swiss/index.php/en/bicycle-gear.
Classified’s Powershift Hub
Phil dropped his comment mentioning Classified’s front-derailleur alternative about the same time that RBR publisher Lars Hundley sent me a story about Belgian pro Victor Camenaerts signing on to use the setup for his classics campaign right now. So it’s already being used in the pro peloton.
Ingeniously, Classified has put their double chainring/front derailleur alternative in the rear hub. It’s shifted with a little button that sends a wireless signal to change the gear. They say it happens almost instantly and it can be shifted under full power.
One of the advantages of single chainring systems is that there’s no cross chaining. Cross chaining is when on a double chainring drivetrain the chain is on the small ring and also on one of the smallest cogs, or on the large ring and one of the largest ones. Cross chaining puts stress on the chain which makes for less pedaling efficiency and also increased chances of chain drops and missed shifts.
The cost of the Powershift Hub runs from $1,579 to $3,160 based on what wheel setup you choose since it’s a rear hub based system. Read all about it on their website: https://www.classified-cycling.cc/powershift-technology.
I hope to see and try the Powershift at the Sea Otter Classic next month. In the meantime watch their video to learn more.
I’m a fan of front derailleurs and double chainrings because it’s proven technology, very light and even with cross chaining, the most efficient system. (Cross chaining is easily avoided just by paying attention and not shifting into those gears).
While Classified says the Powershift Hub is more efficient, it actually works like the Sturmey-Archer hubs many of us had on our “British Racer” 3-speeds when we were growing up, remember those?
Inside Sturmey-Archer hubs and the Powershift are sun and planetary gears that by shifting change how hard it is to pedal. If you take apart one of these hubs you’ll see a whole bunch of small geared parts that all fit together and all turn against each other and on axles. You can see some examples here: https://en.wikipedia.org/wiki/Hub_gear. One of the most impressive geared hubs is Rohloff’s Speedhub.
I marvel at how these hubs work and how well they shift. But they are all heavy and every study I’ve seen shows that while they can be very efficient, they can’t match the efficiency of a double chainring/front derailleur drivetrain.
Another consideration is that it looks like Classified’s system requires their proprietary cassette, which could be part of its high cost. It would also mean having to use only their cassettes when you wear one out.
Still, it’s an interesting invention and I hope I get to try it. Maybe we’ll see reports from pro racing on how it’s working.
Reader Harvey Miller gave the nod to a completely different drivetrain since it doesn’t even use a chain. He’s loving his bike with a belt drive. He didn’t say exactly what he has, but I’m guessing since it’s the only one I’ve seen, that he’s using a Gates Carbon Drive. These have been around for many years and proven across many product categories so there’s no doubt it works well.
Here’s how Gates describes it:
Consisting of two metal sprockets and a high-strength belt embedded with carbon fiber cords, Gates Carbon Drive is a low-maintenance, chain-replacing technology from Gates Corp., the global leader in automotive and industrial belts. Clean, quiet, light and strong, Carbon Drive requires no greasy lube, weighs less than a chain and will not stretch. Due to its low maintenance and cleanliness, Carbon Drive is a technology that makes it easier for people to get on bikes.
And here’s an awesome video showing it in use:
I’ve ridden a few Gates Carbon Drive bikes at the Outdoor Demo during the Interbike Bike Show. This was held on dry gravel trails outside Las Vegas. In this harsh environment the belt drivetrains squeaked. You could wash them off with water and quiet them but once they got covered in dust and grit again they squeaked again.
Still, that wouldn’t be a problem for city riding, which is where I think a Gates drive would be a nice feature simply because you’d never need to lube or clean the chain (a belt drive will never rust). Plus, if you came in contact with the drivetrain it wouldn’t make a mess.
But a belt won’t work with derailleurs. So if you want gearing you need to use hub or bottom bracket gearing systems. Which raises the issues of added weight and slight efficiency losses again.
On top of this, because the belt can’t be taken apart, in order to use it you need a frame that comes apart so you can slip the chain onto it.
If I was going to buy one, I would look at complete bicycles. There’s a company in New York City that specializes in them called Priority Cycles: https://www.prioritybicycles.com/.
If you’re already riding a Classified Powershift Hub drivetrain or like Harvey, digging your belt drive, or running another alternative drivetrain altogether please tell us about it in a comment. Thanks!
Jim Langley is RBR’s Technical Editor. He has been a pro mechanic and cycling writer for more than 40 years. He’s the author of Your Home Bicycle Workshop in the RBR eBookstore. Check out his “cycling aficionado” website at http://www.jimlangley.net, his Q&A blog and updates at Twitter. Jim’s cycling streak ended in February 2022 with a total of 10,269 consecutive daily rides (28 years, 1 month and 11 days of never missing a ride). Click to read Jim’s full bio.
john griswold says
Roughly the turn of the century, I purchased a Green Gear, Bike Friday Twosday….a foldijng tandem. Great bike! I’ve traveled all over Europe and the US on the little bike with my lovely stoker/wife. If I remember right, the bike is originally built with a three speed hub. Maybe its a three speed hub AND a seven speed deraileur. Nonetheless, it didn’t have (as stock) a front deraileur. So you had essentially a twenty one gear selection. The best part of these hub shifters is that when you blow it on a stop, whether looking at a big hill in a high gear or you did a fast stop for a traffic situation, you could go to the low hub gear with a click of the shifter at a standstill. As frustrating as starting off from a dead stop in too high a gear is on a single, you can imagine that on a tandem it can be a real chore, not to mention the immense strain on the drive train. It was added weight, sure. But on a travel bike you have lots of “what ifs” in that trunk over the rear wheel and the extra weight of being able to shift “chain rings” at a dead stop was a life saver.
Jim Langley says
Thanks a lot for sharing how wonderful your Bike Friday Twosday tandem is, John. I have had 2 Bike Friday Pocket Rockets and they’ve been great. I remember that Bike Friday used a rear internally geared hub with a 7-speed cassette on some of their models back in the day. I don’t remember which hub they used though. Maybe one of the nice folks from the company will see this and share all the details. I visited their website and it looks like the geared hub bikes might not be an option anymore. https://bikefriday.com/
Thanks too for pointing out the advantage of geared hubs – being able to shift while stopped. That’s definitely a great thing at traffic stops and you make an excellent point that it’s even better for tandem riders.
Appreciate you sharing!
I just bought a bike which has no front derailleur — it’s a 1X system, which is apparently becoming a lot more popular these days. I have a single chainring up front and 10 cogs in the back. It works well and reduces cost, weight, and complexity. I know there are missing gear combinations, but I don’t feel that rideability is affected. I love riding this bike!
Larry K says
After having endless troubles with the SRAM etap front derailleur dropping the chain, I have gone exclusively to 1x setups on all of my bikes and have not looked back. They all have 12 speed cassettes with plenty of range, even out here in SW Utah where the hills are very steep. Works great on my road and gravel bikes with a SRAM Force XPLR rear derailleur and 44/10 T cassette. And my MTB has a manual Shimano Deore XT derailleur and 52 T cassette. Perhaps the only downside are the narrower chains that might not be as strong?
When I first considered this 1X bike I was concerned that I might be missing out on gear range, but I haven’t found that to be true in practice. I thought I might max out my top gear and need more going down steep hills, but I haven’t. And the lowest gear is lower than than on my previous hybrid, and WAY lower than the one on my road bike!
Shimano di2 “almost never” drops a chain!
David Ide says
I’m not convinced a single front chainring avoids cross-chaining .
Doesn’t it make cross-chaining mandatory on shifts to the largest and smallest cogs ?
Always enjoy your articles .
Would cross chaining be much of an issue on a bike with a single chainring when there is not a front derailleur?
I supppose it would depend on the chain, the cogs, and mostly on how wide the cassette is.
Jim Langley says
Several of you asked the excellent question of whether on a single chainring drivetrain (sometimes called a 1x or one by drivetrain) if there would still be cross chaining occurring when the chain is on the smallest or largest cogs.
The answer is no. The reason cross chaining is only an issue on double chainring drivetrains is because the most direct chainline is in between the two chainrings. The small chainring and the large chainring are offset from the exact middle chainline on the bike. That’s what causes the cross chaining basically – the chainrings being a little off center in the first place.
With a single ring – so long as the chainline is spot on and the ring is right on the chainline, there should be no cross chaining.
Hope this is helpful,
Doug Kirk, Madison, WI says
Jim, I’m hoping you will write about Shimano’s new CUES system. I understand that it will simplify some systems but will also make it harder to use older components.
Jim Langley says
Thanks for asking about Shimano CUES, Doug. I’ve been reading up on it but am still wondering if it will have any real relevance to us. By “us” I mean riders like us who are looking for the same level of ride and performance we’re used to from our road bikes and other types of bikes we’ve enjoyed right along.
My concern is that CUES (from Create Unique Experiences), seems to be a wide selection of Shimano components from their lower ends parts groups that they are now ensuring play nice with each other. It appears that one of the goals is to ensure they have plenty of compatibility with e-bikes across their components. Here’s a link where you can learn more about CUES https://bike.shimano.com/en-EU/product/component/cues.html
The thing about e-bikes is that the motor and drive mechanisms require heavy-duty components. So my concern is that most CUES components won’t be desirable for use by riders who appreciate lightweight road and off road bikes and components. I could be completely wrong about this but that’s my concern so far from what information Shimano has provided.
Thanks for asking,
Doug Kirk, Madison, WI says
Rivendell is complaining that the new system is designed around cable actuation of 1:1 and many shifters are built for 1:2.
Seth H. Shaw says
It’s exciting to learn about new cycling technology. Electric shifting was a major advancement (for me) and internal hub/bottom-bracket gearing is the next iteration I reckon. I think it’s in it’s infancy however.
I’ll be ready for it when a infinitely geared bottom-bracket AND hub, using one chainring and one sprocket of optimal size is developed (and programmable!) in which case we only need one transmission model for any bike, save for weight and shifting speed perhaps.
I wonder if Shimano, SRAM and others see this as a holy grail or the worst thing that could happen to its business? No doubt they could think of variations to maintain differentiation of models. I’m reminded of Tesla’s ability to add features from the cloud for a fee. Could that happen here?
Jim Langley says
Yes, I think we’ll see a lot more Seth, both electric systems and geared bottom brackets and hubs. Driving the trend mostly will be e-bikes, which are motorcycles when you come right down to it. The bike industry rightfully is behind pedal assist e-bikes which require pedaling in order to use the motor boost.
But I believe the majority of e-bike sales are non pedal assist e-bikes. Those have throttles and on demand power, no pedaling required. It makes sense that most people would choose that type of e-bike because it’s more similar to motorcycles, which is what the “average” person thinks of when they think of an e-bike – a bike with an electric motor… “why would I be forced to pedal to use the motor?”
So I think we’ll definitely see e-bikes with electrical or even automatically selected transmissions just like we have in cars sometime in the not too distant future. I don’t have any idea if any of that technology will cross over to pedal bikes though.
Seth H. Shaw says
Thanks for the reply Jim. Do you think fully variable shifting will only be on e-bikes or non-pedal assist two-wheelers as well, which was behind my thinking?
(FYI, Jim knows my age and how close I am to getting an e-bike, but he’s jumping the gun in this case!!)
Jim Langley says
I think fully variable shifting will continue to be available for both standard and e-bikes and I think the shifting systems/geared hubs and bottom brackets will keep improving. Hopefully innovations that come from motorized vehicles will make their way to standard bikes and in a lighter version that keeps the weight down and efficiency up. Right now the added weight is what you feel most when you go to a geared hub or bottom bracket. You feel it less the younger, stronger and fitter you are and vice versa 😉
Russ Marx says
My E-Bike has a 1×11 system, NOT ENOUGH gears. Rpm drops too low going up hill with friends, Have to go up faster & wait for friends. I bought a 11×25 cassette , discarded 13 gear & added to have 15,16,17,19 sprockets to be able to spin 90 rpm when riding with friend at 18 – 22 mph.
I have never ridden a bike with too many gears!
Jim Langley says
Thanks for the comment, Russ, but I don’t understand. Whether or not having the “right” gear isn’t about how MANY gears you have. It’s about whether you have the RIGHT HIGH & LOW GEARS for the terrain you ride. You said your RPMs (pedal Revolutions Per Minute) dropped too low going up hill. But then you said you changed your gears to what look like harder to pedal gears. That doesn’t seem to make sense as that would only slow down your RPM more wouldn’t it?
Chris George says
My belt drive experience: Before I retired (end of 2019) I had been bike commuting to work for almost 30 years. Around 2010 I decided to build a custom commuter. I wanted something reliable, functional for all weather and light conditions, and very low maintenance. I ended up with with a Civia Bryant frame with the Gates belt drive and a Shimano Alfine 8-speed rear hub. With hydraulic brakes, rear rack, fenders, a generator front hub, and high end auto-sensing headlight (with capacitor) I was all set. All I needed to do was keep the tires properly inflated. The belt drive was a fantastic choice I’ve never regretted. All bikes prior I had to be concerned with chain maintenance, keeping my pant leg out of the chain with straps or clips, and slinging lube on the frames/wheels. Also, with the internally geared hub, shifting while stationery is possible and very convenient with stop/start commuting. I’m still enjoying the bike today and run frequent errands with it still – original belt.
Jim Langley says
Thanks for sharing, Chris – great to hear about your belt drive Civia and how well it’s worked for you!
Dave Minden says
I agree with your wisdom that road bike riders and ebike riders are splitting in the direction of parts – with some roadies like Jan Heine going further ‘backwards’ towards simple, light, functional components like his desmodromic derailleur (https://www.renehersecycles.com/product-category/components/derailleurs/). But I’m a bit internally split! As a 69yo who loves to ride I see my most athletic accomplishments behind me yet I want to keep doing rewarding activities like touring with camping gear. This is leading me towards an etourer. Are there enough of us to entice a maker to produce a beautiful well-designed etourer? Nobody’s coming close yet.
Jim Langley says
That’s a great question, Dave. From what I’ve seen so far it looks like the thinking is that since you’ve got a motor to help assist you that it’s okay to make heavier bikes with heavy-duty components (to hold up to the motor, battery and drive systems). Someone ought to be able to make a nice etourer perhaps like Fazua. They make bikes where you can remove the battery and end up with almost a regular riding road bike. https://www.fazua.com/en/ I think a removable setup could make sense for an etourer so as not to change the lightness and nice ride quality and to let you use the bike without the motor on routes where you might not need it.
I bought a hardly used tandem many years ago. Unfortunately, it had 26″ wheels and low gearing. I had heard about the Sachs 3 x 7 hub. So instead of changing cranksets or change rings I had a wheel built with the Sachs hub to gain some top end gearing. Using the Sachs hub with the gearing I had, I ended up with a gear range in the neighborhood of 14 to 140 gear inches. I ultimately changed to a closer ratio cassette. But, boy was 63 gears cool (3x3x7). Sachs later SRAM, did not recommend using that hub on a tandem.
Jim Langley says
Thanks for sharing how well the gearing on your 63-speed tandem worked, Terry. I can understand how/why SRAM and Sachs said not to use it on a tandem too. I’ve seen two strong riders tear the freewheel right off a hub before. The drive gears and pawls inside these hubs aren’t strong enough to withstand the combined force of 2 riders except on relatively easy terrain. I’ve broken 3-speed hubs myself. But, I can definitely see how cool it would be to have all those gears.
Erik Husby says
My commuter bike has the Gates belt drive — like it since I did not have to clean the chain monthly like I used to. There were two downsides: I snapped a belt one morning so walked the remaining 2 miles to work and called my wife to pick me up in the evening. The belt and internal hub made changing a rear flat a bit more work. But after 26,000 miles and 4 belts later, the bike is still riding very smoothly.
Jim Langley says
Thanks for sharing, Erik. I had no idea you could break one of the belts. It’s good to know that. I’m surprised you’ve gone through 4 belts in 26,000 miles. That suggests that they aren’t that much more durable than bicycle chains.
Thanks a lot for your belt-drive insights!
Erik Husby says
Like all moving parts, the belts do wear out. The 4 belts in 26,000 miles were over 10 years. I was commuting all year round in Boston area in all kinds of weather. Before the belt drive, I was cleaning my chains every 6 weeks and would get about 3,000 miles out of them. So if I’d not had the belt drive, I would have gone through 8 chains. I’ve also snapped chains which I was able to repair on the commute whereas the snapped belt was not repairable. The belt was a lot less maintenance.
Dave Minden says
Thanks, Jim. I’m on the hunt…
I’m in Belgium riding a Classified hub on my gravel bike, was an early adopter of the system back in July 21.
The first generation had some issues due to a bearing getting out of whack, which caused rear wheel lateral instability. However, they got this fixed and it’s been solid as a rock for 18 months now.
What can I say except that it works as advertised? You can shift under full load and yes, it’s instantaneous. The command is passed via a satellite button to a wireless through-axle which in turn tells the hub to shift. The axle has to be recharged once every 6 months, the battery of the shifter system (button cell) is good for about 2 years.
I have the subjective feeling that the system is very efficient. Not like a Rohloff where you can hear gears whirring and feel the difference (but then it switches between two gears, not 14).
The system is maintenance free.
You need a rim with integrated proprietary hubshell. Not the hub internals, those can be switched over relatively easily. But the wheel needs to be built up with the shell. Fortunately more wheel choices are becoming available now. Or you could pick your own rim and have a wheel builder make you one.
The cassettes are indeed proprietary. A 12-speed cassette will cost about 170 Euro. These are machined out of a solid billet of SS and very good quality though. No issues at all and it shifts very well. (I’m on SRAM AXS Rival). I’ve only just changed my original cassette and I ride about 12 k km/year in all weather.
So far, it’s not possible to integrate the shifter button with the (wireless) gear shifters of SRAM or Shimano and I don’t see that happening in a hurry.
The price. It’s expensive and adds (deducting the front derailleur) about 1.3 k to the cost of a bike. But for me it’s worth it: no more front mech AND closely spaced gears on my gravel bike.
Looking forward to reading your review.