Mudguards (fenders for some)

[peteremc]

Not a big question but I saw a statement on another recent thread about losing weight off a bike which said "The composition mudguards are heavy and lighter alloy ones would save a few pounds".
My first question is, what is the front guard (fender) on an R65LS made from? I take if from the above that it is a composite material.
My second question is a composite of what?
My third question is, if I wished to shorten up the front guard, what might be the best method?
Thanks all

[Barry]

Mudguards will do for me.  

They seem to be made of a high quality fibreglass and they are quite heavy as mudguards go. I imagine they would be easy enough to cut and refinish. You'll find under the paint that they are an off white colour.

[montmil]

I'm presently rehabilitating the rear fender on my '78 R100S and, yes, the fenders are fiberglas. When first acquired, the fender had been chopped short in an ugly manner. I trimmed it further and it now has a shape kinda similar to the latest sport bikes.

The fenders are easily worked with common tools. I used a Dremel cut-off disc followed by a mill file and a sanding block. Just this week, I've removed the fender for a tune up and repaint.

As with any fiberglas work generating dust, wear a filter and eye protection.

[Luca]

Thin tin will always be lighter than fiberglass.  If you've got the skills or the coin, working a sheetmetal fender could probably save you some weight.  Shortening works too, but you'll end up with more dirt and tar getting flung on the rest of your machine.

For serious unsprung (and rotating) weight savings I'd look to the front brake system.  You could also consider running the front tire tubeless: that's your call.  FWIW, I'm pretty sure the LS wheel is lighter than standard, though the second disc helps make up for that.

[Warbucks]

I thought about changing to metal mud guards and therefore mentioned it to a few older boxer owners. I was advised against doing it. Apparently the vibration from the engine will eventually cause stress fractures around the holes where they are mounted. The result being that you'll eventually need to replace the mud guards. Not so good if you're out on a run three hundred miles from home. Perhaps that's why BMW made them with fiberglass.

If you're considering trimming down your originals, check on the regulations before you do it. If they're cut too short in NSW you can get a defect notice if the cop doesn't like the look of you.

[Matt Chapter]

you can get a defect notice if the cop doesn't like the look of you.

At that point, in my experience, you're getting a ticket because your paint is too bright / dull, visor open / closed, or any sort of nit picky detail.

I do remember looking directly at a cop to my right at an intersection, waiting for the light .... springing away up to 10,000 rpm on the 400F.  Which is a lot of excitement but only 25 mph. Visor down!

[peteremc]

Thanks all. I seriously wasn't sure what the material was, so pretty happy to hear it's easy to work with.
It's pretty easy to believe that a lighter metal guard might crack with stresses around mounting points. Don't think I'll be going there.
Weight is not really an issue for me. This is not going to be a performance bike, in fact probably a little more form over function in a couple of ways. Remains to be seen.
Yeah Warbucks, I'm hearing you. I've checked the design rules that apply up here in Queensland and suspect (no, I actually know) I'll be pushing/contravening the rules, but low risk I figure. Somewhat surprisingly, with all the heat on the outlaw motorcycle gangs up here, the powers that be seem to have a whole different relationship with motorcycle enthusiasts - best of all, they have been educated to tell the difference between the two!
Thanks all

[montmil]

Resurrecting this thread in regards to modifying and painting an Airhead rear fender:

The Airhead fenders are fiberglass. Prior to laying up the glass fabric in the mold, a gel coat is first sprayed into the mold. This is the creamy white color Barry mentioned. Gel coat povides a near flawless top coat. After removal, trim and full cure, the fenders are painted a matte black.

The rear fender on my R100S has been trimmed and the tail light is tucked up under the seat's tail piece. Not quite like the current crop of tall arsed sport bikes. You may notice the fender's edge is absent near the tail end of the fender.

Much of the OEM black painted components on the R100S are now powder coated gloss black; save for the scruffy, scratched matte black rear fender. We're going to fix that.

First photo shows much of the OEM black paint sanded off. Several thin spots in the gel coat exposed the fiberglas cloth weave. These spots are going to be filled along with some pits and scratches. Light smears of body filler and quite a bit of sanding preps for primer.
   Yes, those are some of the grandkids Christmas packages. It was 2016 by a week before the fender was installed

Next photo is of the second coat of high-build sandable primer. First coat was worked down almost to the gel coat and filler. Last coat required only a light touch of 400 grit, used dry. Note: The primer can absorb water which will slow down the job until it all evaporates.

After shooting a couple coats of gloss black and letting the paint cure, I was almost out of time prior to taking off on another road trip, hence no pic of the unmounted shiny black fender. Could not bear to use the weathered hardware so new metrics finished off the install.

Most of the hours rehabbing the fender were spent in sanding. The actual color shoot took about 3-5 minutes for each coat. I spent nearly an hour cleaning the spray gun.

[BPT]

If you had good luck with that paint, what kind did you use?  I was wondering if there were any DIY's on here for painting.  I really want to change the color of mine.  Not sure how well I'd do myself but can't afford to send it out for a "good" job at the moment.  I know that prep is the biggest part of the job.  But some paints can be easier or more difficult, I believe.

[montmil]

If you had good luck with that paint, what kind did you use?  I was wondering if there were any DIY's on here for painting.  I really want to change the color of mine.  Not sure how well I'd do myself but can't afford to send it out for a "good" job at the moment.  I know that prep is the biggest part of the job.  But some paints can be easier or more difficult, I believe.

The rear fender on my R100S is barely visible but I see it every time I open the seat. You are exactly right regarding preparation. At least 90% of your time will be spent doing the nasty part. Actual color spray goes relatively fast.
   For the fender, I bought a half-pint can of Rustoleum Gloss Black enamel. Reduced the paint approx 15% with refined mineral spirits and added a speck of flex agent. Leveled out nicely and the gloss matches the powder-coated tank and chassis.

Painting an entire motorcycle requires the same attention to prep work. When purchased, my 1983 R65 ran beautifully but was butt ugly with terrible, orange peel paint. Did my prep, set up a ghetto, tarp wrapped, paint booth on the patio and shot a BMW metallic blue. The sunshine does a number on the metallics in the paint. It's actually all one color.



Buy your supplies from a legit body shop supply vendor. The '83 got Dupont acrylic enamel with a gloss hardener additive. Reduce the paint with an appropriate ambient temp reducer. Clear coat if you wish but I did not. With a new DIY seat cover. Wrapped headers to hide the fugly pipes and with repop Norton Peashooter muffs, well, I think it turned out rather nice. The silver pinstripes on tank and tail piece are vinyl -from the paint shop store.

Your personal labor is free. Materials for my job ran about $125.00 Go for it.

[BPT]

Thanks for the write up.  I can't afford to send everything out and have it done properly.  I figure I can do a decent job, at least a notch or two above rat rod (not that I'm against that, just not for this one  ).  

I have an English Paint supply place just a few minutes away.  I've been in there before and they are plenty helpful and, of course, have all of the proper stuff.  It won't be too cheap though and that's where I'm concerned about my skills.  Torn between using some basic paint and doing an OK job and not out too much if I really screw up.  Or doing things properly but risking the cost if I screw it up.

If you don't mind, where did you get your paint and how much did it take to do what you showed?  I won't be doing the frame, just the parts you show hanging up (+ the rear fender).  Last time I checked about doing a coffee grinder and a bicycle frame, I'm pretty sure they told me it would be near $100.  The BMW pieces will be quite a bit more surface area.  Then I have to add the sidecar into the mix.......

Also, what about primer, did you have to use a particular one?  I know that there are some "better" ones but there are also some paints that require a certain type - and, of course, they are expensive.  Seems like that might have been partly why it was going to be so expensive for my bicycle frame/coffee grinder project.

        Thanks for the info...........

[montmil]

There's an English Color shop in Denton. At least there was last time I looked. All my materials were purchased at Color Service. Another helpful shop.

I bought the primer recommended by the vendor. You'll do a bit of sanding there. Muy dusty. Also shot a coat of sealer over the primer before color. The items on the "tree" used a quart of a metallic color. I was advised that by adding the gloss hardener to the paint would not permit wet sanding the initial color coats. Delete that paint additive and you could, if needed, wet sand away any minor sags or runs, then shoot a coat of clear. Wherever you shop for your paint supplies, tell 'em your a hobbyist, not a commercial shop. I've always gotten discounted prices from Color Service.

The '83 R65 paint job was completed about six years ago. Like groceries, paint prices may have gone up a wee bit since then. You'll still save some serious cash doing the work yourself.

And clean that paint gun when you're finished. My primary gun is over 25 years old and still works as new. You'll save money there, too.

[BPT]

Thanks for the tips and info.  It looks like Color Service is only in Denton, probably too far for me.  I'll try to absorb all of that.  I don't have a paint gun but I think that my dad does.  He has done this sort of thing in the past so I will be hitting him up for help when the time comes.  I'll run all of this by him and see if any of it rings a bell with him.  

It's going to be a little while before I do anything with paint but figured I'd start looking into it now so I can get an idea as to what I am up against.  I know that the big part of it is the prep and labor.  But it's the details like the things with various primers, what you mentioned about clear coat & wet sanding, etc. that I'm worried about.  I don't mind taking my time and putting in the labor but would like to avoid screwing it up because I didn't know of some small detail like those that make a big difference.

 Thanks again for the replies and sharing your thoughts.