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Old 04-26-16, 05:02 PM   #26
shrooms
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There is no ti folder with disk brakes on the market. That's my point.
Sorry I misunderstood then.
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Old 04-26-16, 07:18 PM   #27
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There is no ti folder with disk brakes on the market. That's my point.
As far as I know, nothing in titanium frames prevents the use of disc brakes. My Ti Swift has them, and the 2nd batch we had built has several ones. Sure that's not the market, but I don't know what your point is.
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Old 04-26-16, 07:37 PM   #28
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I'm not sure what's so confusing about "spend your money on actual bicycles that are actually for sale." The Helix does not exist in anything resembling this form, and I have my doubts that it ever will, or ever will at price points people will pay.
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Old 04-26-16, 08:59 PM   #29
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Titanium tubing isn't that expensive by itself, a lot less than $100/kilo. The bike would have roughly 2kg of material, maybe less. So the raw tubing material cost is not so huge that it would be unrealistic to envisage a bike frame at a reasonable cost.

It's hard to work with, about the same as stainless steel. It's hard to weld well.

So if one assumes that the machinery is up to scratch, especially the welding setup, then you're good to go (also assuming you have experienced operators).

So I don't immediately see why a folding bike at the $1500 price point is impossible. Initially I thought it was a pipe dream until I looked at bulk titanium tubing pricing.
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Old 04-27-16, 07:36 AM   #30
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The bike in my avatar, a Bike Friday Air Glide, uses a titanium beam instead of the traditional seatpost/seat tube arrangement. The rest of the frame is a much more conventional cromoly alloy.

My understanding is that all the beam bikes they produced, including the Air Friday, were discontinued when Green Gear could no longer source those titanium beams for whatever reason: cost, availability, quality, etc. And since the titanium beam is critical to the bike's design and function, those models are gone, perhaps never to return. Glad I got one.

Now extrapolate that to an entire bike frame. As in jur's post above, titanium requires careful handling to prevent weld contamination, which could eventually lead to weld failure, and we don't want that happening.

Long story short, I don't think it's as easy to produce a titanium frame as some folks think.
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Old 04-27-16, 04:01 PM   #31
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Tell me please about your beam. I have never found decent information on the net. Looks great. How does the suspension work. Why does the frame not break! What the suspension like. Whats the fold like.
Thank you.
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Old 04-27-16, 06:59 PM   #32
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Familiar with Softride bikes? They used a carbon fiber beam that was attached to the downtube near the head tube, and terminated the other end with a saddle clamp. The Softride bikes were a little too bouncy in my opinion, having ridden several back when they were popular. You really had to smooth out your pedal stroke, otherwise you went bobbin' along. That effect was very similar to early dual suspension MTB designs where the pogo effect was quite pronounced, and robbed the rider of valuable energy that could have gone into forward effort.

The titanium beam Air bikes from Green Gear are like Softride lite. The effect is not as pronounced, but you still have to smooth out your pedal stroke to avoid the pogo effect, though nearly not as much effort is needed to counteract the suspension effect of the beam as with the Softride.

It's difficult to describe the sensation of the Air bikes without trying one. It feels like I'm riding on a subchassis - the lower end of the bike minus the beam - that is suspended through the saddle. I remember when I got my first one, an Air Friday. I kept bracing myself for impacts on the road like I did with all my rigid bikes, only to discover I really didn't need to all that much.

I traded my Air Friday in on the Air Glide when one became available at Green Gear used. It was not cheap: $3300 was the sticker for the used Air Glide, minus the trade which was valued around $1500, meaning I had to come up with $1800 out of pocket. Never regretted it.

It's my understanding that titanium was the only metal Green Gear considered for the beam. The beam has an interesting ovalized shape; it is not round tube like the rest of the frame. Dismantling the bike for travel means I have to remove the beam from the frame. I also remember that at some point, Green Gear issued a recall on the beam, which consisted of a retrofit bolster that was placed inside the beam, as a few failures of the beam without were reported. To anyone buying a used Air bike from any source other than Green Gear, it's highly recommended to ask the owner if the recall was performed, just like anyone buying a used Tikit should ask if the stem recall was performed. As to why the frame doesn't break, it's well secured; more likely that the beam would break first.

If you've ever ridden a Moulton Spaceframe, it's kind of like that, only the Air bikes typically don't have front suspension with the exception of the Air Llama.

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Old 04-27-16, 08:06 PM   #33
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My understanding is that all the beam bikes they produced, including the Air Friday, were discontinued when Green Gear could no longer source those titanium beams for whatever reason: cost, availability, quality, etc. And since the titanium beam is critical to the bike's design and function, those models are gone, perhaps never to return. Glad I got one.

Now extrapolate that to an entire bike frame. As in jur's post above, titanium requires careful handling to prevent weld contamination, which could eventually lead to weld failure, and we don't want that happening.

Long story short, I don't think it's as easy to produce a titanium frame as some folks think.
Looking on Alibaba, there is now a large, growing body of titanium tube suppliers, driving the price down and availability up.

It is puzzling why Brompton have stopped doing the Ti seatpost; there are by now a number of 3rd party suppliers of Ti seatposts suitable for Bromptons. I have one.

BiFri may have stopped the Air Glide model due to demand being low? There may have been a time when Ti tubing was harder to source but it seems those days are long gone.
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Old 04-27-16, 10:35 PM   #34
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I would be willing to buy the low demand theory. I've seen lots of Bike Fridays in the San Francisco Bay Area over the decades..I've never seen a beam bike in person.
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Old 04-28-16, 03:20 AM   #35
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The birdie was avilable in ti with discs. But I think its a special edition. Cant see anypoint in spending 4-5k on a birdie. Its a compromised bike. But if you travelled or tour with one then maybe.
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Old 04-28-16, 11:10 AM   #36
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Not my understanding that it was low demand that led to the demise of the Green Gear ti beam bikes. They are quite popular with those who own one, including me, which is why I traded up from an Air Friday to an Air Glide.

I remember being at a Green Gear event in Eugene about 15 years ago, and Hanz stunned the crowd by showing off his new Air tandem, which he then proceeded to disassemble into two normal size suitcases in record time, to the astonishment of the crowd. Back then, the Air tandem was around $7800 if memory serves. Lots of folks interested in it.
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Old 04-28-16, 10:12 PM   #37
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Is there a link to a green gear website?
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Old 04-28-16, 10:51 PM   #38
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Is there a link to a green gear website?
Here you go:
Let me google that for you
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Old 04-29-16, 01:39 AM   #39
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I guess you didn't know my searching came up with 0.000% hits,...thanks for the assistance - when I kindly asked someone else.
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Old 04-29-16, 03:52 AM   #40
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Green Gear makes Bike Fridays, but you'll get nowhere Googling the parent company name. Your problem was completely understandable.
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Old 04-29-16, 05:38 AM   #41
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Green Jur, not Grean. Just saying.
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Old 04-29-16, 09:46 AM   #42
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Green Gear makes Bike Fridays, but you'll get nowhere Googling the parent company name. Your problem was completely understandable.
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Green Jur, not Grean. Just saying.
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Old 04-29-16, 01:15 PM   #43
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Cant see anypoint in spending 4-5k on a birdie. Its a compromised bike. But if you travelled or tour with one then maybe.
Compromised? How so?
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Old 04-29-16, 02:21 PM   #44
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Re Birdie compromises.
Well all folders make concessions. Even 4k ones.
Wheel size 18
Steering stability due to front fork design. It does help it fold and yield nice anti drive characteristics.
Folding size limitations, its tiny to pack with wheel removed however.
Touring rear panniers must be small to aviod heel strike or mounted far back meaning the rolling wheels need to be removed.
Hard to set up vbrake noddles at front.
Chainwheel clearence is minimal on frame when folding and rings can get bent.
Clearence issues on wide tyres at back.
Old chain cather can wedge in transmission breaking draillers etc.
The last three issues seem to be addressed by mk3 improvements which i have fitted to my bikes. Ie small cage drailler and chain tensioner with no catcher.

Flawed but genius
And enjoyable.
.

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Old 05-01-16, 12:56 AM   #45
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I'm not sure what's so confusing about "spend your money on actual bicycles that are actually for sale." The Helix does not exist in anything resembling this form, and I have my doubts that it ever will, or ever will at price points people will pay.
What's confusing is your negativity towards the Helix. You obviously did not invest in one.
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Old 05-01-16, 01:36 AM   #46
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What's confusing is your negativity towards the Helix. You obviously did not invest in one.
The chances for the success of the project have been well discussed on the forum and the chances aren't great for the price. Still let's keep fingers crossed for the company to become successful even if it won't be able deliver the bikes to the supporters.
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Old 05-01-16, 03:09 AM   #47
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There's nothing confusing about my negativity. Helix started taking orders for this thing a long time ago, and as of yet there are no signs they'll ever produce a bicycle. If I'm wrong, that's great for everybody. Stay tuned! Or not.
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Old 05-01-16, 06:12 AM   #48
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There's nothing confusing about my negativity. Helix started taking orders for this thing a long time ago, and as of yet there are no signs they'll ever produce a bicycle. If I'm wrong, that's great for everybody. Stay tuned! Or not.
That's not so. Factory setup is almost finished down to making some final tooling jigs. Parts have arrived. Rims are done anodizing. Rear swingarm final prototypes suitable for mass production are built, and looking downright amazing.

That's a heck of a lot further than "no sign". If you aren't a backer then you wouldn't have caught these updates as it is a closed court.
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Old 05-01-16, 06:38 AM   #49
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Well bully for them and I hope it pans out. They stopped sending me emails months ago, so all I have to go on are reports here. Good luck!
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Old 05-01-16, 10:26 AM   #50
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That's not so. Factory setup is almost finished down to making some final tooling jigs. Parts have arrived. Rims are done anodizing. Rear swingarm final prototypes suitable for mass production are built, and looking downright amazing.

That's a heck of a lot further than "no sign". If you aren't a backer then you wouldn't have caught these updates as it is a closed court.
Well said. I'm sure we're all hopeful that the Helix succeeds, as it would be an innovative addition to the folding bike arena, but I don't think anybody is deluding themselves thinking that this is a "sure thing". That's the whole premise of Kickstarter after all.
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