You Can’t Do That On a Bike

Why is it that people’s first reaction to a lot of my riding or any suggestions about riding is “you can’t do that”. There are unspoken preconceptions of what you can and cannot do on a bike, and even what is “normal” to do on a bike.

In general, riding more than 5km is not “normal” on a bike, riding fast is not “normal” on a bike, riding for more than like and hour is not “normal”, folding a bike and taking it on the bus is not “normal”. The list goes on and on, but I will spare you the rambling.

So this comes down to a problem of how we define “normal”.

For most people, this is how it comes out. They don’t do those things like that, so why would anyone else.

Well, here are some of the things that people do on bikes that are slightly out of the ordinary.

Endurance

http://picasaweb.google.com/hellotopeter/Mobile#5471033951220163890

A recent post on Taiwan in Cycles talked out Jure Robic, a Slovene who is considered to possibly be the world’s greatest endurance athlete. The picture above is him after 2,530 miles and 7 days, 9 hours and twenty minutes on the bike. In that time he only got 9 hours sleep and consumed a mind boggling 100,000 calories. At a different time he set a 24 hours riding record of 834.7 km.

The article in the New York Times outlines the metal breakdown he goes through in his attempts at RAAM, a non-stop race across the USA.

Definitely not “normal”

Speed & Distance

http://picasaweb.google.com/hellotopeter/Mobile#5471035309137834018

Bicycles are usually considered fairly slow, but here are some figures…

  • 200m flying start record (HPV): 132 km/h
  • downhill speed record (on snow): 210 km/h
  • 24 hour distance record (HPV): 1041.25 km

These are all records that were set on human power alone. The reality is that these were all achieved with very specialized bicycles and in perfect conditions, which might lead you to discredit them.

But not so fast, because the entire Human Powered Vehicle crowd are basically University students and people who do it as a hobby. There are no big sponsorships and to use a computing metaphor is closer to the open source crowd than to the battles of the big names.

Big Stuff Transport

http://picasaweb.google.com/hellotopeter/Mobile#5471033954412823490

Let’s get a little more practical. Moving big stuff is often a reason for cars, but just like trucks are specialized motorized vehicles more moving lots of stuff, so there are also bike for doing the same thing.

Introducing the Long John. Nope, not a pair of underwear to keep your precious bits warm in the winter, but a bike for hauling big things, typically up to 120 kg or so.

Not for long distances probably, but definitely convenient for errands.

Kid Transport

http://picasaweb.google.com/hellotopeter/Mobile#5468000275273485762

As a parent of two, one of my main struggles is with just how to take the kids along on rides. Oftentimes it is just me by myself, so I need to be able to get both on one bike.

My solution is to take a very standard production bike, put a kid seat on the back and another one between the seat and handlebars. It works, but does lack a bit of comfort for longer rides, which is where my other favorite kind of bike kicks in.

The cargo bike is designed with a very long tail, which adds stability when putting lots of weight over the rear end of the bike.

Take Them Anywhere

http://picasaweb.google.com/hellotopeter/Mobile#5470327669696775330

And finally, if you really need to take a bike with you and are short of space, something like the little guy below fold really tiny and can take you short distances.

How To Choose The Perfect Stem

The wild west. A small and dusty town. A bar.  A derivative walks into the bar. All the functions scatter. In a dark corner, a lone function dares to stand his ground. The derivative walks up to the lone function and asks, “Who the hell do you think you are?” Without skipping a beat, the function, with eyes barely visible from under the brim of  his hat, replies “I’m ex.” The derivative gives a small, knowing grin and says, “Today is not your lucky day, I’m d/dy.” – Original source unknown

So it’s been a while  since whipping out the high school math books. I mean who needs that kind of grief in the real world?

Well, ladies and gents, for the first time ever, I’m going to show you a practical use for your trigonometry classes.

But fear not, I’ll be holding your hand through this, you just need to plug in the numbers.

Why This Is Useful

The best option for choosing a stem is to have yourself measured on your bike and get a stem that matches the angle and length of the one used for measurement. There is no guessing here, and it’s all worked out well.

But what if your bike is not quite right, or if you didn’t have it fitted, or after some time the “correct” fit just doesn’t quite cut it?

Amongst other things, the stem will need to be adjusted.

Simple?

No.

Doable?

Yes.

Because of the angles, every adjustment of the stem affects not only the height, but the distance from the top of the saddle to the handlebars.

How My Dilemma Helps You

I am 6’1″ (185mm) and my build gives me legs that are quite long, but not long arms. I’m like a Tyrannosaurus on wheels.

Ideally I’d be riding a custom built frame that’s just right for me, but I don’t have deep pockets for that kinda stuff, so standard consumer bikes is the only option. Fitting my body on a standard, production bike takes a bit of work, thought and adjustment.

My current mountain bike setup puts the handlebars about 79cm in front of the saddle (measured from where my sitting bones would rest). This is a position I have had on my bikes for over 10 years already, but after riding a small, folding bike that is only 72cm from seat to handlebar, and finding it quite comfortable, I need to make some adjustments to my bigger bike. The vertical difference between saddle and handlebar currently puts the handlebar 2cm below the saddle.

There is one other sure giveaway of being too stretched out. When riding for over three hours I often place the middle of my fingers on the handlebars, rather than the palm. This position eases strain in my back and just feels right.

Target: move handlebars 4cm closer to seat, and raise them by up to 2cm.

Ready?

Let’s go.

Preparation

First, some abbreviations:

  • hl = horizontal length, the length of your stem measured directly forward, parallel to level ground (we’ll calculate this number)
  • vh = vertical height, the height of your stem as measured directly upwards (we’ll calculate this number)
  • sa = stem angle, the angle marked on the stem
  • sl = stem length, the length marked on the stem
  • hta = head tube angle, the angle of your head tube (we’ll measure this)

To measure the head tube angle:

  • Take angle from manufacturers specifications (I did)

or

  • Stand bike securely (lean against something, tie rubber bands around brake levers and handlebars to stop sliding)
  • Find something long and straight (broom, etc)
  • Drop line straight down the head tube to the floor
  • Measure the head tube angle as shown in the diagram, between the floor and that line (you’ll need a protractor for this)

To measure the stem length:

  • Check specifications (often written on the underside of the stem)

or

  • Measure from the center of the head tube to the center of the handlebar.

The Math Part

You’ll need the online scientific calculator (or a real one) for these.

Calculate horizontal length and vertical height.

bignum = 90 – head tube angle + stem angle

horizontal length = cos(bignum) x stem length

vertical height = sin(bignum) x stem length

Original Stem Figures

My current figures are…

  • stem angle = 25
  • stem length = 120mm
  • head tube angle = 72

so…

bignum = 90 – 72 + 25 = 43

horizontal length = cos(43) x 120 = 87mm

vertical height = sin(43) x 120 = 81mm

Find A New Stem

Now you just need to plug in the numbers of a new stem to find the one that is closest to your requirements.

To get 4cm extra height is quite a rise, so I’ll try out a 45 degree stem first. These are available in a range of lengths, this angle is probably right, but the length will make a big difference.

120mm stem with 45 degree rise:

bignum = 90 – 72 + 45 = 63

horizontal length = cos(63) x 120 = 54mm

vertical height = sin(63) x 120 = 106mm

So I’ve moved back 33mm, but moved up by 25mm.

I was hoping to move further back and don’t need that much more height.

Next…

100mm stem with 45 degree rise:

bignum = 90 – 72 + 45 = 63

horizontal length = cos(63) x 100 = 45mm

vertical height = sin(63) x 100 = 89mm

Overall, for my bike, they work out as shown in the table below.

Stem Horizontal Length Vertical Height
120mm, 25 degree 87mm 81mm
120mm, 45 degree 54mm 106mm
100mm, 45 degree 45mm 89mm

Conclusion

Taking the time to get the right stem is worth it. However, this isn’t really needed any more and there are plenty of shops with adjustable stems in their stock. It’s much easier to use one of those to determine the right length, etc.

If you are in the market for a very expensive stem, I’d recommend just buying an adjustable one (not that expensive), and then spend a little less on the full stem when you’ve determined the right size and length.