carleton

It's not cheating.

taras0000

If a material is going to be constant, (apples to apples, alloy to alloy) then Cross Sectional Area vs. Length is going to be the major determinant of stiffness. This is why Young's Modulus (a measure of how stiff a material is) is measured in N/m^2, psi, or MPa/GPa. The outer skin of a material is what largely contributes to this stiffness, so making a hollow cross section is optimal. That steel bottom bracket could have been made stiffer if the builder decided to weld/braze plates onto the small reinforcements. It wouldn't be much stiffer, but it would add to the stiffness. Make something wide and you will stiffen it. Lengthen it, and you will be able to make it flex more.

Carbon is different in that it's not a uniform or homogenous material. Carbon fiber acts in tension, and so, must be engineered to act that way. You can make a large, overbuilt, and heavy carbon frame that's more flexible than a well constructed steel or aluminum frame if you don't orient the fibers properly. But, if you took a poorly made fiber layout, and made it large enough, it would become stiffer.

taras0000

Certainly isn't. It's a material that best allows us to achieve shapes that are closest to maximum theoretical efficiency for stiffness vs. weight. You can try this with steel or aluminum, through hydroforming tubes and sheet, but you will end up with a very heavy frame. BT did this a while back with an aluminum version of their Atlanta superbike.

The Original (carbon version)


And the ALuminum (made by Technique Sports)


Here is a link to one with some more detailed pictures of the frame. He does a great job of restoring it. Good read.
- Australian Cycling Forums - Technique Sports Superbike

Apparently frame and fork were about 5kg. They didn't ride that great either. Museum pieces now replacement parts are no longer available.

And an old CN article on the frame
- www.cyclingnews.com - the world centre of cycling

So gycho, shape is the same, but which frame do you think was better?

carleton

Dang, dude. Those are 2 that I've never seen before. Nice!

It really sucks that the UCI outlawed such designs by mandating the "double diamond" frame. I wasn't active in the sport when it happened, so I'm not familiar with the reasons they presented as to why they did it. But, it sucks*.

*Scientific term.

gycho77

wow
This is amazing!
I am guessing carbon fiber was better than Aluminum, because of carbon fiber properties

carleton

In general, Carbon isn't better or worse. It depends on how it's used, meaning it's up to the builder. Same for Aluminum, Steel, and Titanium.

The bike world (like golf) is driven off of hype.

Specialized, BT, or Felt aren't going to say, "90% of being fast is being lean and training and 10% is the bike. And our carbon stuff isn't significantly better than other materials after a certain point." They are going to say that the 2016 models are "The stiffest, lightest, and fastest EVER!!"

I, for one, have certainly bought into the hype looking for the treasure at the end of the rainbow. The real treasure was in the kitchen, gym, and track.

carleton

Example:

Look at how fast Perkins and Pervis are on 80's tech NJS steel bikes.

gycho77

I definitely agree with what you are saying right now.
Bike manufacturers always say it's the fastest, stiffest, and lightest.
I think most of people know this is driven by hype, but they want those new techy stuffs for no reason

carleton

There is nothing wrong with that.

If it makes you feel faster, you will be faster. Seriously.

But, understand that that's what's happening.

Dalai

Given how much a steel frame flexes under Pervis in the video, imagine how much faster they go when the power goes straight through to the back wheel...

carleton

Yeah, I know the video before even clicking it

How many of us are strong enough flex that bike the same?

Those guys (and ladies) win and lose races by tenths and sometimes hundredths of a second. Remember when Olga Panarina beat Sandie Clair in the 500M by 0.023 in the 2011 World Championships?

I guess my point is that I've never seen anyone hop on a world-class frame and get significantly faster...or even reasonably faster...including myself

I think equipment purchases should be made to solve problems (slipping dropouts, better angles, slipping seatposts, etc..). But, I don't think it's as easy to buy speed with a frame. Wheels, yes. Frame, no.

carleton

I bet that if Pervis raced a steel frame with everything else off of his LOOK (pedals, cranks, wheels, bars, etc...) he'd still be a world-class racer.

It's double for us mere mortals. We wouldn't lose any significant speed by switching to a material that isn't carbon (with all other things being equal).

It's easy to poo-poo steel and aluminum because it's not as sexy as carbon. The bike manufacturers do this all the time. But, that's like dissing a basketball shoe because it uses cotton or leather shoe laces instead of modern nylon

Dalai

Took me ages to find that video again too!

Sacrilege! Can always buy yourself more speed!

carleton

I keep telling people that it's Masters that fund the cycling world. Bike manufacturers should advertise with masters champions more so than elites. They can probably get them for cheaper, too

We know we'll never be elite. It's cool to see what other masters are winning with.

Dalai

I'd still be racing aluminium on the track if not for having written off that bike. Actually my TT, CX and road bikes are still aluminium and I have no reason to change.

Nice to have the curves of the Stealth though. Does look sexy...

700wheel

I recall that the UCI double diamond frame discussion originated when Obree used a "non-traditional" frame for the hour record.

gycho77

I don't get why UCI banned this position.
I heard that they banned this position because the postition wasn't stable.

dunderhi

After a 25mi team time trial many, many years ago, my teammate who rode behind me said he almost got seasick watching my BB sway side-to-side for almost an hour. I might have been a bit too strong for that Reynolds 531SL frame.

himespau 

I've felt a Columbus SLX frame flex under me as I've climbed and run out of gears. Doesn't help that I'm an out of shape fat ass on a 63 cm frame. Better gearing and better shape helped some.

carleton

Yeah, I've flexed the hell out of my old 2010 Tarmac (58cm, carbon) when climbing. So much so that the rear wheel would rub the brakes...which made climbing even harder, hahaha. It took me a couple of weeks to realize what was going on. Then I opened up the brakes quite a bit and it was fine after that.

TrackMonkey7

I'd say it not being safe would be fairly reasonable grounds to ban it, though I think it more had to do with standardizing frame designs. The UCI is known for stifling innovation. I the case of Obree's position, I think the traditional diamond frame mandate occurred in tandem with Chris Boardman's Lotus bikes:



Somebody please correct me if I'm wrong. Perhaps the UCI saw that frame designs were getting too radical and that teams who had deeper pockets to invest in R&D would have a more significant edge over teams that couldn't spend as much. Sort of similar to how racing cars will have road-going versions for homologation purposes. Maybe. Don't quote me one that.

All that being said, I wonder how modern frame designs, wheels, fit and gear compare to Obree and Boardman's. A lot of pursuiters are getting so low and narrow that it makes me wonder how efficient they are through the air.

Koogar

Yes! I would add that a good fit on the bike can go a long way towards making you more efficient, powerful, and faster. Carbon for track frames has made that harder to achieve. Because track is a small market and molds are expensive, in many cases you get a choice of four sizes. The stack is probably super low, too, to allow for aero bars - whether you happen to be using them or not. So many people end up fixing reach and bar drop with wonky stem and spacer setups - or don't - and in either case are never as comfortable or confident with the handling of the bike as they could be. I'm sure manufacturers would say that four sizes cover the vast majority of the population, but that doesn't explain why road frames are offered in finer size gradations or why you see so many "edge cases" when you look around the track. So for fitting, I think carbon has actually made things worse.

carleton

Ha. I hadn't thought of the fact that molds are so expensive that it actually limits the available sizes.

You are dead on about the stack. Most track bikes have a short head tube. Until "short-n-shallow" bars like the Scatto came along, riders would use +17deg stems to get the stack back so they could run drop bars.



Shallow bars like the Scatto (and those that came after) have certainly helped with that.

My personal example, a 58 or 60cm frame would often come with a 11cm head tube. With shallow B125 bars (similar in depth to the Scatto), I still had to use lots of rise:



11cm Headtube on my first Tiemeyer (made as a Kilo bike). This head tube is admittedly too short. This is an early season "comfort" setup that's really high. But, still, I had to use spacers and rise stem.



Look what happened when I had a custom frame made with what I feel is an appropriate 15cm head tube:

I can run a nearly flat steam (-6 degrees I think) and the bars are reasonably deep. Notice the grip distance from the top of the tire.


I can run a -17deg stem and go deeper if needed.

Poppit

A few photos of Wiggins' pursuit bike that he used at the weekend.

carleton

Yup. That head tube is like 8 or 9cm. Waaaay too low.

I guess it makes for a smaller "compact" frame that is stiffer. But, look at what lengths you have to go to make aero bars work. Also, the "low is always better" trend in aero bars is over. Now that aero bar base pads are rising, so should the stack of the frames.