Introduction: Motorcycle Lowers (low Deflectors)

Picture of Motorcycle Lowers (low Deflectors)

Tis the season, once again, to make something for my motorcycle to compensate for the cold weather.
I've been thinking about these for a few years and just didn't get around to making them.

Lowers are deflectors that mount to the forks and deflect the wind away from your legs and keep it from kicking up under the windshield and into your face.

The solution I came up with is fairly simple; easily acquired materials and hand tools will get the  job done.

Before you start, read all of the directions and look at your bike to determine what adjustments in materials you may need for the size and mounting conditions you need to work with. 

If you plan ahead and purchase all the materials you need, you can complete these in about an hour.

Lastly, there will always be those that think these are not finished enough to put on their bike. So don't.
My bike is strictly for commuting and running errands. It is a workhorse and not a show piece (although it still looks pretty good.
I commute down to about 18 degrees F, so I'm more interested in utilitarian concerns during the winter than looks.
That being said, these things are a nice compliment to the windshield and homemade hand deflectors (see other Instructable).

Step 1: Materials and Tools

The following materials were obtained from the local Home Depot and Ace Hardware stores and can be obtained at pretty much any big box or neighborhood chain hardware  store.
  • Lexan polycarbonate sheet: I needed (2)pieces about 17" x 5". I purchased a .093" thick 12" x 24" sheet for around $13 from Home Depot..
  • Aluminum angle: I needed (2) pieces about 17" long. I purchased a 3/4" x 3/4" x 1/16" x 36" piece of aluminum angle for around $7 from Ace.
  • Adjustable straps: I needed (4) straps for approx. 3" diameter application. I purchased (4) stainless steel adjustable straps for about $2.40 each from Ace.
  • Machines screws, washers and lock nuts: I purchased #10-24 x 1/2" stainless steel machine screws, washers and lock nuts from Home Depot.
  • Cardboard for making a template
  • Old bicycle inner tube
  • Some kind of tape - Optional
  • Piece of rubber bungee cord (to act as spacer) - Optional
The following tools were used:
  • Jigsaw for cutting Lexan
  • Hacksaw for cutting aluminum angle
  • Drill (I used a drill press) for drilling aluminum angle and Lexan
  • Sheet metal shears for cutting adjustable straps
  • Files for smoothing cut edges of Lexan, smoothing cut ends of aluminum angle, elongating the drilled holes in angle to make slots, smoothing cut edges of straps
  • Dremel tool for elongating the drilled holes in angle to make slots
  • Screwdriver for adjusting straps
  • Writing implement (I used a Sharpie)

Step 2: Making a Template and Cut the Lowers

Picture of Making a Template and Cut the Lowers

I cut a rectangle of cardboard the approximate size of the lowers I wanted and held it against the fork to get a sense for how big the things wanted to be.

Next, I cut that into a shape that I thought would be appropriate. It was a little wider at the top (about 4 3/4") than at the bottom (about  2 1/2") and held it against the fork to confirm that was the right profile I wanted. I Started a little long figuring that I could always cut it down later.

I traced the pattern onto the Lexan and cut it out with a jigsaw. Use a file to smooth off the edges.

Step 3: Making the Angle Supports

Picture of Making the Angle Supports

Originally, I was going to use a fairly thick piece of Lexan or acrylic held to the forks with some sort of strap, however, the Lexan available at the Depot was fairly thin. This was the same stuff I used to make my hand wind deflectors.

Since the lowers can only hard connect to the upper stationary portion of the fork and I wanted them to extend down past the lower section, I figured the thin Lexan would need something to support its length. Hence the aluminum angle.

I cut the angle slightly shorter than the Lexan and marked where the attachment (adjustable strap) points would mount to the upper portion of the fork. Next, I drilled a series of adjacent holes the length of what I wanted for a slot to fit the adjustable strap through. The holes went right up against the vertical leg of the angle.

I then used the Dremel tool for grinding away the bits between the drilled holes and finished them up with a files to make a nice slot.

Next I drilled (3) holes in each angle for mounting the Lexan to the angle.

Step 4: Fitting the Lexan to the Supports

Picture of Fitting the Lexan to the Supports

Next, hold the Lexan pieces in place on the angle and mark the (3) drilled hole locations and the (2) slot locations.

Drill (3) holes in the Lexan for the bolts and cut / file away the edge of the Lexan at the slots

Remove protective covering and bolt the Lexan to the aluminum angle using stainless steel machine screws, washers and lock nuts.

Step 5: Adjustable Straps

Picture of Adjustable Straps

Wrap a piece of paper around the fork leg and mark the circumference, before you buy your materials, to determine what size strap you will need.

Temporarily fit the adjustable strap around the fork, allowing for a little extra thickness for the inner tube (see next step) and mark the amount of excess strap that can be cut off and discarded. Also determine which portions of the strap would benefit from the liquid rubber and mark the strap accordingly. File the sharp edges.

Step 6: Final Assembly

Picture of Final Assembly

Cut pieces off of an old bicycle inner tube. If you don't have one, go to the local bike shop and they'll give you one from the trash. Wrap the pieces of inner tube around the fork where the straps will go. I used Gorilla Tape to hold it in place.

Since the part of teh fork above the mounting section was a slightly larger diameter, I had an approx. 1/8" dimension the I had to hold the angle off of the fork in order to clear an upper section of fork. Your condition may vary. I could have added extra inner tube, but I chose to cut off sections of a rubber bungee strap to act as a spacer and cushion between the aluminum angle and the fork leg.

Clamp them on and adjust as necessary.


MarieR14 (author)2015-09-28

grandpa5x (author)2015-04-24

Great job, looks professional, definitely going to do this on my Suzuki C50T, after riding this bike for a few weeks I knew I didn't like a windshield (previous bikes had fairings) no one makes lowers for C50T. But now I do, this may save the $500+ for a fairing, Thanks.

yingzhao (author)2013-04-14

Hi! I've made your hand deflectors a couple years ago and love them; now I'm finding I need the knee deflectors too. Do you find that the thin Lexan does the job well enough?

marple200 (author)yingzhao2013-04-15

I have had no problem with the thin material.
It does not deflect and has held up well.

Helder4u (author)2012-04-07

Pretty, and smart.

May I suggest that if You want it almost airtight against the fork, You may mount the Lexan on the outer side of the aluminium angle, with a full lenght metal strip between screw-head and Lexan to ease the mounting pressure?

The inner side of the deflectors can be cut to fit around clamps and lower fork quite tight.

Hammerhead46 (author)2011-12-22

Great Job, Very good looking..
I did something like it on an old Suzuki 750 "Water Buffalo".
I mounted some house siding on the crashbars and then made a collector from the radiator to (2) 3" hose run up into the Faring to bring heat up to my hands
Made for much nicer winter riding.

Helder4u (author)Hammerhead462012-04-07

Simple and Smart. Good work :)

rjbatc (author)2011-12-18

You should probably make a "How to survive motorcycling in 18 F " instructable, it could come really useful to me.

Really man, how?

marple200 (author)rjbatc2011-12-22

I agree with Tumunga.
Full face helmet (I usually ride with the shield open because I wear eyeglasses and they tend to fog up with the shield closed, even though I use anti-fogging coatings)
Motorcycle jacket (Joe Rocket Alter Ego - best) over top of polar fleece and dress shirt (layers)
Overpants (First Gear) over dress pants (layers)
Over-the-ankle boots
Wool socks with dress pants tucked into them (keep the wind from blowing up your pant legs)
I have heated Gerbing gloves. All other gloves I have tried (a lot) didn't do it for me below like 28 degrees for my commute. They were either too bulky to use controls or didn't provide the warmth I needed. My commute is 40 minutes of stop and go, so lots of time on the brakes and clutch, hence, cold fingertips. Therefore,heated grips wouldn't work for me.
Toes and finger tips are the extremities that are hardest to keep warm.

rjbatc (author)marple2002012-01-03

Thanks guys, and what about the tires? Do regular tires not get too hard and slippery at low temperatures?

How I went the last time in 2011 (too cold for me later) :

2 bandanas, large one over the bottom of the face and neck, smaller one on the neck
a vest, a shirt, a sweatshirt or something similar ( regular clothing ) and a normal motorcycle jacket ( double layer )
thermo pants ( not very thermo, only thin ones, so I do not cook myself during the day )
jeans, skiing pants
regular socks, skiing thermo socks, regular trainers.

I am not an old motorcycler or something, I just started -
I got my license in the summer and my Suzuki 125 Marauder in September/October maybe, done 2000km since.
So your advice is appreciated, thanks.

And, not to be so off-topic: You wrote, that someone may find these not finished enough - well, I think they are perfectly OK. From the picture I would guess those are original, straight from the factory. So good work.

marple200 (author)rjbatc2012-01-03

Just got home from work.
23 degrees here in Phila.
The tires don't seem to be an issue, although I've often wondered about that myself.

Tumunga (author)rjbatc2011-12-22

I've found if you keep your head covered with a full face helment, it takes a lot of the unbearable part of the cold away. Cold hands are easy to deal with (I use army surplus arctic mittens with wool liners) and dress in layers. You'd be suprised how much cold you can take on the old motorcycle.

I have a 2003 Victory, and you betcha this is on the winter project list. Right now, without lowers, I get so much air coming up from underneath the windshield, at highway speeds, I can rest my arm on the air like it's sitting on the edge of a table.

skesta (author)2011-12-26

You are my freakin' hero! I have the same bike and frozen hands and legs. High five, dude!

marple200 (author)skesta2011-12-27

Happy to help out.
Let me know how your deflectors work out.

Ricardo Furioso (author)2011-12-25

Simple + Sensible + Useful = Brilliant.

canemaker49 (author)2011-12-23

very nice indeed! some of the local bikers might pay you for a set of these.. as for staying warm, i used military cold weather mittens. i used a scarf and cut it down and put my head through the hole to cover my face. i wore a field jacket or a flight suit. it worked reasonably well. we did not have heated gloves in my day, wish we did, lol. .

kpurse (author)2011-12-22

But if the top and bottom are different sizes, does the lower go into the upper as normal? If so how do they work? Does the plastic bend or does the mount slide up and down the leg when you go over a bump?

marple200 (author)kpurse2011-12-22

The mount is only strapped to the portion of the fork that is stationary.
The lower leg of the fork moves up and down into the section I mounted these to.
The metal angle allows the lower portion of the deflectors to "cantilever" past the bottom edge of the fixed fork section and "float" past the moving fork section.

transeunte (author)2011-12-22

Very nice idea, man.

It would be quite easy to bend the plexiglass if you had a wooden mould around 4" diameter cut in half, a heat gun and lots of patience (maybe an oven would help). It would look even more professional and create less aerodynamic drag, without a noticeable amount of lost "protection".

marple200 (author)transeunte2011-12-22

My plan for my hand deflectors is to change do exactly what you described.
Just haven't gotten around to it with all the other projects I have going on.
Maybe next week when I'm on vacation.
I think the Lexan can be put in the oven to soften up and "lay over" a form.
I'll let you know how that works out.

daryl.bookout (author)2011-12-22

Great instructable marple; thanks for sharing this! How well do they work? After riding with them is there anything you'd change, i.e. size/shape etc?

marple200 (author)daryl.bookout2011-12-22

Even though the Lexan is very thin, there is no noticeable deflection.
Very solid.

bahi (author)2011-12-22

I like your instructables, specially the hand wind deflectors one. I also use my bike as commuter vehicle, I realized too about the importance of a fully dressed motorbike. Cruiser motorcycles usually have confortable riding position, but some are quite naked. Have you noticed any change in fuel comsumption?

p.s. My instructable about homemade windshield

marple200 (author)bahi2011-12-22

That's a nice, easy, clean set-up.
Have you thought about figuring a way to form the plexi on a nice curve before installing it?

f5mando (author)2011-12-22

Excellent idea, well executed and beautifully explained. Thanks for this (I could have have done with this in 1994)..!
Shiny side up~

Ender3D (author)2011-12-22

Very Nice...

I think my Vulcan will be getting a set of these this spring :)

mikeasaurus (author)2011-12-17

Nice job! I would have thought these were stock or aftermarket before homemade, great work!

marple200 (author)mikeasaurus2011-12-18

Thanks Mike.
I appreciate the comment.

About This Instructable




Bio: Architect
More by marple200:Homemade Pier/Bridge Landing Net  (Fishing)Bike trailer modification for Fat BikeLeaf Plow for Zero Turn Mower
Add instructable to: