mikeread

I received delivery of some main frame tubes today direct from Reynolds. Because of past experiences (not with frame tubes) I always like to check things are correct as ordered, so I have given these tubes the once over.

All tubes are labelled correctly and outside dimensions are correct, they are all pretty straight too.

The tubes did seem a bit heavy (though I am no expert and they are all .8 .5 .8 double OS tubes so will be heavier than what I have used before) so I popped them on the scales and did a couple of quick calculations.

My calcs showed that the DT should weigh about 360g - it actually weighs in at 430g I then calculated that a .8mm plain gauge tube would weigh around 450g. I have 2 of these tubes and they weigh the same.

I have de-burred both ends and the tube wall averages just under .8mm at one end and just over .8mm at the other, which seems OK

Is this normal for Reynolds tubing? could they be plain gauge tubes or incorrectly butted? is there any way of measuring butts with simple tools?

Thanks

Mike

unterhausen

I wouldn't want to try to calculate the weight. The fact that the butts are the right dimensions is an indication that they are holding tolerances fairly well.

you should be able to see the butting by looking down the inside. Some people report being able to mark the butt transitions by eye. I never quite figured out how the do that.

A bicycle tube butting gauge is relatively simple to make. Here is a link to one you can buy https://farrframeworks.com/farr-tool...s-butt-checker

Andrew R Stewart 

First thing I would wonder about is whether there's a Reynolds weight published. Next is how the calculated weight accounted for the butt transitions. Third is that some variance from published weights is typical. I've only been weighing tubes seriously for a few frames worth and find a little drift from tube to tube of the same spec to be the norm. But not 60gm (or 15% more or less). Have you contacted the supplier yet? Andy

Edited to add a home made butt checker photo.

mikeread

I haven't said anything to Reynolds yet.

I calculated the theoretical weight using Reynolds quoted butt and transition lengths and Reynolds specified density. The transitions I assumed were a simple bevel and that the average cross section would be half way between the .8 and .5 figures. So I would expect this theoretical figure to be pretty accurate.

It is only reasonable to expect some variation due to machining tolerances but 20% seems excessive and the fact that it is only 9 % off what an un-butted tube would be makes me start wondering if something is wrong.

I am pretty sure of my calcs and I have sort of checked the scales. 1kg bag of rice weighed 1006g and a 500g bag of fusilli weighed 508g. Both including the plastic packaging which probably weigh a few grams.so not far off.

Nessism

To mirror what Andrew stated, if you look on the ID you can see the butts. I'd do that first. Since the OD is correct, and the butt thickness is correct, the only thing that can be wrong is the butt length and/or the center section thickness.

Andrew R Stewart 

I use to determine the butt edges by first cleaning out the tube's ID with a rag and WD40. Then holding the tube up to a light and eyeing along the tube's ID look for the lines of reflection to take a slight jog. This is where the surface angle changes (the butt starts or stops. Using a long thin indicator (spoke) one can insert it into the ID and watch for the end to match up with the reflection's change. Remove indicator and align along the OD to mark that point. Repeat for the other butt changes. This method can work well with a clean tube ID and care. But a gage makes things so much easier.

I have purchased tube that were not what I was tole they were. In that case the seller was a privet hobby builder who had bought a stash from another builder. Turned out what he thought was all Columbus Genius turned out to include a couple of stainless steel tubes. Found out the hard way when trying to fillet the seat tube to the BB shell. Andy

mikeread

I can see something inside the tube in the region the butts would be. It looks like a change in surface finish but is probably a butt.

I have a small milling machine and will see if I can set up a 'quick and dirty butt tester' (I am not going to google that phrase) and measure it accurately. A bar with a rivet in the end clamped on a v block and a DTI in the chuck should do the trick.

unterhausen

I have seen people use a setup like that, should work fine

mikeread

It took all of half an hour today to rig up a butt tester. It is not pretty but I am confident in its rigidity and hence accuracy.
The support bar deflects .03mm with the full weight of a tube on the end but actual error with the tube weight mostly supported by hand is insignificant. The pip on the support bar is turned to a point to prevent 'bridge' error.
I have uploaded a couple of pics, see below, sorry they are a bit big!

I have 3 reynolds 31.7 tubes and 2 x 35mm tubes all are supposed to be .8 .5 .8

The 35mm tubes are most definitely .9 .6 .9 as is one of the 31.7 tubes. The other 31.7 tubes average about .85 .55 .85 but seem to be quite variable. Butt lengths and transition lengths look fine.

These findings explain the greater than expected tube weights.

Andrew R Stewart 

Good job researching a way to discover, then doing it. I like the butt gage. Andy

mikeread

I have built a frame before and the main objective with this frame was to make something a bit stiffer/better handling. I spent a lot of time deciding weather to go double oversize with the new frame to achieve this or use oversize as before, but increase the gauge of the tubes.

If I use these tubes I am effectively doing both and am worried now that the ride will be overly harsh.

Am I justified in sending these back and ordering Columbus tubes instead. Though I am no weight weenie, this will also knock 200 to 300 gramms from the frame weight.

I dont want to be anal about this but neither do I want to build something I am not happy with.

duanedr 

I wouldn't be worried about 0.05mm off of spec - that's less than 0.002" and I have measured >0.020" in bow across some tubes. I suppose a 969 is a ways off from 858 - maybe that's disappointing - but it's better than getting a 747 instead of 858.

There was a posting on another board with a spreadsheet that had calculation for torsional stiffness of various tubes that could be used to assess how much stiffer the thicker walled tubes will be. It won't be perfect but will get a sense.

When the tube is forced through dies and has a mandrel drawn through it, there has to be some variability in the outcome. Just like when a tube is mitered and brazed/welded. It moves. That's what keeps steel real!

Would be interesting to hear what Reynolds says is 'within spec'.

unterhausen

that's a good setup, but I think the inner cone may be contributing to the size difference.

You are not going to be able to feel a small difference in thickness, all the difference in feel comes from the diameter of the tubes. I just scanned an academic article about that yesterday, but I'm not sure where I found it. Don't think of it as being too stiff, think of it as being really solid.

I was regretting making the same choice in tubing size recently, but mostly because the resulting frame is going to be pretty heavy. I'm sure once I have it painted orange, it will be fine. But I'd rather have a bike made out of 1OS Spirit for Lugs. I am really horrible at judging frame stiffness though. Geometry is a different subject, I'm fairly sensitive to that.

mikeread

I did think carefully about the inner cone. If it had a flat 2 mm wide on the end it would give a theoretical error of + 0.03mm on a 30mm ID tube, less on a bigger tube. I machined the cone to a point which should eliminate this error to practically zero.
I thought miss-alignment of the cone and DTI would be a more likely cause of error but this would be negative and pretty darn small.
All tubes were tested along 3 lines at each end and aligned to give the minimum reading at each point.

I tried to be scientific about it and am confident that any errors are small.

Not sure what to do now but will contact Reynolds and see what they say.

Nessism

Framebuilders Supply has actual weight data for a bunch of different Columbus tubing. https://framebuildersupply.com/collections/frame-tubes

mikeread

Thanks Nessism I have seen those figures and assumed (steel being steel) that equivalent Reynolds tubes would be very similar (allowing for butt and tube length differences) That is what prompted my investigations.

Of course the Columbus figures could be wildly inaccurate too :-)

unterhausen

Does Reynolds list dimensional tolerances anywhere? I assume the bulk of their sales go to people that really don't want the thickness to be too small, so they probably aim for tubes that are a little thicker than nominal.

But I totally missed the 9/6/9 tubes, maybe I need to measure my tubes that seem so heavy. Columbus always impressed me as having better control over their dimensions than Reynolds back in the '70s, but that isn't the same Reynolds as exists today. It is, however, the same Columbus.

A telescoping hole gauge isn't expensive, it's probably a better measurement tool for the ends.

mikeread

I cannot find any tolerance figures anywhere but have asked reynolds directly if they have anything they can send me.

Cannot see why they would send out over thick tubes when they go to the trouble of offering a choice of gauges. More likely they had no stock and assumed an amateur numpty like me would never notice a thicker tube, let alone build a butt tester and check

Nessism

If you compare the published Columbus weight specs against actual, the actual is almost always heavier. Not to the extent of those Reynolds tubes though. Maybe Reynold's tooling is getting old and they are not trying very hard to tune everything during the drawing process? Seems plausible to me anyway.

As an aside, I bought some Reynolds seat stays about 5 years back or so and another set recently and the new ones were about an oz heavier each piece. I was surprised...and not in the good way.

Another aside, I lived in the Cleveland area for a while where Joe Bringheli resides, and he let me weigh some of his Dedacciai tubing stock as I looked for some light pieces. There is this nifty down tube they make where it's 31.75 at the head tube end and 35mm at the bottom bracket, and there was more than 30 grams difference between samples.

unterhausen

9/6/9 vs 8/5/8 sounds like a substitution, "always good enough for Raleigh." Even in my wildest dreams i wouldn't think so poorly of them.

Do they do any of their own fabrication nowadays?

mikeread

I assume you mean Raleigh? I cannot remember when I last came across a Raleigh bike being ridden or on display in a shop. I did pop into a vintage cycle tent at a show recently and they had a Chopper.

If they do make anything at all it will be shipped in from the far east.

I did a spreadsheet earlier to calculate tube weights (not much on today) If I substitute 969 for 858 it comes out to within a few grams of measured weight. So it looks like a substitution to me

858 TT calculated 333g 969 TT calculated 383g 858 TT Measured 378g

858 DT Calculated 367g 969 DT Calculated 422g 858 DT Measured 430g

unterhausen

no, I meant does Reynolds make tubes or just market them?

Nessism

They draw the tubing to final configuration. Not sure what sort of raw materials they start from though.

mikeread

I haven't a clue

Andrew R Stewart 

In my understanding Nova is a marketing company. In that they have neither the smelting plants or the drawing mills. Reynolds (and Columbus, Tange, True Temper{now gone** and I think Kaisei) are companies that both process/draw the smelter provided bar into tubing and then market, usually through a intermediary, the tubes.

Another way to look at this question is that every bike brand that has "their own" tube set is also only a marketing company. (Excepting the very few who do make their own carbon matts, tow and tube) Andy