Bike technology: will your next purchase be money invested or wasted?

Joe Beer and Andrew Hamilton look at the latest science behind bike technology and ask, which innovations in bike design are really worth your attention?

The majority of bikes evolved only very, very slowly over the last quarter of the 20th century. However, with the acceleration of computer technology and the expansion of global markets, we have had quantum leaps in frame, wheel, tyre and component evolution. At no time in the history of cycling has so much technological innovation occurred. Road bikes have evolved into specific road, sportive/fitness or time trial versions. Clunky mountain bikes have become specialised into enduro, downhill, free ride, gravel and many other species. Triathlon (where cycling is the biggest chunk of the event), has spawned a huge variation of set ups – akin to the ‘wild west’ mixed in with Darwinian ‘survival-of-the-fittest’ innovations.

As a coach, Joe is lucky as he gets wind of the latest innovation and trends from deep inside the cycle industry via partner companies, friends and some of the best tech gurus out there. Developments such as new frame designs, clothing data, prototype-spy shots, and insider gossip makes it clear to him that this innovation is not slowing down. You the consumer therefore have lots and lots of choice.

But for those of you thinking of splashing out on a new bike, how can best you navigate your way and choose a bike that really will lower your times, while being sensible with the cash? Back in the day, there were just two or three choices– or you just did what was done ten years earlier. Now you have a mass of possible choices every time you buy a new bike. In this article, we will attempt to make the choice more logical, and to give you a rule of thumb or tool to help you spend wisely. You’ll also be able to justify your expenditure to those that really don’t understand why you need another bike – your spouse for example!

Getting the basics right

*Frame materials

Once upon a time, we only had a few variants of steel. Now we have a wide range of materials such as aluminium, titanium, scandium alloys and of course, numerous variants of carbon fibre. Carbon fibre offers particular advantages for frame construction as it can be produced specifically for each location within a bike frame. As the stresses and strains have become possible to measure and simulate (thanks to computing technology) the direction of fibre lay-up, amount and resin choice has become more and more specialised. The top bike companies use this approach to produce superior frames – as opposed to a cheap version, which is just made of bog-standard carbon fibre. Changes of UCI rules controlling frame design occur at regular intervals (see figure 1); thus, frame shape possibilities and the constant drive for incremental gains means that carbon bike frames are constantly evolving.


FIGURE 1: EXAMPLE OF UCI FRAME ELEMENT REQUIREMENTS IN MASS-START ROAD ACES AND CYCLO-CROSS*


Rule of thumb: Aside from the ‘you get what you pay for’ rule (which applies across most aspects of life), choose a bike frame that suits its final function. Basing decisions just on weight, colour or a ‘cool’ aero shape is not enough. Remember that you can fine tune when it comes to other components. Carbon may be king in the weight stakes, but titanium, aluminium alloys and steel still have a part to play where function and cost are ahead of outright cutting edge design. Ask yourself questions such as whether it needs panniers as a commuting bike, does it need wider tires for semi off road “gravel” riding, or is it a fast road bike with a superb blend of aero and weight (see figure 2)? The bike frame is the skeleton of your project so remember that function always beats fashion.

How to choose: Read in-depth reviews, take plenty of test rides (test ride, test ride and test ride!) and seek other riders’ honest feedback.


FIGURE 2: FELT’S AR2

Felt’s wind tunnel-developed AR combines an aero design frame (derived from extensive wind tunnel testing) and low weight. Historically, aero bike designs added weight and traded stiffness for their slippery form. The AR2 however is constructed with Felt’s most sophisticated carbon fibre (UHC Ultimate + TeXtreme), which is both stiff and light. The drawback of course is cost; even though this isn’t Felt’s most recent model, you can still expect to pay around £4,000  ($5,000) for a fully built bike using this kind of technology!


*Wheel design

Box section alloy wheels using clincher tyres provide a great commute, training bike and low-budget solution (see figure 3). However, as carbon fibre technology progresses, manufacturers can produce ever more subtle shapes and blends to improve aerodynamics, widen tyre choice (tubeless, tubular)) and accommodate new brake innovations on road bikes – namely disc brakes. One trend in particular is to use wider tyres, which can improve comfort and lower rolling resistance. Accordingly, rims have evolved. Indeed, some manufacturers no longer spec 23mm tyres (the once standard width) on their conventional calliper brake bikes. In the future, many predict 26-28mm becoming the norm for training on disc-enabled bikes (see box 2 later). Beyond this however, going even wider will not make a bike faster due to the increased weight of a wider tyre and rim.


Figure 3: Box section rims

 

DT Swiss RR21 Clincher rims. A cross section through the rim is ‘box shaped’


Rule of thumb: Buy clincher technology (not stick on tubular tyres). Clincher wheels might not be lightest or most aero, but they are robust enough and are aerodynamic enough. And the reality is that wheels don’t slow you down that much – tyres do. So never go looking for Olympic style Velodrome ‘aero-ness’. Instead, have a very nice spare pair of wheels for racing and good roads/ weather conditions if you have the budget.

How to choose: Wheels can go wrong and punctures do happen so put practicality first.

Disc brakes

Far and away the biggest change in road bikes has been the uptake of disc-brake technology from years of R&D on off-road bikes. So are disc brakes worth it for a time trial/sportive cyclist or for triathletes? Disc brakes work really well in the wet – this is in contrast to conventional brakes which can struggle when the wheel rim is wet. Disc brakes also allow for wider frame clearance, reducing aerodynamic drag. For commuters, they have good longevity, and for those venturing to Europe for fitness training or sportives on the long descents of Tour stages, disc brakes are a plus as they avoid the potential issue of overheating of the wheel rims.

As of 2018, the UCI finally approved disc brakes. Undoubtedly, the pros will embrace these and make good use of the improved and road-specific disc brakes, which will in turn give the public more options and refinement. Also, ask the trade whether disc brakes are likely to take over from rim based brakes on the road in the next decade and the answer appears to be a clear ‘yes’. According to Keith Murray who is the UK Bike Sales Manager at SCOTT Sports: “If you look at cyclocross as an example, virtually all pro and elite riders are now racing on disc brakes, and as a brand, we no longer produce a nondisc brake cyclocross bike. With disc brakes, carbon wheels no longer have to be over engineered to include a braking track, and wheels last longer. Leisure and sportive riders are embracing new technology too”.

Rule of thumb: Test ride a disc-braked bike to see how you like the positivity of braking. But remember that swapping out wheels from a conventional bike is not possible. If your caliper rim brakes have sufficed for you so far, paying handsomely for a disc braked bike could be overkill and unnecessary.

How to choose: Speak to riders who have been early adopters of disc brakes and those used to riding off road with disc brakes. Seek opinions on how easy they are to use and adjust. Look at the info in box 1 to help you decide.

BOX 1: RIM BRAKES AND DISC BRAKES: COMPARING ADVANTAGES

RIMDISC
Requiring only levers, cables and lightweight calipers, rim brakes are significantly lighter than hydraulic disc brake systems which need fluid, hoses, reservoirs and rotors as well as levers and calipers.Hydraulic disc brakes generally provide significantly more stopping power than rim brakes, especially in poor weather when rim brakes will have difficulty gripping the wheel. Disc brakes keep on working even when wet.
Because of all the extra components, disc brakes can be trickier to maintain than rim brakes, and bleeding disc brake systems is not as easy as taking up the slack on your cable. Also, hydraulic brake fluid can be pretty unpleasant stuff to work with.Hydraulic disc brakes are better at providing an accurate ‘feel’ of braking force and how much force needs to be applied. This helps you to feel the limits of tyre traction without locking up the wheels. Rim brakes can’t quite match this ability for modulation, although the newest rim calipers are getting better and better.
With the extra technology and components needed for a disc brake set-up, these are pricier to purchase than rim brakes, and are also more expensive to repair and replace, too.Compared to rim brakes used on the road, disc brakes are much better at coping with mud and debris thrown up from the road surface – important if you regularly train on rural roads in poor conditions.
Other: Fitting disc brakes to existing road bike frame designs isn’t an option. Carbon frames in particular need redesigning to deal with the more powerful braking forces. Similarly, to get the most out of disc brakes you need to use stronger ‘thru-axles’ rather than quick release hubs. However, once you’re used to using discs, going back to rim brakes often feels like a definite backward step in terms of pure performance.

LATEST TRENDS

Having established the basics, let’s consider which of the latest trends in bike tech are most likely to give you tangible benefits:

Q: Which trends are likely to help you to a PB and which are just fashion?

A: Wider clincher tyres. These allow you to increase speed by reducing rolling resistance (see box 2). They also help with bike handling (saving time) and for longer races or triathlons rider fatigue is reduced. Fashion might say tubular tyres, because the pros use them. However, more pro teams are going wider and the move to clinchers is gaining traction (no pun intended) even among those who have only ridden on narrow tubulars.

Q: Which trends will give you the best time savings?

A: Probably clothing followed by better tyres. The rider is the cause of most wind drag and clothing is much more likely to be wrong than right. Pro teams spend thousands just finding a handful of watts of energy savings by tweaking fabric orientation, and the cut and stitching of a riding suit. The fashionable bike tech choices such as super deep wheels or disc wheels should only be considered by experienced racers who have already sorted out all aspects of their clothing (top/shorts, helmet, socks, shoe covers etc).

Q: Which trends offer the best bang for buck?

A: Tyres are evolving and improving all the time, so coughing up for really good tyres is probably money well spent. Remember that rolling resistance never goes away – even on completely smooth surfaces, it saps a significant proportion of the power you put in. The width, pressure and model choice of tyre you use can all make a meaningful difference in helping you to get the best from you and the bike on a given day. Clothing and helmet choices are a close second. The fashionable decision would be aiming at silly weigh-saving gimmicks (I used to chase this so I am as guilty as charged!). Most riders need to be leaner themselves before attempting to get their bike down to 6.8kg UCI bike weight limit

Q: Which trends could help in other ways (reduced injury, more comfort etc)?

A: First and foremost would be the rise in scientific bike fitting services. This helps with bike handling and power delivery, which therefore reduces the risk of back and knee injury – and incidents of falling off due to poor bike fit. Many bike manufacturers now also provide demo saddles to try; given much of your weight is on the saddle, it has to be fit for purpose so you can enjoy the miles.


BOX 2: NEVER MIND THE QUALITY, FEEL THE WIDTH

As we’ve already mentioned, the trend is towards bigger tyre widths, and with good reason – compared to the older 23 or 21mm models, 25mm or even 28mm tyres are more comfortable and often faster, too. According to testing carried out by the Wheel Energy independent laboratory1, the key to minimising a tyre’s rolling resistance lies in reducing the energy lost to casing deformation – not minimising the contact patch. Wide tyres offer a wider but shorter contact patch. All other factors being equal, a shorter contact patch allows the tyre to ‘bulge’ less. With a shorter section of deflected sidewall, this translates to reduced rolling resistance.

To illustrate this point, let’s look at some test data produced by Jarmo Beirman, and which is available (along with other data) on the excellent website bicyclerolling resistance.com 2. In this test, Jarmo looked at the rolling resistance of Continental’s ‘Grand Prix 4000S II’ (aka the GP4000S II – a massively most popular road bike tyre) and compared the data from different width versions – the 23C, 25C, and 28C – to see how weight, size, and rolling resistance varied.

All tests were performed with the same wheel rim, load, speed, and inflation pressures on the same day. Measurements were taken at pressures of 120, 100, 80 and 60psi. The speed used was 18mph (29km/h) with a total wheel load of 94lbs/42.5kg per wheel. The ambient temperature was kept between 21-23°C and the same 100-gram Continental race inner tube was used in all tests.

First, here are the tyre weights (you can see that weight rises as width increases):

Now let’s look at rolling resistance:

The key thing to note is that the wider the tire, the lower the rolling resistance at the same air pressure. When you run lower air pressures, the differences get even bigger. A 28C tyre has less rolling resistance at a very comfortable 80psi than a 23C at a bone-jarring 120psi. This means you can ride a wider tyre at lower pressures and in more comfort without sacrificing rolling resistance – a real boon for cyclists who ride long distances on potholed roads. Remember however that with added weight, a wider tyre loses out slightly in acceleration stakes. It’s also slightly less aero too. Overall however, if your bike frame design can accommodate it, a wider tyre provides a win/win for most cyclists and triathletes.


CASE STUDY: David Graham Lane

When he’s not working as a dentist, David who is 58 years old and lives in Somerset, likes to compete in triathlons and time trials. A triathlete in his younger days Dave competed in the mid 90’s before a knee injury stopped him and he then started a family. Dave lapsed, but took up triathlon again after losing his wife to breast cancer in 2005. As he explains: “I was left to run a business and raise two kids aged 9 and 7. I was getting heavier and unfit and needed a purpose again. A patient challenged me to a local sprint triathlon and I managed to beat him. I knew I was hooked again. After some months I met my coach Joe Beer, and I’ve never looked back.”

Dave is quite modest saying “I’ve no great talent but lots of enthusiasm to do the best I can at whatever I do.” His best times to date are a 25-mile TT time of 56:16 and a 10-mile time of 23:18. He’s also performed well at the 70.3-mile triathlon distance, finishing 4th in his age group at the Weymouth event in 2016, and generally finishing anywhere from mid 20’s to top 10 depending on the size and quality of the field.

Dave is a fan of utilising bike tech to maximise performance, but tries to choose on the basis of science. He currently rides a Scott Foil, which combines low weight with a number of aero features such as an integrated cockpit, internally routed cables, and reduced distance between the seat tube and seat stays, which reduces the amount of turbulence near the rear wheel. As Dave puts it: “I feel it’s ‘free’ speed and daft not to have it if you can afford it. Mentally you can ride knowing you’re doing your best, with a no ‘stone unturned attitude’ and wondering ‘what if…?’ The bike feels faster and I’ve proved it to myself a number of times. I need all the help I can get!”


See also:

References

  1. http://www.wheelenergy.com/
  2. http://www.bicyclerollingresistance.com/specials/conti-gp4000s-ii-23-25-28
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