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Words: Tom Gilroy
Taking a standard subframe and adding a tail hoop has to be the most common modification in the Cafe Racer/Scrambler/Tracker universe. Often overlooked (I’m guilty as well), is the issue of rear wheel suspension travel. If you take a Subframe that looks like this (pictured below), and add a straight tail hoop, you’re going to run into trouble at the first bump or pot hole you it.
I’ve seen peoples tyres worn and popped, as well as whole taillights ripped out and busted, all on the first test ride. Unless you get lucky and weld a straight hoop on and have miraculously no work to do because your suspension travel is still perfect, you have two options as far as I can see:
Modify your suspension – adding longer bump stops, longer shocks and increasing stiffness, or:
Getting smart with your tail hoop mods – use some sleight of hand to get both the look you want and the performance out of your suspension that you need.
In this article, I’ll look at both, as well as the process for fitting your own Cafe Racer tail hoop.
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Step 1 – Modifying your suspension:
In my opinion, this should be your second choice, and let me explain why: When modifying your suspension to accommodate less wheel travel, you’re playing with something that greatly effects your bike’s performance on the road.
Shortening your suspension travel with bump stops will have you bouncing all over your seat throughout bumpy rides, while longer shocks on the rear will reduce your rake angle and effect trail on the front-end.
Increasing the stiffness enough may just have your bike handling like a bathtub on the road, but it can be done – keep in mind every mod you make here will effect another area of your bike’s performance.
One example I have done personally is a Suzuki GN250 Scrambler – from standard, the GN250 has quite a relaxed rake (a lot of people build bobbers from them), so you can afford to raise the rear a bit without getting into dangerous territory up front.
Step 2 – Getting smart with your tail hoop:
A little thought can go a long way here – I’ll go into the tricks I use to try and reduce the impact of the bikes suspension travel, if not remove the impact of adding a tail hoop completely. Generally I use three methods to avoid these issues
A – Positioning the hoop past the apex point of the wheel, using the suspension travel to your advantage:
Positioning the tail hoop right can allow your wheel to travel up inside the frame, allowing better suspension actuation. Shown below, this technique can be good when using a tail cowl, but isn’t so helpful when making a brat style seat.
The sweet spot I’ve found is halfway between the axle and rear of the tyre – it looks good and will allow enough room to have your tyre travel slightly up inside the hoop before you’re worrying about bottoming out. Remember your wheel moves radially – not straight up and down – when measuring this out and welding it on.
B – Sweeping the hoop up at the rear, whether it be manually bending or cutting and welding at an angle:
This one tends to be my weapon of choice on brat style seats – a nice swept bend can really set the seat off well. Having that upsweep on your Cafe Racer tail hoop allows more travel for every mm you raise the rear.
In addition to sweeping the tail hoop up, I’ll add a recess in the seat pan when fiberglassing to allow the wheel to travel up inside the frame while still keeping the straight line of the seat. The foam gets a little thinner, but no one is siting back there anyway!
C – Not looping the tail at all – using the tail cowl to create the line you want but allow the wheel to travel inside it:
I’ve never actually used this method, however I have seen it done many times. Having two straight frame rails, or even leaving the stock tail subframe and building the tail cowl around that, allows you to achieve the look you want without modifying your bike frame at all, resulting in you being able keep your stock suspension travel and setup with no worries at all.
Step 3 – Welding the tail hoop:
Assuming you’ve chosen to weld a tail hoop on (that’s why you’re reading, I hope), here’s how I do the fabrication/welding side of it.
First cut the frame where you see fit, be aware around the suspension mounts as they are often reinforced and will make fitting your slugs a little more difficult.
Once you’ve hacked your old tail off, you’ll need to fit your frame slugs. These can either be solid round bar or thick walled tube that slides down inside your existing frame, and then into the new tail hoop. 80mm long is plenty long enough to do the job.
Next tack weld the slug in place and slide the new tail hoop on and drill a 6-8mm hole on either side of the weld join – these will be used to ‘plug weld’ the slug in place and add strength. I’ll sometimes do one side, and then the seam on the other plug welds depending on the hoop (that’s shown here).
Get your tail hoop aligned and held in place (magnets, tape, chewing gum – whatever you’ve got) and put your final few tack welds in place.
Step 4 – Finishing off:
Once that’s sorted, go to town with your welder. I start on the plug welds and leave the seam join until last. It’s personal preference – its up to you. Finish it back with your grinder or belt sander and there you have it, a new subframe to base your custom seat and/or tail cowl off of.
This how-to guide is presented by:
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