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2181
Joined
7/25/2009
Location
Somewhere in, NJ, USA
Edited Date/Time
10/23/2014 10:26pm
I have been looking around for some good info on using titanium on an MX bike, but found little extensive info that was thorough enough to appropriately inform before laying out a lot of cash to reduce a little weight. Most people buy a few smaller bolts to sprinkle on their bikes because of the cost, but that doesnt really do much and I think few consider how the different properties of titanium may affect their ride.
The purpose of this thread is to stimulate discussion among those with first hand experience using titanium axles, pivots, and such, and to share some of what I learned talking to a few titanium bolt manufacturers.
MXA had a good article on "the evils of unsprung weight" that suggested that unsprung weight was the best place to use titanium because of the effects of unsprung weight and because some of the biggest bolts are the axles and linkage bolts which is a more efficient way to buy titanium than lots of little bolts. MXA did say they had reservations about using titanium front axles because they felt they could feel them flex more than steel.
One titanium supplier that works with the factory teams told me that while one factory rider would be fine with titanium swing arm pivots and linkage bolts, others did not like the feel as they claimed they can feel greater flex than steel.
While titanium is a very hard metal, it has a lower "modulus of elastcity than steel (see stats below), meaning it is more suseptible to flex. I did not know this and it can be a consideration for where you use titanium. While Titanium has twice the modulus of elasticity of aluminum alloy, it has only about half that as steel alloys.
Here is my current thoughts on the use of titanium on MX bikes;
-the single most cost effective bolt on an MX bike that will have the biggest positive impact is the rear axle. I found few cons to using the titanium here. It is about $450+ for a top grade titanium rear axle and nut, but will provide more benefit than $1500 worth of small itanium bolts.
-the other cost effective bolts, if you really want to lose meaningful weight, include the front axle, swing arm pivot. and linkage bolts, but there are some potential concerns about greater flex with titanium in these areas
-aluminum is lighter than titanium and of course much cheaper and is a better consideration for low stress parts such as radiator shrouds, number plates, fenders and attaching any other plastic.
-it is not very cost effective to bother replacing the small steel bolts with titanium.. a lot of money only gets you extremely minor weight reduction and may not offset the cons of titanium; greater propensity for galling of threads and fusing itself to the metal it is inserted into. Taking the bolts out and reapplying a moly paste or antiseize every few races may not be worth it for the minor weight saved. I heard some team were using the stock steel nuts with the itanium bolts to reduce this issue.
-weight reduction will have the biggest impact for the unsprung parts of the bike (at both ends) and higher up on the bike. However, yoiu have to consider the tradeoffs beyond weight. Replacing smaller bolts in the middle or lower part of the bike is the biggest waste of time and money and unlikely to result in a net benefit.
mike
~~~~~~~~~~~~~~~~~~~~
Strength of TI
135,000 psi ( 930 Mpa) Ultimate Strength
115,000 psi ( 790 Mpa) Yield Strength
About 10 - 15% stronger than Cr-Mo steel
And three times as strong as 6061 Al - T6
Density of TI
0.162 lbs/in_ (4.48 gm/cm_)
45% lighter than steel and 65% heavier than aluminum
Strength to Weight Ratio of TI
Based on Yield Strength divided by Density
74% higher than 6061 - T6 Aluminum
102% higher than 4130 Cr-Mo steel
(the most common form of steel used in bike frames)
Elastic Modulus of TI
15.0 x 106 psi (10.3 x 104 Mpa)
50% higher than aluminum alloys and
50% lower than steel alloys
The purpose of this thread is to stimulate discussion among those with first hand experience using titanium axles, pivots, and such, and to share some of what I learned talking to a few titanium bolt manufacturers.
MXA had a good article on "the evils of unsprung weight" that suggested that unsprung weight was the best place to use titanium because of the effects of unsprung weight and because some of the biggest bolts are the axles and linkage bolts which is a more efficient way to buy titanium than lots of little bolts. MXA did say they had reservations about using titanium front axles because they felt they could feel them flex more than steel.
One titanium supplier that works with the factory teams told me that while one factory rider would be fine with titanium swing arm pivots and linkage bolts, others did not like the feel as they claimed they can feel greater flex than steel.
While titanium is a very hard metal, it has a lower "modulus of elastcity than steel (see stats below), meaning it is more suseptible to flex. I did not know this and it can be a consideration for where you use titanium. While Titanium has twice the modulus of elasticity of aluminum alloy, it has only about half that as steel alloys.
Here is my current thoughts on the use of titanium on MX bikes;
-the single most cost effective bolt on an MX bike that will have the biggest positive impact is the rear axle. I found few cons to using the titanium here. It is about $450+ for a top grade titanium rear axle and nut, but will provide more benefit than $1500 worth of small itanium bolts.
-the other cost effective bolts, if you really want to lose meaningful weight, include the front axle, swing arm pivot. and linkage bolts, but there are some potential concerns about greater flex with titanium in these areas
-aluminum is lighter than titanium and of course much cheaper and is a better consideration for low stress parts such as radiator shrouds, number plates, fenders and attaching any other plastic.
-it is not very cost effective to bother replacing the small steel bolts with titanium.. a lot of money only gets you extremely minor weight reduction and may not offset the cons of titanium; greater propensity for galling of threads and fusing itself to the metal it is inserted into. Taking the bolts out and reapplying a moly paste or antiseize every few races may not be worth it for the minor weight saved. I heard some team were using the stock steel nuts with the itanium bolts to reduce this issue.
-weight reduction will have the biggest impact for the unsprung parts of the bike (at both ends) and higher up on the bike. However, yoiu have to consider the tradeoffs beyond weight. Replacing smaller bolts in the middle or lower part of the bike is the biggest waste of time and money and unlikely to result in a net benefit.
mike
~~~~~~~~~~~~~~~~~~~~
Strength of TI
135,000 psi ( 930 Mpa) Ultimate Strength
115,000 psi ( 790 Mpa) Yield Strength
About 10 - 15% stronger than Cr-Mo steel
And three times as strong as 6061 Al - T6
Density of TI
0.162 lbs/in_ (4.48 gm/cm_)
45% lighter than steel and 65% heavier than aluminum
Strength to Weight Ratio of TI
Based on Yield Strength divided by Density
74% higher than 6061 - T6 Aluminum
102% higher than 4130 Cr-Mo steel
(the most common form of steel used in bike frames)
Elastic Modulus of TI
15.0 x 106 psi (10.3 x 104 Mpa)
50% higher than aluminum alloys and
50% lower than steel alloys
I have titanium axles in my xr50. While I'm not putting anywhere near the forces on it as the pros will a big bike, I have not noticed any drawbacks of it. I always use ti lube, so I haven't experienced galling yet.
Will DLC on ti reduce galling?
The Shop
DeCal Works Huge Plastic Inventory of UFO and Polisport kits.
Luxon 4-Post Bar Mounts
$189.95 - $239.95
Another option is !Think Technology's seat foam, once again for price vs weight savings this is a pretty decent option.
As for the linkage bolts, axles, and swingarm bolt, quality is a big thing. I've seen certain teams that can't run their supplier's version of these because of flex and bending.
Back then, Yamaha through their GYT-R program offered ti kits for most areas of the bike. Axles, swingarm pivots, suspension kits, plastic kits, engine cover kits. Got them all and then went in search of misc. other bits of Ti. GYT-R Ti subframe, mag upper triple clamp, bar mounts and mag hubs. Topar Racing made the lower mag clamp. DSP was making all kinds of ti and carbon components and anything that I felt would reduce weight was added, no sprocket, caliper or frame guards. Also, no skid plates. Their carbon airbox, motor mounts, full ti exhaust and ti foot pegs knocked off major weight. Ti shock spring from Renton and alloy shock collar kit from Enzo. Factory R&D had a few trick bits. Trick Components of Canada made me a titanium brake rotor and a set of Pirelli sand tires wrapped up the wheels.
Knocked off twenty or more pounds in all and the most expensive, least productive area was the ti hardware. The $85.00 wet sump conversion took off more weight than a couple thousand dollars worth of titanium bolts and nuts. The $640.00 DSP Ti exhaust took off more weight than all the ti hardware too. Right choice of tires??? same thing. Most impressive though was with all of the weight removed up high made the bike feel a lot less top heavy and less of a pig.
Then of course, the engine scattered in grand fashion....lol.
I looked up the definition of "modulus of elasticity" and it is defined as the mathematical description of an object or substance's tendency to be deformed elastically (i.e., non-permanently) when a force is applied to it. It goes on to say that a material whose modulus is very high is rigid. However, "rigidity" should not be confused with;
-rigidity and strength: the strength of material is characterized by its yield strength and / or its tensile strength;
-rigidity and stiffness: the beam stiffness (for example) depends on its modulus but also on the ratio of its section at its length. The rigidity characterises the materials, the stiffness regards products and constructions: a massive mechanical plastic part can be much stiffer than a steel spring;
-rigidity and hardness: the hardness of a material defines its relative resistance that its surface opposes to the penetration of a harder body
So it seems a material can be harder than steel but less rigid (flexier).
One of the reasons I started this thread was to see if anyone has personally felt the flex from a titanium front axle or swing arm pivot.
Best bang for the buck for me was think seat (1.5 lbs less) for 250 dollars, akro Ti exhaust on clearance for 800 (4.9 lbs less), raptor pegs (.9 lbs less) at 325 bucks, and an RCS Ti spring (1.5 lbs less) for 460, and even one full pound with Xtrigs for 750 dollars. As someone mentioned before, Pirelli tires will save some weight where you feel it, and the Ti disk and sprocket bolts are good too. Alum sprocket and non oring a great clues too. The Ti hardware is cool, and more durable to rounding, but it all added up to maybe 4 lbs, at a cost of around 3k. This is on a new rmz btw.
The exhaust systems seem to be a great way to save weight and in a good place. I was always a bit confused by FMFs significant weight claims for their titanium muffler vs. their aluminum and carbon fiber muffler. They claim a much lighter weight for the titanium piece even though the thickness of the metal on both looks the same. I would think the aluminum and carbon fiber would be much lighter than the titanium.. or maybe it is just marketing.
Pit Row
The stock CRF muffler (only) weighs 6.5 pounds.
A steel Powerbomb header weighs 2.0 pounds, while the titanium version weighs 1.7 pounds. a difference of .3 pounds.
A steel Megabomb header weighs 2.4 pounds, while the titanium version weighs 1.8 pounds. A difference of .6 pounds.
If you had a Megabomb header with a CF capped muffer, the weights would be would be 7.1 pounds for steel/ aluminium vs 5.7 pounds for the titanium unit. That is a difference of 1.4 pounds total.for the FMF units and probably a whole lot more over the stock unit. For their titanium Powerbomb system the difference is 1.5 pounds and at least a 2.8 pound savings over the stock unit. A much better weight reduction deal than the titanium bolts.
Fact of the matter is, the pros don't "need" titanium either. On any given weekend, there are plenty of ti laden bikes getting their asses handed to them by non ti equipped bikes/riders.
Looked at Ti parts and decided I did not need those...LOL
The muffler + header = total system weights are given below;
Stock 2012 CRF450 steel: 6.5 lbs + 2.39 lbs = 8.89 lbs
Yoshimura RS-4 Carbon & Titanium: 5.48 lbs + 1.28 lbs = 6.76 lbs
FMF RCT 4.1 Titanium: 3.9 lbs + 1.8 lbs = 5.7 lbs (Power bomb titanium header is .1 lbs lighter)
FMF RCT 4.1 Mega bomb Steel and Aluminum; 4.64 lbs + 2.4 lbs = 7.04 lbs (Power bomb steel header is .4 lbs lighter)
i wasn't pleased when I put on the Yosh titanium and carbon fiber exhaust system and only saved about .25 bpounds over the steel FMF system. I even said something to Yoshimura.... They need to use titanium for their inserts and inner structure to get down to a reasonable weight. I felt how heavy the Yoshimura muffler was immediately when taking it out of the box. The FMF titanium system would have been more than a pound ligher than the Yoshimura.
Ti looks so f..ing wicked.
I dont understand how titanium "looks wicled" either. A titanium bolt is hardly noticable.. the silver just has a tiny bit different sheen. I have titanium all over the bike now and I dont notice much difference in looks. It is probably the most money I have wasted on a bike ever,
you only go around once.if everything else is taken care of.buy what you like. i promise i wont go any faster but my next fun purchase will be a fmf exhaust . must have that blue can
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