Urban Combat's battered bike of death

Dax motor, two years old, has plenty of miles, mounted on a Trek 930, which was my wedding present back in 1990 from my wife. The bike had a ton of miles put on it in the mountains before the motor, wore through a bottom bracket, a derallieur and even a metal water bottle cage. Then I put a motor on it.... I have been wailing around on this thing, and have completely freaked out all the SUV drivers. The bike now has a sticker on the rack "One Less SUV"...

So far, I'm the only one around here with this. I have seen one rear mounted weed wacker rig, but that was awhile ago. I must say though that having a motor on my bike has made me a better city rider. You have a bit more negotiating power. Top speed is maybe 30. Maybe 35.

At some point I will post some pics of the motor mount we did, it's a bit barbaric, with the welds, but now it holds up well. The frame cracked a bit so we reinforced it with some fence pipe. The curved pipe we welded to that for the front mount ended up being quite sweet.

Bike has a new rear wheel, the first one disintegrated from the city riding, The guy at the shop was like OMG..

- I had to blow 50.00 at a machine shop and have them re-drill the rear stud mounts to 1/4", and then I installed grade B-3 non-metric 4 1/2" studs.
B-3 has a much higher tensile strength, and is way more flexible. If you keep breaking studs, this is what you want. This solved my problem after 3 bolt extractions....(ooy). McMasterCarr.com.

-gas tank leaked and was patched, (long story, My fault) special mount over brake cables to finally keep the tank from vibrating off....
-New gas cap, old one leaked like a sieve, highly reccomend this!!!

-Throttle twisty broke so made a trigger throttle out of a cheap brake lever

-New ball bearing chain tensioner, works well, I recommend!!!

-needs a new seal, oil leaking into clutch case a bit, bleh.

- Been running engine on very high grade racing oil, seems to work well.

- rear red light is a 4.99 6V lantern, looks wierd but is only thing that won't disintegrate from vibration....I wear a headlamp also. I also have two flashies. One is on my helmet. You can find cheap ones at some dollar stores.

- the pedal wouldn't clear the exhaust so I beat an ugly dent in it with a ball-pein hammer, hee, hee. Too lazy to bend the pipe.

- Working on a rechargeable front light. May use the "white wire" post from here, thanks for that. Yes, finally!!!

My favorite: the rear rack is my design. remove the seat with it attached to the post so bike can fit in the van and be locked in.

The carrier box is a metal ice cream rack from a commercial freezer mounted on a fiberglass kid's ski, mounted to the metal rack piece made by Bell. 12.99 at Wal-mart etc. but get rid of the cheesy plastic rack thing. It wobbles.

This rack has great balance, I kinda don't like racks too close to my spokes, I think this is safer. I worry about a loose bungee, etc.

I did away with a cool slick tire in favor of knobbies after picking up some pieces of metal flake, which blew up my brand new slime-tube. yuck!! Slime all over the bike....

I do need a suspension fork for this bike. But the new motor mounts have held up well through the potholed streets, at least for now.

If anyone has a decent, inexpensive used one that will fit this, I might be up for it. I don't need a super gas filled mongoose fork.




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Large Filipino

I like how the flash on your camera highlights all the reflectors!
Nice looking ride,man.


You sound like a seasoned veteran and someone good at improvisation....handy on a trip.
One question....u said u can highly recommend a new tank filler cap cos the old one leaked badly.This new cap was their something special about it,or did u just get the same again from a known supplier?


went back to Dax, (Thatsdax.com) He's lurking here somewhere. He has the new upgraded cap. 9.99. It has a better vent and lock mechanism. The old one leaked when the engine vibrated. Apparently, vibration increases tank pressure, so I couldn't fill the tank all the way. This new cap doesn't do this, well it does if you totally overfill... OMG I was so happy the tank no longer leaked...

Don't bother trying to find one at a moped shop or lawn mover place. I tried. You need the actual Chinese deal.

While you're at it, if you haven't done so, get a ball bearing chain tensioner, and an extra throttle and clutch cable. Expect the factory throttle twisty to break real fast because it's nylon and a piece of junk, but the upgraded ones are real nice. I just Jerry- rigged my own with a brake lever for now, hee, hee.
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More Urbancombat pics, motor mounts etc.

Tore apart my clutch case today and cleaned it out a little more, turns out I might not have a leak after all. Not a lot of oil in there, just some crud. Here's a few more pics of crazy backyard hacking. Thanks Jenna for the tip on the brake lights, that's on the list....

Bike in daylight;
The bike had a plastic mountain bike De-fender on the fron which looked really cool but I took it off because it started coming loose and chewed up my tire. Very cool fender, just make sure it's in that fork tube all the way. The friction mount they use is a bit "iffy".


Rear mount: Grade B-3 (Mcmaster- Carr.com rocks!!!) 1/4" studs have solved the stud breakage issue, had to have a machine guy re-tap the block for 50.00, sigh. 1/4" is slightly larger than 6MM, but there's enough "meat" at the edge of the left rear block to make it. But now I don't have to deal with metrics, yay. As I mentioned before in first post, B-3 alloy is more flexible and has a strength of 125,000 PSI. They use this type of bolt to bolt down "pressure valves" , boiler tanks, etc. 'nuff said. Your average hardware store 6MM bolt is too brittle. You can bend a piece of B-3 grade 6 MM rod almost right angle before it will snap. Mcmaster ships same day and the whole rod was like 3.99 for 3 feet. Machine shop guys all swear by this site.

Spacers around frame are from an old 7-iron. Installed aluminum block behind motor, because it was "hinging" in its mount, causing studs to break, This took me 1.5 years to figure out. Broken Bolt extractions are not fun. We couldn't get one out, so I paid another shop 30.00 to burn it out with electrodes. (before I did the 50.00 re-tap mentioned above)
How cool is that? Turned out the guy has a 1949 Whizzer. Machine shop guys are pretty cool, what these guys do now fascinates me.

The mount was padded a bit on both sides of the frame with a piece of innertube.

I also believe in getting rid of the cheesy thin metal brakets used for under the down tube and behind the seat tube, My theory here is you want to control any flexion of metal, so I went to a nice thick plate for under the downtube (it's that one they want you to use when you drill a hole in your frame. Don't do this!)
.... and and an extra aluminum mount for the seat tube....

I don't bother with gaskets anymore, for the peripheral stuff, I just use Permatex Ultra Copper Gasket Stuff. That's the ugly orange stuff oozing out the clutch case as it dries. I cleaned the oil and crud off the bike so at least it won't catch on fire....



Front mount: cracked the frame in my first week. Be careful of water bottle holes below your motor mounts. I highly reccomend filling them, reinforcing, padding, whatever.

so we welded a piece of split pipe over it, this took all freaking day. The weld job wasn't the neatest because my redneck friend ran out of whatever that gas you need to control the slag is called (acetylene?) We finished right at dark, began at 10AM.

Notice the half pipe mount welded to the frame under the motor. This works really, really well. Of couse, we had to carve slots in the pipe to get the freaking studs past. Sigh.

Eventually, I'll round the corners on the bottom bracket so it won't look so cheesy. These bolts are 6 MM from Ace Hardware. They are not B-7 grade but they've held ok. Ain't broke, don't fix it. I don't think these endure the torque that the rear ones did. The rear torque may also be because of the sprocket/wheel torque, and also because the frame may actually flex when you accellerate. Don't tighten your rear mount bolts too tight, you might crack your downtube.


Of course, you need stupid signage. The Moped sign, though definitely helps in traffic. When people roll up and start asking questions, I just pretend I'm on my phone with a Bluetooth, or I pretend I can't hear them or can't speak english. Whatever, but you need to concentrate, even while sitting idle at traffic lights. pay attention to the vehicle behind you, are they on the phone?

The rear lantern is ridiculous looking from the side, but you will definitely be seen. Dual rear flashers and reflectors all over the place. As a rule, though, if cars start riding my tail, I move over and let 'em pass. Most of the time, you both end up at the stop light at the same time anyway !

I put some red plastic over the rear light lens. I definitely want some sort of rechargeable battery system,
and a real light system. Working on that too. The lantern was 3.99 at Home Depot, comes with a cheesy starter batttery. I think this is how Eveready gets rid of their older batteries. If you want to get some attention at night from people pulling out of driveways, wear a LED headlamp with red lights, (Everready 9.99 at wal-Mart) . When you approach that driver, shake your head like a "NO" from side to side, to them it will look like a beacon/ siren .

I have leaned toward incandecent lights lately. I've broken too many LED's and the electronics in them don't seem to handle the vibrations.

Again. I love this rear rack. While you can't carry tons of stuff in it, its enough for errands, its indestructible, (steel) aerodynamic, (I don't like milk crates, too bulky) and I think a lot safer because the ones with the struts could vibrate right off and go in your spokes and then you die. The fiberglass kid ski for the undermount also flexes when you ride, so you barely notice the difference in balance in maneuvering quickly around pot holes etc. You'd thing it would be wierd with such a high center of gravity, but it's not.


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You should have....

You should be using the 3 hole adapter for the front mount. It will improve your install. Use the 3 hole adapter for the inside and then a steel clamp for the outside so as you tighten it, the steel will conform to your frame contour and make for a super mount. Enjoy the ride..


is this the one where you drill? eek!!! Duane, I'm sure that works fine, but I can't do it.

I have seen some new ideas on this lately, I like the U-bolt idea, if that's what you are refferring to. Someone else also posted an amazing aluminum mount, whicH I can't fine my saved pic of.

I've also seen a 3_hole bracket thing on Ebay with rubber padding, looks wierd but might work well, esp for aluminum frames, my next possible cruiser-build. I do like the idea of some sort of hard rubber cushioning.
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Local time
7:47 AM
Feb 24, 2008
Brainless Island, Wa.

You mentioned looking for a rechargeable battery for one of your lamps.
Is that the rear one or the front one?

A guy I used to ride the boat with, used to work at one of the local TV stations and has been a professional photographer for many, many years.
He's heavily into digital cameras these days and hipped me to "LITHIUM-ION" batteries.
This is a type, not a make.
Check around and see if you can find any that fit the lamp you were referring to.
They're rechargeable, like a NiCad, but last much longer between charges and have a longer "charging life".
More expensive than regular batteries, but worth it, considering the recharging feature.
...you'll need a battery charger, as well, but that shouldn't be hard to find. Doesn't have to be anything special, it just has to fit the battery.