Spa Cycles' Disc Braked Tourer and Audax

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NetworkMan
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Spa Cycles' Disc Braked Tourer and Audax

Postby NetworkMan » 28 Jul 2018, 12:50pm

In steel, both with steel fork, and yes, you can buy the frames:-
https://www.spacycles.co.uk/
I wonder if the Audax has enough clearance for those lovely 35/37 mm tyres?
No doubt Colin will say so soon....

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honesty
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Re: Spa Cycles' Disc Braked Tourer and Audax

Postby honesty » 28 Jul 2018, 2:12pm

Interesting. Is the Aubisque just a steel version of the Elan?

JamesE
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Re: Spa Cycles' Disc Braked Tourer and Audax

Postby JamesE » 28 Jul 2018, 2:14pm

Aha, excellent. I was up at Spa buying a tourer a couple of months ago, and the prototype disc audax was a seriously nice-looking bike. Reckon that'll be my n+1 in due course...

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531colin
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Re: Spa Cycles' Disc Braked Tourer and AUBISQUE

Postby 531colin » 30 Jul 2018, 6:16pm

A short history.....
Being basically a "touring" shop, Spa's first venture into own brand bikes was a tourer. Titanium seems an odd choice for a first venture, but the frame manufacturers want a big order for steel frames, so its actually cheaper to get a small-volume run in Ti.
The original rim-braked Audax was the second bike off the drawing board, again in Ti. The Ti and steel Audaxes are probably our most popular bikes, and they do ride nicely. They are made for the generations of cyclists who won't consider any gear shifter apart from road STIs, so they fit dual pivot sidepull brakes which limits you to 25mm tyres if you want sensible mudguard clearance.....this means I don't own a Spa Audax, because I can't keep to the tarmac, the tracks pull at me.
The original design spec. for the bike which became the Elan was "an Audax with disc brakes and carbon forks".....well, I've been caught before, so I said "Show me the forks". The forks duly turned up, and they were cyclo-cross forks for disc brakes, with clearance for big tyres (good) and only in 45mm offset (not so good). From the beginning I matched the clearances at the rear to the fork clearances, but we still went through a few prototypes; a full carbon tapered steerer replaced the original alloy steerer, so an extended head tube and dropped top tube replaced the big stack of spacers. We bent the chainstays and threaded them between the chainwheel and tyre to avoid putting big dents in them, and after talking to Wayne who used to design the Sabbath bikes we ovalized the top and down tubes.
The design spec. for the Aubisque was "a clubman's steel winter bike with discs" so that's what it aims to be. Its a steel fork so the smaller sizes have a longer fork offset and a shallower head angle so they get toe clearance with mudguards without too long a reach; the bigger sizes have shorter offset and steeper head so they get a longer reach without a wheelbase dimension in the geometry table which would put off people raised on short wheelbase bikes with fag-paper clearances. They are designed for 25 or 28mm tyres without looking too "gappy"....you might be able to cram a 35mm tyre in there, but I wouldn't, I want 10mm under the mudguard.
Its probably a silly question, but why would anybody looking for clearance for big tyres be looking at anything except a touring bike? The perception on this forum (as elsewhere) is that touring bikes are slow, heavy, and the exclusive preserve of bearded, sandal-wearing geriatrics. Anybody who has read this far must be at least slightly interested, so......the tubing for the Aubisque and Wayfarer is the same; 725 main tubes, Cromo fork blades and stays. The fork blades and stays are the same throughout; after all, they are all disc brake bikes. As usual, I vary the diameter of the top and down tubes with the frame size. So the smaller sizes of both bikes have smaller diameter top and down tubes, compared with the larger sizes. About the only difference is the biggest Wayfarer has one size bigger top tube than the biggest Aubisque, just to be sure it can handle an expedition load. The Wayfarer has the same fork offset and head angle in all sizes, and both bikes have the down tube ovalized at the bottom bracket and the top tube ovalized at the head tube. Fitted with the same wheels and tyres, any difference in the "performance" of the 2 bikes is in your head. But you won't believe me.
And why all the emphasis on ovalized tubes? The major determinant of tube stiffness is diameter. But if you double the diameter of a tube and keep the wall thickness constant, (as bike tubing does) then the stiffness doesn't double, it goes up by something like the square or the cube (I can't remember, Brucey or CJ will know)
Bike frames want to be stiff laterally (against pedalling forces and sway) and compliant vertically for comfort. There is a snag; frames are triangulated vertically, but not laterally, which is the wrong way round. Ovalising tubes makes a huge difference to the relative stiffnesses; I reckon its worth about a gear on my Elan compared to my round-tubed tourer.
So, whats next? Yes, we are prototyping a steel Elan, with the same carbon fork with tapered steerer.
But before that I will have in my hands prototype Audax 2 bikes, with rim brakes and carbon forks with alloy steerer (as now) except that we can now get forks with different offsets, so again the small bikes will have different fork offset and head angle to the big bikes, and the frame tubes will be ovalized.

fastpedaller
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Re: Spa Cycles' Disc Braked Tourer and Audax

Postby fastpedaller » 30 Jul 2018, 7:23pm

Great info from Colin. Strangely my Spa steel Tourer is what I would call a fast bike...... when my legs will move it fast :D I've ridden what should be very fast bikes in the past, but on the day they were slow :( (because my legs were!) Biggest factor as always is the engine, but it is indeed good to have a well-thought-out package and that's what the Spa range is from my experience. Thanks to Colin.

geocycle
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Re: Spa Cycles' Disc Braked Tourer and Audax

Postby geocycle » 31 Jul 2018, 9:38am

Thanks Colin, that's really useful for those of us pondering n+1! The elan looks and sounds fantastic, you've done a really great job there and I'm sure I'm not the only one to say wow when I saw the first pictures. From your description there is still a fair amount of overlap in function between the audax and the elan isn't there? I can think of things the elan can do better than the audax (wide tyres, offroad..) but what about the other way around? Why would the Audax be better for say audaxing than the elan? There can't be much in it?

NetworkMan
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Re: Spa Cycles' Disc Braked Tourer and AUBISQUE

Postby NetworkMan » 31 Jul 2018, 12:06pm

531colin wrote:A short history.....
.................Its probably a silly question, but why would anybody looking for clearance for big tyres be looking at anything except a touring bike? The perception on this forum (as elsewhere) is that touring bikes are slow, heavy, and the exclusive preserve of bearded, sandal-wearing geriatrics.

But they don't have to be slow and heavy. With light wheels which suit wide fast tyres you have a bike which is pretty fast on roads and brilliant on gravely cycle tracks. And yes, I'm 70 years old, have a beard, wear sandels in the summer, though not on the bike, and am a vegetarian too :D

Brucey
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Re: Spa Cycles' Disc Braked Tourer and AUBISQUE

Postby Brucey » 31 Jul 2018, 12:31pm

531colin wrote:A short history.....
.................Its probably a silly question, but why would anybody looking for clearance for big tyres be looking at anything except a touring bike? ….


the perception of weight and slowness is one thing (and it is just a perception in many cases) but the reality for many years was that if you chose a bike that was meant for carrying a load then it wouldn't be quite as nice to ride (when unladen) than one that wasn't. I quite often found this to be the case; differences in wheelbase, stiffness, and steering geometry saw to that, I think, even if some of the parts were also chosen with durability in mind rather than speed.
This can be addressed to some extent using modern materials and clever design, but there is still a perception there, and a reality (of some kind) too. Today it is more likely that folk will want to use fat tyres without a load on, too.

I heartily applaud the clubman's machine ( I think I asked what happened to the whole idea of one such about five years ago). IME occasional touring loads are well accommodated even by quite lightweight framesets, so if you tour once a year, without a very heavy load even, buying a full-on touring bike is probably overkill. My offering that might help to square the circle between the aesthetics/function of close clearances/narrow tyres vs occasional uses of fatter tyres is the idea of the convertible dropout; in these there are inserts, which increase the axle to crown distance by 5-10mm when they are turned round (or something). Thus such a bike could (with suitable adjustments to brakes) keep more of the people happy more of the time.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

slowster
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Re: Spa Cycles' Disc Braked Tourer and Audax

Postby slowster » 31 Jul 2018, 1:28pm

It's certainly interesting that the only difference between the two bikes is the fact that one has narrower tyre clearance, and that the only reason for that is aesthetic, i.e. the performance of the Wayfarer with the same tyres would be identical.

My own perception is that it is not large clearances between tyre and frame that catch the eye and possibly offend the aesthetic sensibilities, because the mudguards in between the tyre and frame make the tyre/frame gap much less apparent.

Instead I find that it is large clearances between tyre and mudguard that are noticeable (the width of the mudguard compared to the tyre and the height of the mudguard above the tyre, especially if viewed from the side it is possible to see daylight between the tyre and mudguard).

I suspect that if a Wayfarer were built up with 28mm tyres and mudguards to suit, e.g. SKS P35 with the mudguard positioned 10mm from the tyre, it would not look noticeably different to a similarly specced Aubisque.

Online
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Re: Spa Cycles' Disc Braked Tourer and Audax

Postby Online » 31 Jul 2018, 7:23pm

geocycle wrote:Thanks Colin, that's really useful for those of us pondering n+1! The elan looks and sounds fantastic, you've done a really great job there and I'm sure I'm not the only one to say wow when I saw the first pictures. From your description there is still a fair amount of overlap in function between the audax and the elan isn't there? I can think of things the elan can do better than the audax (wide tyres, offroad..) but what about the other way around? Why would the Audax be better for say audaxing than the elan? There can't be much in it?


Re the Elan, it’s great. Since getting mine about 14 months ago I’ve done a complete RRtY and a LEJOG trip. In winter I put cyclocross tyres on it and did a fair amount of trail riding. I can’t imagine how an Audax would be better.

fatboy
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Re: Spa Cycles' Disc Braked Tourer and Audax

Postby fatboy » 31 Jul 2018, 7:33pm

As an owner of two Spa tourer (steel for commuting (bitser) and Titanium for fun) I find that I hardly ride my road/Audax bike. Yes the audax does accelerate a bit better and the steering is a bit more "fun" but the Ti one in particular is my go to bike. It feels fast and since it's so stable I can really hammer along because it's so confidence building.

Saying all that I do want to change my Audax bike. Probably just change the frame but the disk Audax bikes are interesting!
"Marriage is a wonderful invention; but then again so is the bicycle puncture repair kit." - Billy Connolly

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531colin
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Re: Spa Cycles' Disc Braked Tourer and Audax

Postby 531colin » 31 Jul 2018, 9:32pm

geocycle wrote:Thanks Colin, that's really useful for those of us pondering n+1! The elan looks and sounds fantastic, you've done a really great job there and I'm sure I'm not the only one to say wow when I saw the first pictures. From your description there is still a fair amount of overlap in function between the audax and the elan isn't there? I can think of things the elan can do better than the audax (wide tyres, offroad..) but what about the other way around? Why would the Audax be better for say audaxing than the elan? There can't be much in it?

Theres a lot of overlap in function between all the bikes. The original rim-braked Audax is a traditional-looking clubman's bike, and as such I expect they will continue to sell, even if more slowly. You could ask what advantage does the Audax confer over the tourer, and I might reply "the difference in weight between a steel fork and a carbon one."
There is no reason why we should all want identical bikes, and it would be perhaps a sadder world if we did. And Spa is a business, and its a good idea to offer customers choice. The Elan has been a couple of years in development, and by chance it has caught the current trend for wider tyres; but it only got its clearances because the fork I was shown was a cyclocross fork, and as a touring cyclist myself I saw an opportunity to make a modern bike, which could fit the tyre sizes I habitually used.

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honesty
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Re: Spa Cycles' Disc Braked Tourer and Audax

Postby honesty » 31 Jul 2018, 9:39pm

Colin, any carbon forks you could fit on the tourer or are the canti boss carbon forks you can get all with 45mm offsets?

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531colin
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Re: Spa Cycles' Disc Braked Tourer and Audax

Postby 531colin » 31 Jul 2018, 9:55pm

honesty wrote:Colin, any carbon forks you could fit on the tourer or are the canti boss carbon forks you can get all with 45mm offsets?

I have always worked on the principle that if I want to fit a carbon fork to a frame, I start with the fork and design the frame around it. I don't know of many tourers with carbon forks, and I suspect those there are use cyclocross forks. The dimensions for the Elan forks seem to be an unofficial "industry standard" for cyclocross disc forks, but I think you would be lucky to find a fork which was "near enough" in both offset and axle to crown length to fit a touring bike.

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honesty
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Re: Spa Cycles' Disc Braked Tourer and Audax

Postby honesty » 31 Jul 2018, 10:11pm

The only carbon touring fork i know of is the Columbus Tusk Trekking fork, and that seems to have been discontinued... and has an offset of 45mm