We believe your winter bike should be as good to ride in its own way as your pride and joy summer machine. Why shouldn’t it be? After all you will probably spend half the year riding it! It will be different of course as a bike built for use in the darker, wetter and colder months of the year will need to be tough as well as versatile. It should be designed for mudguards to give you and you’re riding pals more protection on wet roads, but it should still be great to ride. Our answer to the winter bike question is the new EZONA.
It would have been easy for us to do what most other bike brands do – simply buy a frame from a manufacturer in Taiwan, China or Italy and brand it with our decals. It’s certainly the cheapest option and many would argue that importing a frame is the only way to be competitive. However that’s not the Enigma way. We wanted to build the frame ourselves, here in our Hailsham workshop, proudly made in Britain.
How could we do it? Is it possible to build a high quality frame here in Britain using top quality materials and handcrafted construction, sell in numbers and be competitive? Yes it is possible and the years of investment in our workshop, equipment and facilities have made it so for Enigma. We have the know-how, the skills, we have the team and we can do everything from start to finish under one roof. This means that we can be efficient and fast, with no time lost outsourcing the different processes involved in bicycle frame construction.
This blog will follow the process of building the Ezona frames from the tube selection right through to the packing and shipping. It will be interesting for all who have a passion for the bicycle – and these days there are many of us.
Step 1: Tube selection.
Steel is a wonderful material and a steel bike for winter use, commuting, audax and light touring makes a whole lot of sense on so many levels. Steel is tough, it’s relatively straightforward to work and with the right choice of tubeset, great design and construction it’s just brilliant to ride!
So what tubes should we use for our winter frame?
It’s important that the Ezona is light, it must also be robust and deliver the performance, handling and comfort always associated with Enigma frames. The obvious material choice for us was Columbus Zona, a butted nivacrom steel tubeset that ticks all the boxes and in skilled hands builds into a quality frame. For optimum frame performance we opted for a 35mm OS down tube and 28mm top tube and to save a few extra grams we decided to use a Columbus Life 32mm seat tube, which also gave us the right diameter for a band-on front derailleur. For a clean, modern look and to increase front end stiffness we decided to use an integrated head tube design and all-in-all we achieved a front triangle that gives the ideal combination of stiffness and comfort.
The Ezona is designed for short reach brakes with clearance for 25c tyres and mudguards fitted. Clearances and geometry must be nice and tight in order for the bike to handle in the way that we want i.e sharp but predictable with no nasty surprises. The rear chain stay length was set at 421mm, which is just long enough for the mudguard clearance we need and short enough to meet the performance and handling brief. With frame angles according to the frame size and with all other small parts coming from our parts stock the design is set, drawings prepared and we are good to go.
Step 2: Tube cut and mitre.
Now we have all the tubes and frame parts together we can begin the frame building process. The frame will be assembled in our frame jig and so the first step is to set the jig according to the frame drawing. With jig set we start with the head tube, which has previously been accurately cut to length on our lathe and is now placed in position on the jig. The next step is to add the BB shell to the jig plus the rear dropouts and now we are ready to cut and mitre the tubes. Earlier this year we finally finished our custom built tube mitring machine that was conceived, designed and built in-house by Max Norrell who is one of our talented team of frame builders. This machine is a wonder and enables us to mitre all the main tubes of the frame with absolute precision and speeds the process enormously.
It’s the time saving benefit of the mitring machine that allows us to cut our labour cost considerably on the Ezona frames to help make our pricing very competitive.
We start with the seat tube, which must be cut to length and mitred for a super-snug fit at the BB. It’s then the top tube, which likewise must be cut to length and then starting at the head tube end the tube is mitred to achieve a nice tight fit. It’s the down tube next which follows the same process, head tube end first then BB end. Now the front triangle is cut and ready.
So now we turn our attention to the rear triangle, where the process is basically the same but with a slight difference. The chain stays are first and once they are cut to length we use a special fixture on our milling machine to cut the BB end mitre. For the dropout end we cut and fit the tube by hand. Finally the seat stays are cut and mitred in the same way and the frame is fully assembled in the jig ready for all the joints to be tack welded.
Step 3: Tack Weld
The tubes are now all cut and mitred and the frame is assembled in the jig, but the tubes still need to be held together. This we do by applying several small tack welds to each joint and this operation is carried out with the frame in the jig. Tack welds are really just temporary welds but they are the start of the welding process.
Once all the joints have been tacked the frame is removed from the jig and is placed on our alignment table for the first alignment check. This is to make sure that everything is straight and the frame is in-line and within tolerance. Our frames are always accurate even at this stage, however in the unlikely event that a frame is found to be out of alignment at this stage it’s relatively simple to take it apart, re-align it and then tack weld once again.
The frame is now ready to weld.
Step 4: Welding
Every Ezona frame is tig-welded by our tig-maestro Joe Walker. For decades steel bicycle frames were constructed using traditional brazing techniques but in recent years Tungsten Inert Gas (TIG) has come more to the fore and is now the preferred method of construction for the world’s top frame builders. Tig welding asks much of the frame builder and is more demanding than traditional brazing. Technique, great skill and a certain amount of natural ability are the pre-requisite parts in the tig-welders armoury and it can take many years to reach a high standard of competence.
Why do we Tig? We believe that when executed by a skilled technician a tig-welded frame will be stronger and lighter with clean and beautiful joints. There is no need for an excess of material to ensure a strong and stable joint and a tig-welded joint should be fine and simple.
Every Ezona is welded with the same degree of skill and care as the more expensive frames in the Enigma range and the weld process is the same. We do not weld the frame in the jig instead we weld it freehand. When metal is heated it moves and this movement can be significant over the course of welding a whole frame. A skilled builder will compensate for the movement of the frame by using a welding sequence that will keep the frame as straight as possible during the build process. In this way the frame will require the minimum of cold-setting to bring it into line once welding is complete. Most builders have their own welding sequence that is guarded and secret so we are unable to divulge Joe’s sequence in this blog, but needless to say his frames are very accurate and require little or no manipulation after the welding process is complete. It takes around 90 minutes to weld an Ezona frame.
The frame is welded, the alignment is checked and we ready to add the small parts.