SPA CYCLES STEEL TOURING FRAMES

[chocjohn9]

Colin
Interesting as well as great that the disc tourer will have a slightly curved steel fork. I can not be doing with straight forks with an angle at the crown intercept. Hugely asthetically displeasing for me. Each to their own though.

Surly's disc trucker has a curve but it is heavy. I hope this will be an improvement!

[Bmblbzzz]

So far the original question is yet to be answered.

Not that I'm particularly bothered, just interesting to see lots of info, but the original question remains unanswered. Is it a secret or are the bikes multinational.

I haven't read all 11 pages of this thread, so maybe this has been addressed in the meantime, but how could they not be multinational? Almost all manufactured products are. Let's say the frames were welded in Taiwan or China*. Alright, but where did the tubes come from? And the steel in those tubes? And that's just the frame. Let's say it has Shimano components; does that make them Japanese? But they might have been made in Malaysia or various other countries. If it's a Japanese design now manufactured in Malaysia using eg bearings from Korea, then it's... And so on for each item. The only thing we can say for sure is that it was designed in Harrogate, and without that, it wouldn't exist!

*Though as far as I've seen, 531 Colin, who appears to actually know, is not going to tell. It might not even be Asia: there are plenty of frame builders in Russia and Eastern Europe whose prices will be low and quality high - not as cheap manufacturing as Asia, probably, but then shipping will be a lot less and quicker, and if all your sales are in UK, it might make sense.

[531colin]

...........
How does the material/construction and resultant stiffness of the disc fork compare to the non disc one?

Comparing the steel forks for rim brakes and disc brakes.....
(note...the rim brake forks all have low-rider fittings - if you don't want low riders, its readily possible to construct steel forks for rim brakes which are both lighter and more flexible)
Steerer....all the same....inch and eighth steel
Fork crown ...varies with tyre clearance
Tourer (rim brake) and disc tourer use a wide crown....Audax and winter clubman's disc bike use a slightly narrower and prettier sloping crown.
Fork blades ....are all the standard 28 x 20 mm oval at the top to fit standard crowns.
Blades for rim brakes are butted tube (ie thinner wall at the bottom) and taper to 14mm diameter at the tip
Blades for disc brakes are plain gauge and taper to 19mm at the tip, to withstand welding the disc mount and the disc brake load which is all taken at the tip of one fork blade.

I think my conclusion would be that the disc forks are little stiffer than the rim brake forks for low-riders. If you are looking for front-end comfort from steel forks, you should look at a one inch steerer and something like Reynolds 631 blades which taper from just below canti. brake mounts; even then, a big light front tyre run at low pressure is more effective.
The most unforgiving forks I remember riding were 15mm diameter at the tip, but an "aerofoil" section at the crown which measured 36 x 18mm.

[breakwellmz]

Thank you Colin that`s really interesting.
I did think after i asked the question that it may well be something that you wanted to keep to yourself for commercial reasons!
A non low rider fork (not of interest to you at Spa i realise)would be of the same dimensions but of a lighter gauge again i assume?
All things being equal, does a lighter gauge fork and/or large volume tyre have an adverse affect on steering `response`(precision?) due reduced lateral stiffness?

[Brucey]

that is interesting. Except when carrying heavy loads, or when disc brakes are used, I have always favoured a light springy steel fork. The tyre (esp if fat and low pressure) provides most of the comfort but the fork/frame flex is important too.

With some traditional frames/forks the net flex is roughly divided into thirds; 1/3rd in the fork blades, 1/3rd in the steerer, 1/3rd in the frame itself (bending loads in the top and down tubes). Touring framesets (for load carrying) have always been stiffer, but with a modern steel touring frameset the top tube and down tube are liable to be larger diameter and the steerer is usually 1-1/8". This is likely to make the frame and the steerer at least 50% stiffer, leaving the fork blades as the most significant contribution towards the (much reduced) amount of flex available.

If you suppose that the fork blades are about twice as stiff if they are built for a disc brake/heavy load, this might make ~15% difference to a frameset where the front stiffness is apportioned in thirds, but it will be a greater proportion of the whole if the frame and steerer are already stiffer, about 25 or 30% perhaps.

IME a lack of stiffness if the fork/front end is liable to show up under braking (with disc brakes) and/or when under load (tendency to shimmy) well before you would notice any accuracy changes in the steering per se.

In theory use of CF and/or shaped steel tubes ought to allow useful flexibility in terms of comfort whilst preserving most of the torsional stiffness in the fork and frame, and thus retaining enough stiffness to resist shimmy etc. when loaded. In practice this seems a difficult nut to crack, and for the meantime one can expect steel frames/forks which are fitted with disc brakes and/or are designed for carrying a load to be somewhat less comfortable (esp when not loaded) unless the machine is fitted with fattish/lower pressure tyres.

cheers

[531colin]

We have been round this before, I posted the 631 blade data from Reynolds here......https://forum.cyclinguk.org/viewtopic.php?f=1&t=81666&p=1007713&hilit=reynolds#p1007713
Data on Reynolds tubing used to be easy to find, I can now only find it via a website "torch and file".....http://www.torchandfile.com/assets/images/2017%20JAN%20PARTS%20LIST.pdf
If you look at the profile of the 631 fork blade i posted (and its a blade for disc forks) I think the big thing is the taper. It tapers 80mm from the top, and it tapers markedly. The 631 blades for rim brakes start tapering at about the same point, and go down smaller at the tip.
Another blade I have used is EB 708 (on the list)....this suits rim braked tourers with low riders. But.....tube wall thickness is the same as 631 for rim brakes. Oval at the crown is the same, tip diameter is the same.....but the blade is much bigger ("diameter)" at the point where the low rider mount goes. With your weight on the bike, the front of the fork is in compression, and the back is in tension.....when you put the brake on, this reverses. So the best way to mount a low rider is through the middle of the blade, not on the front or the back which experience greater stress cycles.
With the 631 blade i wouldn't mount a low-rider at all.....there just isn't enough "middle" of the blade.....the blade is small diameter there, presumably reynolds intend it to flex there.

I have never noticed a "lack of precision" to the steering which I could attribute to either a flexible fork or a tyre at a (reasonable) low pressure.
....but there again, I have never noticed any improvement to steering "precision" attributable to oversize handlebars and stems....given the choice, I would go for 26mm bars....it seems perverse to seek out flexible forks and stiff bars, on the same bike.

There is no doubt that the frame flexes when the front wheel hits a bump.....but that won't help hand comfort?

The Spa bikes don't use reynolds blades, we decided to stick with Cromo blades of local origin that the factory is used to building with, the dimensions are similar to the Reynolds EB708 blades for the rim brake bikes and the disc blades are similar to the 631 disc blades, except the taper is less pronounced than the 631.

[landsurfer]

Since I started this ......
My only concern would be that the tubes are of the standard they are tagged for.
If it it says 725 thats what it should it should be, and i'm sure SPA have a quality process in place that ensures the tubing is compliant.
It does not matter who makes them as long as they are compliant to the required SPA standards.

I have recently had to dispose of a large quantity of safety critical braking components from a current rail passenger fleet.
The spec for the components was a high grade stainless steel.
The only part of the component that met this high standard was the welded on label detailing the steel standard .... .....

Judging by how easily my top tube dented after being blown over in the Cornish winds (< 50 miles of riding, ) i would say they are to spec, 725 is thin .....

[531colin]

Top and down tubes are half a millimetre thick in the middle, the un-butted bit. Seat tube is a bit thicker at 0.6mm.
Not outlandishly thin for bicycle tubing, but all too easy to dent accidentally, and I wouldn't want to be welding a disc mount to 0.5mm tubing.

[landsurfer]

Top and down tubes are half a millimetre thick in the middle, the un-butted bit. Seat tube is a bit thicker at 0.6mm.
Not outlandishly thin for bicycle tubing, but all too easy to dent accidentally, and I wouldn't want to be welding a disc mount to 0.5mm tubing.

I took advice from John at SPA, and to be honest after years of riding 531 frames with the occasional dent i'm not exactly worried.
I could cover it up with a sticker and blutac, but why bother .... Dents happen.

[barrym]

This has been a very interesting thread to an ignoramus like me. So is it silly to ask what tube would give you a better resilience against modest weight increase. Is there such a compromise or is that what we're looking at anyway?

I haven't had a steel frame since my 531 Carlton in the early '60s. You can imagine how carefully that was treated by a young teenager. Don't recall that ever getting dented.

[fastpedaller]

The Spa bikes don't use reynolds blades, we decided to stick with Cromo blades of local origin that the factory is used to building with, the dimensions are similar to the Reynolds EB708 blades for the rim brake bikes and the disc blades are similar to the 631 disc blades, except the taper is less pronounced than the 631.

I understood the forks for the Spa Steel tourer were built in UK - Is this not true (or has it changed)?
ETA - from Spa website when I bought my frame in 2014

Designed by hugely experienced cycle tourists this is a high quality Reynolds 725 frame built to our specification with a Reynolds steel fork.

The geometry and ride is what you would expect and want from a touring bike, so that handling is reliable and assured when loaded.

Frame and forks option.
(Includes headset, unfitted)
Fork is made in UK by Lee Cooper of Coventry

[breakwellmz]

Top and down tubes are half a millimetre thick in the middle, the un-butted bit. Seat tube is a bit thicker at 0.6mm.
Not outlandishly thin for bicycle tubing, but all too easy to dent accidentally, and I wouldn't want to be welding a disc mount to 0.5mm tubing.

I`ve just picked up a frameset that i think you may well approve of i`m certainly pleased with it- A 1990s Bridgstone Synergy Tourer made of Ishiwata triple butted tubing complete with BB, headset and seatpost for less than forty quid!
It`s going to have a Nexus 8 speed installed

[531colin]

I would expect Lee Cooper's Reynolds forks to have the "Reynold's Flash" transfer at the top of the blade, see these forks on my roughstuff bike....https://www.flickr.com/photos/52358536@N06/29484912954/in/album-72157624571269648/lightbox/

[fastpedaller]

I asked for my frame to be supplied without transfers - alas I didn't consider the tubing transfers! Where the frame transfer usually is on the seat tube, I've fixed a rather nice Gold 'Regina extra' transfer.

[landsurfer]

My dark green metallic frame came with black transfers .... almost invisible ...
The nice chaps at SPA have sent me a set of gold ones .....