How it all started
But developing a velomobile from scratch is quite something else as next to an efficient drivetrain, an aerodynamic body is at least as important. Since air is not something one can physically grab and test, we needed someone with real knowledge and experience in this field to come up with a fresh look for a new model.
Hilgo vs. Mango body
In my experience not only as a long distance rider and velomobile builder/repairer, but also as contact person with our customers, ease of maintenance is very important for riders to remain happy for their choice of velomobile in the long run. In my contacts especially with oversea customers, it showed that it was not always easy for riders to do the maintenance themselves, not in the least because of difficult access to the parts. A bicycle repair man (Monthy Python style) is not available in the Australian Outback. So it was vital to make maintenance of the Hilgo as easily as possible. The parts themselves are close enough to normal bicycle parts, the problem is that it is harder to see them and get to them then on a a normal bicycle. Now when a Mango arrives at the SinnerBikes repair stand, the question usually is: is it worth to take the time to remove the top in order to work easier or can we do the job through the entrance and the foothole openings. Even for experienced velomobile repairers a removed top makes the job much easier and also more likely that the job gets done well.
The KISS principle: Hilgo-gearing.
The break through came when senior advisor Jan coined the idea to replace the derailer with a simple gliding rail that moves the return idler. (Jan held a patent for a sliding cassette, which would be just ideal in the Hilgo, but for it's complexity and high cost of production).Now the hard work of optimizing began: making a prototype, fitting it in the Hilgo and test it on the road. After several iterations we had it nailed. A standard 11-speed 11-40 cassette shifted perfectly with a non-indexed Hilgo gearing which has no spring to push back, but instead two shifting cables, pulling the rail in either direction. Shifting action is very light, so the grip-shift can be twisted even with very sweaty hands.The biggest problem for me as a test rider, was to get rid oft he hand-brain automatisation that I learned from the long use of indexed derailers. The Hilgo-gearing is almost frictionless and has no ratchets to feel when you shift. You shift through the soles of your cycling shoes. Young colleague Donny, who's hobby it is to restore vintage bicycles, showed me the way: "oh, you just pedal along and turn the shifter until you feel that it shifts". And that is really all there is to the Hilgo-gearing. In 5500 test-km the Hilgo-gearing indicates low maintenance and trouble-free use. As for keeping the rail moving smoothly: the first idea was to seal the moving rail to keep it clean. But as this was not all too easy and the system was still in development anyway, this was postponed. After a while of use, I noticed that after lubricating the chain, the rail of the gearing was automatically lubricated as well. Problem solved by itself.... Dust is kept in solution in oil and the gearing keeps on shifting just as smooth as new. The open rail allows for an occasional cleaning, say two times a year.....
All in all the Hilgo-gearing is a true KISS system: Keep It Simple and Straightforward.
Ease of maintenance to the max.To make the ease of maintenance complete I had already decided against chain-tubes and a for an open chain-tensioner that allows for the chain being taken off without opening the chain. One can release the tension on the chain when working on the chainline and a dropped chain can easily be popped on again.
The simple chain tensioner does not have a spring, but a bungee-cord. It may not be high-tech, but at least it is easy to see how it works and a bungee-cord replacement is easy to find and made to the correct length. The chain tension is rather low this way. Now, normally a derailer system on a bouncy road needs a high tension to avoid ghost shifting, but since the gearing is positioned at the mid-drive, it is free from wild rear wheel movements. A low chain tension is great because it means a more efficient drive-train.
The chain tensioner is in front of the bridge and there is enough space for a very long cage. With the standard configuration of 34/50T Compact double and 11-40T cassette, all the gears can be shifted without losing chain tension. This at itself is already pretty revolutionary. That also means that 34/60T double chainwheels is a very real possibility, which makes for an even wider gearing range. One only needs to realize that on the 34T, not all the gears on the cassette can be shifted, so you need to switch to the big 60T ring in time.
Drop-InI was also more than done with the traditional drop-outs that holds the mid-drive axle in the Mango. The mid-drive could literally drop-out when the quick-release was not tightened enough. That usually bent the drop-out in the frame on one side. The drop-out can be bent back and the axle can be held by an additional mount to prevent it from dropping out, but well, it's not a nice thing to happen on the road.
As the ongoing frame from the Mango was also history in the Hilgo, I had to think of something else anyway. It was crystal clear that the mid-drive had to be mounted in a drop-in. That way the weight of the mid-drive could never move itself down and out again. It's now even easier than it already was in the Mango to remove the whole mid-drive assembly for say: putting on a new cassette or replace the secondary chain-line from standard 24-16T to 22-18T for more extreme mountain use.
QNot so very exciting maybe, but still a good improvement is the small q-faktor of the cranks. In other words, the distance between the cranks is smaller than usual with "normal" bikes. It is better to have the cranks closer together, so why is the q-factor of most bikes so wide? This is because of the chainline on normal bikes, The chain has to go next to the frame and the rear wheel towards the cassette and this forces a wider q-factor upon the rider. It's not so bad on a normal bike, since one can stand on the pedals occasionally. At least this is my best guess... On a recumbent and a velomobile one is not so adaptable. You cannot stand on the pedals. This is why it feels better to have a smaller q-factor on recumbents/velomobiles. Although I don't want to generalise: cyclists' bodies and preferences can vary a lot.
Still, for the average velonaut I very much expect better ergonomics with a smaller q-factor. Not to mention that it becomes easier for long-legged persons to fit inside the Hilgo body ;-)
But next to no manufacturer seems to make cranks with a small q-factor. It took ICB some persuasion to get one manufacturer to make a crank with smaller q-factor but alas, the crank length cannot be made shorter than so much.
I did not like to be restricted to an expensive crankset and a shortest length that seems too long for me and possibly others, so I looked on. Then I thought about the old square taper cranksets. While with modern two-piece cranksets you cannot choose the length of the axle, with a square taper bottom bracket you can choose for a much shorter axle. Instead of 107mm or 113mm axle, there are 103 mm and even 102mm square taper axles. They are not commonly used, but they are readily available and that's what counts. Combined with equally readily available BMX cranksets with 110mm BCD that can be ordered in a great variety of lenghts from 125mm to 170mm in 5 mm increments, I found the ideal crankset set-up for the Hilgo, adjustable to individual needs and/or preferences.
Hub-motor in mid-drive?Some clever minds have noticed how the drop-in mid-drive might allow for a compact rear-hub e-motor with the 11-40T cassette to replace the standard 135mm axle. One could ride without motor in summer and only put it in in wintertime when it is that easy to swap between the two hubs.Batteries could just lie on the velo floor and even the controller could be taken out when so desired. Being not very knowledgeable myself about e-motors, I'm cautious about this possibility until we can confirm it. But it sure looks like a real option.
Anything else?That's about all for the moment, but already a lot of ideas come about for the future. A carbon version is in the cards, a top with a very long entrance, front rings that can be shifted while standing still. With a small company like SinnerBikes/Drymer it can take some time for major changes to bring about. I hope for people who see the Hilgo as an open source project. Some things that riders/tinkerers think off and try out might even get into production, others will remain a one-off. We shall see what the future brings. The Hilgo is adaptable....
Personal thoughtsThe whole process of development of the Hilgo, the discussions with Delta Hotel and all the team members of Drymer, the failures and the "Eureka" moments, the hard heads not wanting to budge, finding myself often in the middle and finding the path towards a production Hilgo. It has all contributed to my own development as a person. I have gained tremendously in self-esteem, something I have never had a lot off. I hope I have also risen in the esteem of others :-) I think it is time to call myself not just a velomobile repair-man but also a velomobile-developer. Not.... that I could possibly develop a velomobile all by myself.
Ha, a photo has now been posted on FB with me giving the Hilgo my personal "seal of approval". That is no joke: I truly love riding the Hilgo.