Go Back  Bike Forums > Bike Forums > Framebuilders
Reload this Page >

Distinguishing Aluminum from Titanium?

Notices
Framebuilders Thinking about a custom frame? Lugged vs Fillet Brazed. Different Frame materials? Newvex or Pacenti Lugs? why get a custom Road, Mountain, or Track Frame? Got a question about framebuilding? Lets discuss framebuilding at it's finest.

Distinguishing Aluminum from Titanium?

Old 03-19-21, 01:13 PM
  #1  
pstock
Senior Member
Thread Starter
 
Join Date: May 2008
Location: Toronto, Canada
Posts: 873

Bikes: (shortlist) Cyclops, Marinoni, Mariposa, Air Firday, Pocket Rocket Pro, NWT, SLX Fuso, Claude Pottie (France) x3, Masi Team 3v, Lemond Zurich, Bianchi OS

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 152 Post(s)
Liked 32 Times in 25 Posts
Distinguishing Aluminum from Titanium?

this cannot be a new question, but I have searched the archives and haven't immediate found anything related.

given that frame stickers can be had cheaply that say anything you want (and so you can slap an SLX or Titanium sticker on anything), how could you tell if a painted (paint preventing you from easily tell the color of the material) frame - assumiing it's not one of the top Titanium brands - is Aluminum or Titanium?

weight doesn't seem to be an obvious differentiator - I see an aluminum Colnago is listed as 1308g vs a L LItespeed at 1344g, almost the same.

Last edited by pstock; 03-19-21 at 01:18 PM.
pstock is offline  
Old 03-19-21, 01:31 PM
  #2  
ridelikeaturtle
Senior Member
 
ridelikeaturtle's Avatar
 
Join Date: Nov 2015
Location: Dublin, Ireland
Posts: 1,259

Bikes: Bianchi Ti Megatube; Colnago Competition; Planet-X EC-130E; Klein Pulse; Amp Research B4; Litespeed Catalyst; Trek Y11

Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 596 Post(s)
Liked 476 Times in 258 Posts
The welds on aluminum will be bigger/more evident; also the tubes on aluminum will be much fatter than titanium.
ridelikeaturtle is offline  
Likes For ridelikeaturtle:
Old 03-19-21, 01:33 PM
  #3  
Moe Zhoost
Half way there
 
Moe Zhoost's Avatar
 
Join Date: Sep 2015
Location: North Carolina
Posts: 2,955

Bikes: Many, and the list changes frequently

Mentioned: 5 Post(s)
Tagged: 0 Thread(s)
Quoted: 985 Post(s)
Liked 879 Times in 526 Posts
Tough question. Perhaps verify the serial number with the manufacturer to determine model. Another way is to look for oxidation around areas where the paint may have been scraped. Al may show white blooms while Ti will not. Bottom bracket or rear dropouts perhaps.

Polishing raw alum will turn a light cloth black so you could pull the bottom bracket and rub some polish around the shell lip, which may have been machined (or possibly the shell threads). Of course, you'd have to clean all the gunk before you did this

The definitive non-destructive way would be to have it tested by X-Ray Fluorescence. XRF analyzers are expensive so you won't want to run out and buy one. Best bet is to look for engineering lab companies in your area if you want to go that route.
Moe Zhoost is offline  
Old 03-19-21, 01:36 PM
  #4  
ridelikeaturtle
Senior Member
 
ridelikeaturtle's Avatar
 
Join Date: Nov 2015
Location: Dublin, Ireland
Posts: 1,259

Bikes: Bianchi Ti Megatube; Colnago Competition; Planet-X EC-130E; Klein Pulse; Amp Research B4; Litespeed Catalyst; Trek Y11

Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 596 Post(s)
Liked 476 Times in 258 Posts
Also, but maybe this is just the difference between my Bianchi titanium and Klein aluminum mtb, but if you flick the titanium with your fingernail, it makes a "ping" sound, whereas the aluminum is a "plink" sound.
ridelikeaturtle is offline  
Old 03-19-21, 01:38 PM
  #5  
ridelikeaturtle
Senior Member
 
ridelikeaturtle's Avatar
 
Join Date: Nov 2015
Location: Dublin, Ireland
Posts: 1,259

Bikes: Bianchi Ti Megatube; Colnago Competition; Planet-X EC-130E; Klein Pulse; Amp Research B4; Litespeed Catalyst; Trek Y11

Mentioned: 8 Post(s)
Tagged: 0 Thread(s)
Quoted: 596 Post(s)
Liked 476 Times in 258 Posts
Titanium is also very springy. If you could take the rear wheel out and try to flex the rear triangle, aluminum would be very stiff, while titanium would move quite a bit (and spring back). Again, the aluminum chainstays and seatstays would have a bit beefier tubing as well.
ridelikeaturtle is offline  
Old 03-19-21, 01:39 PM
  #6  
Andrew R Stewart 
Senior Member
 
Andrew R Stewart's Avatar
 
Join Date: Feb 2012
Location: Rochester, NY
Posts: 18,003

Bikes: Stewart S&S coupled sport tourer, Stewart Sunday light, Stewart Commuting, Stewart Touring, Co Motion Tandem, Stewart 3-Spd, Stewart Track, Fuji Finest, Mongoose Tomac ATB, GT Bravado ATB, JCP Folder, Stewart 650B ATB

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4172 Post(s)
Liked 3,793 Times in 2,272 Posts
+1 for ridelikeaturtle. Al welds are generally about 3-4 times wider then that of TIs. Ti's welds are around the same size as steel's (at least TiG'ed steel) but steel is magnetic so that difference is easy to discern. Andy
__________________
AndrewRStewart
Andrew R Stewart is offline  
Likes For Andrew R Stewart:
Old 03-19-21, 02:57 PM
  #7  
bulgie 
blahblahblah chrome moly
 
bulgie's Avatar
 
Join Date: Apr 2009
Location: Seattle
Posts: 1,980
Mentioned: 92 Post(s)
Tagged: 0 Thread(s)
Quoted: 1163 Post(s)
Liked 2,542 Times in 1,065 Posts
Originally Posted by ridelikeaturtle
Titanium is also very springy. If you could take the rear wheel out and try to flex the rear triangle, aluminum would be very stiff, while titanium would move quite a bit (and spring back). Again, the aluminum chainstays and seatstays would have a bit beefier tubing as well.
This is often (usually?) not true. When Damon Rinard did his frame stiffness testing, a Cannondale 2.8 showed one of the most flexible rears of all (over 60 frames tested).

The problem is alu needs to be oversized to have decent stiffness, because it's about half the inherent stiffness (Young's Modulus) of Ti. But chainstays are constrained by chainring and tire clearance, so alu will almost always lose to an optimized chainstay in Ti.

Many early Ti frames had undersized chainstays, due to the lack of commercially-available tapered tubing, so they went with a 3/4" tube that was too big at the dropout and too small at the bottom bracket. Stiffness at the BB is almost all that matters in a test like Rinard, or in the ride feel. The tiny 3/4" chainstays is the reason for any Ti frames in the Rinard list that showed a flexy rear. At least with undersized chainstays you get the advantage of better tire/chainring clearance. No such advantage on a Cannondale.

Ti chainstays should be a bit larger than steel, due to Ti having a lower modulus than steel. Not as oversized as Al, but around 1" is good in Ti, vs 7/8" on classic steel. (Now of course there is also OS steel, a bad idea IMHO.) Back when Rinard did his testing I think there were zero commercially-available Ti frames with 1" chainstays. Maybe on the custom Merlin track frame made for professional sprinter Ken Carpenter — which I happen to know he didn't race on, because it was too flexy for him. I know this because I made the steel frame that he kept on riding when he was sponsored by Merlin. They made him a second frame (supposedly "twice as stiff") after his review of the first one was unprintable, but even the second was called "an abortion" by Ken. They painted my frame to look like Ti, and put Merlin decals on it! But I digress... Sorry I know steel is off-topic for this discussion.

Anyway, most any welder can tell at a glance whether a frame is Ti or Al, so maybe that's the way to tell — bring it to a welder or bike frame builder. The ability to tell by looking can't be taught over the internet unfortunately.

Mark Bulgier
Irony Cycles
bulgie is offline  
Likes For bulgie:
Old 03-19-21, 07:15 PM
  #8  
unterhausen
Randomhead
 
Join Date: Aug 2008
Location: Happy Valley, Pennsylvania
Posts: 24,364
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked 3,664 Times in 2,497 Posts
Take a grinder to it and see what color the sparks are.

But really, the welds. You can usually tell from the inside of the bb shell as well.

I would be surprised if there were any frames where there is much confusion.
unterhausen is offline  
Likes For unterhausen:
Old 03-20-21, 08:19 AM
  #9  
pstock
Senior Member
Thread Starter
 
Join Date: May 2008
Location: Toronto, Canada
Posts: 873

Bikes: (shortlist) Cyclops, Marinoni, Mariposa, Air Firday, Pocket Rocket Pro, NWT, SLX Fuso, Claude Pottie (France) x3, Masi Team 3v, Lemond Zurich, Bianchi OS

Mentioned: 2 Post(s)
Tagged: 0 Thread(s)
Quoted: 152 Post(s)
Liked 32 Times in 25 Posts
I agree that in most cases titanium is obvious.
but take the example of this Aquila bike. Aquila is the private label brand of a local bike shop here and they imported and labelled everything over the years.
they have a Lot of aluminum bikes out in the world too.
would you think this one (attached) was Aluminum or Titanium?

but turn the situation around. imagine someone not very familiar with bikes were selling a bike with what they assumed was an aluminum frame (maybe having tested with a magnet). and you were buying and supected it was titanium. that is a situation where it would be handy to be able to tell the difference between the two.

pstock is offline  
Likes For pstock:
Old 03-20-21, 09:37 AM
  #10  
unterhausen
Randomhead
 
Join Date: Aug 2008
Location: Happy Valley, Pennsylvania
Posts: 24,364
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked 3,664 Times in 2,497 Posts
I think the most difficult frames to tell would be if they had cosmetic welds like a Cannondale and some Ti builders that were ground, post-weld.
unterhausen is offline  
Old 03-20-21, 10:58 AM
  #11  
guy153
Senior Member
 
Join Date: Dec 2019
Posts: 950
Mentioned: 3 Post(s)
Tagged: 0 Thread(s)
Quoted: 321 Post(s)
Liked 261 Times in 212 Posts
Originally Posted by pstock
I agree that in most cases titanium is obvious.
but take the example of this Aquila bike. Aquila is the private label brand of a local bike shop here and they imported and labelled everything over the years.
they have a Lot of aluminum bikes out in the world too.
would you think this one (attached) was Aluminum or Titanium?

but turn the situation around. imagine someone not very familiar with bikes were selling a bike with what they assumed was an aluminum frame (maybe having tested with a magnet). and you were buying and supected it was titanium. that is a situation where it would be handy to be able to tell the difference between the two.

I'm going to go with aluminium for that one. But it does look like the welds on the main triangle have been cleaned up so it's not so obvious.
guy153 is offline  
Old 03-20-21, 02:09 PM
  #12  
unterhausen
Randomhead
 
Join Date: Aug 2008
Location: Happy Valley, Pennsylvania
Posts: 24,364
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked 3,664 Times in 2,497 Posts
Definitely looks like aluminum welds to me, although as guy153 says, they are smaller than normal for aluminum. I think the shape of the welds says aluminum too. Even production Ti bikes I have seen have a concave shape to the welds.

The thing that really gives it away is the shaped headtube. Very few production builders are going to the expense of such a headtube on a Ti bike
unterhausen is offline  
Likes For unterhausen:
Old 05-29-21, 09:17 PM
  #13  
jccaclimber
Senior Member
 
Join Date: May 2005
Location: SFBay
Posts: 2,334

Bikes: n, I would like n+1

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 127 Post(s)
Likes: 0
Liked 133 Times in 108 Posts
1. I'm assuming this is mainly academic because there are accessible non-painted surfaces on most frames even without paint chips. The inside of the seat tube is an easy one to get to, but the insides of any threaded surfaces such as the BB or derailer hanger are others.
2. I'm leaning aluminum on the pictured bike above for the reasons already stated.
3. You could probably figure it out by how fast an ice cube makes a given section farther away cold, but you would need an aluminum or ti bike to compare to.
4. If you can't tell by sight and ride, does it matter?
jccaclimber is offline  
Old 05-29-21, 11:15 PM
  #14  
unterhausen
Randomhead
 
Join Date: Aug 2008
Location: Happy Valley, Pennsylvania
Posts: 24,364
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 4 Post(s)
Liked 3,664 Times in 2,497 Posts
I'm going to assume he figured it out back in March
unterhausen is offline  
Old 05-30-21, 02:43 AM
  #15  
jccaclimber
Senior Member
 
Join Date: May 2005
Location: SFBay
Posts: 2,334

Bikes: n, I would like n+1

Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 127 Post(s)
Likes: 0
Liked 133 Times in 108 Posts
Sorry, that’s what I get for wandering into a different section of the forum at the end of the week and not looking at dates. I am curious what the answer is though.
jccaclimber is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.