By Mark V
Product development and industrial design can bring real benefit to another generation of bikes, but too much focus is spent on marketing gimmicks.
135mm Rear Hub Spacing
Widening the OLD (over-locknut design) of the rear dropout spacing allows a wheel to have less dish and/or have room for more cogs. Once upon a time road bikes and track bikes, both had a single cog, and they were both 120mm for the rear dropout spacing. With the addition of 6 or 7 cogs, the spacing for road bikes spread to 127mm. When road bikes added the eighth cog at the end of the 80s, the spacing went to 130mm. Shimano and SRAM managed to cram another couple cogs onto the same width cassette body (ie maintain the same amount of dish), but the 11th cog is forcing a move to hubs that invariably build up as weaker wheels. An industry-wide move to 135mm spacing would yield stronger, more durable wheels by virtue of plain ol’ physics, not fancy technology or expensive materials engineering.
Don’t get me wrong, I’m not a big fan of the arbitrary introduction of standards. Going to 135mm wheels would essentially relegate two decades of road bike production obsolete (or at least the ones that are not steel, which can often times be cold-set to a wider OLD). But let’s face it, the road bike market is on the verge of a real revolution in frame design due to the introduction of disc brakes. Disc brake hubs, with a few minor exceptions, will be 135mm. The industry may as well use the wider hub across the board.
Undersized Carbon Seatposts
Cannondale’s 2014 Synapse “endurance road” frame debuted at this year’s spring classics with a carbon seatpost a mere 25.4mm in diameter, a size that hasn’t been seen outside of BMX and department store bikes in about 20 years. This as most of the road bike industry, centered primarily on aluminum and carbon frame production, has mainly settled on the 31.6mm size as the default seatpost dimension. Why would Cannondale go skinny?
The skinny seatpost concept is a trend that popped up among XC hardtails recently, though to be honest Specialized always resisted the move to oversize seatposts that started in the mid-90s with Klein. The concept is rather simple; a seatpost smaller in diameter has less stiffness and is typically lighter to boot. Cannondale pushes it a little further by dialing the size even smaller than the once standard 27.2mm and shaping the post to make it even more flexible. Since the modern road frame is proportioned to have a fair bit of post exposed, it is just a ripe spot to use carbon’s flex and vibration damping to isolate the rider from the harshness of the road surface.
As the “endurance road” segment of the market gathers more steam, frame manufacturers have been trotting out all manner of gimmicks like elastomer vibration dampers, the ever popular bowed seatstays, the tapered-but-not-too-tapered fork steerers, etc. A skinnier seatpost is simple to execute, can actually save weight, and doesn’t conflict with all the design elements that are typically focused on making a stiffer drivetrain platform. A bonus is that these seatposts are round and thus can fit into a typical seatpost-clamp workstand, unlike the glut of aero seatposts and ISP that have become a required accessory to the “aero road” market.
15mm Thru-Axle front hubs for disc brakes
On the surface, a thru-axle for road bike front hubs seems like overkill, but already the industry and consumers have accepted all sorts of outlandish variations to the rest of the fork….just how many different diameters lower diameters are really necessary? A 15mm thru-axle more closely links the fork blades than is possible with a typical front hub and quick release, so that the fork functions more precisely without otherwise affecting its flex and damping behavior. And with a front disc brake and the way that the majority of lightweight skewers suck, a 15mm thru-axle is just a natural. In the long run, it’ll be a safer choice for consumers.
Direct-mount front derailleurs
With all the crazy shaping and ridiculously oversize BB areas typical on today’s carbon road frames, many manufacturers are going to braze-on tabs to mount the front derailleurs, mimicking the braze-ons of steel bikes. The problem is that a modern front shifter and chainring combination, unlike the friction downtube shifters and unramped rings of the 70s, is designed to be shifted at full power, and those wimpy little tabs are scarcely up to the task. Mountain bikes have faced similar issues with shifting systems and wildly divergent frame designs; their solution has been the “direct-mount” front derailleur standard that uses a bolt-on interface that provides good bracing to the derailleur and automatically aligns the cage with the chainrings.
Frame/fork clearances normalized for 700C x 28mm tires
No other feature affects the character of bike more than its tires, and for the last 30 years, the standard road bike has been built for short reach brake calipers and 700C x 23mm tires, which is the lower practical limit for road rubber. There are number of explanations why this became the standard back then, even though the steel fabrication meant that axle-to-crown fork dimensions and rear triangle clearance were very easy to manipulate even on a mass production scale. But let’s set the past aside for now and focus on the mid-to-long-term future of the road bike.
In both the independent tests and the highest levels of the sport, the 23mm road tire is no longer just assumed to be the fastest choice available. In many cases, wider tires have proven not only more comfortable but also faster from a rolling resistance and/or aerodynamic perspective. In some races, the professionals are specially modified road frames to allow tires upwards of 30mm wide to deal with rough roads. As potential consumers are drawn to the “endurance road” category and events such as “gravel grinders” (rides and races featuring large segments of gravel roads and unimproved roadways), those individuals could obviously benefit from road frames versatile enough to accept a range of tire sizes. With disc brakes promising to become widespread within the next five years, the outer diameter of the wheel/tire will no longer be a design parameter dictated by the brake. There is no good reason to adhere to the 23mm tire standard anymore. If only manufacturers and designers could see disc brakes as something beyond a marketing gimmick, they could create a product that brings a range of real benefits to riders.
Ed. note: After a good run of 42 issues, our magazine app is no longer available, but we’ve archived the content here on our blog.
Also published on Medium.
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