Blasptwenty: Overdone, over-complicated mod build for video rig
 

First off, all purists be warned before entering! (Can't believe I'm saying that).

**** EDIT: IT ROLLS, IT RIDES! - see last page in thread ****

https://cimg2.ibsrv.net/gimg/bikefor...da23ad5329.jpg

Let me preface this build: I've been using my '70 Twenty for shooting work-related Bike to School events. This is usually done with a GoPro mounted front and back, and these have done well enough for now:

https://cimg9.ibsrv.net/gimg/bikefor...843de757d1.jpg

But it's not good enough. I usually shoot 2.7K video so I can re-crop the footage, and the bitrate on the GoPros (I'm using 4 Silvers now) with that video size is terrible; worse with motion. As a result, the ride footage always tends to look soft and mushy. Color depth is also a bit iffy.

Since then, I've acquired a gimbal and a Panasonic GH5, and I've got it in my mind to finally merge gimbal with bicycle. For the meantime, I've designed a 3D printed plate that'll sandwich the Pletscher rack and hold a cheese plate above it. In turn, the plate will hold a camera mount.

https://cimg0.ibsrv.net/gimg/bikefor...edbe77ecb2.png

It has yet to be printed; I'm hoping I get the word next week that it is done.

But I don't want to modify my '70 Twenty any further than that. I like it original, even though the brakes are abysmal, the wheels are heavy, and the cotters catch my pantleg every second.

Obviously, this is a serious situation of variable "N" in need of "+1." And since I have access to some brazing equipment and other doo-dads over at Mike Terraferma's shop, I figure this was an opportunity to pick up a decidedly bad Twenty so I could do some serious modifications to the frame itself to turn it into a single-purpose vehicle: An all-around, gimbal-equipped camera bicycle.

I don't have much to share at this point, except that the victim has been acquired. I dug up a suitably ratty Twenty - this one also a '70 - on OfferUp. It is essentially identical to my existing Twenty, with exception to being one of the lone oddballs with brazed-on bolt ears on the seattube. In reality, it looks worse than it is with its home-brew paint job...though the AW hub won't engage and most of the chrome is covered in silver paint. (Ok, I take it back - this thing is a turd).

https://cimg1.ibsrv.net/gimg/bikefor...a89920d82c.jpg
https://cimg3.ibsrv.net/gimg/bikefor...2c59204d13.jpg

With the guardian of the fleet:

https://cimg2.ibsrv.net/gimg/bikefor...969143f4da.jpg
https://cimg7.ibsrv.net/gimg/bikefor...41892251bf.jpg
https://cimg9.ibsrv.net/gimg/bikefor...27f121e5d3.jpg

Since I need little more than frame/fork/handlebar, this Twenty should do nicely, and I won't regret putting the brazing torch to it.

This said, I'm envisioning something along the lines of the following (honestly, posting this list is mostly so I just don't forget:

• Steel racks designed to accept camera cheese plates brazed directly to the frame, front and back.
• 26TPI BB threads filled in, tapped to 24tpi, BB faced to 73mm for a square taper or Hollowtech crank, whichever comes first for cheap
• Sun CR-18 ISO 451 rims with Primo Comet tires (possibly a bad idea for smoothness, even with the gimbal, but I'll be able to check this against the 406's on the other '70.
• Modern Sturmey AW so I can stand on the pedals if need be - already have this.
• Drum brake up front - or if possible, convert the fork to disc and shove a set of proper dropouts in the cheap-o Raleigh blades in the process
• Tektro long-reach dual-pivot in back
• Removal of the factory kickstand for a kickstand plate; installation of a double kickstand
• Possible integration of a Pelican case to hold camera/gimbal in stora
• Braze-ons added for a rear wheel lock (like an Abus Pro Tectic)
• Planet Bike Cascadia ALX fenders
• Some other stuff I can't remember at this late a time at night.

Feel free to PM if you happen to be parting with any of these bits I need.

It's decidedly not really a C&V build, but the starting point of the build is. Sure, there are other folders, but I believe in the Twenty and am familiar enough with it that I'd like to start with it as a base.

I've got the rear wheel torn off it in the meantime, but not much else. Cranks come off tomorrow, and I need to touch base with Mike TF to see when I can spend some time modding this thing.

-Kurt

I like. Hal Needham would have approved.

Nice to hear from you again. Or have I just been missing your posts?

The videos I've done for work aren't tied to my personal sites, but they are on YouTube. I started using the dual GoPros in 2017. Here's a playlist of the last 5 Bike to School Day events we did; both 2017 events and the 2018's onboard footage is from the Twenty:


Mind, I'm big into protected bike lane advocacy and Dutch/Danish approaches to utility cycling. Some of the ideas in these videos may not align with my personal beliefs.

Best comment ever.

Just came back a few days ago.

Tell me (and my wallet) about it. ;)

-Kurt

I like the music in 7 time!

+1 on the double-barrel brakes.

While I've always liked the GoPro, I've never liked the mounts. Have you thought about wider bars and hanging a GoPro under it? The "hanging" mounts seem to work better in some applications, though I suppose in theory the vibration issues would be the same. They have mini-steadycam setups now, I think, and the software is pretty good.

The last time I helped anyone with bike-mounted video, we put rubber 0-rings between the frame and all the rack mounts, and put a Sony digital video camera (studio style) right on the rear rack, on a rubber mat, with a 650b rear tire, then he did a lot of editing.

I think I have those tires, just walked out to the Atelier, which is a mess right now. I'll check again later.

edit: sorry, can't find them!

I just came here to say "Hi, Kurt!"

:)

Glad to see you're mind is still wandering...

DD

Good to see you posting again, Kurt. This is going to be a fun build to watch!

I wrote a big reply 5 minutes ago and the browser just ate it. Can't get more "classic and vintage" than that.

Anyway, I'll keep this short:

Tore the back end of the Twenty apart today. Kickstand is in a really sorry state of operation and is the one thing I haven't taken off just yet. Since I want a dual stand to keep it upright when parked, I'm going to cut it off and dress the BB smooth when I get the chance.

Excuse the disaster zone, but I bought some toolboxes recently and am in the middle of reorganizing the entire workshop. Hence, mess.

https://cimg9.ibsrv.net/gimg/bikefor...eb40fc8979.jpg
https://cimg2.ibsrv.net/gimg/bikefor...b403bc9e08.jpg

Soon to be eBay bait (most of it, anyway):

https://cimg5.ibsrv.net/gimg/bikefor...a9c6dd4677.jpg

I decided to verify the operation of the modern Sturmey AW, as I'd never ridden it before. I used the Pastor Bob Stump Dump™ '80 Raleigh Sports (Stumpy?) for testing. This bike has been sitting completely unused in the shed for years, thanks to my grand scheme of putting an FW in the original AW hub shell. I effed up something in the reassembly and never got the clutch to engage.

The new wheel - even as a test - gave Stumpy life that it hasn't had in years. It also gave me an interesting test ride, as you might notice the Weinmann sidepulls were removed long ago for dual pivots that never materialized...

https://cimg9.ibsrv.net/gimg/bikefor...84df00f7ad.jpg

What a modern AW looks like. It must have the spiral-type clutch that Sturmey developed in the 1980's to eliminate sudden disengagement between gears, because the shifting is much more immediate when the shift actually happens. No longer do you lose 10 degrees of rotation at the crank when the shift happens. Not sure if I like it or not from a C&V perspective, but it should cut down vibrations at the camera.

https://cimg8.ibsrv.net/gimg/bikefor...dfd0c83102.jpg


Mounting anything on the bars means a wandering crappy shot. Vibration issues have been OK, if not great, on the existing Twenty; the GoPro image stabilization helps a bit. Gimbal should take care of that.

This is the setup that I'll be using with the new bike:

https://cimg3.ibsrv.net/gimg/bikefor...8f708584a7.jpg


Someone just offered me a pair of built wheels for the project with tires, so this part of the plan may have changed. Thanks though.

I've thought about the headtube. I figure I can keep most of the original setup (which I like) by putting a standard Raleigh upper headset on it and using a shaft collar clamp to keep it from loosening up. Honestly, I'd rather sleeve and extend the steerer than shorten the headtube; after all, the Twenty is short enough as it is in this area. Lots of effort for little result though; probably easier to chop a bit out of the headtube when the time comes.

The cranks and brakes are two of the things I'm immovable upon, the cranks for the following reasons:

1. The cotters always catch my pantlegs at the worst possible moments (e.g., cranking hard)
2. I tend to bend the squared-off Raleigh crankarms that you find on Sports, so the ovalized Twenty arms can't be any better (pretty sure one of the arms on the brown '70 is slightly tweaked, come to think of it.
3. I have access to a framebuilder who can fill the BB with brass so we can tap it out with 24tpi threads
4. I've yet to see someone put a Hollowtech-style 73mm BB and crankset on a Twenty and I just want to be a silly braggart about it (if the opportunity arises to install such components).

The new AW I have (which is probably already 10 years old) is identical to the old externally, except for an aluminum shell. Uses the same exact shaft paired with the thicker centering washers that came out around '77-78 or so when Raleigh finally increased their dropout slot size to match the rest of the world. All I have to do is swap in the older, narrower washers.

If you need another twist shifter, let me know. The modern hub had one tied to it, and I have no use for it.

Hey DD! What have you been up to? Have you resisted the urge to drill every piece of aluminum at the house?

Should be equally fun to build! Looking forward to it - it blends two passions of mine. Hopefully it goes well.

-Kurt

You may have taken warnings about the old AW too seriously. Yes there is a danger of hitting neutral between 2nd and 3rd, but it's not that likely, and it's not sure to cause injury.

And doesn't the new 3-speed hub go by a different model name now?

Hey Kurt. Interesting project. Experience as a post editor has shown me that in-camera stabilization costs you more resolution than you'd like. If your editor is good with After Effects trackers, you can keep resolution high and fix 'shakey-cam' shots. Of course, post costs time and money.

Good Luck.

Precisely why I want the gimbal, as it reduces the need to rely on IS (or for that matter, for IS to rely on the operator. I believe the tech has it's purpose, but one has to know its limits and shoot within those parameters). I've been pretty impressed with even the cheap Panasonic 14-42 lens though, and IIRC, the GH5's sensor is electromagnetically stabilized too. Best of both worlds, and I've been impressed. Definitely superior to Canon's photo-oriented IS.

Premiere or AE's Warp Stabilizer sometimes helps, but it is no silver bullet, any more than point-based motion tracking. Even if you can stabilize the shot, you can't remove the motion blur from the movement. I'm a firm believer that stabilization in post is a crutch for not doing it right in the field.

I fully intend to share some onboard footage once I have the 3D printed plate mounted on the brown Twenty. Should serve as a good proof of concept and prevent any mistakes from cropping up in the purpose-made machine.

-Kurt

I know the AW way too well and know what it'll put up with. I've had a clutch slip between gears under load out of the saddle once, but that was it. Granted, I also don't push the envelope.

I am, however, flippant with the shifter, and often don't hit the shift points just right. It's fear of hitting that dead spot - usually between third and second - that makes me want to use the newer hub.

Sturmey still lists the AW, but with the classic steel shell. If I had to guess, that hub in the '80 Sports right now may be equivalent to the current S-RF3. It's worth noting that unlike any of the current stuff - including the current AW - my hub uses the same exact cones and washer locks as an AW from back in the day.

-Kurt

Great setup, it looks like. I texted my friend who used a Sony something video camera and asked him why he considered it the "industry standard."

He said it was the go-to camera in the porn industry. OK.

One of my favorite pics of Kurt is him with a pipe wrench on a headset and a fairly large boot on the workbench.

Every time I watch the Mecum Auctions and a Mustang comes through like his, I remember him.

Just get a chicken

Thank you! ;) Very tip heavy! Well done! :thumb:

I've gotten to know a rather famous film producer/director (most recent film was The Zoo Keeper's Wife). He looks at nearly everything as if viewing it through the lens of a camera. So it's fascinating to talk "camera perspective" with him and this is where you experience the brilliance of his creativity.

He's back in LA working on a project for Netflix at the moment. If he was here I'd share your plans. I'm guessing he'd very much approve. He'd probably make some suggestions for different mounting points. Maybe ones which are at or near the wheel axles? At least that would be my 2 cents while you have the brazing torch out and are adding mounts.

After you complete the mods, PC it flat black to minimize glare bleed into the camera lens!

OK. I must have misunderstood you to have said that you haven't ridden one before.

That chicken video is great.

One step forward, five back. The 3D printed plate was finished today, and it's a beaut. Fit well too, though I did have to modify it to clear the rattrap. Hey, that's why they call it "rapid prototyping," after all.

https://cimg0.ibsrv.net/gimg/bikefor...d26228f100.jpg
https://cimg1.ibsrv.net/gimg/bikefor...c54c831389.jpg
https://cimg3.ibsrv.net/gimg/bikefor...1a1f03811c.jpg
https://cimg5.ibsrv.net/gimg/bikefor...323d06e15f.jpg

https://cimg5.ibsrv.net/gimg/bikefor...14ab579d91.jpg

Now, while that looks nice, the Pletscher rack cannot really support the extra weight without excessive shimmy that ruins the whole thing. Since the gimbal sits a whole foot higher than this, the result was - to say the least, a bloody disaster.

Heck, mounting the camera directly to the camera mount on the plate gave a steadier - if still rough - result.

So it is back to the drawing board. I know it should be simple enough to braze a steel rack onto the frame of the other Twenty (thanks, RHM), but there's still no guarantee that this will play nice with the gimbal. What's more, I was starting to realize that a lot of vibration was coming through the road surface, which means even the fat ISO 406 tires aren't helping. The 451's are going to make it worse.

I'm really thinking that this rig may force me into one of these wire mount-style isolators. Just what I need, another $400 down the tube:

https://cimg9.ibsrv.net/gimg/bikefor...13787aefdf.jpg


Also looked at the handlebar shock mount that DJI sells for their Osmo mini gimbal. Not bad at all, but half of the reason of doing this is so I can mount the GH5 on the bike and get high-bitrate footage.

Well. Someone has pretty low standards for equipment and hasn't heard about GoPros being the defacto norm for that bunch. :roflmao:

Jokes aside, he was probably referring to the Sony FS700 if his information is old, or the A7S/A7R mirrorless cams if current. The FS700 is an ergonomic nightmare though. Bad enough using it in normal situations.

I ran across the old pipe wrench headset photo in my archives a bit ago but couldn't find it. Will the Mavic Hatter do for nostalgia's sake?

https://cimg2.ibsrv.net/gimg/bikefor...61a449ba3a.jpg


The idea behind the mounts is to make it possible to bolt cheese plates to the bike, and thus allow me to rig whatever I want, and extend the mounting points with rails outboard. Pretty much the same idea, just not as low. I can always flip the gimbal upside down to get a low shot, but then I'll probably have to raise it from rack level. At that point, it'll scrape the ground in a turn.

Flat black is definitely the end color, much as I hate it for aesthetics. RHM is hooking me up with some black wheels, but they have stainless spokes. Will have to do for now.

The chicken is also cheaper. Tempting.

-Kurt

Been through three myself. Still have one, and the blue makes four, not including the service I've done on the neighbor's R20, or the orange one (with the Hans Ohrt shop sticker) that I serviced.

https://cimg4.ibsrv.net/gimg/bikefor...904236a7d2.jpg
https://cimg0.ibsrv.net/gimg/bikefor...f2fe2c26a9.jpg