Archive for March, 2010


March 21, 2010

Passenger handlebars on the mundo are not really stoker bars just some thing for passengers to hang on to. It’s not like they are pedaling or leaning on the bars like a true stoker would be. So I don’t think the position and height is too important.

This may seem like an easy thing to do but I spent a long time on the net zooming in on pictures of other installs to get the details of how to do this on the cheap. I couldn’t find anywhere which explained how to do this  in detail hence the following.

The principal of stoker bars on the Mundo is easy, attach some handlebars to the seatpost. I considered proper stoker bar stems but they are not easy to source (in aust anyway ) and they are about $60 to $100 not counting the bars. Yuba have a kit with bars and grips for $49US which looks Ok but I wanted a cheaper solution and the one I came up with is about as cheap as it gets.

I used an “ahead” type bike stem which suits handle bars of 31.8mm (same as the Mundo seatpost), and a steerer clamp of 1 1/8 inch; that way I could reverse the stem using the handlebar clamp on the seat and the steerer clamp to hold the handlebars. Most stems come with some degree of “rise”, usually 6 deg or so, and of course if you reverse the stem this rise will turn into a sideways offset. So you need either an adjustable stem which you adjust to 0 deg or just get a 0 deg stem, which is what I used. These are not as easy to find as riser types but they are available.

Ritchey do an adjustable stem for about $20-30 on but I just got a very cheap ($6-!) Answer AtacPro 0 deg, 120mm stem (also from Jensen). I also needed a shim for my handlebars, but this depends on what bars you use.

The bars I used were cruiser/riser type (again cheap Dimension brand about $15) but I think they were too wide and I cut them down to avoid taking out pedestrians! I made them slightly narrower than the side loaders.

120mm Stem just fits without fouling the rear carrier.

Total cost all new parts (excepts grips) about $25- and looks like a bought one.


Brake 3

March 20, 2010

The adapter for the rear bb7 185mm disc arrived from Yuba. It seems they have gone to a lot of trouble to have it CNCed and are likely not making any money selling it for $30. I had a lot of trouble working out how to use this adapter (no instructions included) but finally worked out that you need to use one 1/2 of the BB7 adjustment shims with the bolts and washers they send with the adapter. After a bit of  moving the caliper position with washers etc I got it to mount ok.

Correctly mounted adapter before I broke it

 Then I broke it.

The caliper mounting bolts only go into the adapter about 3 or 4 threads deep so of course when tensioning it up I was a bit over zealous and stripped the thread in the soft alloy adapter. I might work Ok for you but watch out you don’t tension it too much. I probably didn’t need to do it up that tight but I have used a similar tension on the original BB7 adapter with no problems. The Yuba adapter is certainly weaker than the original, so maybe it wouldn’t have coped with braking forces over time and I’ve saved myself future problems?

Yuba adapter compared to the original Avid BB7 adapter note same bolt used

OK so long story short I had a 160mm BB7 rotor and after stuffing about with the adapter I thought I would just put that on and be done with it. But it didn’t fit! Certainly not with the standard adapter and mounting bolts. It might fit if the caliper bolts are adjusted/shimmed etc. I may try again if I can be bothered changing the rotor yet again.

I wonder how many people have successfully mounted rear discs on the Mundo? I only know of one other on the web and he mentions having to “man handle” the mounting tab.

So I have the 3 rotor sizes for BB7s and adapters and none of them mount on the rear of my Yuba without significant change to the mounting bolts or using a fairly weak adapter, nice.

Never fear on we go on this glorious rear brake adventure! I would have given up long ago and gone rear V Brake but as I previously mentioned my rims don’t have a V Brake track.

So nothing to lose with the ruined Yuba 185mm adapter I drilled it right through, made a couple of  “shelves” with my Dremel tool and some cutoff discs (a free Dremel tool should really come with every Mundo frame!), and mounted using some longer bolts with nylock nuts. Mounts nice and secure and so far so good with a 185mm rear brake!

Modified adapter

Mounted on the Mundo

My front brake mounting (original Mundo fork) was never all that good (203mm rotor) and needed alignment but I couldn’t get it to line up without bending the brake mount tab slightly and grinding all the paint and some metal off the inside of it. But it seems Ok now, but it does still shudder a bit if I really pull on the brake, not sure if this is the fork or something else.

Victory? Well it feels a hollow victory really. Are you building a Mundo with disc brakes? Ask youself do you really need them? Anyway maybe I’ve made all the mistakes for you. My pleasure that’s what I’m here for!


March 19, 2010

Had a party for my 7 yo the other day. There is an awful lot of plastic involved in a childs life these days, lego and bionicles seemed the most popular!

At least the ice was green powered, kind of.  Could have gone more bags but still not got the back brake working!

five 5kg bags of ice! Could have gone 6 or 7 easy!

With an electric cargo I always get a double take from passers by, once for the bike once for the motor. With five bags of ice on board it was a triple take!