So, you want a new bike, eh?

Sometimes, you just have to stomach the fact that nothing lasts forever. Yeah, it was an old 80s steel-frame racer I found on hard rubbish. It was a long time coming.

I was faced with a quest – if I didn’t obtain a working bike to get my butt into Uni soon, I would go insane dealing with all the wonderful aspects of public transport we all love (to hate).

But it wasn’t an easy quest. The perils of choice aren’t overcome without a fair bit of research and testing. Especially when forking out to be the proud owner of a beautiful new bike.

This is where I’d like to impart my experience to try and guide those who are keen on a new bike in the right direction.

Frame – it’s what holds the bike together.

And it’s certainly one of the biggest influences on how the ride feels (at least it was to me). Today, frames are made out of aluminium alloy, steel, carbon fibre, or titanium. Each have their pros and cons, and everyone has different needs and preferences.

(I’m going to cut out carbon fibre and titanium, since they are quite pricey. I doubt a common Uni student commuter will care much for that.)

F = ma

One big selling point is the mass of the bike. You’ll hear a lot of “you’ll go quicker on a nice light bike” – and sure, you might. Going uphill you have less gravitational force pulling you back, since the force (F) is a function of mass (m) and gravitational acceleration (a or g). It’s also easier to stop and start quickly, because less force is required to accelerate the lighter mass.

Personally, I much prefer a bike with a bit of weight to it. Applying the same principle, the lighter the bike, the more it feels like the wind will blow you over!

P = mv

As well as this, a heavier bike has more momentum (P) – momentum is the product of mass and velocity (v). So, when you pick up speed, it feels like the bike wants to keep going rather than you always needing to push it. The bike is also more stable because it wants to stay upright. This actually makes the ride more pleasant, plus your legs will thank you later when they are strong!

Here’s a bit of a comparison between the two materials.

Aluminium Alloy – a common friend

Mountain bike frame made from sections of Al-alloy. Source: Wikimedia Commons

Aluminium (Al) – atomic number 13, atomic mass 26.98, and most abundant metal in the Earth’s crust.

Alloy – a few other elements chucked in to improve the properties of the metal solid (otherwise your whole bike would bend and warp because Al is so ‘ductile’ – easily deformed under stress!)

Pros:

Al is quite remarkable and incredibly useful due to its low density and resistance to corrosion.

As a result, an Al-alloy bike is light and does not rust. Most bikes these days are made of Al-alloy, too, due to its lower manufacturing costs by automated machines – handy if you’re looking for value for money!

Al-alloy also has better strength-to-weight ratio than steel.

Cons:

Al-alloy is less durable – it has one third the ‘elastic modulus’ of steel, meaning it can be deformed more easily. A few knocks and you’ll be seeing some dents and bends.

It is also, generally, stiffer than steel. This means the energy from any bumps and holes you ride over will travel from the wheel, all the way through the bike frame, and into your body, making the ride a bit harsher.

Steel – a mate for life

The steel frame of a LeMond road racing bicycle from 2000. Source: Wikimedia Commons

Steel is an Iron (Fe) alloy. Atomic number 26, atomic mass 55.85, and the second most abundant metal in Earth’s crust.

And my personal favourite (for commuting).

Steel was big for bikes a few decades ago, but have gone a little out of fashion now. It’s harder to find them first-hand, but they do exist if you look.

Pros:

Pretty much, steel turns the cons of Al-alloy around. Super durable and strong, it can take all kinds of abuse, and it will last a lifetime (if taken care of).

Being less stiff than Al-alloy, the energy from rough surfaces is dampened throughout the frame before it reaches your body. For long trips, steel might mean the difference between misery and pleasure.

Cons:

Steel can rust. Thus, corrosion can eat through and crack the frame if not taken care of properly. This was exactly the demise of my old bike.

Additionally, it is heavier than Al-alloy. But, if you’re like me, that’s not necessarily a bad thing!

 

And so, this leaves me to my best advice: test ride some different bikes. As I said, everyone is different with their own preferences, so finding out what you’re comfortable with is the best way to tackle the challenge.

A bike should be seen as an investment – in your health, in the environment, and most of all, in your pride!


One Response to “So, you want a new bike, eh?”

  1. Rob Dabal says:

    And don’t forget bamboo. Yes that extremely practical grass.

    A mate of mine has made a few bamboo bikes. Light, strong, considerably less embodied energy than any metal could wish for, biodegradable and available.

    Laborious is the down side and the need for carbon fibre to stitch it together.

    http://www.bamboobikes.com.au/author/mikmik/