Wednesday, September 21, 2011

Racing - UCI Minimum Weight and Bicycle Technology

We all know about the UCI's pretty conservative weight limit, i.e. their minimum bike weight. It's 6.8 kg, about 15 pounds, and it's based on some long past assumptions, the main one being that the standard material in a bike would be steel or aluminum. The rule came about before carbon fiber worked so well and after a few documented bike failures.

(If this was Wikipedia I'd need a "cite references" asterix here, but they mainly involved aluminum frames, typically modified by non-engineers "on-site").

Nowadays, with carbon fiber established, bikes can weigh very little. Some bike companies have released factory production bikes weighing in at just over 10 pounds, or about 4.5 to 5 kg. With such a low weight a bike like that would be illegal to use in pro races.

Incredible, right? You and I can walk into a bike shop, plunk down a credit card (with a high limit), and walk out with a bike that's so nice that it's totally illegal to race in the Tour de France.

It seems wrong that this is the case, but it is. F1 drivers don't drive econoboxes, they drive the ultimate racing macines; ProTour racers should but riding the F1 version of road bikes, but they aren't - they're riding weighed down bikes, handicapped by the rules.

With a lighter-than-allowed base bike, racers and their teams have two ways of increasing weight:
1. Add ballast
2. Add functionality


Of course the team can add weight to the bike. Glue a big slug of lead to the seatpost and you instantly increase the weight of the bike.

Cannondale, when the weight rule first came out, made an aluminum bike that easily dipped below the weight limit. They glued weights on the bike, illustrating that functionally the bike worked fine at the lower weight (safety and reliability-wise); the weights glued to the top tube wouldn't make the frame any stronger, nor improve performance. That was Cannondale's point and they made it well.

Not very functional weight.
(Photo taken from here)

The rules didn't change though.

Of course just adding weight on a bike don't increase functionality of the bike at all. Useless weight like this doesn't make sense. If you're going to drag 6.8 kg up the climb, you might as well drag something useful.

This brings us to...


Right now, with a relatively heavy bike required by the UCI, pro teams have the luxury of spec'ing out heavier parts. This weight can bring greater reliability, better performance (typically rigidity), and more information (powermeters integrated into bike parts).

One can improve basic performance by using slightly heavier parts. It seems almost standard for SRAM equipped teams to substitute a steel cage on the Red front derailleur and stiffer chainrings in lieu of the allegedly flexible Red ones. Both these modifications make for a more predictable front shifting setup, making for better shifting performance. Although Red is a light component group, these modifications take a tiny bit of that away.

Of course one can improve reliability and strength. Using heavier rims, bars, stem, or even a saddle can improve durability, make crashing less catastrophic, and make for a more responsive bike. Cavendish's bike is known for its extremely rigid stem, and I'm sure his bars aren't far behind.

One can improve fit too, by using heavier parts. I've seen reports of racers using aluminum crankarms instead of carbon, mainly to get unavailable lengths. If you need a 180mm crank and the carbon versions only hit 175mm, you need to use the aluminum ones. Inbetween lengths (177.5mm for example) will require the racer to do the saLinkme thing.

Finally one can improve functionality by adding parts or features. Floyd Landis used a Powertap hub, one of the first contenders to do so, in the mountains. Taller aero wheels, giving the riders an aero advantage, suddenly become possible all the time, not just when willing to exceed the minimum weight. Likewise aero road frames can be substituted for the "super light" less aero frames.


Of course, even with a functionally optimized bike, a bike can still dip well below the UCI limit. Both teams and manufacturers have become creative in adding weight, with reports of seat tube weights, bottom bracket slugs, and other non-functional ways of increasing weight. The UCI needs to look at a bike that has all the functional weight-adding features and still falls well below the minimum weight limit. Such a bike would be a good starting point for a new, lower minimum weight.

And, thankfully, with the rule a bit outdated, the UCI promised at some point to modify the minimum weight.

Therefore it only makes sense that both racers (i.e. their teams) and manufacturers should be planning on a new, lower minimum weight.

How does that affect us?

Let's say the UCI reduced the minimum weight to something somewhat possible, like 4.5 kg (about 10 pounds). It could be rider dependent, i.e. a percentage of the rider's weight. Such a system would need some kind of broad cutoff points so that losing 500 grams of weight doesn't means redoing the bike. In other words, for each 5 kg increment of racer weight there'd be a proportionate amount of bike weight (a 50 kg rider would be required to have a 4.5 kg bike, a 55 kg rider a 4.7 kg bike, etc).

It could also be related to frame size, so that a smaller framed bike would have a lower minimum weight. This way a bike whose saddle height and bar-saddle distance is a certain amount would have to weigh a certain amount.

To reach these lower-than-friendly weights a team would have to carefully select all its components. Tall aero wheels may not always be possible, nor an aero road frame. Perhaps the racer's favorite (but heavier) saddle will need to be replaced. And getting a heavier, stiffer frame may not be realistic.

In other words all those functional upgrades I mentioned above would have to go away. The racer would be racing a less desirable bike, at least as far as function goes.

This would force teams to actually use products that help make the racer go faster or save energy or something.

One way to deal with a much lower weight limit is to embrace innovative and idiosyncratic technology. Such technologies and ideas currently overlooked will become much more significant when the minimum weight drops significantly.

For example, in a conversation with an industry person (components) about BB30 faults, the main advantage he mentioned was weight, or lack thereof. BB30 is extremely light, rigid, and allows for weight to be used elsewhere. Studies have shown that actual crank stiffness doesn't change that much.

A drawback is that long term durability (after replacing bearings multiple times for example) is suspect, with frame shells distorting and the like.

BB30 (and the SRAM version, PressFit30 or PF30), allow the use a significantly lighter bottom bracket axle, reducing the weight of the overall crank and bottom bracket substantially, without any penalty in rigidity. I know that my crank and BB (with a powermeter in the crank) weighs about 675 grams, much less than the 800-900 gram typical weights for a normal crank and bottom bracket.

Such weight savings become significant if the weight saved allows the racer to then put on some other functionally improved parts, like a taller more aero wheel/set, a powermeter, those longer cranks, stiffer chainrings, etc.

Likewise, if the pros really require the "rigidity upgrades" to SRAM Red, then making those upgrades suddenly have a penalty. I'm sure there are racers who will sacrifice that rigidity to stay at the absolute minimum bike weight. Michael Rasmussen was known for having just one bottle cage on his bike, so he wouldn't be able to carry two - it would be too heavy.

A very low weight limit would also call out inefficient designs cranked out by various manufacturers. Cosmetic curves in frames and such would penalize the racer. Frames would become more efficient, with engineering taking a step forward, "industrial design" a step back.

We'd also see some movement off the bike for various bike things. Right now there are no minimum weights for the rider's clothing or apparel, so it may be that we'll start seeing products mounted on the rider rather than on the bike. For example, instead of powermeters in bike components, racers can use a shoe mounted version. Any weight penalties for electric shiftingLink and other features become significant if they push the bike over the minimum weight.

So what would we see with a much lower UCI minimum weight?

1. Larger axle diameters. BB30 is great for the bottom bracket, but aluminum or carbon fiber axles in hubs saves weight too. Manufacturers will look to minimize weight by increasing axle diameters and using more exotic materials. I suspect carbon fiber axles will become the norm for the BB and maybe the hubs. The steerer tube is already carbon fiber.

2. A reduction in the cosmetic, non-functional frame features. Is having huge stays really necessary? Or a large headtube? Frame manufacturers will quickly optimize their framesets. Those that have poor design staff will end up with less-than-optimal frames.

3. Careful application of aero parts. Aero parts typically weight more than their non-aero counterparts. A tall 90mm rim weighs more than a comparable 30mm rim. Riders will have to be more careful when selecting components for a given day. Flat days will encourage more aero equipment; hilly days less.

4. Less data collecting. Powermeters add weight, and although data comes in handy, there are plenty of pro racers that race without power measuring devices on their bike. A slight (but psychological) weight penalty may be all that they need to ditch such things. Of course if the UCI starts tracking power as part of their anti-doping efforts, this would be a moot point (budget x grams for a powermeter).

5. Equipment malfunctions. Not failures, malfunctions. A less-rigid front derailleur, with a less-rigid chainring, can cause shifting malfunctions.

6. Lighter "regular" brakes. Currently the three main manufacturers have pretty normal brakes, very similar in weight and function. Innovative brakes can save dramatic amounts of weight, freeing up weight for use elsewhere.

7. Failures. Unfortunately lighter bikes, combined with the normal crashes and such, will cause more equipment failures. Although the UCI regulates some minimum strength (they test forks for example, so they don't arbitrarily fold under a rider), a bike that's been crashed may have some unpredictable failures. Hincapie's steerer tube failure is such a thing; hopefully the parts that fail will be less critical, like a rear brake or a seatpost or a saddle or something.

Although not necessarily cheap, lowering the minimum weight on bikes would encourage development of frames and components. Companies currently coasting along would be forced to start development again; companies currently exploring developmental ideas would be rewarded with a year or two head start on performance. We'll see less waste (less material used), better production (because without higher quality the lighter parts will fail), and more differentiation between bike companies.

I'm looking forward to the day the UCI lowers the minimum bike weight. The UCI will jolt the bike industry to action, making for very light, very high performance bikes.

And maybe, just maybe, I'll be able to ride a UCI legal 10 pound bike.


Anonymous said...

That is all fine and dandy yet these cheap plastic frames keep breaking right and left. Maybe they should quit worrying so much about weight and start worrying about performance and durability a little more. I would rather have a reliable and stiff frame that I don't have to worry about cracking in less then 6 months, which is exactly how long my last carbon frame lasted.

Anonymous said...

"ProTour racers should but riding the F1 version of road bikes, but they aren't - they're riding weighed down bikes, handicapped by the rules."

Oh my, were you not aware that F1 has long had a minimum weight and many teams have had to put ballast in the car to bring it up to weight? There are many other car restrictions in F1 that are intended to control the costs of the vehicles and make the human component meaningful, as well as reducing deaths. If they didn't do that then the series would be dominated by the deepest pocketed car company and would be boring and predictable. That has happened to some past racing series with few restrictions such as Can-Am.

Aki said...

Yes I'm well aware of F1's minimum weight rule. I also know that there are material limitations in F1. However, if you compare F1 to any other paved road racing car, F1 is the best - they are embarrassingly fast, have insane grip, and can be tuned for almost any kind of tarmac surface (save an indoor warehouse with slippery concrete floors if I recall a Top Gear episode correctly).

My point is that ProTour racers should be racing the F1 version of bikes, not handicapped versions. A more apt example would be the McLaren F1 street car, which they had to down-power to make race legal for Lemans.

Although you might argue that the race going McLaren F1 would be undriveable in the street (due to ride height, spring stiffness, gearing, maybe turning radius), the argument falls short when you consider that ProTour races take place on public roads. It would be a valid argument with track bikes (which were originally made with round fork tubes on the assumption that a track would have no curbs or potholes - the track fork would fold up hitting something a road fork would handle without a problem). Track bikes are raced on the track so are optimized for that. Road bikes... they're raced on normal (or worse than normal) roads.

For a weekend warrior to ride 10-12 lbs bikes while the pros are forced to ride something heavier, that doesn't seem appropriate. I've seen enough 12 lbs bikes at local races and there are off-the-shelf 10.x pound bikes available locally too. If you were buying a car it'd be like getting a 500 kg F1 car, vs say a 560kg minimum (I think it's that if I subtract my 80 kg weight from 640 kg total).

There are some UCI oddities too. For example, for a long time they weighed bikes only before races, not afterward. This led to some interesting cheats like a seat tube full of ice (that would drip away and reduce weight). One day, on a mountain stage, officials announced that they'd be weighing the top six bikes after the stage. The commentators thought this ludicrous, but as you well know, in F1 they carefully check the cars after the race to make sure they are up to spec (weight, floor wear, legal fuel, etc).