In praise of titanium - and Spa Cycles

[ianrauk]

What?

Indeed.

 

[Globalti]

I've always thought there was a good B.Sc engineering thesis in the way different materials transmit vibration. Identical pieces of steel, aluminium, carbon and titanium and different alloys of those metals could be clamped rigidly and their vibration characteristics measured, much in the same way as when you boinged a ruler on the desk at school. Not sure if any useful information could be gleaned from this test but it would certainly show up some differences.

 

[winjim]

Coupled with knowing which frequencies people tend to find more fatiguing, that could be very relevant here.

I find A flat to be particularly fatiguing.

 

[ianrauk]

titanium picks up on titanium and if this happens you have a big problem, I have had titanium collars pick up on titanium shafts on several occasions, the trick for both Aluminium & Ti is cleanliness & the right anti scuffing paste, I only use carbon posts in my Ti frames.

I have Ti frame, collar and seatpost. All I have used is a bit of Coppaslip and all is fine. As you quite correctly state, cleanliness is the trick. Once a month I take the seatpost out and give it a good clean including a wipe inside the seat tube. Nearly three years down the line and no problems.

 

[Fab Foodie]

utter bollox. You obviously do not actually ride bikes..Alu bikes are very rigid and unforgiving, Steel frames flex and spring, carbon - I can't comment on as I don't have experience as a rider.

The statements in bold are of course very sweeping generalisations .... and are not without substance, BUT.
My Aluminium TCR was very sweet riding when the headset worked .... which it rarely did well. My pals Aluminium Bianchi Pantani replica is smooth as silk and nicely bouncy over rough stuff. My Nivachrome Omega roadie and my 531 MTB tubing Saracen Evans even with fat tyres will take your fillings out. The Planet X Ti that I consisdered before the Rourke also had a reputation for having a stiff and harsh ride. So I wouldn't be quite so vehement about the charactersitics of different materials, it's a bit more complicated than that.
My 531 Holdsworth and 853 Rourke ride just lovely though and will outlast me :-)

 

[Dogtrousers]

Spa have been very good to me, both pre- and post- sales. Not just for my bike either - they've given me good advice by email on component purchase in the past too.

I don't know anything about metallurgy but one of the many bikes I test rode at Spa was Ti. I liked it but went for steel on price and (possibly unfounded) fear of welds cracking.

 

[mythste]

@Yellow Saddle - Without derailing the thread too much, if what you're saying is true and comprehensive (which I have no grounds to disagree with) Then what is it that makes some bikes feel so inherently different from others? Am I to believe that given all materials have zero flex vertically and will make no difference to ride "dampening" (or give it a name, as appropriate") that 2 bikes with similar gemoetries and the same wheels/contacts points but different materials will feel the same?

 

[ACS]

I have a Spa Ti Audax and compared to my commuter (09 Tricross) it's like riding a cloud. The frame has a 10 year warranty and so long a Spa continue trading I think its just about covered.

I have competed about 2500 audax miles on it and still think my purchase was correct even when I consider the discussions above.

I have nothing but good things to say about Spa and their services levels.

 

[John the Monkey]

They can be superb. I ordered rims and spokes from them. A few days later I got a phone call asking what the hub was because the numbers didn't fit anything they used. I explained what it was, he checked and agreed it was OK.

I still treasure Mickle's description of the place;

The shop is something of a legend. I've known about them for years but only recently had the opportunity to drop in. I was somewhat taken aback by the appearance - the window display appears not to have been changed in years, full of old crap. Old crap which had a thick layer of dust on it.

You walk in to an area which looks like someones front room has been turned into a messy bike shop. Which is what it is. Greeted by a beardy man you wander through into an area which looks like a kitchen - complete with sink and dining room table at which someone, another beardyman, sits lacing a wheel. I didn't visit the upstairs, but I'll wager they look like bedrooms whcih someone has filled with cycle clothing. It wouldn't have surprised me to find a member of staff having a kip.

The back garden has bikes lined up on the lawn - new bikes mind, for sale. Andthe sheds and outhouses contain more bikes, many hanging from meat-hooks from the ceiling. Nice bikes though.

F*** Evans, this is what a real bike shop should look like.
(From the Spa Cycles? thread, 2011)

Frame materials - eh. I have an aluminium bike (Giant SCR2) that I find very comfy. It's comfiest with Michelin Pro Race, or 25c Krylion Carbons. I have a steel tourer that's also very comfy, rolling on 42c tyres (Continental Comfort Contact for preference).

I reckon that if you like the way a bike rides, it is a good bike, so long as bits don't spontaneously fall off it, disintegrate or break under the use you intend.

 

[Yellow Saddle]

why would you go stronger but heavier - surely if the material is stronger you use less of it

Yes and no. Firstly, titanium is not stronger than steel, only half as strong. Also half the weight in steel. But that's not the real issue here.
The issue is how thin you can draw the tubing. Already, steel tubing is drawn to approximately 0.6mm (the Reynolds historians can help me out here). Tubing this thin, even when butted (made thicker at the ends) pose problems with welding, attaching fixtures such as water bottle cages etc. The drawing process also cannot proportionally thin out a material according to its strength to just any arbritary figure. There is a practical limit. I'll use an extreme example of some super-strength steel that's drawn so thin that you can squash the down-tube with your hand like a beer can.
Although ti can be hydro-formed like aluminium, it is very expensive and difficult to do it, leaving us with limited shapes, tapers and butting. Hydroforming is a process where a piece of tube is put inside a mould and literally inflated by pumping liquid into it under pressure until it has stretched and conformed to the mould. Modern aluminium bicycles display nice examples of this technique where a slip top tube flares out to mate nicely against a fat head tube for a smooth, organic look. This is not only about looks but also about getting the weld interface just right. If you look at old Cannondales from the 1990s, you'll notice that they managed to get the fat downtube right but where I meets the slim head tube (which was just a straight piece of pipe), they had to do a lot of fillet welding to get it reasonable. Compare that to today's joints where both pieces are hydroformed.
This restricts titanium to relatively small tubes and a distinctive style. part of the style is then a mismatched carbon fork. Ti forks of the right strength are heavy - as heavy as steel forks. Of course there is nothing wrong with the style but it is kinda retro and has an effect on sales.
I quite like the look of a nice titanium weld. The bead is much, much better than alu weld beads and has that distinctive look. Do most people see it? I doubt it. Can most people distinguish between brushed ti and brushed alu? I doubt it.
Titanium is a niche material for frames chosen purely for its aesthetics and cognoscenti appeal. Therefore I say it is an inappropriate material. We could also craft beautiful bicycles from wood and just because the Spruce Goose was made entirely from wood and it could withstand the famous G-forces quoted by the aggressive man above, it doesn't mean we should.

 

[Profpointy]

umm, what does half as strong but half the weight mean in practice - same strength for a given weight? So why aren't aircraft made of steel rather than ti? I realise "strenght" is a somewhat vague term in engineering, but I think the point is fine for our purposes

The difficult to work, and only available in certain sizes points are perfectly valid

 

[Yellow Saddle]

Here's a thought; the way a material absorbs or transmits vibration will also have an impact on how rough or smooth a ride is perceived. Different materials will transmit or absorb shock and vibration differently even if as asserted that a double diamond frame doesn't flex in the vertical plane (and that assumes that the vibration is always applied in the vertical plane).
The other area I think affects ride feel is the interaction between frame and fork - the materials used, the contact area, the solidity if the contact, the angles involved, the compliance of the system and how vibration is propagated from through frame.

I'm not convinced that (carbon apart) that different metals for frames do not feel different ...

This vibration issue is one raised relatively often. Engineers are very concerned with vibration since it is a very destructive force. They measure it and understand how to work around it. I have not yet seen anyone do a vibration analysis on similar frames built from different materials but I bet the minute I hit enter someone will find one on google.
Anyway, until that happens I'll give you a little thought experiment on the vibration issue.
You have ffive tubes of equal dimension and equal mass. Say 30mm dia and 900mm long.
Tube one is a steel pipe.
Tube two is a carbon pipe
Tube three is an alu pipe
Tube four is a wooden pipe
Tube fie is a titanium pipe

You have some sort of vibration machine handy - something that really creates a buzz of sorts. You place the tube's one end on the machine and you place your chin on the free end. You switch the machine on and feel the vibration in your jaw.

Do you really think you will feel any sort of difference amongst the various materials? If you say yes, you have to explain where the compliance takes place in the system.

 

[Profpointy]

This vibration issue is one raised relatively often. Engineers are very concerned with vibration since it is a very destructive force. They measure it and understand how to work around it. I have not yet seen anyone do a vibration analysis on similar frames built from different materials but I bet the minute I hit enter someone will find one on google.
Anyway, until that happens I'll give you a little thought experiment on the vibration issue.
You have ffive tubes of equal dimension and equal mass. Say 30mm dia and 900mm long.
Tube one is a steel pipe.
Tube two is a carbon pipe
Tube three is an alu pipe
Tube four is a wooden pipe
Tube fie is a titanium pipe

You have some sort of vibration machine handy - something that really creates a buzz of sorts. You place the tube's one end on the machine and you place your chin on the free end. You switch the machine on and feel the vibration in your jaw.

Do you really think you will feel any sort of difference amongst the various materials? If you say yes, you have to explain where the compliance takes place in the system.

not saying it'll change the answer (not my field) but shouldn't the tubes be same strength rather than same mass?

 

[Cyclist33]

This vibration issue is one raised relatively often. Engineers are very concerned with vibration since it is a very destructive force. They measure it and understand how to work around it. I have not yet seen anyone do a vibration analysis on similar frames built from different materials but I bet the minute I hit enter someone will find one on google.
Anyway, until that happens I'll give you a little thought experiment on the vibration issue.
You have ffive tubes of equal dimension and equal mass. Say 30mm dia and 900mm long.
Tube one is a steel pipe.
Tube two is a carbon pipe
Tube three is an alu pipe
Tube four is a wooden pipe
Tube fie is a titanium pipe

You have some sort of vibration machine handy - something that really creates a buzz of sorts. You place the tube's one end on the machine and you place your chin on the free end. You switch the machine on and feel the vibration in your jaw.

Do you really think you will feel any sort of difference amongst the various materials? If you say yes, you have to explain where the compliance takes place in the system.

Interesting image!

I've got no idea what the answer would be and I'm not about to build the test in real life, but presumably if there *was* a difference felt then the compliance in the system, or rather the variability of it, would be found in the pipes because the pulsator and the chin would be unchanged?

 

[Cyclist33]

With different densities, how can they have both equal dimension and equal mass?

If they had different wall thicknesses maybe?