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Belts & Braces Gravel Bike

Rich Lambert 13th December 19

I’ve had an interest in ‘internal gear’ systems since I was a teenager in the 90’s. Many hours spent tinkering with derailleur set ups, bent hangers, chains falling off, cables snapping and indexing that was never quite right had me wondering about the alternatives. I remember reading an article about a GT downhill bike that featured a Shimano hub gear, mounted in the frame allowing a high pivot point and removing all the issues associated with derailleur gears of the time.

It must be said that in recent years derailleurs systems have been vastly improved, but it still seems surprising that development of internal gears has not been taken further. It’s not a new concept, Sturmey Archer have been making their 3 speed hubs for over 100 years, and other systems such as Shimano’s Alfine and the reputable Rohloff hub have had some success, but still derailleurs are the dominant option.

Fast forward 20 years from the GT concept bike and Pinion arrive on the scene. Rather than using an existing hub design, Pinion replace the traditional bottom bracket shell with a large plate that allows the gearbox unit to be attached. This sealed unit contains the gears, of course, plus the bearings and axle for the cranks to attach.

Sounds good right? Unfortunately there are downsides to such a system. Planetary or Epicyclic gears are slightly less efficient than a (presumably clean and new) derailleur set up. They are expensive to produce, could be considered heavy, and the Pinion design requires a bespoke frame to be made. Despite these negative aspects (for which there are many good counter arguments) Pinion has quickly gained a following for MTB riders, utility or commuter bikes, where adverse weather and lower maintenance make the gearbox an appealing option.

Whilst gearboxes have become an option for riders with a flat handlebar, many drop bar users are completely unaware of their existence, partly due to the lack of a viable shifter option that works as well as integrated ‘STI’ style levers. That is until now. Another small German company (Pinion and Gates belt drive are also both German) Cinq 5 have started to produce a modified TRP Hylex brake that allows shifting from the brake levers. Left lever goes down a gear, right lever goes up. When we learned of this option we had to give it a go, so eagerly got on the waiting list to be one of the first customers for the new Cinq 5 Shift:R levers.

Enigma are based just outside the South Downs National Park, with a great network of bridleways, country lanes and farm tracks that lend themselves very well to Cross and Gravel bikes. Although some riders will stick to mountain bikes, the off road riding that we have is mostly at the tamer end of the spectrum, and becomes tedious on a heavy suspension bike. In winter, the lack of solid bedrock on the chalk downs also means mud. Lots of mud. You may think a mountain bike is best to deal with this, but in fact the wider tyres don’t mean better grip, you want something to cut through the slop, and the absence of full mudguard coverage also makes winter riding a messy experience.

Enter the gravel bike, now evolved to have decent tyre clearance, confident handling both on and off road, an efficient position for clocking up the miles and practical fittings for mudguards and luggage. Our Escape has proven this format over the last few years, and for many riders is the perfect solution for mixed terrain and all season riding. The only downside has been keeping it clean in winter! When the Pinion / Cinq 5 solution came up, we set about designing a version of the Escape to take the gearbox system, which also gave us an opportunity to utilise the Gates Belt Drive.

Belt drive has been around now for a decade or more and works well for single speed or hub gear use. We had previously built several Rohloff equipped bikes, and even a fixie, so knew our way around the componentry. Pinion can be used with a conventional chain drive, but a belt means no oil or rust, less wear and maintenance, so would seem the perfect combination to use with a gearbox. Like most things though, there are pros and cons. As the belt cannot be broken or joined, the frame needs to have a ‘split’. You’re also limited to certain belt lengths and sprocket sizes which means gear ratio selection can be tricky and needs to be considered in conjunction with the chainstay length of the frame!

I’m sure by now you would like to hear about how it rides, but before we get on to that I think a few of the potential disadvantages should be addressed.

Efficiency - It’s well known that a chain drive / derailleur system is very efficient (95% or thereabouts) with an internal gear system a few percent behind that figure. It’s difficult to be exact with this as there are so many factors, but if you were to compare a worn, dirty derailleur set up, in a gear with a suboptimal chainline, it’s efficiency would almost certainly be less than a gearbox with its permanently straight chain/belt line. A ‘few percent’ difference is about the same as the drag caused by a dynamo hub, and would make a difference of a couple of minutes at most over 100km. To summarise, it’s not the efficiency that will hold you back, it’ll be the headwind, tyre resistance, or most likely, your legs.
Weight – There’s not much getting around this one, a Pinion set up will likely be 400-600g heavier than an Ultegra / SLX derailleur groupset. That might sound like quite a lot, but remember you can have a very light rear wheel as there is no cassette. A light rear wheel makes a bike feel responsive, it accelerates well, and it certainly didn’t feel like the weight was an issue when testing.


Frame design – In order to use a belt, we put a split in the seat stay. This simple arrangement allows the belt to pass through the frame, it works, we have no issues. The slightly bigger issue is the chainstay length / gear ratio factor. Due to the limited variations of sprocket and belt length we found we had to design the frame with slightly longer stays than usual, and use a lower than standard gear range. The bike has gears that approximately equate to a MTB low gear (30T chainring and 42T cassette), and a road bike high gear, (50T ‘ring, 12T cassette). This is a huge range, which matched the style of bike well and should get you up, over and along any terrain in any conditions, however it leads on to what I felt was the only major drawback of the setup.

With 12 gears covering a wide range, I often felt like I couldn’t find quite the right gear, and had to adapt my riding style a little. Over the course of a ride I did get used to it, but coming straight from a standard set up this did feel odd at first. There is an 18 speed box available that would resolve this, and considering the style of bike that it is I don’t think this would be a deal breaker.

Other than the gaps between gears, I was immediately impressed by the way the bike rode. Before riding I was concerned that the ergonomics and shifting style (left lever shifts down, right shifts up) would be so different from Shimano I would find it odd, but actually the shape of the levers was excellent and the shifting very intuitive.

The gear change itself was smooth, as with all internal gears you do have to adapt a little to letting off the power and allowing the gearbox to change. The way a gearbox works though gives a major advantage in that you can change gear when not pedalling – no more getting to the bottom of a descent or stopping at lights in the wrong gear!

The power transmission felt both smooth and responsive, down to the combination of belt/box and the light/stiff rear wheel I mentioned earlier. There was no crunching of gritty chain against cassette when forced to shift under power, the whole set up remained composed and consistent whatever conditions I threw at it.

If you’re in the market for a bike that can take you anywhere, in any conditions, then Pinion is worth considering, it’s not for everyone but it’s more than just a viable option, it’s a great one. Hopefully gearboxes will continue to become more popular and get even better in years to come, but they have already reached a point where there are few drawbacks compared to a derailleur set up.

A complete Escape Pinion / Belt Drive bike starts at £4999 with various options to customise the specification to your needs.

Pease contact sales@enigmabikes.com / 01323 845849 for more information.