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Old 12-13-11, 01:47 AM   #1
NigelHealy
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Titanium - does it improve or worsen performance - does it improve comfort?

I'm in the process of moving parts between 3 Bromptons, two Titanium and one steel, and figuring do I sell/keep a Titanium-based bike for long day rides. I'm not bothered about weight or rust, but on speed and comfort.

I've read Sheldon's muse that Ti is springier and that on areas like curved forks it will make things a little comfier, and on rigid triangles it has no performance impact, but what's anyone's view on this?

I can make a touring-specification Brompton which is a S6R with SRAM rear hub and Sclumpf Mountain Drive, and make the forks, rear triangle and the seatpost either Steel or Titanium, in fact I can pick Ti/steel for each of these 3 components separately (e.g. Ti forks, steel triangle, steel seatpost). I'll sell what I don't want. I don't need 3 Bromptons, this is a matter of do I sell/keep Ti.

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Old 12-13-11, 02:04 AM   #2
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Ti won't rust
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Old 12-13-11, 02:10 AM   #3
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Ti won't rust
Yes I know that, but to be frank, the value of the rusted part isn't much, up to that point its a strength/rigidity/performance discussion.
If, say, the Brompton steel rear triangle is rusted to the point a scrub and paint isn't enough it costs about 110ukp to replace and instantly remove any hidden damage.
So Titanium's anti-rust features aren't important.

I bought Ti for simply easier to carry the folded bike. So back to my question - what is the impact on comfort and performance?
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Old 12-13-11, 02:33 AM   #4
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I'd do a blindfold test, but I doubt the difference can be felt.

titanium is springy, but when drawn into tubes and welded together, not so much. Especially when the triangles are small and the tubes are oversized.
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Old 12-13-11, 05:00 AM   #5
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Two thoughts:

1) The amount of flex in the rear triangle is minuscule compared to the amount of give in the tyre, and in the case of the Brompton, the rear suspension block. The material of which the rear triangle is made, is immaterial. The fork has more give to it, but it is still small compared to the tyre contribution. So for first line comfort, the tyres dominate completely.

2) The material properties can have an impact on how impacts are transmitted through the frame to the rider; a springy material will have a more pronounced filtering effect compared to a stiffer material. So high frequency portions of road impulses will travel less well through titanium than steel, and this may have the effect of feeling less jarring. It is the high frequencies that cause discomfort. For the short tubes of the Brompton, the effect is probably too small to be detected by the seat of your pants.
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Old 12-13-11, 09:35 AM   #6
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Thanks, my next purchase is some Ergon grips, Velox rim tape, fit same Marathon Plus tyre, and then make my steel B the same front-ends as my Ti frame and then ride and make a performance judgement.
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Old 12-13-11, 09:54 AM   #7
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c'mom boys and girls..its 3 times more expensive, it has to feel better ......

otherwise what Jur says ... its hard to draw conclusions when you compare "big bikes" to our clownbikes .... A titanium frame is usually designed different than a steel or alloy carbon frame... every material needs their own small details to be taken care off, but when done right, every material has their small advantages ...
again for our bikes... not so much

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who is lusting for a 20 inch titanium folding/take apart bike
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Old 12-13-11, 10:17 AM   #8
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I'd do a blindfold test, but I doubt the difference can be felt.

titanium is springy, but when drawn into tubes and welded together, not so much. Especially when the triangles are small and the tubes are oversized.
Ride blind folded

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c'mom boys and girls..its 3 times more expensive, it has to feel better ......
I think when I considered buying a Ti Brompton I worked out the effective weight saving of around 1kg was approx 500. That's an expensive KG!

I know for the hardcore racers they spend thousands for weight savings but I would prefer to carry an extra 500 in my pocket and put up with carrying a 1kg heavier Brompton or purchase second standard Brompton even

Regards

Jerry

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Old 12-13-11, 10:29 AM   #9
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When Sheldon wrote that stuff too most TI bikes were built with standard size tubing found with steel. Litespeed did make a bike (can't remember the name of it back in Sheldon's day, the Blade?) that used larger diameter tubes that riders said was a very stiff ride. So Sheldon never rode a TI bike made that way. And modern ti bikes are now constructed to be less flexy, but still springy enough to make the ride comfortable.

If a steel bike is taken care of it won't rust. I have several steel bikes and most of them are at least 23 years old and one is 27 years old and that one was rode a lot by me including riding it in the rain. I use to own a 79 Schwinn Traveler I bought new to ride on the wet sand of So California Pacific ocean, which meant it got drenched a lot of times with salt water! All I did was go home and hose it off but that's it, and that bike sat outside of my apartment where it got rained on. Then I stored the bike for about 15 years and when I moved I pulled the BB out to check for internal rust which there was some, but still usable, but I decided to leave the bike behind since it needed new components because the salt corroded the aluminum and there was some surface rust as well. But your talking about a lot of abuse and the darn frame wasn't rotted. So I have no problem with using steel
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Old 12-13-11, 11:03 AM   #10
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thor
who is lusting for a 20 inch titanium folding/take apart bike
sign me up!
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Old 12-13-11, 11:23 AM   #11
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Right so the considered views is Ti has no impact on rideability whatsoever? If that's true its wasted inside a S6R/Schlumpf build, I would be best keeping the Ti inside a M2L.

I'm doing my blind test possibly as early as the weekend, ordering some Ergon GR2-L next days, S6L vs S6L-X.

Right now I have 3 Brommies configured S6L/BWR, S6L-X/SRAM, and M2R-X, and a Schlumpf Mountain Drive. My plan is to make either a S6R-X/Schlumpf or a S6R/Schlumpf for long-distance touring and the question is purely impact on speed and comfort.

I'm definately keeping Ti on a S6L-X/BWR. So the fallout is do I end up with a M2L or a M2L-X.

There's something inside the Brompton making it slower, I average 2mph slower than the cheapest REI 27speed Alumium $600 bike I have which does most of the mileage. I'd prefer to use Brompton for flexibility of folding or riding to a more distant place to get the bus back but not at 2mph slower.

From what you're telling me, the Ti vs Steel will have negligible impact on performance so I might as well keep the Ti on a 2-speed where it will do the most good (carrying weight). Hopefully by this time next week I'll figure it out because I have to do an evening of parts shuffling to get to the 3 end configs. I need to move the BWR to Ti soon, the chain droops onto the frame when freewheeling on high hub gear, it will for sure ruin the paint if I keep it on the steel frame and I need to move it over and ride it to break-in the BWR and get it more efficient before I then rely on that bike as my regular day bike.

FYI, I picked up in the Brompton dealer the Steel seatpost vs the Ti seatpost - the factor of 3x on the weight is very noticeable.

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Old 12-13-11, 11:44 AM   #12
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Ti UFB project [PDX] is wanting investors , to make a Ti Brompton frame..
10K each.. SRP, for the proposed bike.

Ti Brompton seat post seems to be supplanted by aluminum
due to sourcing and cost issues on the current X spec list..

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Old 12-13-11, 11:55 AM   #13
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An Alu seatpost failure looks painful.

I own 2 Ti seatposts.

The problem with Ti seatposts is they are slippier, they slip more easily, I've had more issues than steel seatpost. Another reason to go steel on a long-distance touring configuration.
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Old 12-13-11, 01:35 PM   #14
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An Alu seatpost failure looks painful.

I own 2 Ti seatposts.

The problem with Ti seatposts is they are slippier, they slip more easily, I've had more issues than steel seatpost. Another reason to go steel on a long-distance touring configuration.
titanium also tends to stick to other titanium bits if left in contact without some anti seize used.

but seatpost failures from the seat post splitting down the circumference are quite rare. Usually the frame, seat post cap or saddle clamp gives up before the seat post does. If it happens, it's usually because someone had too much fun with a drill.
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Old 12-13-11, 02:11 PM   #15
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I think when I considered buying a Ti Brompton I worked out the effective weight saving of around 1kg was approx 500. That's an expensive KG!
You can achieve 1KG saving for only $10 using few helium balloons.

;-)
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Old 12-13-11, 02:53 PM   #16
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Right so the considered views is Ti has no impact on rideability whatsoever? If that's true its wasted inside a S6R/Schlumpf build, I would be best keeping the Ti inside a M2L.

I'm doing my blind test possibly as early as the weekend, ordering some Ergon GR2-L next days, S6L vs S6L-X.

Right now I have 3 Brommies configured S6L/BWR, S6L-X/SRAM, and M2R-X, and a Schlumpf Mountain Drive. My plan is to make either a S6R-X/Schlumpf or a S6R/Schlumpf for long-distance touring and the question is purely impact on speed and comfort.

I'm definately keeping Ti on a S6L-X/BWR. So the fallout is do I end up with a M2L or a M2L-X.

There's something inside the Brompton making it slower, I average 2mph slower than the cheapest REI 27speed Alumium $600 bike I have which does most of the mileage. I'd prefer to use Brompton for flexibility of folding or riding to a more distant place to get the bus back but not at 2mph slower.

From what you're telling me, the Ti vs Steel will have negligible impact on performance so I might as well keep the Ti on a 2-speed where it will do the most good (carrying weight). Hopefully by this time next week I'll figure it out because I have to do an evening of parts shuffling to get to the 3 end configs. I need to move the BWR to Ti soon, the chain droops onto the frame when freewheeling on high hub gear, it will for sure ruin the paint if I keep it on the steel frame and I need to move it over and ride it to break-in the BWR and get it more efficient before I then rely on that bike as my regular day bike.

FYI, I picked up in the Brompton dealer the Steel seatpost vs the Ti seatpost - the factor of 3x on the weight is very noticeable.
It is not the Brompton that is causing you to ride slower. It is the smaller tires. In the perfect world where roads are flat and smooth as glass, tires of all sizes should roll with the similar rolling resistance characteristics. Unfortunately, most roads in the world I had toured thus far is anything but smooth as glass. The third world for instances, roads are rough. The reason you are slowing down a bit compared to a normal sized bike is because, roads have imperfections. These imperfections are easily overcome with bigger tires like a 26, 29er or 700c and treats it like small tiny hills. These same imperfections are not as easily overcome with smaller tires found on clown bikes. What these imperfections look like small hills to a 700c tire is large mountains to a 20" 406 tire. Imagine you have to go through a ton of these imperfections. Not a problem with 700c or 29" tires, but more so with smaller tires. So this is where you are getting your speed deficiencies. Most US roads are good enough that there is little performance penalties. I road with fast riders on Trek Madone and Cannondale carbons with skinny tires and I have no problems keeping up with around 22 to 25mph, but then suffer if they start riding in rougher roads where I do have to work harder.

This brings up your next concern. Will Titanium help you smooth out the roads with a folder. My answer is not as good as running wider tires like the Big Apples. You see, these minor road imperfections is what's causing the increase in vibration feedback from the road. Bigger tires obviously transmit less through was is called a pneumatic effect. Sheldon Brown article concentrates mainly on bigger bikes where the large diameter tires take most of the sting out of the road. The only way you can take the sting out of the rough roads I find is to run lower pressure tires. By the way, wide and lower pressure does not equal slow. In fact, what I found when I was riding with the faster guys is that, my Big Apples on my Mu SL were performing well at 65PSI with the best of both worlds -- comfort and speed. Comfort comes from the pneumatic effect, which is the tire's ability to envelope or swallow these road imperfections without having to go over it! Most modern tires are made with modern technologies that contribute to little rolling resistance. In fact, my brand new snow tires I have now on my car has the rolling resistance similar to the best all season tires! Never felt disadvantaged whatsoever. And the Mu SL is stiff! Made of aluminum but does not ride like one thanks to Big Apples. Plus I run a standard seatpost (no Thudbuster). Comfort is not on the frame material. It helps, but the main comfort is always on the tires first. And yes, I do vary tire pressure to reflect ride terrain. This approach is better and cheaper than buying Titanium which I suspect will not give much bang for the buck.

Btw, I have Big Apples on my full suspension bike that I use for touring and the ride itself in phenomenal on rough roads where my Fox shocks does not do anything much to smooth them out.

Hope this helps.

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Old 12-13-11, 03:35 PM   #17
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I'm not sure how fast I am on the Brompton. . . I can imagine a few possible reasons for being slower that combined might add up to something: suspension bob, hub gear friction, chain tensioner friction, flexy frame. . . plus small wheels. Also, crap brakes make for longer stopping times.
But perhaps there's something mechanically up with your Brompton like hub cone adjustment?
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Old 12-13-11, 03:45 PM   #18
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You can achieve 1KG saving for only $10 using few helium balloons.

;-)
But the aerodynamic drag more than offsets the decreased weight
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Old 12-13-11, 04:34 PM   #19
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But the aerodynamic drag more than offsets the decreased weight
just take a longer line
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Old 12-13-11, 04:35 PM   #20
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ok.. back to titanium .... what i posted made absolutely no sense whatsoever
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Old 12-13-11, 05:14 PM   #21
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You can achieve 1KG saving for only $10 using few helium balloons.

;-)
Imagine the drag, and the weight impact of a puncture.
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Old 12-13-11, 10:20 PM   #22
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All tires do not roll the same even on smooth as glass roads, this is a test done on a slew of tires that will disprove that idea: http://www.biketechreview.com/tires_...sting_rev9.pdf These tests were done in a lab thus the roughness or lack there of does not go into the equation.
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Old 12-13-11, 10:45 PM   #23
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All tires do not roll the same even on smooth as glass roads, this is a test done on a slew of tires that will disprove that idea: http://www.biketechreview.com/tires_...sting_rev9.pdf These tests were done in a lab thus the roughness or lack there of does not go into the equation.
Same brand name tire of all sizes should have similar rolling resistances. Even with the differences, it is not much. You're right. Not all tires roll the same way, but are you saying that a 26" Big Apple tire has significantly less rolling resistance than a 406 version of the same tire?
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Old 12-14-11, 12:00 AM   #24
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Bike Friday used a Ti tube to make a beam suspension for the seat post,
Softride used a specially designed composite to do something similar.
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Old 12-14-11, 05:49 AM   #25
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Same brand name tire of all sizes should have similar rolling resistances. Even with the differences, it is not much. You're right. Not all tires roll the same way, but are you saying that a 26" Big Apple tire has significantly less rolling resistance than a 406 version of the same tire?
I don't have a clue!!
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