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Titanium Swift frame, anyone interested?

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Titanium Swift frame, anyone interested?

Old 08-02-15, 02:33 AM
  #351  
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Fascinating Jur,

Hope you don't mind a few more questions:

1. What is the stock top tube length?

I guess one is trading maneuverability for stability. Some where in there is the proper balance of quickness in steering and stability for each rider. I do wonder how tall the riders are. I'm almost 5' 11" or about 179.5 cm. But have a slightly longer torso than most and shorter inseam so possibly a longer top tube too.

I find it interesting that one cannot easily take hands off on the stock Swift as its wheelbase is pretty typical of a road bike. Perhaps it is the smaller wheel that does not give as much gyroscopic effect? I have no idea.

2. Also, for those who want disc brakes, I wonder if they made the fork stronger given the extra torque on the fork.

3. The other titanium parts are obviously lighter than most aluminum equivalent but I do wonder if they are more flexible. (i.e. seat post, handlebars etc.)

Again, beautiful work!

Thanks!

Blessings,
UL

Originally Posted by jur
So far, all except one case took longer top tubes. Of those, PineCone took 590mm, the rest are 575mm. Nothing is adjusted so the wheelbase becomes longer. It is much more stable than the Xootr Swift, I can ride no-hands and take my jacket off. With the Xootr that won't happen. I will weave all over the way.
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Old 08-02-15, 06:43 PM
  #352  
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Originally Posted by Ultralight
Fascinating Jur,

Hope you don't mind a few more questions:

1. What is the stock top tube length?
55cm.
I guess one is trading maneuverability for stability. Some where in there is the proper balance of quickness in steering and stability for each rider. I do wonder how tall the riders are. I'm almost 5' 11" or about 179.5 cm. But have a slightly longer torso than most and shorter inseam so possibly a longer top tube too.
PineCone has similar proportions, ie longer torso.

I don't detect any substantial difference in maneuverability between my stock Xootr and the Ti versions. Maybe I am not experienced enough in a wide variety of bikes to be able to detect subtle variances. To me they feel very similar, except the Ti one is slightly more stretched out which I like.

I find it interesting that one cannot easily take hands off on the stock Swift as its wheelbase is pretty typical of a road bike. Perhaps it is the smaller wheel that does not give as much gyroscopic effect? I have no idea.
I think that is more due to fork geometry than top tube length.

2. Also, for those who want disc brakes, I wonder if they made the fork stronger given the extra torque on the fork.
I think not. The tubes are pretty stocky so are beefy to start with.

3. The other titanium parts are obviously lighter than most aluminum equivalent but I do wonder if they are more flexible. (i.e. seat post, handlebars etc.)
Maybe the Ti ones have more flex. This is an aspect that I understand to be desirable - you want as mush torsional stiffness as you can get so that the frame does not flex and bend once you start hammering. However to absorb road buzz, vertical compliance is an important factor.

I suspect that this frame is stiffer than say the typical road bike, the tubes have quite a large diameter.
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Old 08-03-15, 04:28 AM
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i feel that the Ti Swift is as rigid as my bike friday pocket rocket rocket pro. it also absorbs much of the road imperfections. great looking and great performing bike.
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Old 08-03-15, 09:13 AM
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marxmini, jur, others with Ti Swift experience,

Is the Ti Swift a significant improvement in absorbing road imperfection vs the current aluminum Swift? I love the Xootr Swift's stiffness/performance, but it does transmit bumps more than any bike I've owned.
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Old 08-03-15, 01:29 PM
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Originally Posted by marxmini
A lovely build. Thank you for sharing.
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Old 08-03-15, 05:36 PM
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Originally Posted by towndock
marxmini, jur, others with Ti Swift experience,

Is the Ti Swift a significant improvement in absorbing road imperfection vs the current aluminum Swift? I love the Xootr Swift's stiffness/performance, but it does transmit bumps more than any bike I've owned.
I rode my Xootr Swift with a carbon post for a long while. That worked so well that often I wondered if my tyres were going soft.

The Ti seatpost is more flexible than the thick aluminium Xootr one. It flexes a bit more and therefore absorbs bumps better. Same argument with the fork and stem riser. For the frame, I don't think there will be a significant difference - relatively large diameter tubing, rear triangle... no flexing there. What might be different is the frame response to high frequency impacts - Ti should be more springy.

You begin to see the language I am using: might be, should be... The majority of road buzz should be absorbed by the tyres, next the seatpost and stem riser, and also the saddle rails and padding before it reaches you. I think those elements are dominant. The frame should be insignificant in that scheme.

My honest assessment, I think the difference is very small in the frame part. I was scared witless about designing the frame and it turns out not stiff enough. So I over-designed it. But the seatpost and riser are great for absorbing, so you will feel it in the feet but not so much the hands and seat.

But because the frame is lighter and from a more springy material, it rides better I think. Very subjective. I certainly enjoy it enormously.
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Old 08-03-15, 10:29 PM
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Originally Posted by towndock
marxmini, jur, others with Ti Swift experience,

Is the Ti Swift a significant improvement in absorbing road imperfection vs the current aluminum Swift? I love the Xootr Swift's stiffness/performance, but it does transmit bumps more than any bike I've owned.
I have no experience with the curent aluminum Swift, but I really like the way my Ti Swift rides. I have the longer top tube version. I rode it earlier tonight and was thinking that while I have built it to be relatively heavy vs. the other builds it is a very comfortable bike to ride. Not twitchy, plenty responsive, reasonably fast. On a ride I do on a regular basis it is slower than a carbon fiber road bike that has a higher top gear and weighs about 4 pounds less as they hit the road. The Ti Swift is significantly faster than a Cannondale Scalpel 29er mountain bike. I could easily build the Ti Swift with ligher components, but it was designed as a rougher-road touring folder, and while I haven't gotten a chance to do a tour on it, it should work very well.

I am running a 1.75" tire on the rear and a 1.5" on the front with 36 hole 3-cross wheels. The road imperfections are muted by the combination of frame and tires. I hope to get my Reach Offroad up and running sometime in the next month which will give another comparison point.

Bottom line... I really like the Ti Swift. Next week I will begin to try it on loose gravel and dirt roads as well as longer rides, but it should handle them well.
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Old 08-04-15, 04:17 AM
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Originally Posted by towndock
marxmini, jur, others with Ti Swift experience,

Is the Ti Swift a significant improvement in absorbing road imperfection vs the current aluminum Swift? I love the Xootr Swift's stiffness/performance, but it does transmit bumps more than any bike I've owned.
i have both swifts, Al and Ti, but i find the latter more stiff and yet absorbs much of the road imperfections. i think that chromoly steel and Ti would have more or less the same stiffness and shock absorbing qualities.

performance wise, i feel that my Ti is faster than the Al. i think that it is because of the Ti's weight.
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Old 08-04-15, 04:27 AM
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Originally Posted by puppypilgrim
A lovely build. Thank you for sharing.
thank you for the appreciation. i love this bike.
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Old 08-04-15, 05:49 AM
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Wish I could get a titanium raw old Moulton F type frame in titanium with the brazing shown like the Brompton raw, that would be my dream bike frame!
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Old 08-04-15, 09:27 AM
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jur, marxmini, Pine Cone,

Thank you for the response and observations re the Ti Swift. jur's point re the stem riser and forks was illuminating - the riser didn't occur to me. I've got a thudbuster, but front end harshness was always the much larger concern. Better grips help (Ergon), but it remains what I'd have to term a sometimes "brittle" ride. "Stiff" almost seems a limp word to describe how stiff the new aluminum Swift frame is.

Happy to hear reports that Ti feels more like chrome moly (whether it's the frame, fork, riser or likely combo that create the effect).

Last edited by towndock; 08-04-15 at 02:22 PM.
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Old 08-04-15, 01:35 PM
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For those who have relatively accurate scale, it would be great to hear how much your Ti Swift weigh and what components are on it. If it is too much work, don't worry about it but if possible, would be great to get some actual weights as a baseline.

Thank!
UL
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Old 08-04-15, 11:09 PM
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my Ti has campagnolo gruppo, brooks titanium saddle, 451 durano, mks pedals, 3t dropbar, and cinelli bar tape. it weighs 9.6 kilos.

Last edited by marxmini; 08-04-15 at 11:27 PM.
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Old 08-30-15, 04:20 PM
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Hi everyone,
Thanks to an e-introduction by Jur to Anita at Titan Products, I have one on the way. Thanks Jur!
OK, so those of you who bought frames designed around 451 wheels, what are your tire preferences? I'm getting parts together for this. Also . . . will 20 x 1 3/8, fit in the frame and fork, or should I stick with 20 x 1 1/8?
Rich
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Old 08-30-15, 04:52 PM
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Both fit well, I am using both on my 2. Good luck with the build! Pic when it's done...
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Old 09-03-15, 09:19 AM
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To Pine Cone, Jur, and anyone else who built theirs up with disc brakes.
Did you go with 140mm or 160mm rotors on the front? Looking at the pictures, the rotors all look like 140s, but maybe I'm wrong about that. Please let me know what rotor size you went with, and if it's 140, what mount setup you used on the fork. I can't find an front IS adapter that will work with 140, and my supplier says only 74mm post mounts will work for 140. Jur sent me all the frame/fork drawings and the disc forks are IS mount.
Thanks! Rich
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Old 09-03-15, 03:21 PM
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160mm. I learned the hard way, now I have several surplus 140mm rotors.
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Old 09-03-15, 10:59 PM
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160mm in the front, 140mm rear Avids on mine
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Old 09-06-15, 06:22 AM
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Originally Posted by jur
The weight of the aluminium Xootr Swift is 2.6kg, the Ti Swift 1.9kg.

I over-designed the tubing to be at least as stiff as the Xootr version.
Great build jur!
Just curious: didn't you spec your second batch frame with thinner tube walls?
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Old 09-06-15, 05:44 PM
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Originally Posted by pibach
Great build jur!
Just curious: didn't you spec your second batch frame with thinner tube walls?
That was something I considered, but later I thought that this might be too risky from a frame flexibility perspective.
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Old 09-07-15, 04:10 AM
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Originally Posted by jur
That was something I considered, but later I thought that this might be too risky from a frame flexibility perspective.
I see. At 1.9kg it is still the lightest (non-carbon) folding frame out there.

Regarding the stem, I've seen this solution:

That seems to be very neat, as it slightly reduces the folded size and serves for an auto alignment as well. Needs to be in proper length of course, the one pictured is too short.
Is this a possible option for future batches?

Then, I would eagerly like to see some pics of it folded. In particular: is it possible to rest the seatpost on the brake stay (put some foam in between to prevent scratches) such that the bike is shorter but still can be wheeled?
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Last edited by pibach; 09-07-15 at 04:15 AM.
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Old 09-07-15, 05:35 PM
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Originally Posted by jur
160mm. I learned the hard way, now I have several surplus 140mm rotors.
[PineCone] 160mm in the front, 140mm rear Avids on mine


Thanks PineCone & Jur . . . I was about to learn the hard way. I checked in with my parts supplier who told me IS mount /= 140mm front.

My frame is on the way. I think I have the front end assembly (steer tube, headset, straight stem) figured out from pics in this thread and my own experience, but I'll probably be back here with questions about that part of the assembly.
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Old 09-07-15, 05:50 PM
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Originally Posted by pibach
I see. At 1.9kg it is still the lightest (non-carbon) folding frame out there.

Regarding the stem, I've seen this solution:

That seems to be very neat, as it slightly reduces the folded size and serves for an auto alignment as well. Needs to be in proper length of course, the one pictured is too short.
Is this a possible option for future batches?

Then, I would eagerly like to see some pics of it folded. In particular: is it possible to rest the seatpost on the brake stay (put some foam in between to prevent scratches) such that the bike is shorter but still can be wheeled?
The frame as I have it is very stiff; I think there is scope for further mass cutting. One example is to use a thinner walled tubing for one of the top tubes; that would still result in a calculated torsional stiffness the same as the original frame. It might be harder to weld though, without it warping too much. Also, the rear triangle could be made from slimmer tubing. Personally, I am happy enough as is, and I don't have enough experience to be able to say if those changes would be wise in the long term.

The stem is a bit puzzling - I can't figure out how it works? If you have more info, I'm very interested. It is most certainly a possibility for the future, as each frame is in fact different from any other (so far at least).

[edit] don't worry, I have just figured it out. The small bit is clamped on the steerer, then the top bit slides over the bottom bit. There is a gap to accommodate the clamp bosses. My stem solution is very close to that one, I don't think there is a real structural difference. Size-wise it could be same as well.
[edit2]In fact my solution is superior in clamping; mine has 2 clamps while that one has effectively one clamp. Mine is probably a fair bit cheaper too.

Last edited by jur; 09-07-15 at 06:06 PM.
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Old 09-08-15, 01:58 AM
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Originally Posted by jur
My stem solution is very close to that one, I don't think there is a real structural difference. Size-wise it could be same as well.
Structurally very close, yes. Mainly the auto alignment feature would be nice. Might also just look cleaner when folded.

Fist time I saw this solution was at this Rob English kickscooter.
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Old 09-08-15, 11:04 PM
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Not exactly what you wanted but fairly close. I can't lower my seatpost becasue of the bottle cage I have attached there.
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