My Mango reached 12000 km last week. I thought it about time I gave it a service...
The Mango has a fully enclosed drive-chain. This is a very important feature for a velomobile. Because abrasive dirt stays on the outside of the body, maintenance is very low compared with most bicycles. All that's needed for a long life with little hassle is that you regularly oil the chain (a few drops every 500 km) and wipe off any excess. You also need to put a couple of drops of oil into the top of the suspension struts. Some people have ridden as much as 40000 km on their first chain by taking care like this. I was a bit more lax with the regular oiling and just managed 12000 km. However, this is still a very good chain life. Chains exposed to the elements will often last only a quarter so long.
Testing with a chain wear checking tool (new chain above, old chain below) it was apparent that my main chain had "stretched" a little beyond the point where I should already have replaced it. To say a chain has "stretched" is a little misleading. The metal does not stretch. What actually happens is that abrasive dust gets inside the bearings in the chain links themselves, wearing it out from the inside. The result is that chain no longer fits the chainrings correctly and it starts to wear them out. Also efficiency is lost. However, all this happens later and to a lesser extent if your drive-chain stays clean.
I replaced the existing KMC chain with brand new SRAM 9 speed chain.
I had a brand new cassette ready to replace the old one. I took apart the old cassette and looked at each sprocket individually. The photo shows the most worn tooth of the most worn sprocket on top of its new replacement. This tooth is where the sprocket is narrowed in order to make shifting easier, but which also means that this tooth wears out quicker than most. However, there is almost no wear at all. That's really very impressive. It helps a lot that the cassette is mounted inside the body, away from any dirt. The front chainrings were also not worn.
The second chain in the Mango uses 3/32" chain, but an 8 speed chain will do in this locations, so I used a PC-830. This chain was really only half worn, but I replaced it anyway. As you can see, the teeth on this sprockets for the rear chain barely have any wear at all. Even most of the paint remains on the sprocket on the intermediate drive.
The idler wheel under the seat looked a bit rough. The plastic from which it was made has actually distorted. That curvature is real, not just an artifact of the photo. Perhaps this was due to the effect of oil on the plastic. However, I'm not complaining. This was a prototype idler from Alligt, made of softer plastic than the production versions. The teeth on the wheel inside folded over quite soon, and the wheel itself had actually started to deform quite quickly. I rode with it for a whole year because I wanted to see how long it would last. While it looked bad, it didn't fail. Actually, it still works just fine except that the deformation has got bad enough that it now rubs against the bracket which it was mounted on. The replacement is the new design of idler from Alligt.
There's now quite a bit of play in my steering so I also need a new plastic block for the universal joint. That will come from the Ligfietsgarage next week.
To check your transmission you need just the chain wear checking tool. To replace it you need chains and other parts available here. For a main chain of the Mango you need about 2.5 normal chains (buy 3 the first time you do the job, and you may need just 2 the second time) and for the secondary chain you need just one.
I'm looking forward to more adventures over the next 12000 km, but shouldn't have to do much maintenance.
Read my review of the Sinner Mango Velomobile.
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