Tubing diameters

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fatboy
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Tubing diameters

Post by fatboy »

As part of my mid-life crisis I've booked myself on a frame building course (Bicycles by Design) and now I'm thinking details and I've got thinking about tube diameters. I'm looking to build an Audax style bike (28mm tyres, mudguards, saddlebag only, I've got touring bikes for more weight carrying adventures) and would like it to be traditional (the frame will be lugged), but I'm not sure how traditional!

I haven't riden a good traditional tubed framed bike (I had 70s BSOs but that doesn't really help) and have oversized 725 framed bikes. I guess what I'm interested in is what is different between an oversized frame and a traditional and why the thinnet tubes became obsolete? Any thoughts welcome
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slowster
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Re: Tubing diameters

Post by slowster »

Larger diameter tubing is stiffer, which is potentially a good thing for race bikes, for touring bikes used for cycle camping with heavy loads, and also for tall people needing very large frames. Narrower tubes went out of fashion because manufacturers standardised on oversize tubing for all types of bikes and all types and sizes of customers, and most people who would have benefited from narrower tubes had little or no choice but to have oversize tubing and/or were not aware of the pros and cons.

My advice:

1. The benchmark brake for 28mm tyres plus mudguards, Shimano's BR-650, is no longer made. A better option would be to specify the frame design for 32mm tyres - or if possible 35mm - with mudguards. The availability of fast 32mm and 35mm tyres, e.g. Conti GP5000 and Schwalbe Marathon Supreme, means it makes sense not to limit tyre choice to 28mm.

The obvious brake choice would then probably be long drop calipers, e.g. Tektro R559 calipers, with the pads at or near the top of the slots. The latter is important both to maximise mechanical advantage and get the best braking, and also to maximise tyre clearance (tyre width clearance in particular is less with pads at the bottom of the slots)*. Cantilevers or centre pulls would be alternative, more costly options, especially if the very nice models made by Rene Herse Cycles or Paul Components are used.

(I assume that it is a given that you are not planning to have disc brakes, which would be completely inappropriate on such a frame.)

(* If you decided to use Tektro R559 calipers, I would suggest buying them and taking them with you to Bicycles by Design, so that they could take measurements to determine precisely what the A-C (axle to crown) measurement needed to be to get the pads at the optimum height, with clearance for a mudguard as well.)

NB The fork crown needs also to be correspondingly wide enough for the tyre width. Be guided by Bicycles By Design: if they suggest a flat crown would be better than a more modern looking sloping crown, I would go with their advice.

2. In combination with the narrow tubes and wider tyres, a 1" threaded headset, quill stem and 26mm clamp bars will maximise the comfort of the front of the bike (as well as look all in proportion). Having your bike fit/set up sorted before getting a custom frame is more important with a traditional horizontal top tube and quill stem than with sloping top tubes and threadless stems. Quill stems give a range of height adjustment, and quill stems with extra long shafts are made by Nitto, but if you want your handlebars level with the saddle, it may be that an extended head tube and/or extended steerer with a spacer under the stem locknut would be better (that sort of attention to detail is part and parcel of good custom frame building).

3. Be guided by Bicycles by Design as regards tubing choice etc. Don't insist on 853 because you think it must be better/you want the bragging rights, if they tell you that for your needs and design you would be better off with 631 or 725 or whatever. They are the experts on the selection of tubing and the design of the frame and its geometry. You will just be the plumber who is going to put it all together.
gxaustin
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Re: Tubing diameters

Post by gxaustin »

I built a frame at BBD using small diameter tubing, to be more old school. I love it and it rides really well. 25" frame. I loved the course and had a great time.
fatboy
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Re: Tubing diameters

Post by fatboy »

Thanks for the really useful info and advice and (assuming they don't advise against) I will go for a traditional frame.

I will discuss brakes in detail and let them lead on material choice (that was already on my list). Also great to hear first hand that a traditional frame built there is good and that the course is good too.
"Marriage is a wonderful invention; but then again so is the bicycle puncture repair kit." - Billy Connolly
Valbrona
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Re: Tubing diameters

Post by Valbrona »

I don't think anyone who runs those courses market them as 'an opportunity to build your ideal frame'. You get a standard kit and a chance to learn basic framebuilding skills.

Oversized frame tubes will of course require a set of oversized lugs.
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fatboy
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Re: Tubing diameters

Post by fatboy »

Valbrona wrote: 16 Oct 2021, 8:21am I don't think anyone who runs those courses market them as 'an opportunity to build your ideal frame'. You get a standard kit and a chance to learn basic framebuilding skills.

Oversized frame tubes will of course require a set of oversized lugs.
Given the conversations and information shared it certainly isn't a standard kit of parts. But obviously there are limitations i.e. must he lugged and lugs can't be very fancy and no stainless steel etc. For me the opportunity to build a classic frame tailored to me is really exciting.
"Marriage is a wonderful invention; but then again so is the bicycle puncture repair kit." - Billy Connolly
peetee
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Re: Tubing diameters

Post by peetee »

I have a range of quality steel framed bikes in both traditional sized tubes and oversized and I am a bit of a frame critic. I ride a 24” frame and even with a modest power output I can tell the difference in frame response between standard main frame tubes of 25.4mm top and 28.6 down tube and oversized 28.6mm top and 31.8 down tube. The latter is far more responsive when riding out of the saddle. I cannot say if that frame design is more efficient, but it certainly feels so.
The best riding frame I have ever owned was a 531 Pro. A very thin-walled tubing and probably not a good choice for a 24” frame but wonderfully compliant and more comfortable over rough surfaces than anything else I have ridden. I would have expected it to feel dreadfully bandy on a tough hill climb, but not so. That accolade went to a Holdsworth Elan in standard gauge 531.
The older I get the more I’m inclined to act my shoe size, not my age.
Jdsk
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Re: Tubing diameters

Post by Jdsk »

slowster wrote: 15 Oct 2021, 10:17pm3. Be guided by Bicycles by Design as regards tubing choice etc. Don't insist on 853 because you think it must be better/you want the bragging rights, if they tell you that for your needs and design you would be better off with 631 or 725 or whatever. They are the experts on the selection of tubing and the design of the frame and its geometry. You will just be the plumber who is going to put it all together.
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531colin
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Re: Tubing diameters

Post by 531colin »

Some interesting websites to whet your appetite........

"Torch and file" is an American outfit listing tools and supplies for framebuilding. They have a complete list of Reynolds tubes sizes etc, but just now I couldn't find anything as clear as the list I remember.

"Ceeway" is an English firm supplying lugs, dropouts, tools, and should be an indication of what is commonly available, including reasonably pretty fork crowns with room for sensible size tyres. They still list lugs for inch top tube and inch and eighth seat/down tubes (thats 25.4 and 28.6 for those who insist on using such unwieldy numbers). Those tube diameters still appear on Spa frames, but only at the small end of the size range, because the longer the tube the more it flexes for the same load.....and big frames (may?) have a heavier rider. Somewhere Brucey supplied us with the numbers, ie exactly how much more flex you get for specific increases in length.

As already said, most comfort comes from tyres, but under some circumstances I can notice the difference between 631 fork blades and anything else I have compared them with; the 631 blades taper starts high up, about where the canti. studs are, other blades taper lower down.....the fit at the crown is the same, as is the tip diameter. Big fat seat/chainstays should also be limited to load luggers and disc brakers, in my view.

I don't believe in Jan Heine's "planing", but if somebody says they pedal better with a certain degree of frame flex, then I must believe them. Too stiff a frame is also achievable; some muppet made us some Audax prototypes with silly oversize frame tubes. Comparing with the normal frames, riding them over granite chip surface was like having the soles of your feet beaten with a stick, and thats with the same wheels, 25mm tyres, carbon forks and steel seat/chainstays.

Where's Brucey? I miss his breadth of knowledge and his clarity, particularly as my clarity (such as it ever was) is ebbing. My recollection is that Brucey said you could use full size Vee brakes with NSSLR levers, if you chose the position of the pivot carefully.
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531colin
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Re: Tubing diameters

Post by 531colin »

peetee wrote: 16 Oct 2021, 9:29am ...................
The best riding frame I have ever owned was a 531 Pro. A very thin-walled tubing and probably not a good choice for a 24” frame but wonderfully compliant and more comfortable over rough surfaces than anything else I have ridden. I would have expected it to feel dreadfully bandy on a tough hill climb, but not so. That accolade went to a Holdsworth Elan in standard gauge 531.
I have come across a lot of the "last of the British made" 531 Galaxies over the years. Some of them are dreadfully floppy. As the tube size and type doesn't vary, I have attributed the lack of rigidity to poorly mitred tubes or incomplete brazing.....the mitred tubes should fit closely and be brazed together under the lugs.
slowster
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Re: Tubing diameters

Post by slowster »

531colin wrote: 16 Oct 2021, 1:08pm Some interesting websites to whet your appetite........

"Torch and file" is an American outfit listing tools and supplies for framebuilding. They have a complete list of Reynolds tubes sizes etc, but just now I couldn't find anything as clear as the list I remember.
The 2020 parts list is here - https://www.torchandfile.com/assets/ima ... 20list.pdf, but the information is laid out more clearly in the 2018 list here - http://www.torchandfile.com/assets/imag ... 202018.pdf

PS 531colin, the bike set up link in your signature is not currently working (nor is the link to the document on this Wheel Easy webpage - https://wheel-easy.org.uk/bike-set-up/). I presume it's something which needs to be fixed by whoever manages Wheel Easy's server.
peetee
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Re: Tubing diameters

Post by peetee »

531colin wrote: 16 Oct 2021, 1:15pm
peetee wrote: 16 Oct 2021, 9:29am ...................
The best riding frame I have ever owned was a 531 Pro. A very thin-walled tubing and probably not a good choice for a 24” frame but wonderfully compliant and more comfortable over rough surfaces than anything else I have ridden. I would have expected it to feel dreadfully bandy on a tough hill climb, but not so. That accolade went to a Holdsworth Elan in standard gauge 531.
I have come across a lot of the "last of the British made" 531 Galaxies over the years. Some of them are dreadfully floppy. As the tube size and type doesn't vary, I have attributed the lack of rigidity to poorly mitred tubes or incomplete brazing.....the mitred tubes should fit closely and be brazed together under the lugs.
This certainly echoes my thoughts. The pro frame was craftsman built with cast lugs, the Holdsworth was a production-line job with nasty bulge-formed lugs.
The older I get the more I’m inclined to act my shoe size, not my age.
Jamesh
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Re: Tubing diameters

Post by Jamesh »

I really should build a frame, with Ellis Briggs only a stone's through away it's criminal not too.

Maybe for a big birthday?!!

Problem is what type audax or full touring!

Cheers James
slowster
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Re: Tubing diameters

Post by slowster »

531colin wrote: 16 Oct 2021, 1:08pm under some circumstances I can notice the difference between 631 fork blades and anything else I have compared them with; the 631 blades taper starts high up, about where the canti. studs are, other blades taper lower down.....the fit at the crown is the same, as is the tip diameter.
That probably explains something which has long puzzled me. Dave Yates has stated he considers 853 forks far too harsh, largely based on his experience of building the frames which he rode on some of the very long distance Audax events, and consequently for many years he has typically advised his customers to have plain Reynolds 'R' butted fork blades. I could never understand how that could be the case, since 853, 631 and R blades are all offered in 1.0mm/0.6mm gauge, and it is the thickness and diameter of the tube that determine stiffness, not the particular grade of steel. But if the tapers start at different points in the blades (something which does not appear to be publicised in the Reynolds literature), I can appreciate that might make a very significant difference to how two otherwise identical forks might feel.
fatboy
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Re: Tubing diameters

Post by fatboy »

Ceeway is the company that they seem to use. Additionally I have found an old Reynolds catalogue which gives butt information (unfortunately I have no idea what it means).

Regarding brakes I am fitting dual pivots. I know that it's unfashionable but I hate v brakes (mini and standard), prefer cantis and love dual pivots (I've got them on my current audax and my brompton). Need to choose the best sort.....
"Marriage is a wonderful invention; but then again so is the bicycle puncture repair kit." - Billy Connolly
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