Motorized Bicycle Brakes

[Lurker]

I need to upgrade my brakes in the worst way but I want it to look time period correct. I am currently running a Avid bb7 in the front with no rear brakes and it is beyond useless. I have a Sach moped rear hub which has a very large internal drum brake, but that is going to be a real pain in the butt to build the wheel. I guess what I am looking for is some feedback from Sportscarpat or any one else who uses a similar setup before I try to build this wheel. I had also thought about the worksman front drum brake. How well does that work? I would also like to know about any other braking system that is not a rim or butcher brake. Thanks guys.

 

[harry76]

Ive been thinking about whether it would be possible to use a small disc brake rotor (6" i think) but make a cover for it to make it appear to be a drum brake. I dont know how good you could get one to look with a cover but if you could pull it off you would have the best of both worlds.

If your current wheel is disc brake compatible it is an option. But maybe more trouble then it would be worth?

Im thinking something like on old triumphs with the air scoop would look nice. Or perhaps even modifying a drum like this for a cover.

http://thumbs1.ebaystatic.com/m/mdWSpWpyis0rrSUgpcjF5eg/140.jpg

 

[Venice Motor Bikes]

You can lace in almost any kind of hub/brake as long as it has the same # of spokes as the rim.

 

[cobrafreak]

Upgrade your front Avid that is 180 mm to a 203 mm. The way to more brake stopping power is rotor size.

 

[harry76]

Lurker, i presume you know that you can buy a tophat adaptor that allows a sprocket and disc brake to both be mounted to a rear disc brake hub. Although im not sure thats what you are after if you wish to keep it period correct....

 

[42blue15]

I need to upgrade my brakes in the worst way but I want it to look time period correct. I am currently running a Avid bb7 in the front with no rear brakes and it is beyond useless....

Uhhh,,,,, I realize it doesn't look antique, but what about an Avid BB7 is "useless"? It's probably the best non-hydraulic disk brake out there.

As far as lacing up the moped hub into a bicycle rim, it isn't that hard if they both have the same number of spoke holes, and 36 spokes is common for both bicycles and moped wire-spoked wheels. You just need to take the hub and rim to a bicycle shop, so that they can measure the hub diameter & width, and from that they can figure out the correct length to cut the spokes to and then thread them.



If you did not know... bicycle spokes come "uncut" in a length long enough to fit a 29" wheel; the uncut spokes I have on hand measure about 12-3/8" long, which is at least 1-1/4" too long for a 26" wheel. The head and bend is formed on one end, but the other end is left plain--unthreaded.

They must be cut down to size for smaller-diameter wheels, and then the ends must be threaded to screw into the spoke nipples. The bike shop has the stuff to do that, but they need to know the diameter and width of the spoke holes in the hub to figure out how short to cut the spokes.

 

[sportscarpat]

Hi Lurker,
If you want the vintage look then to me drum brakes are the way to go. Engine choice is a big factor to consider, though. On builds where I use a centrifugal clutch on the engine I run the rear drum. Reason being that all the drums are cable actuated and the brake lever needs to mount to the left side of the handlebar. If you have a manual clutch, which also mounts the control lever to the left side of the handlebar, then go with the coaster brake rear with a good sprocket adapter, and the drum up front. Something else to consider is engine offset and hub widths. Some of the big drums are 135mm wide and the sprocket offset will not work with a China two stroke designed for 110mm hub spacing. One last thought is that moped hubs are not a simple bolt on. They require careful offset of the rim, and the backing plates receive a fair amount of modifications. The torque arms also must be solidly anchored which requires a good strong tab welded to the frame.
Pat

 

[harry76]

Yeah theres nothing wrong with coaster brakes, maybe not as good as a disc, but i think my coaster brake (cant recall the brand) work work just as well, if not better then a bicycle drum brake. I cant comment on the moped brakes.

But Lurkers bike is probably pushing speeds, or at least capable of speeds very few people on here have even dreamt of. So what constitutes good brakes on my/ours bike might be crap on his trying to pull up 6.5HP..... just my opinion

 

[cobrafreak]

Lurker, you can do double front disk brakes if you want to. You will need to get a front hub fabbed to bolt on the extra disk. You can run the caliper on the right on the opposite side of the fork. I used to have a 79 Trans Am with 4 wheel disk brakes. GM didn't make a right and a left rear disk brake caliper so they used two lefts and had the left one behind the axle and the right one in front of the axle. Worked great.

 

[bonedeath]

If you did not know... bicycle spokes come "uncut" in a length long enough to fit a 29" wheel; the uncut spokes I have on hand measure about 12-3/8" long, which is at least 1-1/4" too long for a 26" wheel. The head and bend is formed on one end, but the other end is left plain--unthreaded.

They must be cut down to size for smaller-diameter wheels, and then the ends must be threaded to screw into the spoke nipples. The bike shop has the stuff to do that, but they need to know the diameter and width of the spoke holes in the hub to figure out how short to cut the spokes.

This is only partially true. Most shops don't feel the need to buy a professional cutter/threader being as they are a couple of grand... shops aren't really making alot of money off of custom wheel builds anymore seeing as the consumer has a number of options to fulfill their needs. That being said I've worked at one shop with a pro cutter/threader and it sure is nice but they also charged 60-65 for me to build the wheels + cost of parts. Every other shop I've worked at I've ordered the spokes (if we didn't have them in stock already) and charged 40-45 a wheel + cost of parts. Saves labor costs and turn around is much quicker. Keep in mind spoke length doesn't have to be exact to build a wheel..there's a number of ways to shred/add a few millimeters with different nipples. Regardless every shop ive worked at atleast had a handheld mechanical threader... one even had an electrical, which I don't recommend at all.

As far as braking power, those bb7s are pretty awesome without graduating to hydraulic and I couldn't agree more that increasing your rotor size will increase your stopping power. They aren't vintage but they are definitely powerful and much lighter than a drum brake.. Hydraulic would definitely be an upgrade however they get pricey. Do you know what gauge spokes those moped hubs take?

 

[42blue15]

This is only partially true. Most shops don't feel the need to buy a professional cutter/threader being as they are a couple of grand... Regardless every shop ive worked at atleast had a handheld mechanical threader...

I don't know what they use, but I know they can do it. I just bought a half-dozen spokes a few days ago to test the flange fit in a hub I'm making, and they asked what length to cut them to and if I wanted them threaded. I said I didn't need either, so they gave me six un-cut, un-threaded spokes,,, but obviously they had some way to do it.

...Do you know what gauge spokes those moped hubs take?

I have no idea, haven't ever even seen one up close. Just seen a few online that used them... Also now a lot of mopeds come with mag-style wheels, but (in the USA) the Chinese "mini-Harley" style motorcycles and the dirt bikes/pit bikes still usually have wire-spoke wheels. A motorcycle shop should be able to get the spokes to lace them into a 26" bicycle wheel.

 

[Mr.B.]

How authentic do you want to be?

Early BTR’s usually didn’t have any brakes at all or just the same rear coaster’s than most street bikes used well into the mid-teens.

The next common brake style was a contracting band- Just a metal strap around a drum that would be pulled tight, and again it was just found on the rear wheel.

Drum brakes weren’t popular until the late 20’s and only then were to become common on front wheels. Even then the drum was tall, skinny and towards one side of the hub.

Disc brakes- Way later...

Having said that, personally I like the idea of being able to stop quickly and compromised by lacing a big drum brake into the front wheel of my retro 1909 project.

It came from a heavy 1.75” X 16.5 inch 36 hole rim so I assume It may be from a small motorcycle or an perhaps an older moped ( ? ). I just cut to length some 11G spokes I had from some old Schwinn tandem wheels and rolled new threads.

I borrowed a simple thread roller from a friend. You clamp it into your vise, adjust the roller wheel spread, insert a spoke and turn a small hand crank.

Bingo- Fast, simple and effective!

I don’t have any photos of the roller or know the brand name, but I do recall he said it only cost around $75 when he bought it new online a few years ago.

-Kirk

 

[cobrafreak]

After breaking my rear band brake for the second time I am going with a rear disk to work with my front drum. I have a flip flop hub in the back and I found an adapter to spin on a brake disk so I can run a mechanical rear. I feel I can hide it rather well as it is sitting next to my 50 tooth chain ring in back, so all I need to do is put a faux drum cover on the left hand side and you wouldn't see it. Here is a link. It's a WinZip CE and the reviews are not bad. They say it's the only mechanical brake caliper that moves both pads to clinch the disk at the same time. And it's only $59.00!
http://www.bicycledesigner.com/bike-parts/brake/disk-brake-kit.html