1995 Slingshot RDQ-2

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QuangVuong
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1995 Slingshot RDQ-2

Postby QuangVuong » Tue May 09, 2017 4:27 pm

Slingshot is a company born in 1982, who started making bicycle frames in 1988. Rather than a standard down tube, they replaced it with a cable and spring. They made revisions to the design over the years, but even up until today they are making frames with a cable and spring down tube. There was a good amount of history on the Mombat site however it is currently down. Hopefully that comes back up sooner or later, but for now, it can be seen here: http://web.archive.org/web/201612040111 ... gshot.html (Thanks to find_bruce and clydesdale scot for letting me know)

Looking at the US Patent US5080384 A for the Slingshot bicycle design, the reason behind the cable and spring was that it would absorb the shocks of rough riding particularly for 'dirt bike racing'. It also apparently provided an additional push on the pedals at the dead spot during pedalling (the up stroke), as the spring relaxes after being compressed from the spreading of the frame during the down stroke. I've only hopped on the bike for a few hundred metres and all I feel is the BB flexing all over the place. I will have to keep riding it more to see if the claims are true.

My frame was found on Gumtree, a rarer 700c road version. NOS with a couple marks on the paint from storage. Made on 3-2-95 as per the serial number on the BB shell and never been put together until now. I chose to go with a Shimano 6400 which was what I had lying around, and was one of the original groupsets available. The Slingshot frames were all the same, but each was equipped with different components. The RDQ-1 came with Dura Ace or Sachs New Success components, then a step down was the RDQ-2 which had Shimano 600 or Sachs 5000 components, then the RDQ-3 came equipped with 105.
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I had issues with finding a suitable seatpost. From mentions online, I found that many people use a 31.8mm seatpost. From my measurements, the ID is 32.227 mm with an OD of 35.17 mm. The OD would suit a 34.9 mm FD clamp, but a 31.8mm seatpost is far too loose.

ID measured with a 3 point internal micrometer.
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OD measured with a Mitutoyo 25-50 mm micrometer.
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So I ended up making a shim to suit a 27.2 mm Kalloy seatpost. It was turned from a scrap piece of aluminium that I found around my work place. A more retro seatpost would be nice, but it is hard to find one that is long enough. The seat tube is only 46 cm c-t even though it it a 55 cm effective TT.
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For a frame that does not have a DT, and has a shorter ST I would've imagine it to be lighter than a normal steel frame, but it isn't. The frame weighs 2260g with a 535g aluminium fork. The frame is made with True Temper tubing, but it must be thicker gauge than what was available from the other tubing manufacturers.

Anyway, it was unveiled at the 2017 Sydney Classic Bicycle Show. Unfortunately it lost out to a Colnago Mexico.
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Here are more pics
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Got some retro white/red fade bar tape.
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QV sticker goes on the bare HT.
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The spring force can be adjusted with the nut situated above it.
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Other end of the cable.
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Flex joint in the TT. This stops fatigue failure if it was a solid TT. This is made of Scotch Ply which is a 3M product made of fibreglass.
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Gold chain as always
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These generic dropouts have eyelets as standard. Why were they not removed? I really wonder as there's no space for mud guards nor a rack.
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Interesting FD cable routing. I am actually not sure if this is the correct way, but it seems like it is. The cable comes down, then wraps around the roller and crosses itself before coming up to the FD. If wrapped around the other way, then the cable will rub against the backside of the FD.
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Years ago I built these 18 spoke wheels. 36h 6400 hubs were laced to 18h Velocity Aerohead rims which I got as warranty replacement. With the help of Joshua Beck of XLR8 wheels I built my first set of wheels. I never really used them much, until now.
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Rear hub is DS 12 spookes 2x with NDS 6 spokes 1x.
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Last edited by QuangVuong on Sat Aug 26, 2017 3:33 pm, edited 4 times in total.
VillaVelo, by the Vuong brothers

Blog: https://villaveloframes.wordpress.com/
FB & IG: @villaveloframes

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find_bruce
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Re: 1995 Slingshot RDQ-2

Postby find_bruce » Tue May 09, 2017 5:12 pm

Love it Quang, very sad I didn't get to see it in the flesh. I love the dead-ends and backwaters of innovation.

The usual goal is lateral stiffness & vertical compliance. The slingshot design achieves vertical compliance, but as you have already noticed, at the loss of lateral stiffness. I suspect the extra weight is a result of trying to recover some of that lost lateral stiffness.

The mombat site is still available on the web archive

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Derny Driver
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Re: 1995 Slingshot RDQ-2

Postby Derny Driver » Tue May 09, 2017 5:13 pm

Looks amazing QV. Beautifully done.

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WyvernRH
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Re: 1995 Slingshot RDQ-2

Postby WyvernRH » Tue May 09, 2017 8:57 pm

Like your head badge logo, very cool!
I remember trying these frames out when they came out way back and even for a low powered tourist like me they sucked badly compared to 'classic' steel frames. I'm told some MTB guys back in the day liked them but I suppose the more advanced suspension available today has negated that.
Nice trip down a design variation that in the end lead to nowhere unfortunately.

A good example to keep for posterity with all the other things that re-surfaced with the 80's to 90's MTB redesign enthusiasm craze (or resurrection of old ideas depending how you look at it...) like offset cranks, high level chain stays and the like.

Richard

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RobertFrith
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Re: 1995 Slingshot RDQ-2

Postby RobertFrith » Tue May 09, 2017 11:03 pm

Fascinating read and great photos, thanks :-)

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cmh
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Re: 1995 Slingshot RDQ-2

Postby cmh » Mon Apr 09, 2018 9:47 am

Man, that bike is a beauty. When I bought mine in '94 I ran into the seatpost sizing issue, and at the time I was in college and working at a bike shop, and the only seatpost I could find that would fit was a Syncros and it was $90 or something horribly out of my price range. So, I had to get really creative otherwise I wouldn't be able to ride the bike - so wandering around the shop I discovered the down tube of a Specialized Allez of the time was the right 34.9mm outer diameter with a 26.8mm inner diameter which matched standard seatposts of the time. I cut down a spare seatpost I had and epoxied it into the top of the section of down tube, then sanded off the clear coat and had a seatpost. Early photos of the bike you can still see the "LLEZ" from the logo! Amazingly enough, that post worked and I've still got it, although since then I've swapped it with a 400mm 34.9 post from a Scott Scale.

What's interesting is the seatpost size difference between the two years. I wonder if it has something to do with the 700c wheels, as mine is 650c.

The other thing was the handlebar position - waaaaay too low. I wound up having Salsa create a custom stem that was 190mm long and quite steep - at the time that didn't seem like a horribly bad idea. :D

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GaryF
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Re: 1995 Slingshot RDQ-2

Postby GaryF » Tue Apr 10, 2018 5:31 pm

Great reading with great feedback too. I was attracted to the Slingshot way back when but was always too nervous to actually take my curiosity further.

I am very interested to read about your thoughts regarding the bottom bracket but I'm afraid an initial sloppy feel would have put me off the frame back then. Now, I think I would like to have one just because it is different - so different. Congratulations keeping an open mind on the flexy BB.

Your refurbishment and build is first rate - as usual, and I'm not surprised to read you achieved a runner-up award. Nothing has been overlooked like cable casing lengths and perfectly clean everything. Absolutely well done. Nicely turned and slotted sleeve as well. I too love the 'QV' on the head tube.

Congratulations QV.

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