Change fork to retro fit drum brake?

[zzpza]

So I have an old 1980's Raleigh Sensor made from hi-ten steel. I want to fit an SA X-FDD (combined dynohub / drum brake) front hub. Do I need to change the stock fork (as the braking force is now in a different location) for a more beefy one, or will the original be OK?

Pic of bike including stock fork:


Shopping Fixie by zzpza, on Flickr

TIA!

 

[TheDoctor]

Well, my answer really helped!!!
(100% Don't know)

 

[Rickshaw Phil]

I'm afraid I also don't know, but I'd be interested to know the answer as I have a notion of investing in a drum brake hub at some point in the future.

 

[Jon2]

I don't know exactly how drum brakes work, but my opinion would be that it's fine. My reasons for this opinion are as follows...
At the moment, with rim brakes, you are trying to slow the wheel down, and effectively trying to create a pivot at the point where the brakes are attached to the fork and the rest of the the fork and wheel move backwards. This gives a very long lever on this pivot, although the forces are quite low as the brake works on the outside of the wheel.

With disc brakes the forces are much higher, but the lever would be much shorter as the pivot is much closer to the hub of the wheel.

If my understanding of drum brakes is correct, then this lever would not exist as the brake is attached to the fork in the same place as the hub.

That's my opinion, but I fully expect someone to come along and tell me I missed something.

 

[mrandmrspoves]

Issues you may have are;
You may not have clearance for the actuation lever where it attaches to the drum.
You may need to rig some type of cable stop on the fork.
Apart from those issues I don't think the fork would need to be changed and certainly not because of the improved braking force exerting more pressure on the fork......because it will probably not give improved braking except possibly in the rain.

 

[sidevalve]

The actual retarding force is still transmitted via the wheel centre to the fork whatever you brake with so I suspect that if you can get it to fit and as above sort out some form of cable stop etc then it shoud be ok.

 

[zzpza]

So I got up extra early yesterday and laced up the X-FDD and S2C hubs to some rims.


New Wheels by zzpza, on Flickr

The fork does bend a lot more than when I was using a rim brake. I guess before the distance between the brake and the pivot point (where the steerer tube goes into the head tube) was very short before, but is now much longer, which is accounting for the extra flex. I would prefer it not to flex so much as I am concerned it is going to crack at the crown. I have measured the distance between the guard and the down tube to use as a datum for measuring any permanent bent.