Yellow Saddle
Guru
- Location
- Loch side.
Where is the clearance issue at the rear when removing a wheel, at the brakes or elsewhere?My supersix evo just about takes 25mm tyres and you have to deflate the rear to get the wheel out.
Road bikes unable to accept wide tires
- Thread starter mustang1
- Start date
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Yellow Saddle
Guru
- Location
- Loch side.
Stiffness is not determined by length.
mjr
Comfy armchair to one person & a plank to the next
- Location
- mostly Norfolk, sometimes Somerset
They probably omitted the qr to save weightI suggest at the brakes unless you undo the caliber quick release.
mjr
Comfy armchair to one person & a plank to the next
- Location
- mostly Norfolk, sometimes Somerset
I think you are a bit out of date. I have a 2015 Focus Cayo running 28mm tyres and and older Kinesis GF with 28's and mudguards.
If you fix the diameter and wall thickness, as was the case in the olden days of steel tubing*, then stiffness is proportional to length.
Try bending a 6" length of tube then a 6' length.
*when almost all competitors used the same or similar tubesets.
25mm IS the wide size of which they speak. For non-racing use, 28mm has always been a favourite of Audax riders and commuters.
Yellow Saddle
Guru
- Location
- Loch side.
No it is not. Stiffness is indicted by Young's Modulus and there is no length dimension in there.
https://en.wikipedia.org/wiki/Young's_modulus
fossyant
Ride It Like You Stole It!
- Location
- South Manchester
My two road bikes will only take 23mm. Steel is real. Not fitting no MTB tyres to my road bike.
the snail
Guru
- Location
- Chippenham
That's the stiffness of the material, but what matters in a frame is the stiffness in bending, and the deflection of a tube varies with the cube of the length IIRC.
Smokin Joe
Squire
- Location
- Bare headed cyclist, Smoker
It's no use buying a race frame and then complaining you can't fit 28mm tyres to it. You want tyres that width you need an audax or touring frame.
potsy
Rambler
- Location
- My Armchair
MAMILS want to look like pro's, they don't want no tractor tyre.
Yellow Saddle
Guru
- Location
- Loch side.
The key words are deflection over length, as you point out. But I'm really onto the point about frame stiffness and the nonsense spoken about it. First of all stiffness is moot at the levels we're talking about but I want to see someone say that a frame made for 23mm tyres is stiffer than a frame made for 28mm tyres. We're talking about 1.5mm difference in each of the three dimensions at the points where the tyre could touch the frame. Even if you cube that, you still get....zero-ish.
The real reason in the days of steel was that extra clearance required a dimple in each of the two chainstays and possible in each of the two fork blades. Framebuilders preferred to use straight tubes and save some labour.
Today's mould-formed composite frames? I can't think of a rational reason why they would restrict tyre width that much. I've seen arguments of improved airflow, stiffness (obviously, stiffness is the holy grail of explaining everything) and restrictions for brake caliper opening. None of these make sense. There's even a trend to slam the back wheel right up to the seat tube (and into a niche carved into it) so close that grit scrapes the frame. This I've seen justified as a measure to "improve climbing", I kid you not.
We shouldn't eat the rubbish the industry feeds us. However, once the industry has the upper hand and you have no choice anymore, you will be force fed.
Smokin Joe
Squire
- Location
- Bare headed cyclist, Smoker
I've often wondered about that. Another pet hate of mine are seat tubes ovalised to the point of being a very thin oblong, in the interests of aerodynamics. My neighbour has a TT frame like that and it cracked along the tube from the top down. Hardly surprising with a built in stress point.
