There's a fascinating, and very new, class of nano-laminate magnesium alloys called Long Period Stacking-Ordered (LPSO) alloys. These are very lean -- the standard version is 97% Mg + 1% Zn + 2% Y -- and they have outstanding mechanical properties. At an equal weight, they're much stronger and stiffer than 6061 aluminum, and the kicker is that this is generally true only if they're extruded. If they're not extruded, the laminate-like grain structure doesn't form properly.
Could make excellent bike frames.
Magnesium corrosion would still be a problem, though. I got some LPSO-Mg samples from Fuji Light Metals, in Japan, and they were quite badly degraded within weeks.
https://www.elmycycles.co.uk/m21b0s365p4804/1992-Kirk-Revolu...
https://www.bikeforums.net/classic-vintage/1279777-kirk-prec...
https://www.independent.co.uk/news/uk/magnesium-in-frame-to-...
https://www.flickr.com/photos/11521783@N05/albums/7215764801...
A friend had one. It cracked.
> "Kirk Revolution cast magnesium"
Cast magnesium is really weak/brittle compared to forgings and extrusions. Its use was not a great design decision on Kirk's part. I suppose they could have wrapped the casting in carbon fiber or something like that, to give it extra bending strength and spread out loads that might cause fractures, but then it would get expensive.
With modern understanding of composites, and complex layups with UD fibre, the "not comfortable, too stiff" is less and less true. The reduction in road buzz I got when I finally moved to CF handlebars was noticeable.
Presumably they'd also benefit from SMAT and other forms of surface modification.
That said, they're really good as extruded, and they don't appear to benefit as much from SPD as some steel and aluminum alloys do.
At a glance, though, the problem doesn't seem insurmountable. FSW appears to work.
That said, I wonder if there is a way to make frames more comfortable without having the flex absorb pedaling energy.
That said, we can extrapolate from mechanical properties. If we assume that both materials are tubes with the same wall thickness, and that we're looking at T300 carbon fiber (by far the most common type) in epoxy resin vs a standard research grade of LPSO, then:
- The CF will be stiffer
- The CF composite will be slightly less dense (1.6 gm/cc vs. ~1.8 gm/cc)
- The CF composite will have a slightly higher tensile strength, but the difference is very small and could be nonexistent in practice.
- LPSO-Mg will be more damage tolerant -- with better resistance to abrasion and better capacity to flex in a recoverable way in response to extreme mechanical stress. (Cast Mg alloys are undoubtedly worse than CF, but LPSO-Mg is a lot more like an aluminum alloy in this respect. It's a pretty ductile material.)
- LPSO-Mg should in principle be cheaper, though this is likely not going to be the case for a long time.
- LPSO-Mg will have better mechanical damping properties, so might transmit fewer vibrations to the rider.
That was when I realized what site I was on.
On the flat, weight only affects you during accelerations - at a steady speed, it has no significant impact on performance. Aerodynamic drag and rolling resistance are constantly sapping away power, so features that reduce these losses are nearly always worthwhile even if they increase weight. Even on a moderately hilly road stage, aero trumps weight by a considerable margin; on the track, weight is almost entirely irrelevant, particularly in longer events.
A lot of riders like the feel of a lightweight bike, a lot of them believe that light bikes are faster, but that's only true on exceptionally steep stages or hill climbs.
The discipline of cycling that's the most weight-motivated is hill climbing. Track cycling really doesn't have that as an issue, and definitely does have a materials strength issue, so I'm not shocked they're not building to a weight limit.
stripped example: https://weightweenies.starbike.com/forum/viewtopic.php?t=153...
https://www.reddit.com/r/cannondale/comments/1d9nind/2009_ca...
This time it was “Sheldon Brown’s personal bicycles” https://sheldonbrown.com/org/bicycle.html
That’s the essence of a great website.
https://en.wikipedia.org/wiki/Graeme_Obree
With his "old faithful" bike he built himself
I was looking at it in the museum last week and it still impresses me how intuitive he was about cycling. Things like integrating the pedal and shoe to save on height, and also reducing the q-number with the narrow bottom bracket.
I remember doing time trials with Graeme before he had created "old faithful" and he was just incredible
Graeme wrote a book on training a few years ago - its very home brew - but he was ahead of his time saying that you need to ride 25-28mm tyres on the road, rather than the 20-23 which were fashionable at the time.
I remember seeing an old aluminium bike in the Manchester industrial museum
This is from 1896 https://collection.sciencemuseumgroup.org.uk/objects/co84092...
And theres this https://collection.sciencemuseumgroup.org.uk/objects/co25722...
Doesn't give a date, but this is the one I remember, and seem to recall it being 1901
It's his wife! Harriet is Sheldon's wife!
This trend has continued -- it is very noticeable in road and mountain bikes.
But this trades off against impact resistance, aerodynamics, and the can-it-fit-between-your-legs-metric.
Frame “tube” dimensions driven by layup mold & mandrel/bladder requirements to minimize tooling and layup time
Press fit to reduce inserts and post mold operations with a “simpler” molded interface
Flat mount brakes to simplify mold shape and support simpler insert components
UDH and direct mount again the simplicity of molded in shape, minimal inserts, reduced post mold operations.
“Modern” UDH hangers move threaded components off the frame. much simpler than the old syntace style which need both precise thread alignment and/or frame tooling operations and/or additional inserts.
You could probably throw head tubes in here too; split races to avoid reaming, molded bare pseudo-press fit “cups”, and the absolute ridiculous sizes like IS47 and larger.
Many/most of those only help manufacturing costs for major frame factories. And are middling to suck for other materials and small volumes. Ex steel flatmount and IS47 is an absolute joke.
Rider weight massively outweighs the relevance of bike frame material, especially in the West where obesity epidemic has biased BMI upwards over the last half century.
Also, heavier riders are generally faster downhill as they have a greater terminal velocity.
No, unless they're Russian, they're not free falling. They have greater potential energy. And also increased traction, increased rolling resistance, and increased losses in wheel bearings and drive components due to friction.
If you push 300W on a 5kg bike or 20kg bike, the "workout effect" will be the same.
At the end of the day, if you are looking for "workout effect", it means that you're trying to achieve something, like winning races or going faster.
And for a given rider, with a certain weight and certain physiological abilities, they will go much faster on a 5kg bike than on a 20kg bike.
There is a whole world between <$1k bikes and those >$2k ones. Weight being an important part. Not only because it reduce the total weight of bike + rider, but also because a 5kg bike behave in a very different way than a 20kg.
It's like saying that cooking with a chef knife is the same as cooking with a sword.
Sure, after a certain point, the race for removing a few grams here or there is a luxury and many people tend to believe that spending $$$ on a lighter bike will fix their lack of fitness.
But modern bikes provide a completely difference than the old, heavy ones.
Yes, rider weight trumps it, but modern bikes in general just ride nicer and most of us who are not pros only test a dozen different bikes at most. It's a hobby, people like to splurge.
I learned last week that my colleague bought a commuting bike from an old friend. A true once in a lifetime barn find. Mid 90s Klein Attitude, only used for a few weeks before being stored in the barn until 2023. My colleague is currently putting it through its second winter on salted, snowy roads.
What's the alt. timeline for the bike? Stored as a collectors item?
Ships in the harbor and all.
https://web.archive.org/web/20061103174315/http://www.kleinj...
I've have a lite ghisallo frame which I think was under 2lbs. The whole bike is under 15lbs and still manages to carry my 200lbs of weight.
I'm less convinced. Firstly, I'm not convinced by the frame flex theory of ride comfort - I believe that the tyres are by far the biggest contribution to ride comfort due to the amount that they can flex which is far more than the tiny amount that the frame can.
Secondly, aerodynamics is far more important (if you care about speed/effort) and titanium is tricky to get into highly tailored shapes unless you resort to fancy 3d-printed frames.
Carbon would be my choice due to the design flexibility - by orienting the carbon fibres differently, components can provide strength/stiffness in one direction whilst allowing for compliance in other directions. Also the shape can be relatively easily changed - no need to always use circular tubes.
It'd be interesting to see a 3d-printed titanium frame that uses some kind of honeycomb internal structure to provide super strong/light frames, but I suspect it would be exorbitantly expensive.
However, you might find this interesting -- No. 22 bicycles has a (very expensive, prototype) titanium aero bike: https://22bicycles.com/products/reactor-aero . It hasn't actually seen a wind tunnel but at least it looks like an aero bike and they're talking about putting it in one. It is made using 3d printing (additive manufacturing) at least in part.
> Pricing for the final production version has not yet been finalized, but we anticipate a frameset (frame, fork and headset) price in the range of USD $10,000 to $15,000.
You would need enough force for the tires, wheels, saddle, handlebar, stem and seatposts to break/explose before the double triangle start flexing.
Cinelli also had a version of their legendary Laser [2] bike with that setup.
1: https://bikecult.com/works/archive/03bicycles/takhionVVVV.ht...
2: https://www.pedalroom.com/bike/cinelli-laser-aero-pursuit-34...
There's some good info on bike frame materials here: https://bike.bikegremlin.com/11144/bicycle-frame-materials-e...
With a "diamond shaped" traditionnal cycling frame you have nearly 0 chance of a frame failing catastrophically. Usually the weaker part crack and your bike just end up creaking horribly and/or feel noodly. I have suffered and witnessed a number of alu and alu+carbon bonded frame failing at the glued joints.
Don’t need a bike manufacturer to do that for you though
Even Mullvad ad-blocking DNS is available for free, no app (and def no account!)
https://mullvad.net/en/help/dns-over-https-and-dns-over-tls
Nice thing is you can set your DHCP to hand this out to all devices.
