Saturday, 8 January 2011

12000 km service

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.


Dave Telling said...

Nice post, timely for me - I'm having a new chain fitted this weekend. I've done 1,300 miles, mostly through the Glaswegian winter months. I've also gone for a SRAM chain, has a 'powerlink' so I can simply unhook it and remove for cleaning, which I do almost daily *sigh*

amoeba said...

The running costs of the Mango seem pretty negligible, especially when your 'mileage' is considered.
Do you know how they compare with a typical Dutch roadster?

David Hembrow said...

Dave: I think you perhaps need a chain-guard !

Amoeba: Yes, running costs are low.

It's much the same story with Dutch town bikes due to their enclosed chain. I replaced the chains on both the children's bikes about a month ago, one with a KMC and one with SRAM (just because I thought I'd see how they went).

Both were worn, one of them a bit too worn. However, they'd also both been used for three solid years of cycling every day, and been oiled perhaps twice in that time.

I've still not done my bike or Judy's. I know mine is a stretched, and in fact I'm intending to recycle the old rear chain of the Mango (which was barely worth replacing) onto my town bike.

Most people here simply want a bike which works for everyday use. They don't want to do any maintenance beyond occasionally pumping up tyres. That's why most bikes look like this.

Paul Martin said...

Great post David, thank you. I was about to ask how many chains are required when replacing the chain(s) on the Mango - and you've answered my questions!

I'm currently in the middle of an overhaul of a friend's road bike - the drivetrain is a complete mess. In contrast our dutch bikes (Gazelles), with their enclosed chain cases, need almost no maintenance - it really does make a difference having such a bike as a transport tool. Many friends have road/MTBs as 'commuters' and they're always having problems with them...

I've taught myself bike maintenance from books & internet sites and have a nice collection of tools now. It is very satisfying, particularly when the skills can be used on the road to help others... but it is not as satisfying as not having to do any maintenance! ;)

When people ask what my Mango is I tell them that it is my latest 'Dutch Bike'. :)


dr2chase said...

I was also going to ask about chain length, but also about the number of bends. My longtail (Big Dummy) uses about 1.5 chains (as you would know). I have a chain case up front, and fenders front and rear to cut down on the slime/grime, but when it was time to replace the chain, the cog in the rear would not mesh smoothly with the new chain, and the front chainring was obviously worn. My thinking was that the wear was proportional to the number of bends in the chain line, or perhaps the number of bends under load, and that the longer chain would wear more slowly because it based through the bends less often -- but the cogs would wear at the same rate.

(So, since it's all worn, but still working, I am collecting new parts, and waiting for as much winter as possible to pass before I expose the new parts to grit and salt.)

hercule said...

Your comment about the "second chain" has intrigued me and I realise that I know nothing about what goes on beneath the shell of a velomobile. I had assumed it would be a straightforward single chain derailleur drive like on my own Trice QNT but clearly it isn't. Can you point me in the direction of information on what's under the bonnet for the technically curious? I've just read the owner's manual which has done nothing for my ongoing desire for one...

David Hembrow said...

Hercule: There's an intermediate drive beneath/behind the seat, and the derailleur is split in two. The tensioner part is in the front while the part which pushes the chain side to side is at the intermediate drive. I'm not sure where to point you beyond the manual to find information on this. Perhaps this video. It's rather difficult to take good pictures of it, as it's rather dark down there.

Without the intermediate drive it wouldn't be easy to get a high enough gearing ratio with the 20" rear wheel. You'd need either an oversized chainring, which doesn't work well with standard derailleurs, or a Dual Drive in the rear wheel. That solves the ratio problem, but brings two problems of its own: First it's less efficient to use the step up gear of the Dual Drive, and second it requires mounting on both sides, so you lose the convenience of a single sided rear wheel when it comes to swapping tyres or mending punctures.

Another alternative is to have a bigger rear wheel. Some other velomobiles do this. However, they then suffer from having a bigger body which takes up more room, but less luggage space due to it being full of wheel. It also reduces luggage space, increases weight and means that you need to carry more spare parts when touring.

Kevin Steinhardt said...

This is why I want to move to Groningen: close to the Tea Museum, Ligfietsgarage(s) and relatively few tourists. My 'idler wheels' looks much the same, David.

Gerrit said...

Hello David , I dont now if you read this but i, am still going to ask a question.
That drop of oil in the suspension you mentioned , do you just drop that on top of de suspension , in the middle of that wire end wich the suspension holds on its place.

sorry for my english.

I have a almost 6 month old Mango+ if it matters for your answer.

David Hembrow said...

Gerrit: Yes, the oil goes into the top of the suspension struts, above the wheel arches inside the body. Just a drop in each one.

Gerrit said...

Okay , Good to know , thank you.
i didnt know this so i never did it in nearly 5000 Km , the suspension will surely like it.


Gerrit said...

Still another question , you mentioned you changed the idler under the seat for a idler from alligt but these are 68 mm and the idler in my mango + is 49 mm , will this idler van alligt fit in a Mango+ ?

David Hembrow said...

Gerrit, yes the larger idler fits. I have it in my Mango, and there is no difference between a Mango, Mango Sport and Mango+ so far as where the idler is mounted. The difference in radius is only 9.5 mm. This gives a slightly larger chance of your seat touching the idler, though only if your seat is exceptionally low within the Mango, but at the same time, because the chain runs a little lower with the larger idler there's a smaller chance of the chair touching the chain.

You can buy the idlers here.

Gerrit said...

Thank you David for your answer , i replaced the original after 5000 km, really soon, for an original .
I will soon place a order by you for a replacement idler.

Gerrit said...

Today i received my order from your store and you where right about the idler , it fits .While changing it i notice that the original has no teeth while it is in the pulling chain , strange. The chain that goes back does not have a idler in my mango+.
So i think i have the right idler now since i bought the Mango.
Also i used the chain wear checking tool and find out that my chain is lubbed out and need to be replaced after 7000 Km , a bit soon i think ?