Moebius strip bike

 Before launching into this post I wanted to show a few pics of a moebius strip. It would be best just to make your own though! Cut a strip of paper, bring the ends of the paper together, twist one end of the paper through 180 degrees, and then join the ends. Here are a few pictures.

Moebius Strip

Another view

Strip as mounted in the bike. Imagine the fingers rotating and the mark and join moving across the photo as they rotate.

Chain with twist in top (drive) side.

 When my friend George passed away, his widow Christine gave some of his bikes to me. These were Linears, a bike made in the USA with a long, cherished back story, dating back to before 1985:  before most modern recumbent makers. I sold 2 of George's Linears to raise funds for OzHPV, the Australian Human Powered vehicle association. 

A third Linear from George and Chris's garage was only a frame with remote steering. I spent a bit of time kitting it out with a drivetrain, gearchanger, and front and back wheels and brakes. There was quite a bit of rummaging in the shed involved, and I bought the front wheel along with its tyre and tube from a local bike shop associated with BYK bikes. 

The bike just stayed like this as a rolling chassis as I had other bike projects going. I lacked motivation on this one, so it just stayed there for a while.

Then I accidentally put a half twist ( moebius twist ) in a chain I wanted to assemble onto a bike. This was a mistake, but it made me wonder about the possibilities on other bikes.  Most of the recent bikes I've made and ridden ( like the one here, pic 14 ) have twisting chain front wheel drive, but the chains twist through much less than180 degrees.

A bit later, I found this on the web,  an actual use of the moebius form for producing an output drive on a different plane to the pedals.  My application is a bit different, its just putting a twist in one side of the chain of a long wheelbase bike. In this case, its the top (driveside) of the chain. The wiki page for mobius strips says one of its applications is to even out wear on a drivebelt, and while this is a possibility for my use of the strip, its not really my purpose, it's just to have fun and make something interesting.

Anyway, the moebius chain works, and it works when riding the bike too! The seat I put on the bike is temporary and I can only just ride the bike because my legs are almost impossibly cramped when I ride it. Debut of the bike was on a rainy Saturday afternoon, I rode most of the way around the block on the footpath though, with the awkward riding it's not super safe on the road. Next morning I rode to our local cafe and my good friend Simon filmed and photographed me on the bike.

 I will work on the seat and see if I can make it a bit easier for me to ride. Meanwhile (tada) here is my introductory video and here (tada) is Simon's video of about the third or fourth time it had been ridden. 

This bike mod is very easy to try if you have a bike with a long chain and no chain handling hardware (pulleys and tubes) on the bike, plus a quick link in the chain which can be retrofitted. This bike has about a metre between the front and rear cog centres.

Rest in Peace my Dad, David Nurse, 1931 to 2025.

 

 

 

 

Cruzbike Quest Hi Racer

 

New version of Quest with 500mm chainstay and aero, load carrying seat and tailbox.

Quest with 290mm chainstay and original seat

Quest with 360mm chainstay and 16" rear wheel and aero, load carrying seat and tailbox.

Scoping - rear suspension removal

Scoping - this folding bike frame has a very cheap version of the suspension pivot in Cruzbike Quests

Trying an MTB rear swingarm in the Cruzbike. It was slightly too wide. The visible parts of the suspension bushing were later removed.

Trying the folding bike swingarm

New 500mm fork weight is 850g in steel.

And the old 360mm fork is 330g

Similar difference in pivot hardware weight: 45g aluminium from Cruzbike

versus 110g steel from MTB

Final assembly with accidental fisheye effect

Preparing for final assembly

Widening the slots at the bottom of the chainstay from 6mm to about 10 mm was done by wearing away the steel using drills, and stepping up the drill size by 0.5mm each time. Before this slotting was done, a steel sleeve was brazed over the chainstay end to thicken it and ensure there was enough material.

Lower part of chainstay done

To reduce the width at the bearing, the lip on the outside of the bushing was removed allowing it to be pressed further into the housing. Loctite secures it in place

New top part of chainstay and old chainstay

Initial measure up. With a 500mm chainstay, the bottom bracket would be in about the right position.

Hi

 

The above photos show some of the work I've put in over the last few weeks, adapting a rear suspension system from an old, heavy mountain bike to become a long chainstay for a Cruzbike Quest. The result is shown in the top photo, it's sort-of a Cruzbike Quest Hi-Racer.

I have 2 Quests, both of which I tinker with extensively. I've already made 2 load carrying seat / tailbox sets for them, and have fitted hub dynamo lighting to one of them.  They are nice bikes, and the moving bottom bracket front wheel drive system is interesting. But for me, one of the chainstays (see pic 2) was way too short, so I've made steps to change that, looking out for, and eventually finding bike bits compatible with the Cruzbike chainstay. I bought the bits home from the Wecycle shed several months ago, and now we have some action on the building,  woohoo! During construction I used the bike as a jig. By removing the existing chainstay and moving the top tube up, I was able to place all the components together before "tack-brazing" them together. Then the chainstay came off the bike and brazing together was completed before painting.

Will report later on how it rides after a few tweeks.

For now I have been around the block and noted the following.

If, in your excitement, you forget to put your taillight on for your twilight blockie on your newly modified bike, you are a doofus. I am that doofus.

And possibly more relevant, the handlebar is too low and my legs bump into it. Moving brakes, reflector and bell would help but really the whole handlebar needs to be shuffled out of the way somewhere. 

From all my handlebar stems, I sorted out potential options for improving the handlebar position, and they are at left.

Settled on this one particular stem for now but might try others

With me on it. I'm reasonably horizontal but still comfortable. Compare with pic 2. Also note the rear suspension is compressed!  I think these sort of photos are the only simple way of assessing the suspension. The tail fairing is a bit low at the top and should be level with my shoulders.

 

Another Mixte

New front derailleur is at the back. The other one had been rubbing on the chain for a long time and is almost warn through. Both are ....

the Suntour Spirt "normally in high gear" type as described here in Frank Berto's book The Dancing Chain

Chain before replacement.

Completed bike

Milk crate = Preston Pannier mounted on custom adapter. There are 2 3d printed crate locaters, files for printing them are available on Thingiverse here.

Also 3d printed are plastic bushes for the Suntour thumbshifters.

Reflector came from the donor bike.

Chain after fixing

Original brochure from 83 / 84 Repco Catalog

This bolts to the underside of the rack to keep everything in place

Twin Thumbshifters

Donor bike

This bike (Repco 83/ 84 mixte) was listed for sale on Facebook marketplace for $20.00, and was about 1km away from where I live. So I was able to ride to pick it up, and wheel it home, riding one bike and wheeling the other. 

I was quite pleased to find it had interesting Suntour gears on it, and despite some plastic bits broken, I was able to fix them. It now rides quite well. I didn't touch the brakes: all the fixing was in the drivetrain, and I regreased the bottom bracket and used the donor bike chain. Very pleased with how it turned out and I like the sombre dark purple colour.

Fixing a Mixte

 

Mixte as traded

Huashen folding bike as traded

Mixte at home with home-painted handlebars and stem.

Initial weigh in with steel brakes, brake levers, front mudguard, cotter pin cranks and steel 27" wheels, 15.28kg

To accommodate more bikes I disposed of these ones - mixte bottom bracket is from the pink bike, and rack is from the teal bike.

Hi

Bicycles are poetry! Bikes are quite small thing compared to other transporters of goods and people (ships, cars, submarines, trams, trains), and don't even have their own motors, but they can accomplish much. If a car is a novel, then a bike is a poem, it often does the same thing, but just in an abbreviated form. Please excuse the philosophy, but my design blog post has similar themes and got me thinking about all this!

But you know, if you are surrounded by bikes all the time, the fact that they might be poetry wears off, and you just deal with them as highly repairable, highly malleable, enjoyable objects. But every now and then, a nice bike comes along and reminds you of the poetry, which is why I still muck around with them I guess.  I consider Mixtes a great design and have enjoyed resuscitating this one. I like the position of the rear brake in some mixtes. They are just in a direct pull line along the top tubes so there's a bit less fuss there compared to other bikes. Here is a link to another Mixte from a Hobart public bike shed.

A few weeks ago, a friend texted me with a "dead bike alert" including the top 2 pics as follows:  

"Bikes in hard rubbish halfway up my streer" . I'm pretty sure she meant street! Anyway, despite the fact that my house often looks like a hell for bicycles that have misbehaved - with bikes left languishing and half disassembled - I took up her tip and put the bikes in the back of my small Kia on the way to visit my Dad.

The bikes were an old mixte which I thought I could fix up, and a white folding bike. I have been eying off this style of folding bike (on Facebook Marketplace) for a while because it has rear suspension a lot like my Cruzbike Quest, and I thought they could be mined for parts. More on that later...

When I got the bikes home, I weighed and photographed the mixte. It had been partly spray painted grey and looked a bit manky.

Scavenged parts fitted were alu centre - pull brakes, cassette bottom bracket with square taper shaft, alu crankset, steel handlebars, shifters, Alu brake levers, alu 700C wheels, rack and rack adapter for milk crate,

The "after" photos follow, I'm happy with the result but I haven't ridden it yet. Still on the to do list are 

Attach rear reflector

Fit bell

Reattach rear derailleur  by drilling and tapping into frame. This is to move the back wheel further back to fit in with the size of rear brake I've fitted.

 

 

 

New brake position is under top tubes to avoid damage to brake cables when mounting the bike. (Practical but sightly less pretty and poetic) Also, wooden rack adapter is shown

Crate mounting detail.

Bike with crate attached

Woohoo, I have bling! A full set of brake and gear cable outers was gleaned from the white folder.

Just about finished

With rack and crate adapter, the bike weighs just a bit more than the original