Bobbing Around: Building a Bespoke Harley Custom. Part 7

Building a full custom motorcycle is often an exercise in packaging, making all of the necessary parts fit together within the frame. This is very true for my oil tank. I know the space that my oil tank will occupy (the usual spot behind the rear cylinder on a Harley), but before I start I need to consider any other restrictions that could get in the way. The main one is the battery, as this will sit directly below the oil tank. I want to be able to remove the battery when the bike is fully built up.

So before I make the oil tank, I need to mount the battery. BUT before I can mount the battery, I want to at least know where my rear mudguard will sit so that I can space everything out correctly. Therefore I am going to talk about how I go about fitting my rear mudguard…

Don’t Be Offended!

I purchased a Gasbox rear fender (they’re American before you bite my head off!) as I like the shape and sturdy design. The metal is a bit thicker than normal aftermarket mudguards, which I like because I will be drilling and welding to it.

Next I did what most people do when fitting a new rear mudguard, and fit something around the circumference of my rear tyre to give the proper spacing. It is worth noting that tyres expand when riding, so you always want to leave a bit of room to avoid shredding your tyres. I used the spare roller chain that I mentioned before for checking sprocket alignment, and a couple of zip ties to hold it in place. This gives me about 15mm of clearance over the tyre. You don’t have to use a chain of course, you can use a garden hose, or even bits of wood. Just so as long as it gives you consistent clearance around the whole circumference.

Step Back and Take a Moment

Then I sit the mudguard on the chain and have a look. I rotate it around to where I want it to sit, make sure it is central on the tyre. Then I prop it up with a few bits of wood so I can stand back and see how it fits. Annoyingly it doesn’t sit right, the curve of the mudguard is greater than the curve of the tyre. They have different radii. This means that if I get one end of the mudguard nice and snug, the other end sticks away from the tyre and looks wrong.

Now I could increase the distance that the mudguard sits off the tyre, until the curvature sits correctly, but then you end up with a big gap and that looks silly. I could also try and hide the inconsistency by spreading the error around the whole of the wheel, rather than just at the end. But I think we all know by now that I can’t stand for such imperfections, and have to take a more drastic approach. This is a custom bike after all!

Tricks of the Trade

One way of doing this that I have tried on a previous bike is to slightly stretch out the sides of the mudguard: This pulls the whole curve tighter. Incidentally it also works the other way as well. However there are issues with this method, the main one being that it is really hard to do evenly so you don’t twist your mudguard.

With this in mind I opt for another method, which is to cut up the sides of the mudguard (radially) but stop when I get to the flatter top section. I do this on both sides and use some tape to make sure that the cuts are in line. Because I have used an angle grinder to do this, the cut has a small thickness. That allows me to slightly kink the mudguard, and tack weld the sides of the cut together, thereby decreasing the overall curvature of the mudguard. Hopefully the pictures will help that make sense!

Getting There

I only need to do this in three places to bring the mudguard in line with the tyre, which means that the bends in the metal are invisible to the naked eye. I have just tack welded the cuts for now, and will finish welding them up at a later date (there is plenty more fabrication work to do on that mudguard!).

With that done I can start thinking about the mount for the battery. More fabrication work incoming!

Words and Pictures: Tom Shaw

Read the other parts in this excellent series: