Over in Taiwan, manufacture is continuing as usual. Since our last update, our manufacturing partner has completed our first batch of injection molded parts, so we thought we’d explain a bit about the process and the importance of these parts too.
They may look small, but these injection molded parts are really important to the lifespan and reliability of the bike – they protect it from everyday wear and tear!
All boxed up and ready to go! These parts are the rear light case that connect the rear light to the battery.
Injection molding explained
Injection molding is the process of making plastic parts by injection filling a mold with molten plastic. With the molds ready to go we can pump out thousands of these parts in a single day, but making the mold itself is a long process.
The mold consists of two or more plates with cavities in the shape of the parts being made. These plates are pressed together and then filled with molten plastic under pressure. The plastic cools as it touches the mold and quickly becomes a solid.
One of the things that makes designing the part and the tool so challenging is distortion. As the plastic cools it contracts and if some areas of the part have already set while other regions are still cooling, internal stresses develop which can lead to pretty big distortions. These appear as warping and sink marks in the finished part.
Even with a good part design, the mold will sometimes need to be revised a few times to get a perfect part.
Some experimentation is required with the molding parameters too (molding time, pressure, tool cooling etc). This is why injection molding can be such a lengthy process and requires a lot of experience.
At FLIT, we are looking to use advanced software tools that allow simulation of the molding process, reducing the need for this trial and error approach. This should allow us to speed up our manufacturing and reduce waste.
Some of the injection molded parts from our first batch. These are made of a tough plastic called polyurethane – the same material used to make skateboard wheels! Below we explain what each part is for, and where it’s located on the bike.
When the bike folds there are metal parts that contact each other, like the suspension block and yoke (the bit that interfaces between the suspension unit and the rear swing arm).
Repeated contact leads to a damaged paint surface. These plastic inserts prevent this and also act as mini shock absorbers to reduce the impact forces acting on the parts during folding. This not only protects the paintwork, but makes for a longer lasting frame.
The hinge endstops, located on each of the hinges, function similarly to doorstops – but instead of protecting a painted wall, they protect the bike’s paintwork when the bike is being folded and unfolded. The same goes for the headset endstop.
If you’ve read this far, you’ll have noticed that we’ve launched a brand new website! You also may have noticed that we’ve updated the specs to the final design.
As you know, we’ve refined the design considerably since our initial prototypes, making for a better riding, more robust and easier to maintain final version. Some of the changes have impacted the final weight of the bike, which is now 15kg. This is mainly due to the headset redesign (+400g), the upgrade to more puncture resistant Schwalbe Marathon tyres (+330g), and the safer, and better looking anodised metal battery case (+200g).
It’s worth mentioning that some components can be swapped out to reduce the weight. We can’t stock everything ourselves, but we can let you know what is compatible with the FLIT-16 (eg. swapping to less puncture resistant Schwalbe Kojak tyres will save 380g of weight).
Secondly, due to a supply issue we changed the cells when building the batteries. These are still high capacity (230Wh), and won’t affect the range much, which we still estimate to be 40-50km on a single charge. We have measured this: Alex was riding Blaze to commute in Cambridge (85kg rider, level 3 assistance, mostly flat) before the coronavirus lockdown and was hitting 50km before the battery cut out.
With such complicated engineering behind a folding ebike, there are always going to be trade-offs when making design decisions. We’re really happy with the final design of the FLIT-16, and we can’t wait to deliver yours to you!
You can check out the full bike specification here.
Some more shots of Marengo, our brand new demo bike
A couple of weeks ago, we revealed Marengo, our brand new demo bike. We had some requests for more shots so that people could see the different components, so here they are with’s Dave’s garden as a backdrop. If you have any requests to see particular parts then let us know and Dave can send you some photos.
Dave is currently assembling our blue demo bike, Maya, as well. We look forward to introducing you soon.
As always, if you have any questions feel free to get in touch. You can reach us by email or phone – our lines are still open and we’re always happy to chat!