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-   -   swift folders (http://www.bikeforums.net/folding-bikes/83711-swift-folders.html)

charles vail 09-02-07 07:12 PM

metal fatigue
 
The whole frame failure idea with aluminum is what kept me from purchasing a Swift. I would have to get a steel frame regardless. Manufacturing tolerances are fairly broad when it comes to seat posts in my experience. The I.D. of the frame hole might be larger in one bike over another and the seat posts might be smaller by a few thousandths. This would make for a sloppy fit and after enough cycles of creaky seat post, that aluminum will just crack in half. If I ever end up with a Swift, it will be a steel bike and a custom fitted seat post that I know is machined round for a precision fit. This is the only weak point in the design of the swift frame that I can see, other than the choice of material.
Perhaps the builder could beef up the frame with larger diameter aluminum and epoxy steel sleeves inside for the seat post. These could be closer tolerance and force the often warped, post welded tubing, round to create a true round hole for the seat post to slide into. All that folding and unfolding over time will make a sloppy fit causing early failure with heavier riders.......maybe user replaceable bushings/sleeves etc. could be engineered to maintain a tight fit and account for wear.

awetmore 09-02-07 07:29 PM

Quote:

Originally Posted by jur (Post 5192692)
Whoa. That is the second Xootr that failed like that. Now I am leery of the design...

Why are you leery of the design (instead of the implementation?)

The steel Swift Folders have been around for about a decade and this doesn't seem to be a common failure with them.

jur 09-02-07 08:08 PM

While I don't want to get deep into a steel vs alum for frame material debate, I understand that alum is not per se weaker than steel if you stay withing its elastic limits. It's just that for alum, the elastic limits are much smaller, right? So the idea of a precision fitting seatpost which limits movement sounds good.

On the other hand, Xootr does have a life guarantee on the frame. They wouldn't offer that if there was a low confidence on the frame life, would they?

jur 09-02-07 08:27 PM

Looking at the design, it seems to me that the QR on the top section of seat tube would be better placed at the joint instead of at the top. Placing it at the joint would provide better holding of the seat post accross the joint.

Another mode of flexing which hasn't occurred to me before, is torsional movement of the seat post, with the seat tube section rotating wrt the other at the joint. This would compress one strut and stretch the other. Or if one of the QRs is not very tight, it would allow slip, allowing the post to rotate inside the seat tube.

Paul Braithwait 09-03-07 02:33 AM

Making sure the Q/Rs are tight is obviously important. I always tighten the top Q/R first (having set the seat height) then put my weight onto the seat as I close the bottom Q/R. This ensures that both parts of the frame are pushed tight with each other. I don't know if this makes much difference but it keeps me happy! The Swift is such a great little bike I hope the cases of frame failure are isolated ones. It will be interesting to hear what Xootr have to say about the subject.

creaturely 09-03-07 08:30 AM

A Lion in Winter
 
San Francisco, Hawaii, Australia-- so lovely but ao temperate! So any of you hardcore longtime Swift riders live in lands of snow and ice? Today is a beautiful day, but in Chicago you can smell winter around the corner. How will my Swift handle in snow and ice? Do I need to buy what everyone regards as the fairly lame Innova studded tires that (as far as I can tell) are the only options for a 20 in bike? Or will some bmx knobblies do the trick? Reverse treads, as Peter White seems to suggest?

Any other tips for riding a little bike through winter?

Someone with experince in the white stuff, please advise!

awetmore 09-03-07 08:37 AM

Quote:

Originally Posted by jur (Post 5196936)
While I don't want to get deep into a steel vs alum for frame material debate, I understand that alum is not per se weaker than steel if you stay withing its elastic limits. It's just that for alum, the elastic limits are much smaller, right? So the idea of a precision fitting seatpost which limits movement sounds good.

I wasn't trying to start a steel vs aluminum debate. The failures mentioned here don't have anything to do with the material. It sounds like a couple of examples of the aluminum frame have had less precise seatpost machining which has created ovalized seatpost holes.

UncleGreg 09-03-07 04:30 PM

Hi There,

Anybody have an established locking system for the swift (other than, "take it inside with you")? I've realized that though the rear triangle is lockable, someone could take my top tube and fork, while leaving the triangle and cabled wheels. (Assuming they have a wrench)

One crafty solution might be to fashion some sort of facade that covers up the hinge so it isn't very evident- anybody try that?

Thanks,

GR

jur 09-03-07 05:21 PM

Quote:

Originally Posted by awetmore (Post 5199209)
I wasn't trying to start a steel vs aluminum debate. The failures mentioned here don't have anything to do with the material. It sounds like a couple of examples of the aluminum frame have had less precise seatpost machining which has created ovalized seatpost holes.

Just had a look at some of your blogs, almost looks like you & I came from the same mould! :)

The fitment tolerance of the seatpost is indeed to be closely scrutinised. It is obviously (with hindsight) a critical parameter. (The debate remark was actually aimed at the post just before yours...)

charles vail 09-03-07 07:00 PM

design
 
The design of the Swift is excellent except that the material choice at a critical pivot point lends itself to premature wear. It kind of rubs me the wrong way ( no puns intended ) when I see the application of aluminum with high wear areas. The use of steel or some other harder material as a bushing for a steel sleeved seat post makes more sense to me, rather than just letting a aluminum post slide in a aluminum hole. If the bike was rarely or never folded, the current configuration would be fine, assuming a good fitting seat post and tight clamping levers. The re-engineering of the alum. Swift would add to the price but it may be worth it, long term. Instead, I'd just make the bike out of steel since the weight penalties wouldn't amount to much, considering the fact that most riders are at least 5 pounds from ideal weight anyway.

Bop 09-03-07 09:55 PM

And, of course, it is available in steel. Seems your concerns are of the result of the trade-offs of mass production in aluminum. Cheaper is not always better overall.

SesameCrunch 09-03-07 11:17 PM

Quote:

Originally Posted by kb5ql (Post 5192921)
I'm thinking of going the BikeFriday route for the front derailleur now. Since I've moved to the Bay Area/San Francisco, the number of hills has increased dramatically. I'll probably pull a james_swift and convert the swift to a fixie.

Have you considered a SRAM DualDrive hub in the back? That gives you a 3 speed internal hub X whatever number of cogs you have on the cassette. On my Dahon SpeedPro, I get 25-125 gear inches - more than enough! They cost about $200, much less than a Bike Friday :).

kb5ql 09-04-07 12:27 AM

Quote:

Originally Posted by SesameCrunch (Post 5203687)
Have you considered a SRAM DualDrive hub in the back? That gives you a 3 speed internal hub X whatever number of cogs you have on the cassette. On my Dahon SpeedPro, I get 25-125 gear inches - more than enough! They cost about $200, much less than a Bike Friday :).

Two words Heav-y. ;)

I'm trying to keep the bike in the 9kg/20 lb. range.

SesameCrunch 09-04-07 12:29 AM

Quote:

Originally Posted by kb5ql (Post 5203891)
Two words Heav-y. ;)

I'm trying to keep the bike in the 9kg/20 lb. range.

Can't argue that one :(...

charles vail 09-04-07 01:15 AM

right on
 
Quote:

Originally Posted by Bop (Post 5203264)
And, of course, it is available in steel. Seems your concerns are of the result of the trade-offs of mass production in aluminum. Cheaper is not always better overall.

That seems to be true in this case. I know the Swift is available in Steel. For most people, I think the Aluminum bike is probably alright, especially for lighter riders. Its interesting that some have made the ultralight SS/FG work nicely as a commuter and I can't argue with the lightweight thinking on that. I think a more utilitarian machine with an internal hub would be a better all around commuter. Of course this is what a folder is about I presume.

Simple Simon 09-04-07 04:24 AM

Quote:

Originally Posted by charles vail (Post 5202206)
The design of the Swift is excellent except that the material choice at a critical pivot point lends itself to premature wear. It kind of rubs me the wrong way ( no puns intended ) when I see the application of aluminum with high wear areas. The use of steel or some other harder material as a bushing for a steel sleeved seat post makes more sense to me, rather than just letting a aluminum post slide in a aluminum hole. If the bike was rarely or never folded, the current configuration would be fine, assuming a good fitting seat post and tight clamping levers. The re-engineering of the alum. Swift would add to the price but it may be worth it, long term. Instead, I'd just make the bike out of steel since the weight penalties wouldn't amount to much, considering the fact that most riders are at least 5 pounds from ideal weight anyway.

FWIW, both Brompton and most Dahons use a thin plastic sleeve to avoid direct metal-to-metal contact. Swift owners may be able to use these (maybe cut down to size), they cost very little. Obviously the next sized down seat post would then be needed. I have wrecked several aluminium seat posts on non folding bikes - where they have 'picked up' or sort of welded themselves to aluminium seat tubes. When released they have made huge scratches. On a folding bike where this is done upto 4 times a day avoiding this is critical.

jur 09-04-07 05:34 AM

Quote:

Originally Posted by Simple Simon (Post 5204160)
FWIW, both Brompton and most Dahons use a thin plastic sleeve to avoid direct metal-to-metal contact. Swift owners may be able to use these (maybe cut down to size), they cost very little. Obviously the next sized down seat post would then be needed. I have wrecked several aluminium seat posts on non folding bikes - where they have 'picked up' or sort of welded themselves to aluminium seat tubes. When released they have made huge scratches. On a folding bike where this is done upto 4 times a day avoiding this is critical.

I wouldn't trust a plastic sleeve unless it was approved by the designers. But I agree with what you say, I have considered it.

I may compose a letter to Peter Reich and hear what he has to say about these failures. Perhaps it is a storm in a tea cup.

james_swift 09-04-07 06:43 AM

Quote:

Originally Posted by jur (Post 5204272)
I may compose a letter to Peter Reich and hear what he has to say about these failures. Perhaps it is a storm in a tea cup.

Excellent idea. An electronic petition of some sort where those concerned can sign their names as well (count me in). ;)

JonathanG 09-04-07 10:43 AM

It was the failure of the seat stays on my Xootr Swift frame (see here ) that prompted the most recent discussion of the frame.

Just a quick update on the response from Xootr. I'd emailed Xootr over the holiday weekend so wasn't expecting a response until the start of work today. Unlike James I wasn't emailed back within 30 minutes or at all. I called just after noon and was told that the person who was usually in charge was on vacation but that someone should be around at 4:00 who might be able to help. I'll get back with more information when I have any.

Jonathan

JonathanG 09-04-07 05:18 PM

Good news!. I got in touch with the very nice people at Xootr, and they're sending me a whole new bike with pretty much no questions asked. :D

Brian, the person I reached, explained that they'd had some instances of breakage and so now were making the bike with thicker tubing, which has increased the overall weight by about a pound.

I am not an engineer and can't comment on the long term stability of the design, but their willingness to stand behind the frame inspires confidence in me, and I really, really like the way the Xootr Swift rides, folds and takes standard parts.

Jonathan

jur 09-04-07 05:26 PM

That's excellent!

james_swift 09-04-07 05:42 PM

Quote:

Originally Posted by JonathanG (Post 5208425)
Good news!. I got in touch with the very nice people at Xootr, and they're sending me a whole new bike with pretty much no questions asked. :D

Brian, the person I reached, explained that they'd had some instances of breakage and so now were making the bike with thicker tubing, which has increased the overall weight by about a pound.

I am not an engineer and can't comment on the long term stability of the design, but their willingness to stand behind the frame inspires confidence in me, and I really, really like the way the Xootr Swift rides, folds and takes standard parts.

Jonathan

Such was my exhilaration upon receiving my new bike (no questions asked as well). Glad to hear it. :)

pm124 09-04-07 05:51 PM

[QUOTE=Paul Braithwait;5137474]This is what "Butterfly bars look like on a Swift. They are very comfortable and coupled to an adjustable stem give a huge variety of positions. No more stiff neck, sore back or numb hands!





http://i175.photobucket.com/albums/w...n/DSCN3847.jpg

I considered those. They are super cheap at nashbar (http://www.nashbar.com/results.cfm?c...A%20Handlebars), but they weigh a half kilo! So, I went with bullhorns. The problem with bullhorns is that they are suboptimal for off road use since they are so narrow at the stem. I did find a pair that was 25.4 clamp and 22 brake for a mountain setup.

pismocycleguy 09-04-07 08:14 PM

Steel Frame Swift Folder
 
Is Human Powered Machines in Oregon still a viable site to purchase a steel frame Swift Folder?
Is Jan VanderTuin still affiliated with HPM. I thought that I read, or heard, that he is now working with Bike Friday in Eugene, Oregon. Any comments or corrections?
Since I am located on the West Coast I would like to purchase from a closer location than New York.
Thanks for the help.
PCG

Pine Cone 09-04-07 09:44 PM

Quote:

Originally Posted by creaturely (Post 5199176)
San Francisco, Hawaii, Australia-- so lovely but ao temperate! So any of you hardcore longtime Swift riders live in lands of snow and ice? Today is a beautiful day, but in Chicago you can smell winter around the corner. How will my Swift handle in snow and ice? Do I need to buy what everyone regards as the fairly lame Innova studded tires that (as far as I can tell) are the only options for a 20 in bike? Or will some bmx knobblies do the trick? Reverse treads, as Peter White seems to suggest?

Any other tips for riding a little bike through winter?

Someone with experince in the white stuff, please advise!

For lots of suggestions on how to cope with winter cycling, check out http://www.icebike.com/

Not many choices in 20" studded tires. You can always make your own with sheet metal screws...


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