RonK wrote:jasonc wrote:were you getting in trouble at the law courts?
Hehe, I live in Tank Street, across the road.
will have the blast the airzound the next time i go through there
open topic, for anything cycling related.
You are forgeting the ability to manufacture moulds for carbon in almost any shape you want. This results in some pretty oversized cross section at points of stress and flex. The bottom bracket being one of them.
Since you mentioned Cervelo, and since I have a couple I thought I'd post a couple of photos to illustrate my point.
Those ti roadies you posted are nice. I'm not about to replace my S5 with one though.
As far as mark up goes I reckon the quality ti is right up there with carbon. They certainly aint cheap.
Ti is expensive for a reason.
It is not simply stamped out of a mold and then massively marked up.
And the ability to shape CF is awesome if you believe the hype about oversized BB's, tapered head tubes and all of the other marketing gimmicks that the bike companies throw at you to get you to buy the newest, shiniest bikes that they bring out.
I think the process of manufacturing out of carbon is a little more complex than stamping it out of a mould. I agree they make a fair bit of money out of them though. Ti is also expensive though and there isn't anything hitech about them to justify the prices being charged. Just labour costs and profit based around a subjective reputation that ti seems to have. Move production to China/asia, scale it up and the price could be down with cheap chinese carbon frames.
The S5 is very stiff to ride, the large tubing and bb profile certainly does work. It stands to reason that if you increase the cross section it will be more resistant to flex than a smaller cross section of the same material and material thickness.
You are right about much of the marketing hype though. I spose they have to crap on with something to keep their sales turning over. Doesn't mean I'll be buying a new bike very couple of years though, too many bills for that anyway.
yep fair point...
better to buy something with a massive mark up and a decent warranty, compared to alot of brands with the same massive markup, who leave u in the lurch with a busted frame...
On the "stamping out of a mould", it is probably not the best way to think of the production.
I am including a few videos and accept that we are seeing low production examples in these videos and that they are also a little old and not taking into account newer Carbon Fibre manufacturing technique, though even with high volume production it is worth clarification. There is no "stamping" out of moulds, carbonfibre is first cut then usually wrapped around a bladder (or core with inserts etc) then placed in a mould under heat where a bladder is inflated before heating. After the mould cools, the frame is finished (i.e. cleaned up) before moving on in the production process with decals and paint.
This is a few years old and for a custom frame though shows the layup process.
Trek - US Factory
Pinarallo - though without specifics of actual carbon layup
But how much do these "improvements" actually translate into a faster bike for the average weight rider with average power? And do massive tubes, tapered head tubes and larger BB sections actually create more aero drag? Do all ITT bikes have large BB sections and tapered head tubes? Does a larger 30mm spindle BB which is stiffer actually offset the friction drag of the bigger bearings for someone who is a "spinner"? I notice Shimano on their latest DA 9000 group are still using the standard external (or press fit) 24mm spindle BB which now uses smaller bearings that they claim have 50% less drag due to better seals. Obviously Shimano is moving in another direction to most of the bigger_is_better crowd in this instance.
There doesn't seem to be a whole lot of objective testing in the bike domain in which people can firmly attribute each general design aspects to a defined percentage increases in efficiency. Many of us are trusting the manufacturers with logic like, "It must be better, otherwise why would they build it that way if it wasn't?" or "Mr Pro rides it in the TdF so it must be better." Usually that last one is extended to mean better at everything, not just pro racing. I prefer logic/sayings like, "Show me the data!" or "One good test is worth a thousand expert opinions."
By the way, have you figured out exactly how much faster the S5 is in average Km/h for you?
A road bike out of the 1980s will perform within a few percent of modern bikes!
Even if you consider the worst case the bike might be 4kg heavier which works out to be about 5% heavier based on 80kg rider & bike mass. So up steep hills modern bikes are really only 5% better. Changes in aerodynamics and rolling resistance of modern bikes vs 1980s bikes is pretty minor.
So all this "performance" is simply marketing.
They are made in a mould.
There is minimal labour cost vs cutting , mitering, shaping, welding etc a hand made ti, steel or even aluminium frame.
There is also not the high cost of the ti tubes in the first place.
So again my point is monocoque CF frames are stupidly cheap to manufacture whilst ti is expensive. However in the end the purchaser pays about the same price.
Find a tough, long climb.
Head out on Tuesday. Complete it at max effort. Time yourself.
Then head out on Thursday. Carry a backpack with 5kg of dead weight. Complete at max effort. Time yourself.
Report on your results not only in terms on time, but how you felt.
I've done this before (not for purposes of testing). 4-5kg of weight might be 5% heavier, but translates to way more than a 5% decline in performance.
My maths say 15% decline in performance for 5% increase in weight.
Having said that - there is definitely an argument that many a portly gentleman should ease off the bakery treats rather tan saving a few hundred grams off their wheels.
Disclaimer: I'm a very lean 65kg.
Then again those same portly blokes may not be sufferring from too many bakery treats and may think a 15 kg backpack is nothing but a slight annoyance.
Disclaimer: I'm not very lean but am very fit 115kg
I'm sorry but anecdotal reports don't sway me when faces with clear and simply science. Increasing weight will increase the energy requirements proportionally. Thus as long as the cyclist can maintain the same power levels then performance will decrease proportionally with weight. This is undeniable.
On the assumption that you are NOT maxing out your low gear range (or min speed threshold), then there is no good reason why power levels can't be maintained. If you ARE maxing out your low gear range then far better and cheaper performance gains could be had by increasing your low range gearing.
(Carrying a backpack is FAR from a fair test as it puts other strains on your body that aren't present in bike weight. This is particularly true if you are out of the seat.)
Sumgy, if this is you view then fine.
Average climbing grade for an average ride is ~1%.
Using Bike Calculator with:
230W average rider output, 80Kg rider, 1% grade with all other settings default:
11Kg bike gives 28.5Km/h
7Kg bike gives 28.8Km/h
Difference is 28.8 / 28.5 X 100 = 101.05% so 1.05% difference. More power makes less percentage difference.
As for a backpack, it adds stress directly to the body structurally and also reduces cooling capacity.
Edit: Missed a 0 in the results. Now 1.05% rather than 1.5%.
Last edited by Nobody on Fri Jan 18, 2013 8:45 am, edited 2 times in total.
FYI, from bikecalculator
10% hill with 73kg,230W rider, 7==>11kg bike... Time goes to 4.7% slower for a 5% performance weight gain. So on steep hills it gets very close to the weight gain as would be expected.
(Though as previously described it you are hitting other limitations like backpack on back, not enough low gears or speed too slow to balance easily then your power produced might be affected.)
Hey guys isn't this getting a bit off topic. Whilst an interesting distraction I am not sure it is helpful to the debate overall.
My interest in this thread is however a result of my weight and fear of a carbon frame breaking under me against a titanium frame and whether it will break or not.
You also get all the extra energy you put in going up, back going down the hill. If it wasn't for the extra wind resistance you would get it all back as extra speed. Anyone who has tried to chase someone down a hill who is 20Kg or more heavier has seen the difference it makes.
Last edited by Nobody on Fri Jan 18, 2013 8:27 am, edited 1 time in total.
At 115kg, the chances of either breaking under you are probably the same. What differs is the way they break.
Neither. If you main goal is about strength then don't mess with bling-bling materials trying to save weight. Get a durable steel frame. It is as simple as that. Seriously when absolutely durable frames are still under 2.5kg does weight really matter for much else than pose value?
If you want a frame you can absolutely trust with heavy use get a frame from a company which DOESN'T consider weight a priority. I would feel pretty damn comfortable going with Surly! True, our frames are not the lightest out there, but then they’re not supposed to be. Instead, they’re a balance of excellent ride quality and durability.
The cross-check is a classic at 2.2kg. -There’s a reason we still offer the Cross-Check after all these years. The frame is comfy and tough as nails. Though for ultimate durability the Long Haul Trucker has got to be up there. (2.35kg)
Review by AusHiker of the Long Haul Trucker is here.
It is relevant due to some cyclists' obsession with weight. This leads manufacturers to make frames on the limit for durability when used by heavier riders.
If I was 115Kg I wouldn't be worried about frame weight and just buy what I believe to be the most durable for my application. Other than going custom, I'd probably try to source a CX or touring frame for road bike use.
Last edited by Nobody on Fri Jan 18, 2013 8:57 am, edited 1 time in total.
As you've alluded to it's more than just the power calculation - I invite you to do it yourself and see the results. With the extra weight you're probably going to end up pushing a lower cadence and get into the hurt zone far quicker.
Even with a compact and 28t rear you'll likely run out of gears fast up a 10% avg grade, assuming we are talking a 'real world' 10% grade hill which would include a few tough spikes.
Not sure what this has to do with the topic.
A ti, Aluminium or steel framed bike is not going to be anywhere near 5kg heavier than an similar sized CF frame.
My Moots as pictured earlier weighs about 7kg for a 58cm frame.
I am 6'2" and weigh about 83kg.
And in your case 4-5kg actually equates to about 7.7%.
Going by your math that means a 22% decline in performance.
At my weight 5.9% so closer to your calculated 15% decrease in performace.
Then again who is to say that I would not perform better at a higher weight if that additional weight was muscle?
Who is to say that a loss of weight by me will actually result in a greater benefit (especially if I am losing muscle and perhaps power)?
Also by your calculations you are more in need of staying away from the pies than someone a little heavier.
Amazing what you can do with numbers and statistics.
Frame stiffness also helps over a long climb.
The actual weight difference (frame only) between a high-end carbon and titanium frame is about 200 grams. Add on another 200-300 grams for an equivalent steel frame.
The bikes I've test ridden (Giant TCR/Defy, Trek Madone, Baum Corretto) were all much stiffer than my current Reynolds steel frame. It makes a huge difference when you are accelerating. Funnily enough the Moots CR didn't 'feel' as fast and stiff...but the Strava times said otherwise.
Who is online
Users browsing this forum: No registered users