Why Titanium Full-Susser?

[RodTi]

Hello all,

 

The below is a purely hypothetical question, well - at least until the boat comes in - but I've been wondering about this for a while...

 

I'm lucky enough to ride a Ti hardtail - but have always been under the impression, gleaned from many website reports as well - that whereas Ti is infinitely suited as a material for hardtails, due to its intrinsic flex and lightweight qualities, that this very characteristic was unsuitable for full-suspension bikes...

 

The theory being that you specifically don't want flex in a full-susser, what with all the bearings and pivot points built in to the design in the first place - and instead rather want a non-flexible material that allows the full-susser frame design to do all the work of soaking up the trail noise...

 

Which kind of makes sense...

 

And yet - many of the major Titanium producers (On-One; Van Nicholas aside??) have full susser options - Moots; Merlin; Litespeed; Titus; Dean all, for example, have a full-susser option...

 

So I'd be real keen to hear what the local opinion is on Ti being used on a full-susser - is it feasible - or rather, do the advantages offered on a Ti hardtail also apply to a full-susser design?

 

Any thoughts?

 

 

 

 

RodTi2009-11-10 05:30:51

[Johan Bornman]

Most of the properties given to Titanium by the marketing department is nonsense.

 

Firstly, titanium has half the atomic weight of steel and double the atomic weight of aluminium. In other words, it is not as light as they will have you believe.

 

Secondly, it has half the tensile strength of steel and double that of aluminium, which puts it sort of halfway between steel and alu. However, an alu frame can be made stronger and lighter because the alu tubes can be drawn thinner than Ti ones. Ti doesn't like to be "worked". It gets hard as it is machined/bent/welded and also cracks easily if the heat treatment after welding isn't perfect.

 

Now as for the frame and flex. Those same companies will tell you that the frame is "Stiff yet compliant." This is like saying the priest is Holy yet Satanistic. In reality, metal frames dont' bend in the vertical plane and they all flex about equally in the lateral plane.

 

The little bit that it bends contributes nothing to comfort or any of the other qualities claimed in the brochure.

 

The truth is that a full suspension frame has an incredible amount of machined parts and making those in titanium will be very, very expensive and about double the weight of an aluminium frame of equal strength.

 

Titanium is OK for plain frames (even though they crack like drivers on an N1 commute) where the weight penalty is not that great. But the minute the parts get complex, the bulk and weight shoots up relative to that of an equivalent alu part and the bike becomes too heavy for the current fashion trend.

 

In my view, Titanium is wholly unsuitable and inappropriate for any bike frame. It comes with a heavy carbon footprint and offers no advantage over other metals.

 

 

 

[Slowbee]

can someone please explain flex in a bicycle ?

 

in normal eeeengglleesh pleaze.

 

 

 

[Johan Bornman]

Flex is bending. If you stand on your bike's right side crank and lean the bike over, you'll notice you can bend the bike sideways by pushing the BB over to the left, and vice versa.

 

It can also be seen when you pedal hard in the big blade and it touches the side of the FD with each pedal stroke. That is flex in the seat tube and down tube. Where the bike does not flex much is in the two frame triangles. Triangles are strong and rigid structures. That's why if a frame manufacturer tells you it has made the seatstays from XYZ material in order to provide compliance (flex used as a suspension), they're talking through their noses. It has been claimed by just about every big-name frame company.

 

 

Johan Bornman2009-11-10 10:47:01

[EigerSA]

I'll have a bash at explaining this...

 

Basically when you pedal away on your bike, a number of forces act on the frame. The two biggest are on the power stroke, the first being the physical push of the pedal, and the second being the act of pulling on the handlebar. Now we know from Newtons laws that there must always be equal and opposite reactions taking place, so if you work out how hard you pedal (lets say a value of 10) and how hard you pull (lets say a value of 5) then you need to find a value of 5 elsewhere... and that's the flex in your frame. Flex is also known as deflection, and is basically the measurement of how much out of true you bike moves whilst under stress.

 

What I think is really interesting, is that most people think the frame itself flexes which it does to some tiny degree, but there is more flex on the handlebars and bottom bracket than anywhere else (Bicycling Science, Gordan Wilson). This means that having a lighter and stiffer frame should offer no advantage, and generally couldn't even be felt by the rider!

 

At the end of the day, always remember that terms like "stiffness" and "flex" and "dampening" are usually terms attributed to bikes by marketers who have one goal and one goal only, to market and sell a bike, they are surely not experts! You need some flex in the bike, it makes a ride a bit easier since it helps in dampening vibration as well as adding some "spring" to your pedaling action.

 

This help at all Slowbee?

 

[rock]

titusti on thehub has a ti, full suspension, 29er....thats like a trifecta of bad ideas :-)

 

 

 

to be honest I think all three are great........and yes, am insanely jealous and hope that one when I grow up I'll be big enough to ride a 29er.....

[Procrates]

 

 

 

 

I beg to differ you can clearly feel the diffrence between alu vs ti.?

And JB where do you hear of all the ti's cracking? that must then be the cheap ones that arent welded in a proper argon environment.

[EigerSA]

There was a test run last year where a bunch of riders were handed "un-branded" frames and asked to test them for comfort and quickness and a few other things. All the bikes were set up with the same components. At the end of the test period, there was no consensus between the riders as too which bike was the fastest or the strongest. The only category that had a clear leader was the comfort one, and a steel bike won, with titanium 2nd, then carbon and lastly alu. But at the end of the day the data was judged to have been far too close to be able to say that "this one is better than that one", tire pressure made more difference than frames did. All that could be concluded from the test was that every rider out there had their own ideas as to what constituted a good ride, it was all relative to the strength and experience of the individual riders. I personally would go even further and say that 90% of riders wouldn't be able to tell one frame from another.

 

[RodTi]

Interesting reading...

 

Kind of surprised more people didn't wade in with some thoughts though - since JB appears to be stirring a huge pot!

 

EigerSA - I'm pretty much with you in regards to most people not being able to tell the difference - and I'm most certainly one of them...The last time I rode an alu frame was back at school - and then only after "upgrading" from steel ---- since my return to riding, I've only been on Ti - and so I don't really have anything to compare it to...

 

But then again - I guess frame choice is similar to beer choice - die hard fans of a particular brand almost always get it wrong in a blind tasting...

[GoLefty!!]

Ti Looks pretty so it makes a great road bike.

 

A Ti fullsusser is like gold mags on a taxi; Oppulence for the sake of it.

 

In fact, the stiffer the frame of a full susser, the better it is. Aluminium is still the best frame material

[Gumpole]

 

I'll have a bash at explaining this...

 

Basically when you pedal away on your bike' date=' a number of forces act on the frame. The two biggest are on the power stroke, the first being the physical push of the pedal, and the second being the act of pulling on the handlebar. Now we know from Newtons laws that there must always be equal and opposite reactions taking place, so if you work out how hard you pedal (lets say a value of 10) and how hard you pull (lets say a value of 5) then you need to find a value of 5 elsewhere... and that's the flex in your frame. Flex is also known as deflection, and is basically the measurement of how much out of true you bike moves whilst under stress.

 

 

[/quote']

 

Not really relevant, but the difference between the '5' force and the '10' force in your example makes the bike sway from one side to the other..... or fall over... no ways that the frame is flexing because of this, in fact I'm pretty sure that the forces are almost identical - but somebody more technical can explain.

 

On the original topic, have never ridden a Ti frame

 

[splat]

There was a test run last year where a bunch of riders were handed "un-branded" frames and asked to test them for comfort and quickness and a few other things. All the bikes were set up with the same components. At the end of the test period' date=' there was no consensus between the riders as too which bike was the fastest or the strongest. The only category that had a clear leader was the comfort one, and a steel bike won, with titanium 2nd, then carbon and lastly alu. But at the end of the day the data was judged to have been far too close to be able to say that "this one is better than that one", tire pressure made more difference than frames did. All that could be concluded from the test was that every rider out there had their own ideas as to what constituted a good ride, it was all relative to the strength and experience of the individual riders. I personally would go even further and say that 90% of riders wouldn't be able to tell one frame from another.
[/quote']

 

And that's where the marketing departments step in.

[linnega]

I would suggest that any frame from any material could be built to be as stiff (and to feel as stiff) as any other frame of a different material.  Primarily the geometry of the bike would determine how stiff it felt.  The primary differentiators in the materials is how light the bike can be built and what it will cost.  Ti is neither light nor cheap, but has a certain aura about it.  Like the difference between diamonds and diamante - there is little to choose between them but the man with deep pockets or a guilty conscience will always go with the diamonds.  Steel is heavy and needs to be very thing to be competitive in the lightness stakes.  It is also more expensive than Alu.  Carbon can be built lightest of all without compromise, but this comes at a cost.  Alu is effectively the second lightest material, but costs significantly less and is very easy to work with.  So I agree with Lefty - alu wins.  As for a ti full-susser, it will be expensive and to make its ride comparable to aluminium, it will need to be helluva expensive.  Perhaps compare the Giant alu range to the Titus range to see that.  I would suggest that there isn't much to choose between the two from a performance perspective, but no doubt I will get flamed for saying so.

[Dirtbreath]

Had the opportunity of getting off my Yeti asr straight onto a Yeti asr carbon. The sensation was one of a much stiffer ride. The bike felt extremely responsive and very different to mine which has similar if not exact geometry.

 

Was this purely a placebo of getting on a bike that is pure bling or attributable to frame material/geometry. The carbon also has an integrated seat post. Could this make a difference?

 

[RodTi]

Would love to be able to find the picture of the Ti bike a spotted a while back on mtbr.com...

 

Some niche mtb manufacturer in the States... the name of the company starts with a "C" - they've designed a hardtail Ti frame, with the seat tube and seat stay area designed in such a way that they 'meet/join' very close above the bb - the saddle was planted on a ridiculously long titanium seatpost - stretching all the way down to the post, and in this way introducing "flex" into the ride, and (allegedly) offering the qualities of a soft-tail...

 

Will do some googling....

 

 

 

[Johan Bornman]

 

 

I beg to differ you can clearly feel the diffrence between alu vs ti. 

And JB where do you hear of all the ti's cracking? that must then be the cheap ones that arent welded in a proper argon environment.

 

 

Like Hannibal Lecter said when Clarise visited him in his cell.  "Personally, I can't." Some of us have better senses than others.

 

Cracking Ti. Pro Rata, more titanium frames fail from cracking after incorrect heat treatment than aluminium frames. Especially in the highly heat-stressed zones such as the BB. These cracking frames come through in batches. Replacement after replacement of the same frame type crack, indicating batch problems. I'm talking fancy pantsy brands here.

 

Argon welding is cheap enough for even the poorest ti framebuilder to afford. And, the "environment" you talk about is merely a secondary nozzle on the torch that blows Argon and floods the work area.  It is easy to create and monitor the presence of oxygen as you weld.