Cycling UK Forum

531colin wrote:

honesty wrote:.......... I want the same bike, just with larger clearances for bigger tyres..........

^^^^^THIS...This is why its lunacy to use a FAULT of road STIs and dual pivot sidepulls to define an "audax" bike......Poor clearance is a FAULT........unless somebody can demonstrate that its a benefit.....and that is a challenge.
Why not have a bike where you can fit 35mm tyres if you want to?....you don't have to, you can use 23s in a bike with room for 35s.....but you can't do it the other way round!

amediasatex wrote:Hello, I was just wondering if anyone has one of the 48cm 26in versions of this frame who could take a picture for me? Or direct me to some pictures online as all I seem to be able to see are the 700c versions.

I've have the geometry sheet and have a pretty good idea of what it looks like but would like to actually see one if possible!

thanks
Matt

meic wrote:
However your cantibrakes will be designed to work with a fatter rim. With a narrow rim they will be working at a greater arc from the vertical. This means that on application they will be pushing with a greater downward angle on an arc that is heading substantially down as well as in.

Now if in the exhilaration of some lively Audax cycling your cleat lets go on the upstroke and you strike the canti-arm with your heel, it could pass your rim and go under it as the narrow rim flexes more easily and then you get accused of not setting up your cantis properly. A bit of a far fetched chain of events but anything is possible. ....

Brucey wrote:

meic wrote:
However your cantibrakes will be designed to work with a fatter rim. With a narrow rim they will be working at a greater arc from the vertical. This means that on application they will be pushing with a greater downward angle on an arc that is heading substantially down as well as in.

Now if in the exhilaration of some lively Audax cycling your cleat lets go on the upstroke and you strike the canti-arm with your heel, it could pass your rim and go under it as the narrow rim flexes more easily and then you get accused of not setting up your cantis properly. A bit of a far fetched chain of events but anything is possible. ....

FWIW I think that the 'old' canti boss pattern (2-1/2" boss spacing) still makes a lot more sense than the modern (3-1/4") boss spacing, on a road bike certainly. Worst case (usually with tyres fatter than ~40mm or so) is that the tyre needs to be partially deflated before it can be taken out of the frame.

It is a shame that the range of brakes that works with the narrow boss spacing is so limited these days.

cheers

The red bike on the Spa website (picture 5 of 5) is listed as a 26" wheel with 48cm frame. Neither 531Colin or myself think it is (we reckon 700c/51cm) so it might be worth ringing Spa and asking them to put up a new picture (they probably won't but they might at least correct the text ).

531colin wrote:

samsbike wrote:Cheers for that Colin, how do you feel the difference between a stiffer and more compliant fork - is it vibration, chatter or just experience of what you like?

Careful definition of terms needed here!
On that Ti bike with a Kinesis carbon disc fork, and 32mm marathon supremes at 60psi front, 70psi back (those are the pressures I use on tyres that size, at 11 stone ....rightly or wrongly!) its absolutely fine on tarmac.
However, off-road I think I get more jarring through the bars on any disc fork I have ridden, compared to 631 forks. (which are quite light....no low-rider bosses)
I will do a back to back comparison again, but the sort of stuff I'm talking about is hardpacked earth with lots of stones protruding maybe an inch above the earth..... my impression is that I need to take that sort of stuff a bit slower with the disc fork than with a 631 steel fork, on the same tyres, at the same pressures.
Its fair to say that the stretch of local bridlepath that I will use as my test track is somewhere I look where I'm putting my feet, even when wearing walking boots.
I suppose if you used a narrower tyre at higher pressure something might show up on tarmac

Freddie wrote:One can surmise from the Thorn's wider steerer tube that they will be stiffer than the Spa forks.

531colin wrote:Thread resurrection alert!

531colin wrote:

samsbike wrote:Cheers for that Colin, how do you feel the difference between a stiffer and more compliant fork - is it vibration, chatter or just experience of what you like?

Careful definition of terms needed here!
On that Ti bike with a Kinesis carbon disc fork, and 32mm marathon supremes at 60psi front, 70psi back (those are the pressures I use on tyres that size, at 11 stone ....rightly or wrongly!) its absolutely fine on tarmac.
However, off-road I think I get more jarring through the bars on any disc fork I have ridden, compared to 631 forks. (which are quite light....no low-rider bosses)
I will do a back to back comparison again, but the sort of stuff I'm talking about is hardpacked earth with lots of stones protruding maybe an inch above the earth..... my impression is that I need to take that sort of stuff a bit slower with the disc fork than with a 631 steel fork, on the same tyres, at the same pressures.
Its fair to say that the stretch of local bridlepath that I will use as my test track is somewhere I look where I'm putting my feet, even when wearing walking boots.
I suppose if you used a narrower tyre at higher pressure something might show up on tarmac

I have borrowed the prototype again, and done a back to back comparison on a reasonably dry track.
Same tyres, same pressure, I get a lot more jarring on my hands with that Kinesis carbon disc fork (alu steerer) than with 631 forks (inch steel steerer)
I don't notice any difference on tarmac.

Samuel D wrote:Interesting test, Colin. Do you have any idea how your 631 forks compare to the Thorn Audax forks with 1 1/8" steerer tube?

samsbike wrote:...........cheers for that. Are they running the same tire size and would wider tires with the carbon fork make a substantial difference?

531colin wrote:......All you need now is to get the same information from Thorn, and you will have a basis for comparison......