Disc Brake Adapter

RedB66

RedB66

Active Member
Disc brakes for front forks. I came across this site that offers an adapter for use on front forks (any). They use a free wheel rim on the front turned around so that the disc brake adapter threads on and then there is a seperate bracket that holds the brake caliper. Pretty neat idea!! The bracket for forks without caliper tabs is near the bottom of the page.

Brakes
 
I have dealt with that supplier quite a bit being as we are both north of the border and he has been great to work with.
 
Good find, Red,
They have some great looking things. My new Jag project is crying for either disc or drum brakes, especially in the front. Thanks.
Tom
 
I have read that if you loosen your axle nuts and your front wheel can drop out of the fork on its own you should never equip that fork with a disc brake as the action of the braking pulls the axle out of the fork.
 
GeneFiorot said:
I have read that if you loosen your axle nuts and your front wheel can drop out of the fork on its own you should never equip that fork with a disc brake as the action of the braking pulls the axle out of the fork.
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The bracket is independent from the brake. I don't really understand your point here. "If you loosen your axle nuts and the front wheel can drop out" I would think that part of the installation requires you to tighten the nuts up after you mount the bracket.
 
MY point was on of a safety issue. If you have the type of fork that when you loosen your axle bolts and you lift the wheel off the ground and the wheel simply drops out of the fork it is not recommended to use a disc brake with this type of fork. The reason is the torque applied to the disc when braking tends to pull the axle out of the slot. I have no knowledge of adapters simply what I have stated for others to research as I have done regarding adding disc brakes and the limitations of certain forks notwithstanding using adapters.
 
I can't see how that would happen. The torque applied at the disk would be no different then the torque applied by caliper brakes. If your axle nuts are tightened properly there shouldn't be any problem.
 
This was not the first place I read this I am looking for the original comments....

A correctly secured quick release is unlikely to be ejected from the dropout in normal use where rim brakes are in use, although recently there has been some evidence, notably from James Annan, a British scientist working in Japan, suggesting that the moments in disc brake systems can cause quick-release front wheels to be ejected past the lawyer tabs. A small number of serious crashes have been attributed to this cause. This is controversial, and the fork manufacturers have not admitted a fault, although there is some evidence that they may accept the principle, and advice on checking quick release tension has been strengthened. [3][4] A complete solution to ejection risk would involve mounting the front disc brake caliper in front of the fork blade rather than behind, as the reaction force on the disc would then be into, rather than out of, the fork-end. However, this would involve major retooling by fork and brake manufacturers, though British manufacturer Cotic has placed the disc caliper mounts on the front of the right fork blade on its Roadhog fork. This allows standard brakes to be used, and also makes it easier to mount mudguards.
 
GeneFiorot said:
I have read that if you loosen your axle nuts and your front wheel can drop out of the fork on its own you should never equip that fork with a disc brake as the action of the braking pulls the axle out of the fork.
Click to expand...

That doesn't make sense... Every factory bicycle I can think of that has a disc brake on the front, has a fork that allows the wheel to "drop" from the bottom!
I don't think any bicycle factory would sell a bike that the front wheel could pop off from using the front brake!!!

Also, the struts on many springer forks have a closed loop on the wheel end that wouldn't let a wheel "drop off".

To sum this up... I think front disc brakes are the best kind of brakes for stopping MB's, & will not cause any problems is installed properly. IMHO
 
It does say Quick release in this explanation. Although that was not in the original source that I had read. I am still looking for that source. But in any case this problem is cited more than one time. Whether it is a serious problem or not lends itself to the controversy that is also cited in the source. One can only consider it , look for more evidence of it , or ignore it to ones peril possibly. I only offered it as information and possible discussion. A defense of bicycle equipment manufacturers seems off the point.
 
More links on this subject please? I don't see this clearly yet. My currant front disk brakes are of factory design down hill rock shock triple crown. Just woundring?
 
GeneFiorot said:
It does say Quick release in this explanation. Although that was not in the original source that I had read. I am still looking for that source. But in any case this problem is cited more than one time. Whether it is a serious problem or not lends itself to the controversy that is also cited in the source. One can only consider it , look for more evidence of it , or ignore it to ones peril possibly. I only offered it as information and possible discussion. A defense of bicycle equipment manufacturers seems off the point.
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My point in mentioning the bicycle manufacturers is this... They are so careful of possible lawsuits that they would never sell dangerous bikes that could have the wheels fall off during braking.

And as far as quick releases go; walk into any bike shop & tell me how many bikes with front discs also have a quick release??? (all of them!)

Yes, a wheel with a disc could come off if it's not tightened properly, but that's the rider/ users fault, not the disc brake!
 
As a dealer I would think you might be more open to the subject in light of easily available documentation. In any case others might be interested in the following:

Disk brake and Quick Release problem

Technical Q&A with Lennard Zinn - Funky Disco Drop-out - VeloNews

http://pdf.velocam.com/20030709_-_B...ers_verify_axle_slippage_and_QR_loosening.pdf

Speaking of lawsuits have you paid your insurance? If he has not read it, I will point this out to Jim Manic Mechanic for his opinion. Maybe he will share his thoughts here.
 
Kevlarr said:
I can't see how that would happen. The torque applied at the disk would be no different then the torque applied by caliper brakes. If your axle nuts are tightened properly there shouldn't be any problem.
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At first thought, this would sound crazy but if you think about it, with caliper brakes, the moment is traveling forward at the point the pads grab. Resulting force on the wheel would be rearward at the axle.

With a disc, the disc caliper is usually right behind the fork tube and the moment is traveling UP, not forward at the point of pad grip. The resulting force on the wheel is DOWN at the axle. It sounds a bit confusing at first but I'm sure an axle pull out is possible especially if the axle isn't very tight. If you are using a disc brake, check you axle nuts/quick releases often, keep them tight but don't over-tighten them either.
 
I'm going to bump this old thread because I did some research on the issue of disc brakes and quick release rims prior to installing them on a bike that originally had rim brakes.
One point that was not brought up here is something called, 'Lawyer Lips'. No, it has nothing to do with attorneys.

A lawyer lip is the indented or concaved portion of the front fork/dropout, that is designed to keep the axle from falling out unless the nuts or quick release is extremely loose. Loose enough that any amount of common sense would tell the rider there's a problem before the wheel falls off. I don't have the data in front of me but early bikes did not have lawyer lips but all bikes made or sold in the U.S for some years have had this required improvement to fork design. I have an 80s vintage Roadmaster that did not have the feature so the law must have been passed after it was built.

Goat Herder posted some links a while back, to studies done on the issue of quick release (QR) rims and disc brakes. In the article they explain the potential for a wheel to be pulled out of the dropout by the forces applied on it by a disc. They go on to say that bikes with Lawyer Lips are pretty much immune to this danger.

And while we're on the subject of disc brakes, if you've never had them and then install them, you'll never go back to rim brakes again. Guaranteed.
Tom
 
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2door said:
I'm going to bump this old thread because I did some research on the issue of disc brakes and quick release rims prior to installing them on a bike that originally had rim brakes.
One point that was not brought up here is something called, 'Lawyer Lips'. No, it has nothing to do with attorneys.

A lawyer lip is the indented or convex portion of the front fork/dropout, that is designed to keep the axle from falling out unless the nuts or quick release is extremely loose. Loose enough that any amount of common sense would tell the rider there's a problem before the wheel falls off. I don't have the data in front of me but early bikes did not have lawyer lips but all bikes made or sold in the U.S for some years have had this required improvement to fork design. I have an 80s vintage Roadmaster that did not have the feature so the law must have been passed after it was built.

Goat Herder posted some links a while back, to studies done on the issue of quick release (QR) rims and disc brakes. In the article they explain the potential for a wheel to be pulled out of the dropout by the forces applied on it by a disc. They go on to say that bikes with Lawyer Lips are pretty much immune to this danger.

And while we're on the subject of disc brakes, if you've never had them and then install them, you'll never go back to rim brakes again. Guaranteed.
Tom
Click to expand...

If you use disc brakes on the Monark or Schwinn style springer forks?, you don't have to worry about that problem because the Monark dropouts face forward & the Schwinn fork has closed ends on the struts; (so the wheel can't fall out.) ;)
 
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