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Jurien’s titanium folding small wheeler from Titan

And now, as a bit of a late Christmas present, we have something slightly different. Jurien likes his small wheelers and is a big fan of the Swift folders made by Xootr, but what to do when your current bike is coming to the end of it’s life and you want something unique to replace it? You go custom of course…

My aluminium Swift is now 7 years old, still going as perfect as ever, but I don’t expect it to last forever so I am turning over in my mind what to replace it with. I’d really like a titanium frame but Swift don’t make one…

So I started talking to a titanium frame manufacturer about making a Swift-like frame. There might have been copyright issues, so I decided to approach Peter Reich from Xootr about the idea too.

Interestingly there’s no real way of copyrighting a frame design, but it’s only polite to ask! In this case Peter said he’d be happy for Jurien to go ahead with making a frame for himself so they could see how many other people might want one too.

The Swift frame design is quite an interesting one, it uses the seat post as an integral ‘pin’ that holds the frame together, remove that and the bike simply folds in half. You can pack it down further by popping off the handle bars and stem, indeed Xootr show the whole bike fitting rather neatly into a large suitcase!

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Wow, now that looks pretty special! (This must be the second frame that Jurien had made as it’s got a ‘braze on’ front mech mount)

The dream.

Jurien approached Titan Product as he’d bought a titanium seatpost for a Brompton from them before. They quoted US$1200 for the frame and $200 for a matching titanium fork, pretty reasonable considering the unique design.

I was faced with the difficult choice between weight and frame stiffness. I was very concerned that I would end up with a frame that is too flexible to be able to ride hard, so I chose to err on the side of caution and spec’ed thick-walled tubes for the main tubes.

The other good thing about going custom is that it allows you to tweak the geometry and sizing to your own preferences. The standard Swift comes in one size fits all so Jurien took the opportunity to make himself more comfortable as well as taking care of a few other features too:

  • The twin top tube design came about because the builder did not have a large enough oval tube. I did some engineering calcs on the tube torsional stiffness and tried to get something close to the aluminium frames stiffness.
  • I designed an easier-to-produce pivot for the frame, and a way to place the pivot with the dual tube design.
  • Small change to the geometry to accommodate a slightly shorter fork.
  • Made the top tube 25mm longer for a slightly taller average rider.
  • Omitted the v-brake bosses as I will use this one with a disk brake on the front and a road calliper on the back.
  • Added cable stops, cable tie points and a cable pulley boss at the bottom rear of the seat tube for easier derailleur cable installations.

One of the issues with small wheelers is the need for a large chainring to get the gearing high enough, and if you’re running two chainrings, how to mount the front derailleur. Getting the position of a ‘braze on’ fitting just right can be tricky so Jurien decided to play it safe and go with a standard clamp mount front mech.

The metal.

Doing something different will always give you sleepless nights about the multiple things that might go wrong. Will you have a dream machine that’ll be a joy to ride, or just a pile of metal tubes only fit for the recycling?

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Right. I’ve got the Ti Swift in my grubby hands.

The whole frame weighs around 1.9kg, about 0.7kg lighter than the current aluminium frame. Considering that’s with the over-designed main frame, I am impressed!

Headset went in without a hitch, as did the bottom bracket.

But things would be boring if they just went together first time, right?

I can’t get the 2 clamps to keep proper tension on the headset. It works loose quickly. I am thinking of adding a friction powder between the clamps and the steerer.

Because of the way the stem comes apart to help with the folding process keeping the headset adjusted correctly can be tricky at the best of times. Jurien partly solved the issue with a very handy adjustable headset spacer from Problem Solvers (worth a look as they have lots of nifty little gizmos that might come in useful):

http://problemsolversbike.com/products/micro_adjustable_headset_spacer

The bottom stem clamp would not stay put; the huge lever force generated while riding would slide the clamps up the steerer and loosen the headset. Even grit for extra friction didn’t help. So in the end I put an additional O-ring between the headset and the bottom clamp to create a little separation which has done the trick.

The challenge.

And now for the big one – you remember how the seat post holds the whole frame together? And also how we’ve put a hinge in the middle of the frame? So how do you make sure everything lines up correctly…

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The crucial joint – if things don’t line up here then the frame won’t be rideable!

Corresponding with Peter Reich, he made me very aware of the trouble Xootr had/are having with seat tube alignment. After this, I re-designed the hinge area to try and eliminate this problem, and exchanged numerous emails with Titan about the seat tube alignment issue. I suggested they inserted a piece of seatpost-sized tubing through the frame to hold it together while they assembled and welded it up.

Suffice to say they ignored my advice and came up with their own scheme, which didn’t work. They started out with a SINGLE piece of seat tubing and assembled the whole frame with the hinge also in place around it. Then, right at the end after all welding was done, used a cutter to cut the seat tube into the final 2 pieces!

The only problem was that cutting the seat tube into two created a gap the size of the cutter between the 2 pieces of seat tubes. Inserting the seatpost was possible, but not while the gap was closed (of course not!). So what did they do to solve that latest problem? Well they drilled/ground the hinge hole out over-size to allow the seat tube gap to be closed while the seatpost was inserted. Theoretically. I could insert and extract the seatpost only with the utmost of force, while twisting and pulling (and turning the air blue). So technically it could fold but in practice… No.

I scolded them into submission, that they should have contacted me BEFORE trying their own dodgy solutions, and they sent me a 2nd frame at a much reduced price where the problem was solved.

Definitely a point to note there; Titan appear to have overlooked the way the frame fitted together and were happy to send Jurien something that plainly didn’t work.

Unfortunately that’s one of the risks you take when you’re dealing with a workshop in another country producing something they’ve not made before. It’s not great that they didn’t take 100% responsibility for the situation but at least Jurien was able to reach a compromise with them about having a replacement fame made at cost price.

Subsequent frames that Titan have made appear to have solved this issue now – but there was one report of a frame that needed to have the seat tube reamed out to get the post to fit. This appears to have been a tube warping issue rather than an alignment problem but it’s still worth keeping an eye out for.

Finally – time for a ride!

You have to admit that the end result does look rather stunning, Jurien’s elevated the workman like commuter machine to something a bit more special!

The Ti Swift is a dream to ride. Geometry-wise, it’s an improvement over the aluminium version. On my standard Swift, I can’t ride with my hands off the bars but with the Ti Swift I can pull on my wind jacket as I’m going along!

At 8.5kg it’s a good deal lighter than the standard aluminium model too! Bearing in mind that this frame was deliberately overbuilt, I’ve got plans to take things further and should be able to trim another 200-300 grams off.

Sounds like Jurien got what he was after in the end, although it took a few goes for Titan to get things sorted properly. It’s worth bearing that in mind if you’re after something unique. You can cover yourself to some degree by making sure you triple check any drawings before you sign them off. Other than that it might have been worth asking Titan to take a video of the whole folding process, with a seat post fitted, before they dispatched the frame.

If what you have delivered isn’t what you expected then do open up negotiations with your builder and see if you can come to an agreement – don’t forget to be polite!

After seeing his stunning bike a few other people said they would like one too and so Xootr allowed another six more to be built. That gave some people the opportunity to take things further, this batch features curvy stays and adjustable dropouts to allow a belt drive amongst others:

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This is one story that’s still running, you can check on progress via the original thread (grab a cuppa and some hobnobs, you could be there a while…)

http://www.bikeforums.net/folding-bikes/930714-titanium-swift-frame-anyone-interested.html

Have you had something unique made in the Far East? Do drop me a line via the contacts page and let me know all about it!