Relative weights of Spa touring and Audax bikes with and without discs

General cycling advice ( NOT technical ! )
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531colin
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Re: Relative weights of Spa touring and Audax bikes with and without discs

Postby 531colin » 29 Mar 2019, 10:06pm

geocycle wrote:I'm prepared to accept that disc brakes are more effective in many if not all situations. But for me V brakes have been excellent on my Thorn. I'm less convinced about the cantis on my Spa audax although tweaking has improved them and they are now good enough.

With hindsight I could have paid more for a disc model and taken the 400-500g weight hit (according to Spa) to get better braking but....


Audax has always been dual-pivot sidepulls.
Tourer has mounts for cantis/vee brakes.

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Re: Relative weights of Spa touring and Audax bikes with and without discs

Postby 531colin » 29 Mar 2019, 10:24pm

531colin wrote:
horizon wrote:The great attraction to me of the Aubisque is that it does have a steel fork! And tyre clearance means it is a practical proposition. I might even be persuaded to overcome my reluctance to discs (I don't want them for practical reasons not because of the weight or fork issue). Maybe an Aubisque with cantis for now and discs later?

531colin: would you care to hazard a guess at total carrying capacity?


Cross-posted with my rather long post.
I don't think the weight-carrying capacity would vary much between Tourer and Aubisque, unless my recollection is at fault.
If you want to tell me what size you would look at, i can look up tube sizes....chainstay length should be on Spa website?..........


Horizon, I'm just re-posting this, in case you missed it.
But....(sorry if I'm mis-remembering all this).....isn't it you who rides with a VK adapter (also known as a heavy great lump of metal) to get your saddle far enough back, and then has difficulty getting your drop bars close enough?

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531colin
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Re: Relative weights of Spa touring and Audax bikes with and without discs

Postby 531colin » 29 Mar 2019, 10:36pm

fastpedaller wrote:
531colin wrote: all the Spa steel bikes are 725 main tubes and Cromo forks and stays, and this is mainly because I think the advantages in having the factory work with what they are used to outweighs any advantage from having a more exotic material. (for example, in the newer designs, the chainstay is bent to "thread the needle" between the chainwheel and tyre, flattening the stays is not necessary.)


I thought 725 was a chrom moly tubing - am I incorrect? Are you making the distinction between 725 being butted and the forks and stays being plain gauge?
As an aside (I undestand this may be top secret though :wink: ) are the steel forks also made in Taiwan?
I am very impressed with my Spa Tourer BTW - I can't see how it could be improved :D


Sorry, just being lazy.
Forks and stays are Far Eastern made tubing. Main tubes are Reynolds 725......"Famous brand" cachet. Forks made in Taiwan.

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Re: Relative weights of Spa touring and Audax bikes with and without discs

Postby fastpedaller » 29 Mar 2019, 11:03pm

531colin wrote:
fastpedaller wrote:
531colin wrote: all the Spa steel bikes are 725 main tubes and Cromo forks and stays, and this is mainly because I think the advantages in having the factory work with what they are used to outweighs any advantage from having a more exotic material. (for example, in the newer designs, the chainstay is bent to "thread the needle" between the chainwheel and tyre, flattening the stays is not necessary.)


I thought 725 was a chrom moly tubing - am I incorrect? Are you making the distinction between 725 being butted and the forks and stays being plain gauge?
As an aside (I undestand this may be top secret though :wink: ) are the steel forks also made in Taiwan?
I am very impressed with my Spa Tourer BTW - I can't see how it could be improved :D


Sorry, just being lazy.
Forks and stays are Far Eastern made tubing. Main tubes are Reynolds 725......"Famous brand" cachet. Forks made in Taiwan.


Thanks - that's interesting to know. I have to say I'm impressed with the quality which is far better than 70's/80's mass produced frames made in uk. Sad but true that we lost our manufacturing way.

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Re: Relative weights of Spa touring and Audax bikes with and without discs

Postby horizon » 30 Mar 2019, 1:31am

531colin wrote:If you want to tell me what size you would look at, i can look up tube sizes....chainstay length should be on Spa website?..........

Horizon, I'm just re-posting this, in case you missed it.
But....(sorry if I'm mis-remembering all this).....isn't it you who rides with a VK adapter (also known as a heavy great lump of metal) to get your saddle far enough back, and then has difficulty getting your drop bars close enough?


It would be a 54. And yes, that's me. On a 72.5 seat tube I still use a VK but the saddle is pushed forward (a 72 might just do the trick). This is a supremely comfortable position: Brooks saddle, bum where I want it (i.e. not overhanging the back of the saddle), cleats spot on. And then the bars ... Actually a short stem and I'm fine but when I get round to replacing my Club Tour (it's an L size) it should be about right. I'm putting it all down to a long femur relative to height and a fairly rigid back. Mind you the bar comfort changes during a long ride from fine to "I wish the bars were just a bit nearer".
Let's just get Brexit done so that we can get on with the important job of re-joining the EU!

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Re: Relative weights of Spa touring and Audax bikes with and without discs

Postby 531colin » 31 Mar 2019, 5:57pm

horizon wrote:
531colin wrote:If you want to tell me what size you would look at, i can look up tube sizes....chainstay length should be on Spa website?..........

Horizon, I'm just re-posting this, in case you missed it.
But....(sorry if I'm mis-remembering all this).....isn't it you who rides with a VK adapter (also known as a heavy great lump of metal) to get your saddle far enough back, and then has difficulty getting your drop bars close enough?


It would be a 54. And yes, that's me. On a 72.5 seat tube I still use a VK but the saddle is pushed forward (a 72 might just do the trick). This is a supremely comfortable position: Brooks saddle, bum where I want it (i.e. not overhanging the back of the saddle), cleats spot on. And then the bars ... Actually a short stem and I'm fine but when I get round to replacing my Club Tour (it's an L size) it should be about right. I'm putting it all down to a long femur relative to height and a fairly rigid back. Mind you the bar comfort changes during a long ride from fine to "I wish the bars were just a bit nearer".


It must be good for me to review lots of my old decisions at once....its been quite interesting.
At size 54, all of the (steel) bikes have 28.6 top tube and 31.8 down tube (seat tube is common throughout)
all of the (steel) bikes have 22.2 x 0.9 chainstays, tapered/ovalised.
The Tourer and the disc braked bikes have 16 x 0.9 seatstays; the rim braked audax bikes have 16 x 0.7 seatstays....all tapered.
In other words, Aubisque frame will be just as stiff as Tourer, in the 54 size....in fact, Aubisque will be stiffer, as some tubes are ovalised.
And, I keep saying this, very little difference in the construction, and therefore weight of any of the frames....More difference in weight of the parts than the frames. In the big sizes, bikes designed with loaded touring in mind will have bigger top and down tubes than (say) the rim braked Audax bikes.

now for the interesting stuff.
54 aubisque chainstays are 435mm, 54 Tourer are 20mm longer, more chance of heel strike with Aubisque,
Aubisque front centre 605, ETT 565 (Effective Top tube)
Tourer front centre 625, ETT 577
But, Aubisque seat tube is half a degree steeper than Tourer, which equates very roughly to 5mm on the top tube;
SO....Tourer has 20mm longer front centre, but only about 7mm longer ETT....where has 13mm gone?
Answer; 9mm is fork offset, the rest is head angle.
Now to Horizon's fit.
I'm not sure about the long femur bit....KOPS is I think a useful rule of thumb for getting a fair proportion of people "about right" in terms of how much weight they put on the bars. '
I'm 71 years old and counting; I can promise you that as you get older you want less weight on the bars (ie saddle further back) and your stiff back doesn't get any more flexible. I'm assuming Horizon is younger than me, because most people are....but even if that's not the case, I think its daft buying a new bike or frame that's right on the limit of adjustment, right now....because whats comfortable will change. So, if we accept that your present riding position is "as comfortable as you can get it" I think you are shopping for a made to measure. Seat tube angle of 71 degrees will get your seatpost roughly 15mm further back than it is now.(10mm per degree) That should put you in the position where you actually don't have the saddle all the way back, and give a bit of wiggle room for the future. I don't know if Thorn still think their steering geometry is "state secret" material, but its quite easy to measure.
Measure front centre, reverse the forks and measure again. Fork offset is half the difference, as close as we need.
You can get an app for a smartphone to measure angles, it should be accurate enough if you apply some sensible control measures, like standing the bike on a level surface, measuring stuff at leas two different ways, checking the seat tube angle also.
The furthest I have gone is 60mm offset and 70.5 degree head, you can do a "back of envelope" calculation to see how much reach that could save you compared to the Thorn. (60 and 70.5 gives perfect stable tourer steering...if you need more off the reach, I would be happy to use 65mm and 70 degrees)
Then its just a case of looking at your favourite front centre dimension (is toe overlap a big issue for you?) and seeing if you can get ETT short enough.
(For example, if the Thorn is 54mm offset and 71 degrees, then 60 offset and 70.5 degrees gains you roughly 10mm)

A couple of asides...what seatpost are you using? long layback posts are not on every street corner!
If you move the cleats back so your feet come forward on the pedals, can you then move the saddle forward?
When you "wish the bars were closer" whats happening? Stiff neck/sore hands???,

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Re: Relative weights of Spa touring and Audax bikes with and without discs

Postby Samuel D » 31 Mar 2019, 6:28pm

While we’re on tubing, do the 54 cm and 58 cm Spa Audax rim-braked models use the same tubing?

I ask because I just got a 58 cm and it weighs around 250 g more than my 54 cm, which is slightly more than I expected … but I hadn’t given much thought to weight differences across frame sizes.

Spa added a 60 cm Audax of unspecified geometry to the range a while ago, and I wondered if maybe that coincided with a tubing change of some sort in the 58 cm.

I haven’t built up the 58 cm yet and am curious to see if it feels any different from the 54 cm that I know so well.

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Re: Relative weights of Spa touring and Audax bikes with and without discs

Postby geocycle » 31 Mar 2019, 6:44pm

Just back from fantastic ride on my Spa audax, thanks Colin! The brakes just about held me on the descent int Dentdale from Kingsdale, they are of course side pull not cantis as I mentioned by mistake above. Just wanted to say what a great ride this is.

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Re: Relative weights of Spa touring and Audax bikes with and without discs

Postby 531colin » 2 Apr 2019, 11:22am

geocycle wrote:Just back from fantastic ride on my Spa audax, thanks Colin! The brakes just about held me on the descent int Dentdale from Kingsdale, they are of course side pull not cantis as I mentioned by mistake above. Just wanted to say what a great ride this is.

Thats a proper descent, that is. Its OK if you know about the gate.....
Did you stop and look at the waterfall?

I think somebody was asking why we don't have tourers with disc rear brake and rim front brake so we can have a flexible, comfortable fork. The answer is that its the front brake that stops you...on a descent like that one into Dentdale your weight is forwards, and its quite easy to lock the rear wheel with a rim brake. Despite the fact that most people I ride with have rim brakes, I have seen people overheat their disc brakes three times in the dales....two occasions the brake wouldn't come "off" until it cooled down, the other occasion the disc went a nice straw colour. That's solos, not tandems, and we weren't camping. They don't dump enough heat to be used as a "drag" brake all the way down a long hill.

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Re: Relative weights of Spa touring and Audax bikes with and without discs

Postby 531colin » 2 Apr 2019, 11:29am

Samuel D wrote:While we’re on tubing, do the 54 cm and 58 cm Spa Audax rim-braked models use the same tubing?

I ask because I just got a 58 cm and it weighs around 250 g more than my 54 cm, which is slightly more than I expected … but I hadn’t given much thought to weight differences across frame sizes.

Spa added a 60 cm Audax of unspecified geometry to the range a while ago, and I wondered if maybe that coincided with a tubing change of some sort in the 58 cm.

I haven’t built up the 58 cm yet and am curious to see if it feels any different from the 54 cm that I know so well.


Yeah, same tubing, even the same diameter top and down tubes.
Depending how the butted lengths work out vs. the tube lengths, you might end up having all the extra tube lengths in thicker wall.
Head tube is the thickest, and always plain gauge.

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Re: Relative weights of Spa touring and Audax bikes with and without discs

Postby PH » 2 Apr 2019, 11:50am

531colin wrote:I think somebody was asking why we don't have tourers with disc rear brake and rim front brake so we can have a flexible, comfortable fork. The answer is that its the front brake that stops you...

It's an option that Thorn have been pushing. After years of deriding discs they've had to partially give in to market forces. I went for it on a Mercury Rohloff frame, I'd have preferred V's on both wheels, but that wasn't an option and the frame is otherwise excellent. Having since tried the same bike with a disc fork and the same 32mm tyre any difference is too subtle for me. I made the choice partly because I already had a Grizzly and SON front wheel and I preferred the cleaner look of the V fork. Braking wise, the rear disc makes no difference though it still has the advantage of eliminating rim wear.

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Re: Relative weights of Spa touring and Audax bikes with and without discs

Postby geocycle » 2 Apr 2019, 12:04pm

531colin wrote:
geocycle wrote:Just back from fantastic ride on my Spa audax, thanks Colin! The brakes just about held me on the descent int Dentdale from Kingsdale, they are of course side pull not cantis as I mentioned by mistake above. Just wanted to say what a great ride this is.

Thats a proper descent, that is. Its OK if you know about the gate.....
Did you stop and look at the waterfall?



Terrifying descent and what a daft place to put a gate! I stopped about 6 inches from it..... The audax was wonderful through Barbondale on the way home, much more shallow graded of course and the bike just hugged the road.

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Re: Relative weights of Spa touring and Audax bikes with and without discs

Postby Sweep » 2 Apr 2019, 1:41pm

PH wrote:
531colin wrote: I'd have preferred V's on both wheels, but that wasn't an option .

Clearly Thorn aren't going to be relinquishing their reputation for dogmatism any time soon :)
Sweep

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Re: Relative weights of Spa touring and Audax bikes with and without discs

Postby Sweep » 2 Apr 2019, 1:44pm

geocycle wrote:
531colin wrote:
Terrifying descent and what a daft place to put a gate! I stopped about 6 inches from it.....

Maybe the same devil who interfaced one with the lancashire cycleway between downham and barnoldswick. I know someone who came across a rider flat on the floor in front of that one.
Sweep

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Re: Relative weights of Spa touring and Audax bikes with and without discs

Postby horizon » 2 Apr 2019, 1:47pm

531colin wrote:
Now to Horizon's fit.
I'm not sure about the long femur bit.


Sale details on ebay for 54 cm Spa tourer
Medium Size. I'm 5ft 10 with inside leg 31 inches and is shown set up for those dimensions. Could suit someone a little taller or smaller. 54cm frame.


I'm 5ft 10 with inside leg 34 inches so you can see the problem. I mention the femur because I'm guessing that a long leg would simply involve raising the saddle but a long femur involves moving the saddle back, a trickier proposition with the obvious effect on handlebar position.
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