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MIT Aluminum Bicycle Project 1974 (2016)

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Re: MIT Aluminum Bicycle Project 1974 (2016)

#141

Post by grogenaut »

loeg wrote: post #132
grogenaut wrote: post #121

Earlier quoted context omitted.

could you expand? I get the expensive part, but they're also hand built customs so...

Rim brakes are not great in wet conditions and limit tire sizes to about 28mm. Lightweight steel tends to be flexy and susceptible to dents.

definitely with you on rim breaks... I thought they mention in one place they can put discs on these. I'm a large person and live in Seattle so I've been rocking discs on a cyclocross style bike since 2010 back when everyone was anti discs, they're far superior glad people finally got sane about them.

Re: MIT Aluminum Bicycle Project 1974 (2016)

#142

Post by loeg »

grogenaut wrote: post #141
loeg wrote: post #132

Earlier quoted context omitted.

Rim brakes are not great in wet conditions and limit tire sizes to about 28mm. Lightweight steel tends to be flexy and susceptible to dents.

definitely with you on rim breaks... I thought they mention in one place they can put discs on these. I'm a large person and live in Seattle so I've been rocking discs on a cyclocross style bike since 2010 back when everyone was anti discs, they're far superior glad people finally got sane about them.

> I thought they mention in one place they can put discs on these.

Yeah, they can do it, but they'll be a little heavier than those relatively light rim brake steel bikes linked earlier. (The rotors/calipers, hydraulic, fluid, stronger fork leg required all just add mass.)

I'm also in Seattle! Disc brakes all day.

Re: MIT Aluminum Bicycle Project 1974 (2016)

#143

Post by sudosysgen »

kevin_thibedeau wrote: post #140
sudosysgen wrote: post #26

Earlier quoted context omitted.

A heavier bike would slow down less. At the end of the day the energy is lost to friction.

Wind resistance is the primary force slowing you down at speeds where riders care about such things. The tiny micro-accelerations after every dead zone add up in spent calories when you have a more massive bike+rider system.

That's my point exactly, wind resistance is the principal loss of energy.

The microaccelerations in the dead zone will be lesser in magnitude when you have a heavier bike plus system, but it will be more calories per m/s to recoup - while a lighter system will accelerate easier but have more acceleration to do. In the end the dead zone acceleration are calorically going to be exactly the same no matter the weight.

Re: MIT Aluminum Bicycle Project 1974 (2016)

#144

Post by loeg »

ndsipa_pomu wrote: post #65
m463 wrote: post #62

Earlier quoted context omitted.

I thought stiff was a problem with aluminum - stronger is better but is stiffer better? That said, I wonder if there is a way to make frames more comfortable without having the flex absorb pedaling energy.

I don't believe that the frame material makes much difference to comfort. The part that can deflect/absorb bumps and vibration the best is the tyre. So the answer to your question is bigger tyres at lower pressures.

Tires and to some extent seat post -- more exposed post deflects more than very short posts (like classic steel bike shapes).

Re: MIT Aluminum Bicycle Project 1974 (2016)

#145

Post by loeg »

magic_smoke_ee wrote: post #112
ndsipa_pomu wrote: post #83

Earlier quoted context omitted.

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.

Terminal velocity still applies. Yes, it is because they have more potential energy (per CdA).

Rolling resistance increases are pretty marginal with compensating tire pressures (i.e., higher). Wheel bearing losses are de minimis.

Drivetrain component friction is not a function of rider weight.

Re: MIT Aluminum Bicycle Project 1974 (2016)

#146

Post by loeg »

ginko wrote: post #73
xpe wrote: post #23

> Use larger diameter tubular components - Strength goes up as the cube of the diameter so unless there are geometric constraints, use larger diameter tubes with thinner walls to get a lighter structure with increased strength and stiffness. 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-me…

My main gripe with those large diameter tube frames is that they're just ugly.

Taste is personal; and of course, you can still buy skinny-tube steel frame bikes, with probably more options available than at any other time in history.

Re: MIT Aluminum Bicycle Project 1974 (2016)

#147

Post by loeg »

eigart wrote: post #67

Just an anecdote thats been horrifying me for the last week since Klein is mentioned. 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.

Bikes are for using, not sitting in barns.

Re: MIT Aluminum Bicycle Project 1974 (2016)

#148

Post by loeg »

ndsipa_pomu wrote: post #71
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.

> I'm convinced titanium is a pretty optimal bike material. 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 tri…

I share your skepticism about Titanium as a frame material, both in terms of comfort claims and tube shape limitations.

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.

Re: MIT Aluminum Bicycle Project 1974 (2016)

#149

Post by loeg »

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.

Carbon hiking poles are the way to go, they're very light and very affordable.

Re: MIT Aluminum Bicycle Project 1974 (2016)

#150

Post by tpm »

loeg wrote: post #113
tpm wrote: post #45

Earlier quoted context omitted.

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…

Yeah EU. One example I can give is this, Specialized Aethos 2024 for 2200 but only one size available, Giant TCR Advanced 2024 several sizes 2400, plenty others. This is a reputable retailer and there are some other with same/lower prices.

https://www.bike24.com/road-bikes.html?dynamicAttributes%5B2...

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