95 Kona Explosif - Long build history

Hi

Great find at a bargain price.
another old kona on trails.
Well done

Chris

Welcome Stu

Looks great and loads of fun. I think that if whatever you put on it makes you ride it then thats got to be a good choice.

Also searching for the correct parts as you say is part of the draw of retro bikes, many on here search for ages for the parts, some including myself still are you found the bike after all, so dont give up the search, you never know what you might find, usually something you didnt even know you wanted

mark

Thanks, your point is so true and will be proved later when I post pics of the current build.

A few more pics. After riding the bike a few times I realized that this bike was to become my main ride. With this in mind I decided I defintely wanted to build her up as a Retro-Mod sort of bike to take advantage of modern technology but retain the Old School feel.



Fork upgraded to a 2008 RS Reba with 85mm travel and custom gold decals:


2008 LX Crankset:


Aerozine BB:


A Bit of bling in the cockpit area:


Again, a pic while out on a ride:

Eventually the bike evolved into full on trail bike mode. I made a 1x9 conversion using a 11-40 sunrace cassette and surprisingly the original M900 8 speed derailleur seemed fine with just a longer b-tensiion screw. A shorter 60mm stem with 780mm bars were added and the fork travel extended to 115mm.

Very nice bike, I do like a Kona

Here is my Explosif, assembled by Retrobikes very own THM, Its the most fun bike I have

I like this bike.

Similar to the plans i have for my Kilauea.... a retro with a modern flavour!

I rode the bike like this for a few months until towards the end of last year the "Mullet" brake set up (Disc/V Brake Combo) annoyed me and I decided I to do something about putting a disc on the back.

I didnt want to weld a tab on the frame. I have always had this feeling that one day I would like to restore her to a period correct build. (More on that later.) There doesnt seem to be much in the way of adapters available, especially for skinny steel tubed bikes with small drop outs. The only option I had was to make something myself. Good thing I am an engineer, although not in the bike industry.

We have a really nice high tech 3d Scanner at work that is used for metrology. One day during lunch I decided to scan the frame so that I would have a CAD model to work with.


Next step was to design something simple to make that would bolt on. Its basically a bent plate that is connected to the brake boss and sandwiched between the frame and wheel. Its also bolted to the rack mount to hold it in place when the wheel is removed. The plate is 5mm thick but machined down to 2mm at the point where it is sandwiched. This minited how much flexing of the frame is needed to still get the wheel in and also meant there was still some axle in contact with the drop out.


I did some FEA analysis to check its strength. To be honest I have no idea what forces go through something like this but made some assumptions and I am still alive.


And finally, here is the finished product. Its not pretty but it works.

Quite ingenious but not particularly easy on the eye
I may have missed what material you used... aluminium ?
Does it add much weight ?

Yeah, its not pretty but was effective while I had it on the bike. Made it from aluminium and think it weighed around 130g which I think is pretty reasonable.