SS Coupler Military Bike stupid idea?

[Yuhan Wu]

Hi guys, I've decided to add ss couplers to my hunqapiller finally. Because I want a 29er I can easily fly with to mountains/parks or some gravel races like dirty kanza. I was interested in the vintage military bikes which has a hinge on the top and down tubes. These bikes could be folded and carried with shoulder straps by the soldiers. Interestingly, the idea is very similar to the modern couplers. But the vintage hinge locates in the mid point of the top tube while modern coupler is closer to the seatube. I heard one reason making it closer to seattube is for easier boxing large frames. My bike is only 54cm. So that shouldn't be an issue. 

I wish to know your guys' experience/opinions of the ss couplers. Does the position of the toptube coupler matters in terms of riding quality, strength etc? Is it not realistic that carring the bike on your back when the terrain is too rough and then ride the bike when it's ridable? Thank you so much!

I'm adding a diagram shows the frame cutting position and the shape of the two half. 

[Kainalu V. -Brooklyn NY]

I've only opinion to share, but I think it doesn't matter where you split the frame, as the S&S couplers, when properly tightened, will add some rigidity if anything. But that's only based off of what I've seen, not experienced. Experienced coupler pros like Bilenky in Philadelphia would be your best bet at an accurate assessment.
Enjoy that bike, wherever you decide to cut it in half!
-Kai

[Jim M.]

I almost bought one of the BSA paratroop bikes at American Cyclery's garage sale one year. They may still have a couple. Cool but kinda wobbly, which may be from the hinge being old.

I would think that if you have butted tubes, you'd want the coupler closer to the thickest part of the tube. But a real frame builder can probably answer that.

jim m

wc, ca

[Benz Ouyang, Sunnyvale, CA]

On Wednesday, August 5, 2020 at 2:56:26 PM UTC-7, Yuhan Wu wrote:

Hi guys, I've decided to add ss couplers to my hunqapiller finally. Because I want a 29er I can easily fly with to mountains/parks or some gravel races like dirty kanza. I was interested in the vintage military bikes which has a hinge on the top and down tubes. These bikes could be folded and carried with shoulder straps by the soldiers. Interestingly, the idea is very similar to the modern couplers. But the vintage hinge locates in the mid point of the top tube while modern coupler is closer to the seatube. I heard one reason making it closer to seattube is for easier boxing large frames. My bike is only 54cm. So that shouldn't be an issue. 

I don't know whether a hinged frame, even if it's a 54cm, will fit in a 26x26x10 box, because a normal S&S coupled bike isn't packed as if it's hinged at the couplers. Furthermore, if you're portaging your bike, I don't know if it needs to have the frame broken down, because AFAIK, superhuman Lael Wilcox doesn't ride a collapsible frame and she occasionally portages her bike (mostly through trails on her routes that do not allow cycling).

I have a S&S coupled bike, but I have no idea if it's stiffer than a non-S&S twin, because it wasn't converted. However, I imagine a rather big chunk of thick-ish metal is probably stiffer than whatever tubing it replaced. This will be your case, because you're converting and probably won't/can't be redesigning the entire bike to accommodate the stiffer S&S coupled tubes.

Finally, despite owning a S&S coupled bike, I'll recommend your reconsider/reevaluate. if you don't travel a lot, it may not be worthwhile to retrofit S&S couplers. Use bikeflights, shipbikes or something similar. These use larger boxes, and you'll spend less effort trying to disassemble/reassemble the bike at your destinations. Breaking down a S&S coupled bike is rather involved (30+mins per) because it all has to fit in a small box in a particular way. With the bicycle shippers, you can use larger boxes that will require less disassembly.

[Yuhan Wu]

Hi Benz, thanks for sharing your experience! I do travel a lot. Internationally sometimes. So the couples make sense to me. I'm 145 pound. Huqapillar is a little overkill already for most ridings except for some really heavy load camping or grocery shopping. I shop tons of food during the qurentine. It did amazing job carrying 50lbs goods. Sometimes I carry 3 big watermelons on the front rack. It still feels very stable with a 70cm wide bar. Taking the racks off it feels like a fast gravel bike with dirt drop and supple tires. Stiffness wise, I'm not sure if it will make too much difference for me since it's already kind of overkilled. That's why I only use 2.0 - 2.3 tires for hunq. Maybe I should ask rivendell for some advice about the tube butting!

Benz Ouyang, Sunnyvale, CA <benzo...@gmail.com> 于2020年8月6日周四 下午4:13写道：

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Yuhan

[Yuhan Wu]

Yeah, I think in the butted tubing case, the riding should dictate rather than the folding/hiking. Thanks for the advice!

Jim M. <math...@gmail.com> 于2020年8月6日周四 下午1:31写道：

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Yuhan

[Yuhan Wu]

Thanks for the suggestion! I'll probably go for the Bilenky. The 29er hunqapiller is definitely the most fun and comfortable bike I ever have!

Kainalu V. -Brooklyn NY <kaivi...@gmail.com> 于2020年8月6日周四 上午11:53写道：

I've only opinion to share, but I think it doesn't matter where you split the frame, as the S&S couplers, when properly tightened, will add some rigidity if anything. But that's only based off of what I've seen, not experienced. Experienced coupler pros like Bilenky in Philadelphia would be your best bet at an accurate assessment.
Enjoy that bike, wherever you decide to cut it in half!
-Kai

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Yuhan

[Michael Hechmer]

I have two SS coupled bikes, a bilenkey tandem and an old (1984) Trek 620.  I don't think it makes any difference  in the ride, but it can make a difference in the packing.  I would suggest you use a bike builder with experience and just his/her judgement about the latter.  Having two somewhat equal sections makes it easer to stow, both in a case and in a car.  I have had more hassle with the cable disconnects, poorly positioned, when trying to clamp a TT in a repair stand.

Tandem's require a great deal more thought and experience.  I've got that one dialed in.

Michael

[Yuhan Wu]

 Thanks Michael! 84 trek 620 is the first vintage steel touring bike I ever owned! It rides great but I didn't like the vintage components. Sold it years ago. Still miss the beautiful pewter color under sunlight. I don't know what kind the paint they used back then. The quality feels better than many modern bikes including Riv in my opinion. Maybe because it's thicker? The paint on my hunqapillar gets chips pretty easily.

I couldn't find any bikes with a coupler in the middle of TT on the internet. So I was skeptical. I want to learn people's experience before going to a builder. Thanks for the input! I think the disconnects shouldn't be too hard to fix by swapping out cables. But the disconnect would be too far away from the cable housing stop which is not ideal?

Michael Hechmer <mhec...@gmail.com> 于2020年8月9日周日 下午12:14写道：

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Yuhan