[danburbridge]

Ride comfort (on a rigid bike) is primarily a function of the tyres (size/inflation/construction).

A bike with cheap 23c tyres at 150psi will rattle the fillings out of your teeth.

The same bike with decent 25c or 28c tyres at e.g. 50-70psi (depending on rider weight) can float along with a magic carpet like ride.

[Yetanfou]

Why call those 23c tyres "cheap"? Why mention price at all? Ride comfort is a function of tyre size, not tyre price. You can buy very "exclusive" expensive 23c tyres, pump them up to 7 atm. and have just as hard a ride as the person who just overtook you on his "cheap" 23c tyres.

That "magic carpet" ride does come at a price but it is not monetary: the softer the tyre, the more resistance and with that the slower the ride.

[_Wintermute]

> That "magic carpet" ride does come at a price but it is not monetary: the softer the tyre, the more resistance and with that the slower the ride.

Unless you're riding on a velodrome, pumping your tyres up to 120+psi doesn't decrease rolling resistance, infact the the opposite is true. If the tyre can deform around small bumps it rolls much more easily. This is why very expensive and fast tyres have casings with a high thread count (sometimes even made of silk) so they are more supple.

[Lio]

Fast Fitness produced a little spreadsheet to calculate optimal pressure based on tyre width, bike+rider weight and a very granular assessment of surface.[1]

Something else to take into account is the aerodynamic trade off as tyre width grows. I think I read somewhere that 25mm is roughly the sweet spot. What you gain in lower rolling resistance by going up to 28mm you loose in drag. That's a bit anecdotal (sorry) but I have heard it mentioned in a couple of places. The best source I could come up with was from Zipp's web site.[2]

Of course that might well be worth it to be more comfortable if it means you can keep your body in a more aero position as that will dwarf any loss from the tyres (again a guess).

Hopefully there's some numbers somewhere to back that up. Maybe Bicycle Quarterly or Tour Magazine might be a good bet for anyone interested.

Also https://www.bicyclerollingresistance.com/ is always very interesting ...assuming you obsess over bike tyres as I'm sure everyone does. :P

[1] https://www.youtube.com/watch?v=Clk_LLBYFzA [2] https://zipp.com/support/faq/faq.php

[adrianN]

It makes a big difference if you ride on asphalt or similarly flat surfaces, which many bike commuters do.

[danburbridge]

I am not suggesting that all 23c tyres are cheap, but that tyre quality (which comes at a cost) as well as size has an important part to play in comfort.

My 23c handmade FMB tubulars (definitely not cheap) are a much nicer ride than cheaper tyres.

Rolling resistance is far more complicated, on anything other than a wooden velodrome, the road surface actually means that there is a sweat-spot in terms of pressure - too low and rolling resistance will be high, as you say, this decreases up to a point at which the effects of the microbumps in the road start to cause energy losses through hysteresis and eventually the tyre bouncing over tiny bumps.

For a 23c tyre and a 70kg rider the optimum tyre pressure is actually typically in the 80-90psi range (5.5-6ATM) although again this is dependant on tyre quality, an expensive tubular tyre with very supple silk sidewalls can be run at higher pressure than a touring tyre with tough reinforced sidewalls.

[Yetanfou]

I don't know how much you ride and in which conditions so I can't comment on the choice of your un-cheap 23c handmade FMB tubulars. What I do know is that those would not last very long for me, handmade magic pixie dust notwithstanding. I ride year-long through the Swedish countryside with temperatures ranging from a maximum of 37°C to -25°C, on roads which vary from reasonable to hard to find on map and landscape. I mostly ride a steel-framed 24-speed with 47-622 knobbly tyres (in other words "fairly fat tyres on 28" rims) at around 5 atm. as those give both speed as well as traction. Microbumps and similar concerns don't apply here, the bike is meant to take me from A to B no matter how many picobumps I encounter. Still I average around 30 km/h on the flat, easily reach 50 km/h downhill.

In other words, I use my bike as I use my motorbike: as a form of transport. Maybe that takes a different approach, maybe not, as said I don't know how you use your bike. What I do know is that I generally don't hold with the 'cultures' which form around specific areas, no matter whether it is biking (silk-walled handmade tyres adapted to your personal preference), audio (audiophile-grade left-turning 99.999999% oxygen-free oriented-strand meteoric copper power cables), food (organic free-range lettuce grown on virgin soil from heritage seeds fertilised with certified manure from Swiss highland cattle) and other such things.

[gameswithgo]

>Ride comfort is a function of tyre size

And tire construction. Though price likely does not correlate well with how supple the tire construction is.

[Angostura]

Yup; I prefer the hard ride and not to feel like I'm peddling a tractor.

[ljf]

Very true - but a great seat post and saddle can help - I stuck a carbon seat post on my alu bike and it was amazing, and even on my full carbon I moved to a carbon seatpost and carbon (unpadded) saddle - soaks up the vibration even though I have the tires at 100psi. People often comment on the lack of padding on the saddle, but with a nice pair of bib shorts it is fine. And 250g for the seatpost and saddle ;)

To clarify - vibration that it best dulls is 'road buzz' which you can really get on a alu bike, esp with high pressure tires. A carbon seatpost and seat can be as little as £50 for both - I got my seat post from wiggle and seat from china - happy with both - and recommend to all my friends.

Yes this will have little impact on 'bumps' - though the saddle def soaks some of them up.

I posted this to refute that 'only' tires have an impact on ride - frame, wheels, seat post, saddle, bars and bar padding, shorts etc can all have a positive impact on ride - and allow you to ride at a high tire pressure and get all the benefit of lower rolling resistance.

[fyhn]

True enough, but the more magic your carpet is, the more likely you are to get flats.

[matthewowen]

Eh, this is another area where construction is a factor. Flats due to low psi are usually pinch flats, which is a clincher issue. If you can bear the expense and inconvenience of running tubulars, pinch flats are no longer a concern.

[Lio]

I guess you could try tubeless as an alternative to tubulars too. They also tend to offer lower rolling resistance than tubs.[1]

I’ve got tubs on my TT bike but for general summer riding I like latex tubes in clinchers. Latex seems to be more resistant to pinch flats as long you take care fitting them. Spare tubes are butyl but not had to fix a latex puncture in the last 2 years.

(Winter and commute bikes are butyl for convenience)

[1] https://www.bicyclerollingresistance.com/

[Yetanfou]

...but tubular tyres at too low a pressure tend to separate from the rim in interesting ways - hope you brought tape or glue to stick them back in place.