Downhill Bars

A rant with a twist - the frustrations of a propeller head in the bike biz

I try to be mellow for the most part (If you know me better than this don't blow it for me okay? I'm just doin' a job here.). Anger doesn't do me much good. But I do occasionally have strong feelings about a few things.

Actually there are a lot of things I like or don't like, passionately. Most haven't anything to do with bicycles, and I don't want to turn this column into a political soap box. But I am going to wing it once

 

Downhill bars

They have an extra bend on both sides. This is not a good thing. They're lame. Lameness is a technical term by the way. Lameness is a cumulative property of a structural (or non structural) part, like stiffness or weight but more comprehensive. It's a combination of strength, performance, manufacturing complexity, value I'm sure the advanced engineers and materials scientists out there will back me up on this one.

 

Design some bars

If you wanted to design a new handlebar, what would you do? We've been through all of this before. Decide on what's important. Start with how it fits onto the bike and what has to attach to it. Often this is what determines what the basic part looks like, and constrains the design to a very limited number of design parameters. It does with handlebars.

What are the engineering specifics in this instance? At an absolute minimum the handlebar has to fit onto the bike and work with all of the bits that attach onto the bars themselves. You don't want to have to re-design levers, grips, stems, and bar ends!

 

With that done you can go on to next step. What should the bar do, (and what should it never do)? Think about the bar's material, strength, weight, and shape as it relates to performance.

The material, weight, strength bit is simple. Sane folks agree that a bar should be durable enough to survive its intended use reliably for an acceptable period of time. If it is overloaded, it should behave as safely as possible. No justification of this is necessary by now right? A good bar is as light as possible given all of the above.

The fit issues are really simple too. The bar should be offered in a variety of widths and angles, to work properly for a range of riders. No quibbles there except from the people who have to control the inventory. How many handlebar SKUs do you want to create? You get half that, and consider your self lucky to have those.

I'll add one more thing to the list. It would also be nice if the bars were affordable if you want anyone to actually be able to use them (another way to say that you actually want to sell some - the greedy capitalist in me bares its ugly form). I admit that this is an ethical and regional issue; you don't have to worry about how much something costs if you live in Marin County or if you work for a magazine. How nice it would be to live in a world so disconnected from reality.

If you think about it, you can't mess too much with this list. This is all there is. With this and the basic shape you already have, you design, test, qualify and manufacture something that meets all the requirements. If you did your work properly you've got a good bar. It sounds easy. It's not.

The trick is to get the mix right. For example, it's not too tough to make a heavy flat bar meet these requirements. Adding metal makes everything easy. The real challenge is to make a light, strong bar that doesn't cost a fortune. It can be done. There are quite a few good bars on the market that match up pretty well with this list. It is not an unreasonable list of requirements.

 

How does a high rise bar do in this game?

Assume that you design one of these bars and that it's executed so that it fits in a stem and that the parts that are supposed to fit onto it do. The assumption is made slightly more difficult because of the handlebar's shape. The bends take space to execute, and there's not much left out at the end for bars and grips unless you make the bars wide. It is possible though. Given that, what about the rest of the list? How does a bar with an extra couple of kinks in it fare?

From an engineering perspective, the things are a disaster in principle. They will inevitably weigh more (1), cost more (2), increase manufacturing complexity (3) and have less strength at a given weight and cost (4) when you compare them to flat bars of the same width. How's that for striking out? The unique feature of the bar's shape, the high rise, is hard to justify or even live with when you play by strict engineering rules. Tests, both fatigue and impact, show it clearly.

The score? Flat bars - 4, high rise bars - 0.

Why the engineering world conspires against the high rise bar.

There are two reasons. One is simple. The lightest, simplest structure that joins two points generally is shaped to follow the path of minimum length between the points. The shortest distance between two points is a straight line. You could quibble and say that the real problem in handlebar and stem design is how to connect three points together, and go on to argue that flat bars and the current stem shape is sub-optimal. You may be right. But this thread won't lead to high rise bars - I promise.

The second is that it's difficult to bend high strength materials into this shape. Materials that have proven to be good to make flat bars out of are not happy about being bent into tight radii when they are shaped into thin tubing. Tube materials that are happy about being bent, well, do you want bars that are made out of materials that are happy being bent? Makes sense if you think about it. There are some complexities I'm waving my hands over at this point concerning manufacturing sequences, heat treatments, and bending in an annealed state. Tight bends can be executed in high strength aluminum, but not without a substantial increase in complexity and cost.

Economical bending processes weaken the bars. The degree to which the bent cross section is distorted and the material is strained reduces it's fatigue strength. You have to use a lot more material to fight this off. If you do manage to pull off a bend in thin material, you may be creating a bar with a very short fuse. Anybody want to know why cross braces are so popular? They are a good idea, a good way to address the shortcomings of a fundamentally wrong design.

High rise bars will always be heavier (or weaker) and more expensive than an equivalent flat bar.

The last inning, two out, no one on, behind by 4, 1 strike on the batter.

On to the last issue - rider fit? Everyone agrees that a bar should be shaped in such a way that the rider can hold onto and operate the bike efficiently and comfortably, and be in control (to the extent that bars influence this) in any and all reasonable situations. Right?

Does the high rise bar have an advantage in this regard? The width (wide) and swept back angle (more) of the bars are arguably the design's only strong play. If there is an advantage here it is because the shape offers an ergonomic improvement to some or all riders, somehow.

This is a fancy way to say that the high rise bars put the grips into some new orientation with respect to the rest of the bike. When you use high rise bars can you position your grips somewhere that you can't get them into with flat bars?

No.

There are only two degrees of freedom in a handlebar design, and flat bars have both of them. These are the width and the angle the ends make (where you hang on). That's all there is.

High rise bars seem to have a third degree of freedom and this fools some people. As you rotate them around in the stem, you move the grips with respect to the saddle and pedals. You can make small adjustments to the location of the grips this way, forward or back, up or down, point them up or down a little at the ends.

But the different movements are not independent of one another; each is coupled together with the others because you are only rotating the bars. You may come up with something comfortable this way but the range of useful adjustments are very small. It starts getting weird if you rotate the bars too much. And the possibility of any particular set up is not unique to high rise bars. You can get your grips into the same position with a flat bar and a given stem.

Strike 2.

High rise bars are shaped differently than flat bars. They are wider, they sweep back more, and they raise the grips above the stem clamp and this is apparently something a lot of riders either like, or can adapt to. The bars don't accomplish this very efficiently with respect to any of the rules in bar design, but they get it done.

You can see where this is going now. If you really wanted to do this right, you could do it better with a wider, more swept back flat bar and a new stem with a different angle. If a rider only needs wider bars, it's simple to make flat bars wider. If a rider only needs the ends of the bars to be swept back more, flat bars can be bent more. Actually, if you think about it, if you fit well on a bar with a given width and angle, you would expect that a wider bar would also need to be swept back slightly more to fit you as well. If a rider wants to raise his or her grips it's simple. Use a stem with an angle that raises the bars.

There's a huge problem with this, not a technical problem, worse. Wide flat bars will not work because no one will like the way a high rise stem looks (they come on low priced bikes because novice riders like high bars and the truly hard core don't like the look). It's not going to look cool. Fashion uber alles.

Foul ball

There are a few other things buzzing around about high rise bars. They are flexible and more comfortable. It's possible, but very unlikely. If you use a cross brace, I think it's probably not true. The cross brace stiffens the bar up. If you don't use a cross brace the bar may be a bit more flexible than a flat bar, though I would be dubious about it if the bars were a reasonably durable design. The ones that last use a very thick wall in the middle, and this will stiffen them up. I can't argue it to the death here but, if it was desirable to make the bar flexible in a certain way, a flat bar would be the best way to do it.

Fouled off again

 

So what's going on? If all of this is true, why are so many of these bars out there?

A base knock. There's hope folks.

Wider bars make sense for a lot of people, simply from anatomical arguments. There were rumblings about this years ago. Why aren't bars wider? They probably should be for large riders, based simply on what the roadies know. No argument there. I limit the width of our current bars to keep control of the loads on them. It's not a problem to re-engineer the bars to be wider.

Another hit

And maybe wider bars are better in some circumstances for riders of more typical stature. I think the bars are showing riders another way to fit on a bike, maybe even something that should happen if rider's habits are changing a little.

Wider, higher bars may be an advantage in some very rough technical situations, though my experience is that the claimed increased leverage in steering is not important. It takes a few ounce inches to steer a bike in the hardest situation. Not many riders have a problem generating this kind of force.

The extra height and width can make it easier to hang on when the going gets real rough. You are braced better for big hits. I think there is also an advantage to hanging onto the bike in certain circumstances, especially when a rider shifts his or her weight rapidly and radically sideways. Need to hop the bike laterally over a parallel rut on a single track? Coil down and to the side, lean a bit, launch it, and land on the other side but out of shape. Wider bars put you in a position to do this and get away with it, better, and with more control. You can be out of position more and still have one hand outboard of your center of mass. You have a bigger range of motion and more leverage. It's speculative, but it's what I think is happening.

The bars are typically swept back more. I think it's because they are wider to some extent. And more bend is more comfortable to some riders. No big mystery.

It's hard to drag this out of people without leading them to it. I've tried. The typical response to "why do you like these bars" is something like "I dunno there more moto, ya know. I just like them.". If there weren't riders who I respected saying this I would blow the whole thing off as BS. But, I tried them, and I think this is what's going on.

The next batter gets walked

The tension builds.

 

What do you give up if you switch?

Three things from what I can tell.

Weight. This is the death to the idea for cross country racing at a high level unless the courses get much more technical and less hilly. It's not an issue for pure downhillers, but it has been for XC recreational riders for the last few years. Climbing on a light bike is more fun. There aren't too many parts that riders want that are much heavier than they have to be, and this will probably be true of handlebars again once the current fad loses momentum.

Strike one.

The out of the saddle climbing position on the bar ends that XC racers use on non technical climbs. It's similar to the climbing position on the brake hoods of a road bike, and this is also deep in the XC racers toolbox and not likely to be surrendered at the journeyman level. The wider bars are okay for climbing out of the saddle, not as bad as I expected, but not as good as bar ends on flat bars. How important is this to recreational riders? Depends. There's no right answer.

Put bar ends on high rise bars? It looks goofy but might work.

Strike two.

 

Strength at a given weight. No way around it.

It's a long fly ball, deep to center field, he's going back, back, back, and there's some clown hanging over the fence, reaching out for the ball, ready to interfere with the game.

But fashion is driving the trend hard right now; high rise bars are the bars to have if you want to be trendy. The mountain bike biz is a fashion industry, right?

The clown misses, so does the center fielder. The ball's off the wall, three runs score, the equalizing run is at third.

So what the hell - I say we make something for everybody. Better high rise bars and wider flat bars with more bend. At least we can do a little engineering on them and make some better parts than the others out there.

The next batter wiffs and strands the runner, the game is over.