Are titanium things lighter and stronger? Or weaker?

Discuss light weight issues concerning road bikes & parts.
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Geodroid
Posts: 21
Joined: Wed Jul 03, 2019 3:59 pm

by Geodroid

Thought of getting titanium skewers, but people say its too dangerous. Also titanium bolts for my stem, would that make it more dangerous or will it be lighter and hold my stem better and safer than alloy bolts?

by Weenie


whyamihere
Posts: 55
Joined: Tue Aug 05, 2008 7:18 pm

by whyamihere

Ti will be heavier and stronger than aluminium, but lighter and less strong than steel. I certainly wouldn't use aluminium for stem bolts. I'm ok with using ti bolts, but I check them regularly.

XCProMD
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Location: Cantabria

by XCProMD

Ti has roughly half the young modulus of steel whereas aluminium’s is a third, but then Al is a third of steel’s density.

Ti fatigue strength to UTS ratio is comparable to steel’s, no welds involved of course, with similar Wöhler curves. Al is no match in that regard.

So it’s more complicated than any bicycle company will tell you.


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XCProMD
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by XCProMD

Then the above is very simplistic as “Ti” means the usual structural Tu alloys and the same goes for steel and Al.


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Alexbn921
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Joined: Wed Apr 10, 2019 6:39 pm

by Alexbn921

Geodroid wrote:
Sun Jul 21, 2019 5:33 pm
Thought of getting titanium skewers, but people say its too dangerous. Also titanium bolts for my stem, would that make it more dangerous or will it be lighter and hold my stem better and safer than alloy bolts?
Titanium is strong enough for stems and lots of other bolts on the bike.
It has too much flex for QR skewers. It's half as strong as steel and has more elongation. You will feel the flex and lack of compression. Not dangerous, but not ideal, especially for big or strong riders.

AJS914
Posts: 3579
Joined: Tue Jan 28, 2014 6:52 pm

by AJS914

I wouldn't mess with stem bolts to save 5 grams. Do you know that you would be getting the highest grade aerospace grade replacement bolts or some ti bolts off ebay made wherever? It's not worth the risk or bother IMO.

I've had fine luck with ti skewers. The problem with many light skewers is the rest of the skewer lever and plastic washers/cams. Get a Ti skewer with a quality mechanism. I like Zipp aero ti skwers. They use a brass cam. No plastic.
Last edited by AJS914 on Sun Jul 21, 2019 8:13 pm, edited 1 time in total.

biwa
Posts: 153
Joined: Fri Sep 21, 2018 8:39 pm

by biwa

Ti bolts yes if from quality sources, Ti skewers no esp. with external cam design

JerryLook
Posts: 293
Joined: Thu Dec 07, 2017 2:18 am

by JerryLook

I’ve used Ti skewers for about 2 years now without any issues. And a lot of people on this forum use Ti skewers without any issues.
I haven’t heard of any cases of them failing, but I’m sure it’s happened before.
My last pair wore out the little concave washer, but the skewers are still fine. And I’m 85kg, and remove my wheels about once a week for cleaning.

Also lots of guys change out their stem bolts for Ti. Like mentioned above, just make sure you get the bolts from a good source.
2010 Orbea Opal 54cm
5.97kg

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pdlpsher1
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Location: CO

by pdlpsher1

I’m using Mavic QRs with Ti shafts with no issues. It’s the only QR with an external cam and a Ti shaft that I’m aware of. They are some 80+ grams a pair. Lighter than Dura Ace or Campy QRs.


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RocketRacing
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Joined: Thu May 10, 2018 2:43 am

by RocketRacing

Geodroid wrote:
Sun Jul 21, 2019 5:33 pm
Thought of getting titanium skewers, but people say its too dangerous. Also titanium bolts for my stem, would that make it more dangerous or will it be lighter and hold my stem better and safer than alloy bolts?
There is a marginal gains podcast on materials that covers some of this.

Weight (for a set volume of material): steel>titanium>aluminum

Strength: steel>titanium>aluminum.

Aluminum is about 1/3rd the density of steel, but also 1/3rd the strength. Where aluminum gets an upper had is by using larger thinner tube profiles to get the same strength as steel. (Carbon does the ssme... thus the start of chunkier, but lighter frames).

The problem comes when you have parts of a fixed size. Steel will always be the strongest. Aluminum the softest. So for a given size, a steel skewer or bolt will be strongest, aluminum softest.

The trick is sorting out what parts can get away with softer/lighter parts. Titanium works for skewers, bolts etc. Aluminum bolts i would only use for expander caps (tighten with steel bolt, use aluminum as placeholder), and bottle cage bolts. Sram used aluminum bolts in their etap hood clamps... and they have a bad rep.

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C36
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by C36

When talking about material you have to consider 2 things:
- the material mechanical properties: in cycling mostly strength, stiffness, density
- then the shapes: thickness, diameters...

On the mech properties you can have performance ratios. Stiffness to weight or strength to weight. The formulas to calculate those ratios depends of the constraints (traction, flexion , torsion, the formula is different).

Now where does Ti sits? It’s Strength to weight is better for all the pieces that have a defined shape, then is a good option for screws (a 5mm screw... has to be 5mm).
In terms of stiffness to weight, in pure traction (qr axle for example) Ti, steel, aluminium are surprisingly equals. In other words, if a QR-axle is lighter... it’s will be softer / stretch more, the material won’t compensate for weight loss. Now when it’s too much? for the came activated QR, the 40s g versions are probably too soft and will generate less clamping force.

Now for aluminium, in the screw example you can’t compensate the lower absolute strength by more material, then screw strength is really limited and not acceptable for most of the applications with stress (stem, shifter clamp). Some larger « screws » are big enough to use aluminium (cranks for example).


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Juanmoretime
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by Juanmoretime

I’ve been using titanium fasteners for decades and the only time I broke some on a stem was in a bad mtb crash. Otherwise no issues, Always use anti-seize and a torque wrench. Treat them with love and they will love you. Same for titanium skewers. Never had one fail.
RESIDENT GRUMPY OLD MAN.

alanyu
Posts: 132
Joined: Thu Jun 06, 2019 1:10 pm

by alanyu

My personal experience:
Al bolts on bottle cages, DA9100 chainring bolts (origin ones), DA9100 RD H&L (origin ones);
Ti bolts on stem, EE brakes, left crank, seat rail clamp, FD and RD;
Ti QRs;
All without any issues.

by Weenie


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