A recumbent bike project
by Olaf Johansson
   
 
Small & simple

This is a small, simple recumbent bicycle. With its 16" wheels Monty is a portable vehicle which easily can be dismantled. I wanted a bike that I can bring on trains, buses and other means of public transport. Since there are hardly any small foldable recumbent bikes on the market I decided to build one myself.

Centre steered

I have chosen centre steering because this design makes the bike simpler to build. There is no need for a handle bar or steering column. Once the riding technique is mastered it is a relaxing way of biking. The rider sits in a comfortable, recumbent position and does not only pedal with his feet but also steers with them. Hands can rest in one's lap or you may comb your hair or even operate a camera while riding. As steering pivot an ordinary bottom bracket of cassette type is used. The quadratic shaped axle fits into slots in the pivot fork where it is locked by crank bolts.

Simple design

I wanted as few components as possible so I chose a 3-gear hub with back pedal brake. The only lever or shifter I have on Monty is the gear shifter below the seat. With the coaster brake I am able to brake without using my hands and this enhances the freedom of the centre steered bike even more. The simple design also makes for lesser items on the bike that can hook on to things during transport. I did not want suspension because it would have made the bike heavier and also more complicated to build. To give myself best possible comfort the bike is equipped with cushy 2,0" Schwalbe Big Apple tyres.

Inspiration

Apart from my own needs for a small bike there has been three major sources of inspiration for this project. One is Hanno Hirsch who built the Twist which is also a centre steered recumbent with 16" wheels. Major difference between Twist and Monty lies in frame geometry. While Twist is a miniature of the commercially produced Flevo bike, Monty is a smaller version of Jürgen Mages' python. The Flevo utilises a positive steering trail while the negative trail of the python allows the bike to be built very low and compact. The third source of inspiration is Dirk Bonné from Copenhagen who willingly shared his own experience from building a python.

Specs and materials

Frame material is 35 x 35 x 1,5 mm mild steel tubing for the middle part and in the front part I used 30 x 10 x 1,5 mm. The rear fork is a shortened front fork from a 20" mountain bike.

Rims 305 mm 36H
Wheelbase 880
Seat height 270
Weight 11 kg

2007-01-28 Monty is two years old and already a pensionist.While I do enjoy riding the bike now and then it has drawbacks that limits its usage as a bring-along-bike.When parted the frame is bulky and I have not found a way to make the frame parts hold together while carrying the bike onboard buses and trains. In a mood of resignation I bought myself a Brompton, Concerning transportability the Brompton is excellent. It folds rapidly into a small package. For a foldable it behaves well on the road. The B is ideal on short trips like shopping or a daily commute. But it isn't a recumbent. After a while I suffer the usual uncomfort on different parts of my body. The upright position makes it slow when windy, giving me plenty of time to dream about a new and better design for a foldable recumbent. So I believe this is not the end of the Monty story. I will try again.

Brompton versus Monty. I am afraid Brompton is the winner except regarding comfort. And if I may say so, Monty has a more compact and exciting design.

But when folded Monty takes farewell of compactness. Brommie wins game set and match.


2005-06-26 Longest trip yet with Monty: 90 km. We kept good pace through the blazing sun at around 30 km/h. All was fine until the bottom bracket turned loose. Had to take the train back home. Impressions: Monty is not the best long distance bike but with different gears, narrower tyres, a higher bottom bracket and 3,5 kg shaved off from the weight ... hm,

Dirk Bonné and his 20" Baby python. Who the fat guy with the funny hat is I don't know. Photo by Charlotta Ljungberg.




2005-06-11
A recumbent lifeboat. If my regular recumbent bike would fall to pieces while on the road I can switch to Monty. With rear wheel detached the small bike easily fits on my one wheeled Yak trailer.

Never without a recumbent.



2005-05-29 Some show cycling for the public. The bike is so small and low you don't see much of it when ridden.


The photo was taken at Dockan in Malmö by Sverker Fridqvist.




2005-05-17
The steering pivot is an ordinary bottom bracket in it's shell. The pivot fork has slots where the axle is pushed into. The axle is held in place by crank bolts in each end. This way there is very little load on the bolts.



Having the gear shifter upside down is probably not good in the long run. Will add this to the improvements list.



2005-05-10
After a couple of new weldings to stabilise the seat I mounted mudguards and did some painting. Monty is ready to meet the world. All is fine except the bike is not as small as I had hoped for when folded/separated.


A front mudguard (fender) is essential unless you want your face sprinkled with small stones and muddy water.


Monty has only one wire (for the gear shifter) and it is not more than 17 cm long. I like that.


In spite of his young age Monty can already stand for himself. Just tilt the front part 90° and put pedal to the ground.


Quite a package but at least smaller than my regular recumbent. Separated like this Monty measures 900 x 700 x 400 mm. Removing right pedal will lessen the width another 100 mm.




2005-04-29
The first few rounds around the workshop while weldings are still warm. The bike behaves well and seems easy to handle.


All the vivid test riding made some tack weldings fall off. The picture and this film was taken before giving Monty the final touch. Camera: Jan-Inge Ljungberg.





2005-03-17
The making of a jig can drive you crazy but making a bike without a jig is crazier.


Like most home made bikes Monty was born from a heap of iron.



Beginning of 2005
Some sketches were drafted.



Measures of the steering pivot fork. On second thoughts the opening for the pivot axle could have been made without the angled opening. It does not facilitate the assembly.



The front part as seen from above.



I am not sure all the measurements are the same as on the finished bike. Use them as a guidance only.