Posts Tagged ‘bicycles’

Steel is Real

December 26th, 2009 3 comments

Ah the oft mentioned quote by any steel bicycle aficionado. Steel is indeed real. Well many will say that aluminium alloys are carbon fibre are hardly Unobtainuim but let’s just say that steel is indeed the real thing. Sadly this is not a view that pervades the general buying community.

Steel offers some great properties when it comes to bicycle frames, however to get real performance from steel with acceptable weight now involves using what are known as alloy steels.  But before I go any further let me say this there is no such this as an aluminium frame bike. They are aluminium alloy frames, aluminium is almost never used structurally in it’s pure state, it is too weak. Moreover to call an aluminium alloy frame an alloy frame is so erroneous it is not funny. For example, steel is an alloy, it is an alloy of iron and carbon, solder is an alloy on tin and lead. So we should be saying an aluminium alloy frame not an alloy frame  or aluminium frame.

I carry a bias here, when I finally replaced my recumbent trike (oh the folly), I sought out an alloy steel frame bike. The right price and look (and availability here in Australia) came for me in a Jamis Quest (2007 model). This has a Reynolds 631 alloy steel frame. This is a steel with additions of chromium, nickel and molybdenum, which actually means the steel air hardens. This allows the welded joint to improve its hardness and strength after welding. Unlike the related (and more expensive) Reynolds 853, Reynolds 631 does not have heat treatment done on the tube after being drawn out, so it has a lower Ultimate Tensile Strength (UTS). But it has stength to weight ratios equal to or approaching most aluminium alloys and importantly its stiffness to weight ratio is better than all aluminium alloys except X100 Aluminium lithium alloy.

So the main players of our story are steel, aluminium alloys and carbon fibre.

But isn’t aluminium alloy the best stuff?

Well no, in fact aluminium alloys offer some advantages to the hard core sprint cyclist but not the average rider nor the long distance rider. Aluminium alloy frames are made very stiff and as a consequence have very little flex, this means power is transmitted very well, but they tend to be “buzzy” particularly on rough roads or coarse chip bitumen reads we see in Australia.  They do tend to be lighter than a steel frame (particularly a low quality steel frame), and of course they are less likely to suffer detrimental corrosion than steel.

Now ignoring corrosion, because we can address that the big advantage is weight. But we are talking tiny variations when we get to high quality steel frames. My Jamis Quest with its Reynolds 631 alloy steel frame is about 200 grams heavier than a Jamis Ventura Elite (2007 model) 7005 aluminium alloy road bike with similar components. Interestingly the Jamis Ventura Race is exactly the same weight as the Quest, also with a 7005 frame.  Why?  Well in part it is due to the varying components on the three bikes and then in part due to the frame materials.  So let us stay with the 200 gram difference. Gee 200 grams. Let me consider that difference, if I eat a sandwich before a ride then that is the saving gone. Or if I carry two water bottles instead of one there it is gone again. Or I actually lose 2 kg and the  difference is shattered. Let us be serious that is bloody tiny. So for that 200 gram weight advantage I get a crap ride, yes there is no way that aluminium alloy frame will be as nice to ride as the steel frame. It will be stiff and uncomfortable and for a recreational rider like me the Quest will be significantly more comfortable.

Furthermore aluminium alloys have poor resistance to metal fatigue compared to steels. Metal fatigue is failure of a metal well below its traditional breaking point by repeated cyclic loads. This is like flexing or bending something constantly. Now a steel frame with good fatigue resistance can flex and absorb road shocks. While aluminium alloy frames must be built very rigidly to stop flexing due to its poor fatigue resistance. This is why many aluminium alloy frames have big thick tubes to avoid any flexing and then why they fail to have the vibration absorbing ride of steel.

Now the aluminium alloy is probably cheaper, because the mass production of aluminium alloy frames if down to a fine art now and the economies of scale mean it will be cheaper than the Reynolds 631 frame which requires a little more care in the welding stage. But what price comfort.

So why not buy carbon fibre?

Carbon fibre is the preserve of the hardcore racer who turns over bikes every three to five years. Many say carbon fibre gives the ride of steel but is lighter than the best aluminium alloy frames, but it is hardly durable. Carbon fibre does not fail plastically but moves straight to brittle failure. Sorry to get into serious material language, but when metals and their alloys fail they tend to deform elastically (non-permanent), then move to plastic deformation (permanent) then they fail in a brittle manner at the end (snap). Carbon fibre just snaps. So one day you hit a pot hole and… snap. No plastic deformation first. So carbon fibre gives the ride of steel but saves quite a bit of weight. But the price for that is a frame with less life, more likely to fail without warning and is more susceptible to damage from knocks on tubes. Finally find a carbon fibre frame with eyelets for a rack. Why carry a rack? Well humanity has invented these amazing luggage options that mean you don’t need a backpack. Backpacks are for walkers, I expect my bike to carry the luggage not me. So carbon fibre bikes being for hard core racers have no rack mounts which means you can’t carry your change of clothes and laptop to work unless you use a backpack.

Finally if steel is expensive compared to aluminium alloys then that falls apart against carbon fibre where you pay a lot more for that weight saving, oh and fragility.

Look my personal view  is backed up by my knowledge of metallurgy and an admitted clear bias towards ferrous metals, not by half truths of marketing. But marketing and ease of mass production means the days of huge numbers of fine steel frame bikes are gone. Most steel bikes are cheap clunkers that are the entry models before aluminium alloy. But if you get the chance to ride a good alloy steel frame you will understand exactly what I mean.

For a comparison of frame materials check out the Reynolds site. Alternatively check out the Columbus page on steel.

See a brief review of the 2008 Quest here.

Jamis Quest – Best value Enthusiast Road Bike