MIT Aluminum Bicycle Project 1974 (2016) • Hacker News Board

Re: MIT Aluminum Bicycle Project 1974 (2016)

#111

Post by magic_smoke_ee » Thu, Nov 28, 2024, 5:26 PM UTC

briansm wrote: post #85

tomaskafka wrote: post #78

Earlier quoted context omitted.

That’s what I tell myself when picking the bike - just get a competent basic $700-ish bike, and if you want it 2 kg lighter, lose those 2 kg instead of paying thousands.

In evolutionary terms, being taller, fatter and more muscular is advantageous, but in practical terms it's just a lot of extra weight to drag around for a lifetime, along with all the extra calories of energy needed to do so.

Yep. That's what I keep telling myself. ;) In the end, those will all kill me sooner because they're each opposed to longevity in a safe environment.

Re: MIT Aluminum Bicycle Project 1974 (2016)

#112

Post by magic_smoke_ee » Thu, Nov 28, 2024, 5:29 PM UTC

ndsipa_pomu wrote: post #83

briansm wrote: post #72

I find the obsession minimizing bicycle weight funny. It's not the bicycle weight that matters, it's the combined weight of bicycle and rider that counts. 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.

Weight isn't that important for bike racing unless you're specifically doing hill climbs. Aerodynamics will make more of a difference, so there might be some advantage in having a bit of belly fat to enable a smooth airflow. Also, heavier riders are generally faster downhill as they have a greater terminal velocity.

> 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.

Re: MIT Aluminum Bicycle Project 1974 (2016)

#113

Post by loeg » Thu, Nov 28, 2024, 5:31 PM UTC

tpm wrote: post #45

loeg wrote: post #30

Earlier quoted context omitted.

Low quality steel is very cheap but also really heavy. You can get a whole crappy bike for a couple hundred bucks. Higher end steel isn't as cheap but is still relatively heavy (compared to aluminum or carbon). You can get this kind of bike in the $1000-2000 price range (e.g. Surly). Aluminum bikes tend to be inexpensive, but also not the lightest. These can also be priced at $1000-2000 (Specialized, Trek, Giant, ...…

For about the last year and a half you can usually get a carbon road bike from major brands with basic components starting from 2000 euro (right now I see Bianchi, BMC, Cannondale, Cube, Giant, Specialized listed around that price).

Yeah, I think in particular prices have come down dramatically in the past 3-6 months.

The specific 2000EUR figure might be European pricing. The lowest I'm seeing for any carbon road bike from e.g. Specialized with US pricing is $2400 for a two generation old Tarmac SL6 (this generation was current 2019-2021) or $2800 for a current Roubaix. The least expensive carbon road bike offering from Giant is $3300 US (TCR or Defy). (Though I'd expect to be able to find better deals at retailers trying to move old inventory than direct from the manufacturers.)

Re: MIT Aluminum Bicycle Project 1974 (2016)

#114

Post by loeg » Thu, Nov 28, 2024, 5:33 PM UTC

cenamus wrote: post #54

loeg wrote: post #5

It's interesting that trackies in the 70s were trying to reduce weight that much. I don't think it's perceived as especially advantageous these days. The high-ish end track bike I'm assembling now will be a little over 8 kg (almost 18 lb). We also race much bigger gears (typically 95-110 gear inches in mass start racing, bigger for sprinting) than mentioned in the article (72 gear inches). The position that is consid…

Maybe that's just mostly due to the UCI regulations? No point to develop a fully fitted 5kg bike if it has to be 7kg anyways I suppose

If it mattered, though, every track bike would be exactly 6.8 kg -- and they aren't.

Re: MIT Aluminum Bicycle Project 1974 (2016)

#115

Post by prmoustache » Thu, Nov 28, 2024, 5:39 PM UTC

benj111 wrote: post #74

What was the patent for? 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

I also rode an aluminium frame my granddad owned that was from the 1950's, with weird 700A wheels by today's standards.

Re: MIT Aluminum Bicycle Project 1974 (2016)

#116

Post by [deleted] » Thu, Nov 28, 2024, 5:40 PM UTC

Scoundreller wrote: post #61

yapyap wrote: post #59

nice story but the ads are awfully annoying, and b4 u suggest an adblocker, I’m on a phone.

I suggest an adblocker for your phone

[deleted]

Re: MIT Aluminum Bicycle Project 1974 (2016)

#117

Post by prmoustache » Thu, Nov 28, 2024, 5:41 PM UTC

yapyap wrote: post #59

nice story but the ads are awfully annoying, and b4 u suggest an adblocker, I’m on a phone.

I was browsing this page on my smartphone in an airport with the ublock origin extension blocking the ads...not sure what you are talking about with that weak phone excuse.

Re: MIT Aluminum Bicycle Project 1974 (2016)

#118

Post by prmoustache » Thu, Nov 28, 2024, 5:46 PM UTC

ndsipa_pomu wrote: post #70

trhway wrote: post #66

aluminum is nice, yet once in a blue moon you get something like this year an aluminum hiking pole broke when i lost my balance on a slippery slope and put a lot of weight on the pole and falling i almost got skewered by it's broken off jagged lower piece. I really want steel poles now, yet can't find them to the point of pondering DYI-ing from some Home Depot steel tubing.

That's a problem with aluminium - no fatigue limit. This means that cyclic loads on an aluminium frame (or pole) will eventually cause it to fail. Steel does have a fatigue limit such that cyclic loads below that threshold won't cause eventual failure. There's some good info on bike frame materials here: https://bike.bikegremlin.com/11144/bicycle-frame-materials-e...

It is only really an issue with aluminium forks and non traditionnal construction.

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.

Re: MIT Aluminum Bicycle Project 1974 (2016)

#119

Post by prmoustache » Thu, Nov 28, 2024, 5:49 PM UTC

fnord77 wrote: post #18

I'm convinced titanium is a pretty optimal bike material. I hate aluminum frames, too stiff, some amount of flex makes a bike so much nicer. Hate carbon, too. Steel is nice. 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.

Frame flex of ti bikes is pure fantasy/placebo (at least on the vertical plane) on traditionnaly shaped frames.

You would need enough force for the tires, wheels, saddle, handlebar, stem and seatposts to break/explose before the double triangle start flexing.

Re: MIT Aluminum Bicycle Project 1974 (2016)

#120

Post by btbuildem » Thu, Nov 28, 2024, 6:43 PM UTC

With all the mods ("hardcoded" seat, no stem, custom shafts and bearings) It's funny he decided to keep the toe clips -- would've easily shaved a few ounces there!