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Old 01-24-07, 09:24 AM   #1
Stacey
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Adding a Front Brake ~ Concept Stage

Hi all,

I'm working on restification project, an older leading link front suspension 'BMX' bike.




It looks like I'm going to run alloy hoops with a freewheeling rear hub (either single or multi speed, I haven't decided). This means I'll want to add brakes. Rears are no problem. However, in the front tere is no way to mount a brake caliper to the fork crown as the wheel will move in relation to the crown. The only place that is fixed in realtion to the wheel is the horizontal member of the leading link suspension.



Any thought on the rigidity issues of mounting an old long reach sidepull caliper at the rear apex of the "U" shaped link?

Or, should I just look for a coaster brake hub?

TIA
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Old 01-24-07, 09:33 AM   #2
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Not too sure if drilling a hole at the apex of the horizontal linkage will affect rigidity. It might, but that depends on how secure the axle connection is.

You could have some BMX '990' U brake mounts brazed onto the horizontal linkage.
They look like Cantilever posts, but are mounted further out from the axle.

Then you could use a BMX front brake, which has the cable pulling from the side. Zip tie the housing to the fork and Bob's your uncle.

Oh.. and an interesting thing about mounting the brake there, when you apply the brake the suspension will raise.

Last edited by lyledriver; 01-24-07 at 09:44 AM.
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Old 01-24-07, 10:10 AM   #3
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I'm not sure I understand what you mean by "that depends on how secure the axle connection is."

There's no (minimal) movement save for rotation at any of the joints and the front axle is secure in the ends of thre horizontal link, so that dimension won't change.

I just don't want to be on first ride, grab a handful of front brake and tear up the tubing there. I'd of course use some of those cresent cut brake bridge shims like is used on a brake bridge or steer tube on both sides around the fixing bolt.

I had a BMW moto with the Earls fork, It would rise under front braking as well. The nature of the beast.
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Old 01-24-07, 10:34 AM   #4
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I'd braze in a piece of tubing in the hold you drill to make the hole stronger,and a washer top&bottom to give the brake a flat service to bolt to.Other than that it should work fine---you could experiment mounting the brake top or bottom to see which gives the best stopping.A drum brake would also work for this set up---sam
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Old 01-24-07, 10:44 AM   #5
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Stacey,I took another look at you pics---that horizontal bar will also move--when the front wheel goes up the U bar will dip at the rear--this would thro the brake pads off the rim--or at least make them a bit dicey.Can you mount a regular caliber behind the crown?Or did the bend in the forks mess that up? You may have to use a drum.
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Old 01-24-07, 11:05 AM   #6
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Quote:
Originally Posted by frameteam2003
Stacey,I took another look at you pics---that horizontal bar will also move--when the front wheel goes up the U bar will dip at the rear--this would thro the brake pads off the rim--or at least make them a bit dicey.Can you mount a regular caliber behind the crown?Or did the bend in the forks mess that up? You may have to use a drum.
Look again Sam. Regardless of where that horizontal U shaped arm is on the diameter of the wheel it will always be at the same tangent/radial. Yes, if the front wheel moves up, the back of that arm will move down, but its relation to the wheel won't change. I ran a similar fork on a BMW moto using disc brakes instead of a caliper, of course, with no problem.
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Old 01-24-07, 12:16 PM   #7
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I've often wondered about an Earls fork on a bike---had to really study what you said about the arm/wheel not changing.Should work fine then---and ---you may have just solived the problems of the fork I want.What shocks are you using?---sam
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Old 01-24-07, 12:38 PM   #8
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Re: post 1......Stacey- to me it looks kind of borderline. It's hard to get a clear idea of how much metal will be left around your hole if you drill one for a caliper brake. Also, the steel you're working with there looks slightly rusted. My sweetie's old department store bike was set up so that under heavy braking, the rear brake pads basically run into the seatstay tubes. (as would happen if you used a flexible caliper and mounted it below rather than above the U-shaped bar.) This takes stress off of the mounting point. next to the pads there were these metal L-shaped things that were clearly put there to keep the brake pads from fitting themselves between the seatstays and the rim, instead keeping them securely behind the seatstays and allowing them to spring outward when the brakes were released.
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Old 01-24-07, 12:44 PM   #9
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Originally Posted by cerewa
Re: post 1......Stacey- to me it looks kind of borderline. It's hard to get a clear idea of how much metal will be left around your hole if you drill one for a caliper brake. Also, the steel you're working with there looks slightly rusted. My sweetie's old department store bike was set up so that under heavy braking, the rear brake pads basically run into the seatstay tubes. (as would happen if you used a flexible caliper and mounted it below rather than above the U-shaped bar.) This takes stress off of the mounting point. next to the pads there were these metal L-shaped things that were clearly put there to keep the brake pads from fitting themselves between the seatstays and the rim, instead keeping them securely behind the seatstays and allowing them to spring outward when the brakes were released.
I have a set of those calipers & wings. That's one thing I was considering
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Old 01-24-07, 12:49 PM   #10
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Originally Posted by frameteam2003
I've often wondered about an Earls fork on a bike---had to really study what you said about the arm/wheel not changing.Should work fine then---and ---you may have just solived the problems of the fork I want.What shocks are you using?---sam
These are just the 'shocks' that came on the fork. Really nothing more than a telescoping unit with a heavy spring. There is no dampening.

I have no idea what this fork came off of. I have seen production bikes from that era with this Earls fork on it.
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Old 01-24-07, 01:37 PM   #11
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personally, i would go w/the coaster brake rear. then you wont have a bunch of brake lines either (more aesthetic).
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Old 01-24-07, 01:39 PM   #12
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I was thinking along those lines, tho I don't have a 36 hole coaster brake hub to lace a rim to.
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Old 01-24-07, 02:30 PM   #13
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Why not just weld on some reinforcements? It looks like there's plenty of clearance for the tire, you could maybe even add a brake bridge of your own.
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Old 01-25-07, 10:44 AM   #14
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Problem solved! I just picked up a $10 donor bike at Salv. Army. Nice set of, I think 40 spoke, too many for 36, alloy wheels with a coaster brake rear. Just a little spring on the rear triangle and it dropped right in.

Next question: Black walls or wide whites? See first picture.
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Old 01-25-07, 11:30 AM   #15
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Originally Posted by Stacey
Problem solved! I just picked up a $10 donor bike at Salv. Army. Nice set of, I think 40 spoke, too many for 36, alloy wheels with a coaster brake rear. Just a little spring on the rear triangle and it dropped right in.

Next question: Black walls or wide whites? See first picture.

White walls are for classy bikes and "nice" rats. Black tires look better on bikes like that, so it just depends on how much your going to clean it up. If you're going to paint or primer it, go with white walls.
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Old 01-25-07, 11:48 AM   #16
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White walls are for classy bikes and "nice" rats. Black tires look better on bikes like that, so it just depends on how much your going to clean it up. If you're going to paint or primer it, go with white walls.
Oh, a paint job for sure... maybe something camo or textured. Nothing real high zoot.
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Old 01-25-07, 01:27 PM   #17
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Originally Posted by Stacey
Next question: Black walls or wide whites? See first picture.
i would suggest 2 things-

1. sand and spray the bike flat black again. that is a unique looking old-school muscle bike, not some cookie-cutter custom. it would be good to do it some cosmetic justice.

2. i was always fond of red w/black. i think a nice set of tires with some red on them would look sick. i know of two kinds- one is black with just a red pinstripe on the sidewall (not that flashy), and the other is all red, the whole tire (more flashy). i believe kenda/pyramid makes both styles, i believe the all-red is called the "kontact" because i have a set of all-blue ones on a bike of mine.
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Old 01-30-07, 05:01 PM   #18
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Drum brakes.... or just forget the front brake. Who needs it on a sweet ride like that?

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Old 01-30-07, 05:32 PM   #19
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Although you've now got a coaster brake, you might still want to add a rim brake in the rear. I don't particularly like running a coaster brake without a backup, especially on ZooBomb. In fact, I usually use the hand brake as my primary and the coaster brake as my backup - I get better control that way - and I prefer the handbrake on the rear for ZooBomb. Also, coaster brake alone is no good if you throw a chain, then all you've got for backup is your feet.
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Old 01-30-07, 05:58 PM   #20
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Oh, a paint job for sure... maybe something camo or textured. Nothing real high zoot.
In that case I say you go with flat black, red rims, red chain and chainring, white walls and some chrome for good measure.
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