There are many different ways to do this with just as many shortcuts.

However, from what I’ve found this seems to be the best and safest way to make a custom fiberglassed seat pan.

Make sure you do this in a well ventilated area and ALWAYS in the shade. Take your time and most of all.. Good Luck..

How to make a fiberglass Seat Pan:

Before you start, there are a couple of things to you need to figure out.

First: What shape do you want your seat and seat pan to be.

Second: How will it sit on your sub-frame. I recommend you trim the backrest
area a little heavier in height. Remember that you’ll be adding about two
inches of foam to the bottom so you will need to have enough seat pan left for some back support.

Do not get too crazy with the shape of your pan. Something
smooth or to a point is ok but when you start doing abstract shapes the more difficult it is to make a flawless cushion. So KEEP IT SIMPLE..

Lastly you’ll need to figure out how you are going to mount the seat to the sub-frame. Since almost every bike is different, the way to mount the
seat is different and this needs to be figured out at the start.

Some bikes can utilize a tongue on the front that can hook into something or maybe a couple of bolts glassed into the pan somewhere is your method of fastening it.

What ever you decide; now is the time. Just don’t use Velcro like some people do, they tend to fly off at high speeds.

So let me start off this tutorial with the most important thing you’ll need to complete this project:


Fiberglass seat pan Materials List:

• 24 oz. polyester fiberglass resin and hardener.
• 2 yards 3/4 oz. fiberglass mat.
• 1/2 yard fiberglass roving or cloth.
• Couple of cheap 2" brushes.
• Mold release wax, car wax or bowling alley wax.
• 3m Paint tape.
• Aluminum a/c duct tape.
• Cardboard.
• Couple pairs of rubber gloves.
• Heavy duty gloves.
• Face mask and eye protection.
• Plastic or Boat Mask.
• Mixing cup and stick.
• Tools for trimming the pan

There are a few other things one needs to complete this job that’s more of an accessory rather than part of the material list.

Those things are:

• TIME TIME TIME
• A few good friends
• A couple cases of beer


OK… Let’s get glassing….


STEP #1:

We start with 3M Paint Tape to create a base or if you have a finished frame project use it to protect paint.




STEP #2:

Use cardboard to cover wide openings/holes and to make the bottom smooth.





STEP #3:

Tape off every section where your seat pan will sit. Also, if it’s a finished paint project tape as much as possible to protect paint.





STEP #4:

Now use your A/C aluminum tape and tape over first the 3M tape carefully. Notice that the fender bolts have been covered with cardboard to flatten that area out.





STEP #5:

Cover bike with plastic. Be safe not sorry. Wrap as much as possible to protect from resin splatter.





STEP #6:

Put on gloves and wax area with mold release wax. Bowling alley wax works or can use car wax in a pinch. You’ll need about 3 or 4 coats. Wax every nook and cranny to make removal easy.





DON’T FORGET: Cut your fiberglass mat for your layers ahead of time, a little larger than needed. You’ll need to make at least 3 to 4 layers of mat. Cut a few short strips as well. You may have to add a piece if you are short in an area.


STEP #7:

With gloves, mask and eyewear on; mix your resin according to directions and the weather. REMEMBER: do this in the shade.

Use your brush to spread a coat of resin onto the tape.





STEP #8:

Take your first layer of fiberglass mat and start putting it down with your brush. Use only enough resin to soak fiberglass.

Use the brush to push excess resin and air bubbles out towards sides.

More resin does not make the pan stronger.

Try to get it in every area and as even as possible.





STEP #9:

Make sure to use a layer of roving or cloth for extra strength. (I found fleece works well too)




STEP #10:

This is where the TIME aspect comes in. You’ll need to let it dry over night. Now if you get up early in the morning and get it done, you’ll be able to work with it later that the evening.

(early mornings are no excuse for not bringing your friends over and drinking the above mentioned beer)


STEP #11:

Using thick gloves, grab an end and pull up carefully. Pull the pan off the sub-frame and mark where you want to trim it by using a Sharpie marker.





STEP #12:

It is always easiest to start marking your pan with a center mark.

When you start to trim go easy and take your time.

You can use an air saw or a band saw or even a cut-off wheel to trim your pan.





STEP #13:

You’ll have to trim and reinstall several times so you get the shape you want.





STEP #14:

Check the fit and try to get the pan as symmetrical as possible. When you are happy with the shape, sand all edges as smooth as possible.





STEP #15:
Add your fasteners to do a dry attached run to make sure your fastening system works before you get your seat upholstered.


STEP 16# (last step):

Take your seat pan to an upholstering shop or attempt to upholster it yourself, finish up the project and attach it to your bike.


There you go, a custom seat pan…

I hope this helped you out.. Good luck..

Remember to post picks if you give this a shot.. let us see your work.