[BSA rules]

Is the trend for fitting larger volume tyres to carbon road bikes an admission that the frames are too stiff especially for lighter riders? All bikes have to be designed and manufactured for the safety of the heaviest riders, I don’t think a 65 kg rider on any carbon bike even a sportive model will feel any of the comfort advantages associated with this type of bike if it has been designed to be safe for a 120 kg rider, hence I’ll be adding my 28 mm tyres running 70 psi, a carbon seat post,and the best cycling shorts I can find, anyone agree?

Topic

[Miller]

Comfort is heavily influenced

Comfort is heavily influenced by tyre pressure. What pressure do you run?

[BBB]

“…Is the trend for fitting

“…Is the trend for fitting larger volume tyres to carbon road bikes an admission that the frames are too stiff especially for lighter riders?…”

Large volume tyres are fitted to almost all, not just carbon bikes these days.

Perhaps it’s an admission that the role of pneumatic tyres is to provide suspension not to emulate wooden carriage wheels? As we all? know, vehicles with effective suspension roll faster. In other words it’s progress driven by science and common sense rather than the strong convictions of some local club “gurus”. 

In comparison with suspension travel offered by tyres which can be easily observed and meassured, any “vertical compliance” of the frame is almost insignificant. Oh, and let’s don’t forget about the seatpost and saddle flex, too. The feel and comfort of a bike is almost entirely dictated by tyre setup, fit and contact points. 

 

[EddyBerckx]

There’s a massive, massive

There’s a massive, massive difference in feel depending on which bike frame/wheels/tyres etc you go for and I can’t help but think you’re over generalising here.

You sound like someone who wants a steel or titanium bike but doesn’t want the weight penalty (they can be made pretty light if you are willing to spend a bit).

What bike are you on btw? You’ve tried different tyres and tyre pressures I take it? Tbh I’m not sure 120kg is the limit that manufacturers go to – I’ve had bikes where it’s been 100kg. Don’t forget people do load bikes up with accessories and bikepacking bags and so on and so they wouldn’t want the hassle of making a too light frame that cracked all the time

[Chris Hayes]

I’m far from 65kg, but have

I’m far from 65kg, but have two Ti bikes (Litespeed Siena and Vortex), two carbon (Factor 02 and Colnago C50) a steel frame (Gios Torino) and an aluminium / carbon Pinarello Prince all of which are set up similarly Thomson / Deda Stems / carbon bars, Fiz:k seats and I long since came to the conclusion that wheels are massively overlooked when judging ride comfort.  Only the Factor is post 2004. 

I can turn my C50 into a bitch by riding on stiff Shamal wheels on UK roads that are smooth as silk on better road surfaces.  And Mavic Ksyrium wheels seem to shake my vertebra apart. 

That said, these are all decent, well built frames. I suspect that if you were to pit a cheap aluminium frame against a mid range carbon Roubaix with similar components then the Roubaix would be significantly more comfortable.  Higher volume, lower pressure tyres will enhance the comfort of any bike –  if the road surfaces are bad enough (i.e. if you live in the UK).  

[Anonymous]

TBH every time a bike

TBH every time a bike manufacturer brings out a new model they always say “stiffer, more aero, x watts saving… and x% more comfortable”. I think you can safety put a lot of it down to marketing blurb. Frame weights certainly aren’t going up.

[BSA rules]

Hi, thanks for your input, I
Hi, thanks for your input, I can only say that I chose a carbon ” sportive” bike after reading lots of reviews, and I wanted the extra comfort discussed in the reviews with this type of bike,I am fully aware that I was choosing comfort over outright speed, I would assume that’s why most riders make this choice, the more upright riding position is better for me, but I am disappointed to find besides the more upright riding position that it’s lack of comfort on the rough sections of road is a major disappointment and similar to my now ageing carbon 2005 Trek madone 5.2 SL it was bought to replace.

[OnYerBike]

Cervelo recently admitted

Cervelo recently admitted that the old R5 was too stiff (admittedly this admission only came in order to plug the new, less stiff R5…). But I do think you’re right – until recently, it was viewed as stiffer = better, and that mantra has driven design of modern bicycles. However, I also think there are signs of that changing, for a few reasons:

Firstly, more real-world data. It’s easier than ever to look at power and speed data, and work out what actually works and what doesn’t. We don’t have to rely on what “feels” fast before – which is good because “feeling” faster doesn’t always translate to going faster. 

Secondly, there’s (some) recognition that comfort is related to performance – so even if your machine is a few watts slower, if this means the rider is able to keep up for longer, then that will be worth more.

Thirdly, I think it’s fair to say that it makes a difference which bits of the system are stiff, and which bits are compliant. I’m no engineer, but it certainly seems to make intuitive sense that a stiff frame with large, supple tyres would be better than a flexible frame with solid tyres, even if the total amount of “flex” in the system is similar. 

[wycombewheeler]

BSA rules wrote:

BSA rules wrote:

If the design brief is to “accomadate” a 120kg rider surely they would have to add more carbon fibre to the frame making it stronger and stiffer ? Making the bike less accomadating for a rider that’s half the weight it was designed for?

no necesarily, It is likely to oriovide the optimum ammount of flex for an average 80kg rider, while heavier riders will get more flex (but still be close to breaking) and lighter riders will get less.

I don’t see why this would be different with any frame material.

But of course the real point of NGs post was to remind us that we are inferior cyclists to him because he rides 23mm tubes, and that anything more is only needed by people who are not in optimum shape, the same as riding 11-25 cassette.

[BSA rules]

If the design brief is to
If the design brief is to “accomadate” a 120kg rider surely they would have to add more carbon fibre to the frame making it stronger and stiffer ? Making the bike less accomadating for a rider that’s half the weight it was designed for?

[Anonymous]

Quote:

Is the trend for fitting larger volume tyres to carbon road bikes an admission that the frames are too stiff especially for lighter riders?

No, it’s an admission that the target market is generally getting fatter. Fat tyres for fat arses, anyone riding 28mm or above is tacitly admitting this. That said, bikes aren’t designed for 120kg people, just to accommodate that weight at the limit.

I have 2 carbon bikes, one with 23mm tyres and the other with 25mm. I run them at around 100psi and I weigh 66kg. They are both more comfortable than my CX aluminium bike which runs 35mm tyres, although admittedly also more expensive. Some bikes and wheels just have a harsher ride than others.

[Secret_squirrel]

I have a carbon framed

I have a carbon framed endurance bike and a ti gravel bike with similar width tyres both running tubeless at 70psi sometimes 65.
The carbon is a little stiffer at the same pressure but there is less than 10 psi worth of comfort difference. I used to have an 853 steel bike which was somewhere between those 2. I’m 72-74kg. 

You’re overthinking it tbh. 

[BSA rules]

Hey Matthew, thanks for your
Hey Matthew, thanks for your response, after spending big money on a ” carbon endurance bike” in size 53cm, I find it overly harsh on anything but perfect road surfaces, I think it would be an idea for a manufacturer to design a more compliant endurance road bike for lighter riders with a say an 80 kilo weight limit, like they do with some road wheels, cheers.

[matthewn5]

I’ve been thinking about this

I’ve been thinking about this too over the summer, as I rode around on my 21 year old steel framed Brian Rourke 653 with its lovely curved fork blades. The bike still has a 700x23C on the front on a nice wide 19mm modern rim. Despite this unfashionably narrow tyres – there’s a 25 on the back – the Rourke has an absolutely sublime ride quality.

Meanwhile I see all these modern bikes with super rigid straight carbon forks, necessitated we are told because of the forces from disk brakes, and needing fatter and fatter tyres – and fatter rims to match.

Have we lost the plot with these ever stiffer frames and resulting ever fatter – and heavier – tyres?

[Geoff Ingram]

Well an aluminium bike will
Well an aluminium bike will also be built for 120kg, so it evens out. I had mountain bikes (on one 456) in ti, steel and carbon and the carbon was vastly superior in comfort while losing little in stiffness. But rather lacking in crash tests, which is why I got the ti. Road bike PX carbon again more comfortable even on thin tyres But aluminium perfectly OK. I always feel good bike fit is the most important followed by tyres.

[Welsh boy]

At around 66kg I can honestly

At around 66kg I can honestly say that the 3 carbon frames I have owned have been much more comfortable than my 4 aluminium frames.  Save your money, dont buy a carbon seatpost, I have had 1 snap, 1 delaminate and one deform around the clamp bolt, the deformed one was a Cinelli, the delaminated one a cheap eBay job and the snapped one was a Selcof.  Think about it, the transmission route for road buzz from road to your bum is through tyres, wheels, frame, seatpin, saddle and shorts/tights padding to your bum, how much difference do you think the seat pin makes in that combination (forget the marketing rubbish)?

[Author]

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