Why are track forks different?
 

I am just curious why the blades on track forks are round, rather than the normal oval shape of most forks? What difference does it make in the performance of the bike, if any?

The road fork oval is designed to withstand greater forces straight on like bumps and braking while track forks are stronger and stiffer side to side to counter frame flex.

I think.

I'm guessing but, a track is much smoother than the road, the round blades are stiffer and the rake less, because the bike turns more by leaning than turning the wheel. But some road bikes used round blades too.

What about road bikes that have track style forks? I imagine they have a correct amount of rake, but what about their strength for handling the forces of braking and all the straight on bumps roads provide? Do you think they just use a different steel to make up for the additional strength needed on the road?

Remember round came before oval tubing way back when the safety bicycle was young. Part if it is Styling. Way back a sprinter wanted a beefy bike, 24 mm round blades filled the bill. Some builders such as Hetchins, as their examples are easy to find on the web, used 22 mm round blades on the road if you asked. Then more styling later, Imperial oval and Continental oval blades, the Continental oval eventually winning favor. Allegedly as they were stiffer side to side, Allegedly. The fork crown I think plays a bigger part in how the fork flexes or not. Eddy's hour bike used continental oval blades.

There weren't a lot of C&V road bikes with typical round section track forks, as far as I can see. In those instances, we would hope that the designers/builders did their jobs correctly.

Rake is related to size, frame angles, wheelbase and purpose too so you may be imagining wrongly. Are you thinking of putting a track fork on a road bike?

I don't know about the blades shape but I believe they are much shorter also. alot of track bikes I have seen there is little clearance between the tire and crown and also the crown itself is shorter and not drilled.

I have a vintage road bike with the track style forks. That is why I asked. I know it is not anything special, but it just got me wondering why the difference for track bikes. Lots of clearance on mine though, with plenty of room for fenders or whatever.

Oval blades withstand braking forces much better than round ones.

what kind of bike? and what makes you think it is a track fork? is the bridge drilled?

Maybe so, but the Raleigh Professional Mk.V (road) used Continental ovals, which can be easily confused, if you haven't seen the two side-by-side. My '87 Basso (sloping crown) has Conti ovals as well. Same for the Peugeot PY10, but that's metric 531SL/531P.

-Kurt

Are you stating that round blades are unsafe?

Good trolling question for Trackies or SSFG. :innocent:

I've got a few pairs of very old track forks in the stash and I've always hesitated to use them in a build. I'm heavy and they just look a little too slender.

Not one bit. Traditional track bikes with round-bladed forks wouldn't have had brakes at all, so this would be a moot point anyway. But put a 200# rider on a "track" fork with round blades and a brake, and a "road" fork with oval blades, and with the same speed, braking force, etc., you'd be amazed at how much the front hub on the track frame moves "backwards" from braking force. I've seen it. It happens.

Falcon and some of the English builders (like Hetchins, already mentioned) used round fork blades on road bikes. And track bikes could have oval as well...

I had a Jack Taylor cross frame with round-bladed fork.

Taken from "The Custom Bicycle" in 1978 by Kolin and De la Rosa

Since a road bike is fitted with brakes, the fork blade must be oval to eliminate the shuddering which would otherwise result under hard braking. Track Bicycles, which have no brakes, have round fork blades due to the greatly increased stresses caused by centrifugal force and side-loading caused by the banking of a track. Since tracks have a smooth surface, the neccesity for a fork to act as a shock absorber is reduced.

My 1948 Raleigh Record Ace has round section fork blades, and it's definitely a road bike. I haven't noticed any abnormalities in the handling.

I understand why round blades would be stiffer side-to-side while D or elliptical blades would be stronger front-to-back, but I really doubt it would make any difference to someone of my weight, and I am disinclined to think it would make a difference to anyone. Bicycle designers and theoreticians often get an idea about something or other and proceed to base all their designs around it, without ever really testing them properly. Whether this is such a case, I don't know; but it sure wouldn't surprise me if it is.

As I recall, that Kolin/De la Rosa book is full of statements like "Signor such-and-such believes blah-blah-blah and therefore designs all his bicycles to conform with this principle."

^ true that, plus riding conditions and demands for everyday riders vs pro level riders are quite different. I doubt most of us would detect any brake or stiffness performance difference for round vs oval blade forks, ... maybe in emergency stops.

No, just more flexible if you mount a brake.

The bike I have with track style forks is a 1974 Nishiki professional. Fortunately, I am only 130 lbs. so I doubt I will have much problem from braking force flexing the forks. At least I hope that's the case.

Are the round blades wider than an oval blade when viewed from the front? If not, I think the argument for side to side strength is probably not valid or the differences are negligible.

Yes, the forks are wider when viewed from the front.

+1. I've been told that the Wright brothers succeeded in their aeronautical endeavors while others were failing because they were bicycle mechanics and understood that to turn, you need to lean (or bank if you're in an airplane).

I believe the oval blades are essentially the round blades, but flattened some.