Was 531ST heavier than 725?

[foxyrider]

Apart from tube gauges the big weight impact will be construction method. 531 will almost always be built with lugs, 725 as has been observed is designed for lugless construction. So whilst the tubes can be the same weight the lugs on the 531 will add a chunk to the overall weight.

[Brucey]

This is for normal, not over-size 725. I have a feeling any answer will come back with caveats ... Assumes same frame dimensions and fork in same material in each case, 531ST or 725. And I suppose the question is, would 531ST have produced a different bike? Apologies if your response is ...

the simple answer is 'yes, probably'.

However 531ST would/could be a very different tubeset depending on when you bought it, the frame size, and the mood of the framebuilder.

And 725 (with its indeterminate stays etc) is available in different wall thicknesses too.

cheers

[pwa]

I've never considered 725 to be especially light, at least not on the two examples I've had. Both have had tubing that, compared to 531ST, is oversize. So any reduction in wall thickness is offset by increased tube diameter. And the wall thicknesses have not been whittled down all that much. I'd be very surprised if 725 and 531ST touring bike frames vary much in weight, not that it matters much.

Having had touring bikes in both tubesets I prefer 725 because with my 6ft+ height and bulk I appreciate the potential for extra stiffness in the main triangle.

[horizon]

I've never considered 725 to be especially light, at least not on the two examples I've had. Both have had tubing that, compared to 531ST, is oversize.

725 does come in oversize and that is used on larger size bikes (maybe yours in fact). AFAIK, Spa vary the tube diameter according to bike size which makes complete sense. My impression is that 725 in its normal sizes is used for light touring bikes (as opposed to Audax bikes). For this reason, I believe that a Surly LHT will be heavier/less sprightly than Thorn Club Tour or indeed a Spa tourer (even though heavier than an Audax).

I realise that not only is this a lot of conjecture on my part but that given components and frame dimensions, it probably doesn't matter. However it does give a clue as to the intentions of both the builder and rider: as components and usage are added, the bike gets to make sense. It would seem pointless to get an Audax bike and huge tyres. Cross bikes are quite funny in this respect (ballerinas in Doc Martens?) but in their usage (light, fast but off-road) they too make sense.

[531colin]

I've never considered 725 to be especially light, at least not on the two examples I've had. Both have had tubing that, compared to 531ST, is oversize.

725 does come in oversize and that is used on larger size bikes (maybe yours in fact). AFAIK, Spa vary the tube diameter according to bike size which makes complete sense. My impression is that 725 in its normal sizes is used for light touring bikes (as opposed to Audax bikes). For this reason, I believe that a Surly LHT will be heavier/less sprightly than Thorn Club Tour or indeed a Spa tourer (even though heavier than an Audax).

I realise that not only is this a lot of conjecture on my part but that given components and frame dimensions, it probably doesn't matter. However it does give a clue as to the intentions of both the builder and rider: as components and usage are added, the bike gets to make sense. It would seem pointless to get an Audax bike and huge tyres. Cross bikes are quite funny in this respect (ballerinas in Doc Martens?) but in their usage (light, fast but off-road) they too make sense.

You need to state exactly what assumptions you are making.
What difference are you assuming between a light touring bike and an audax bike?
Last time I looked, LHT used the same size tube for all sizes of frame. So a small Spa tourer will be lighter built than a small LHT; by the time you get to the big sizes, they may be similar, or the Spa might even be heavier built.
What is heavier than which "Audax"?
Is this your assumption about Audax bikes?....Audax bike = narrow tyres? I think that comes from Audax bike = pseudo-race bike = STI and dual pivot sidepulls, which restrict tyre and mudguard clearance. Once you break out from the STI/dual pivot stranglehold, you can have bigger tyres which are more suitable for minor roads and the occasional track. You can see this on the modern rash of Gravel/FauCX/call it what you will bikes with STIs and disc brakes, and you always had tourers with cantilevers for tyre clearance, long before STIs were invented.

[horizon]

You need to state exactly what assumptions you are making.

My assumptions about Audax bikes are based on what I see when I look at bikes called Audax bikes - I'm not saying they should be like that - in fact I agree with you 100% about tyre clearance - and so do thousands of other people judging by the popularity of cross/gravel bikes.

As you know from my other posts, I'm trying to tease out the difference between touring bikes. I hear lots of conflicting views e.g.:

1. Audax bikes must be as they are in order to cope with very high mileages i.e. audax rides. Traditional touring bikes are therefore a non-starter (what I hear, not my view).
2. You need a full-on touring bike to tour on (again, not my view and refuted by many and on that basis, an Audax bike would make more sense for some people).
3. All touring bikes are the same after the addition of luggage: heavy and slow. I don't think they are judging by the bikes I have but I cannot say exactly how that difference is achieved (so many factors). Hence my question on this thread.
4. The difference between an Audax bike and a touring bike is wafer-thin if you change the wheels/tyres and keep the components light on a touring bike (I would go with that from what I surmise).
5. You can make a huge difference to a touring bike in this way (true again IMV).
6. On that basis, a touring bike would make more sense for some people.

There's a vast amount of opinion out there on this topic, most of it highly contradictory. I speak mostly from complete ignorance (We can see that, horizon! Ed.) so wading through it and trying to make sense of it isn't easy.

[Brucey]

A lot of 'touring bikes' are (as Colin says) built in such a way that the frame is overbuilt in small sizes, underbuilt in large sizes, because they don't vary the tubing with frame size enough. A lot of touring bikes are built to take a load, too, so are built to be stiff enough for this even in the large sizes.

I think that fitting 'lightweight wheels' etc to a typical touring bike (esp in small sizes) is often a recipe for an uncomfortable ride; the frame may just be ridiculously stiff and plank-like.

Well-designed audax frames are intended to carry a smaller load and (ought) to be appreciably less stiff. This means that they can ride well on most roads, even with relatively skinny tyres and lightweight wheels etc.

So all kinds of broad brush statements about 'x ought to be the same as y with the right parts on' could be right, could be hopelessly wrong; it all depends!

cheers

[531colin]

OK, so heres a scan of my 2016 Reynolds list for 725......



Look how few frame tubes there are!
AG455 and AG457 are the 28.6 seat tubes for small and large frames....the 1.2mm wall thickness is at the seat cluster where it has to withstand lots of welding and also reaming for the seatpost.....if you look carefully at one of these seat tubes, you can see/feel that the tube is bigger outside diameter at the top ("bulge" in Reynold's terminology) so that the internal diameter accepts the seatpost.
AG401 is a single butted 28.6 tube....I have never used it.

AG206 and AG208 are 28.6 double butted frame tubes.....the shorter tube is thinner wall.
Apart from 28.6, there are only 3 other frame tube diameters....25.4, 31.8, and 34.9, and they are all only available in 0.8/0.5/0.8 mm wall gauge.

There really, really isn't a huge range of frame tubes to pick from......but there still seems to be enough to build both touring and audax frames.

For the smallest bikes, both audax and touring, I use 25.4 top tube and 28.6 down tube........these are the classic "old" inch and inch and eighth diameters which were used on lugged frames in all sizes....these tubes look really skinny to people brought up on aluminium. For middling size bikes I use 28.6 top tube, 31.8 down tube. There is actually a difference between the big bikes; the tourer gets 31.8 top tube and 34.9 down tube, while the audax stays with 28.6/31.8.
Its just as logical to increase the diameter of the seat tube on big sizes, but there are no bigger seat tubes in 725, which saves me making a decision whether to use 2 different sizes of tube with the attendant different seatposts and front mechs. (As far as I know, most manufacturers don't change any frame tube diameters with the bike size.....but I'm prepared to be wrong!)

Stays are cromo for both bikes; chainstays traditional oval to round, audax gets butted, tourer gets plain gauge, seatstays traditional round tapering, 0.7mm for the audax, 0.9mm wall for the tourer, for seatstay mounted brakes and luggage.

The biggest "load" on any bike is the rider, and the biggest differences between an "audax" bike and a "touring" bike isn't the frame tubes. Things like carbon forks, lightweight wheels and cycle parts, and light tyres make much more difference.

EDIT

[steady eddy]

Lunch aside - the wheels and just about everything else on my Galaxy are far heavier than those on my son's Giant Defy but the speed difference over a day out is imesurable . I have to conclude that frame weight on its own is fairly irrelevant. Looking at my bike as a whole the stem is thicker, the seat has more padding, I have a rack and mud guards and of course a triple chain set. These quickly add up to extra weight but improve the utility of the bike no end. Then when we go out, I put a bag on the rack to carry my spare clothes and his of course, because he has no rack. Then when we get back I have to clean his bike because he has no mudguards, and if I didn't clean it then it would probably get put away dirty! But that's sons for you and don't you just love them all the same. I bet the difference in the frame weight though I about 250 gms. I have to pedal harder to keep up - but I put that down to age.

[Paul Smith SRCC]

Conclusions when comparing 725,531 and 'Touring' versus 'Audax' spec' bikes are always down to the individuals perception. I don't play tennis, give me Andy Murray's tennis racket and then ask me to compare it with another half the price and I dare say it will feel no different to me; yet to Andy....

It is important to focus on the design as well as material used, the Spa Tourer is not set up to offer the same riding experience as an Audax bike. Compare the two examples from the same designer, even if hypothetically they were made of the same material, in the same way, weighed the same, with the same finishing kit interms of equipment; by design they would perform differently.

I repeat it's always down to the individuals perception, the ideal solution if possible is to test the relevant choices yourself to determine your own conclusions; 'no difference' to one maybe a 'deal breaker' for another.

[531colin]

..........
It is important to focus on the design as well as material used, the Spa Tourer is not set up to offer the same riding experience as an Audax bike. Compare the two examples from the same designer, even if hypothetically they were made of the same material, in the same way, weighed the same, with the same finishing kit interms of equipment; by design they would perform differently. .......

Same material, same weight, same wheels, different performance. Due to what, exactly? Half a degree on the seat tube angle?

[Brucey]

IIRC 'traditional' steel frames used 28.6mm (1-1/8") down tubes, not 31.8mm (1-1/4") down tubes. A size variation between

28.6mm, 31.8mm, and 34.9mm

might not sound like much but (at constant wall thickness) the bending stiffness goes with the cube of the diameter, so (approximately)

28.6mm is +43% stiffer than 25.4mm
31.8mm is +37% stiffer than 28.6mm
31.8mm is +95% stiffer than 25.4mm
34.9mm is +33% stiffer than 31.8mm
34.9mm is +82% stiffer than 28.6mm
34.9mm is +160% stiffer than 25.4mm

Whilst you wouldn't go up four sizes (eg from 1" to 1-3/8", thus making the frame x2.6 stiffer), going up one tube size in both the down tube and the top tube will make the frame about 40% stiffer. Going up two sizes in the down tube(alone) will make the frame about half as stiff again.

My view is that these changes are not small! However they arguably need to be large, because of the effect of tube length on end deflection (assuming that is one aspect of frame stiffness. Simply increasing the length of every tube in a frameset by 20% will increase cantilever type deflections by about 70% , i.e. the frame might feel about half as stiff in a large size vs a small size, unless some kind of change is made in the tube stiffness.

cheers

[531colin]

Sorry, TYPO of the worst magnitude!
Of course the old traditional sizes are 25.4 and 28.6.....I got it right with the imperial measurements, had a brain fart with this new-fangled metric stuff.
So for the audax bikes, I go up one increment of tube diameter for both top and down tubes over the size range, for the tourers its 2 increments.

It "sort of feels about right".
Next, I'm looking at ovalising tubes.

[Paul Smith SRCC]

..........
It is important to focus on the design as well as material used, the Spa Tourer is not set up to offer the same riding experience as an Audax bike. Compare the two examples from the same designer, even if hypothetically they were made of the same material, in the same way, weighed the same, with the same finishing kit interms of equipment; by design they would perform differently. .......

Same material, same weight, same wheels, different performance. Due to what, exactly? Half a degree on the seat tube angle?

It will be the sum of the parts Colin. The seat tube may only be half a degree but there are other differences that in my opinion will add up and influence the riding experience. These include the head angle, chain stays, wheelbase, head tube length-height and potential bike fit, these also differ. Regarding the longer higher head tube that not only effects the bike fit but how the bike handles. I referenced hypothetical weight as the touring version will weigh more. Yes weight is a consideration, but I wanted to highlight that the geometry will also influence how the bike performs.

Colin you mentioned up thread "..the biggest differences between an "audax" bike and a "touring" bike isn't the frame tubes. Things like carbon forks, lightweight wheels and cycle parts, and light tyres make much more difference". A valid point and just how much more is much more of course; but I would not dismiss the significance that geometry can have on the overall set up.

In my opinion the performance difference is enough that I would encourage someone to ride both so they can conclude for themselves just how much difference there is. For many a touring bike and audax bike are so similar they are the same, I repeat it's always down to the individuals perception. Personally I do notice the difference between and audax and touring frame geometry. The audax frame feels far quicker, more lively and responsive, unloaded it's a wolf in sheep's clothing and responds to me feeble efforts. Many may say they don't care about speed, but from me it is about making it easier as much as it is about going faster; that equates to an extra mile more than and an extra mph; or simply that I get home less tired.

[PH]

For many a touring bike and audax bike are so similar they are the same, I repeat it's always down to the individuals perception.

My two steelies are a Hewitt Cheviot SE Tourer which is Reynolds 725 and a SOMA SE Audax (or Sports Tourer in USA speak) which is Tange Prestige.
My perception is not that they're the same, but that if built up similar there would be too little difference between them to warrant having both.
The names, Audax, Tourer, Road, Gravel, Expedition... are useful handles to act as a starting point, but they're no more than that. I did my longest, toughest Audax to date (Last years National 400) on my flat barred, hub geared hybrid. It's my lowest geared most comfortable bike and I decided those were the things I wanted most for that ride, it was the right decision. Yet the growing trend in Audax is for lighter carbon frames with narrower tyres and a move away from mudguards as standard. Obviously different people have different criteria even on the same ride, they may also have a different objective, one of the joys of Audax is it's such a mix.
The original question "was it heavier" might be better asked "does it matter" though the chances of a definitive answer are just as unlikely. I can pass an extraordinary amount if time on such conversations on the internet and when the likes of Colin, Brucey and Paul get involved it's a pleasure to learn from their expertise. But it's nothing compared to a good ride and my experience is that doesn't have much to do with what bike.