uncle uncle

Assuming there is no markings to indicate material, is there a way to tell if a replacement fork is chromoly (or other higher test steel) than just pedestrian high-tension steel? Asking for a friend... me. Thanks for your responses in advance.

branko_76 

Ask your friend to weigh it and measure the length of the fork blades as well as the steerer tube. Post the results here and I'm sure some of us can compare the findings to forks we own.

JohnDThompson 

Spark test, if you're willing to grind the fork:


https://en.wikipedia.org/wiki/Spark_testing

Otherwise, weight will give you a rough idea of whether an alloy steel of some type was used, but not necessarily the specific alloy, with carbon steel generally thicker gauge and heavier than chrome-moly or manganese-moly steel.

uncle uncle

I'll try to find a way to weigh the fork, when I pull it from the bicycle. I used to be able to weigh things at work (but I was let go), so, will need to figure that out too.

Velo Mule

It is a fork so you can hit it against an object or hit the object against the fork. A wooden or plastic mallet would be good. A high tensile will be a B# and a chrome moly will be a B sharp.

Ok, I just made all of this up, however, higher tensile steels should have a higher pitch. Think about the ring of a good quality wrench compared to a plain piece of steel. But how much higher pitched chrome moly will be and factoring in other variables may make this useless. The biggest other variable and it is a big one is the length of the fork legs. There is also the weight of the fork ends. Oh, one more, the difference in the taper of the tube.

Don't ring the fork to find out.

fietsbob

the whole idea of using a more expensive, higher strength steel alloy, is you can get the job done with less..

so tube wall will be thinner..

T-Mar

Some high grade steerer tubes were are butted with ridges at the bottom, on the inside. Columbus used five, helical ridges on their CrMo steerer tubes. Tange used six, helical ridges. Ishiwata's high grade steerer tubes had five, straight ridges. This only applies to 1" steerer tubes. Once, steerer tubes went over size, the ridges were no longer required to enhance stiffness.

Other high grade steerer tubes, such as Vitus and Reynolds didn't have the ridges but were still single butted. If you have a proper diameter stem with a long guill, such as a Nitto Technomic, you can see how far down it goes into the sterer tube. Butted steerer tubes typically will impede the stem about 2'' from the bottom, though if it's a very small frame, framebuilder's will shorten the butt end to achieve a safe amount of stem insertion. If it's not butted, the stem will insert at least as far as the crown and possibly pass all the through if it not pinned and the brake mounting hole has no burrs. Alternately, you can try inserting the proper diameter stem into the bottom of the steerer tube. If the tube has been de-burred and the stem fits, it's almost certainly a lower grade, non-butted steerer tube.

Stamped dropouts and requiring stems under 22.2mm (or 22.0mm for metric standard fframes) are also rules of thumb for lower grade forks.

Piff 

I weighed the fork from my Raleigh super course a while back and it came out to 1.8 pounds. Hi-ten. I didn't measure the steerer tube, but it's a 23" frame.

clubman 

Looks like a botany test!

uncle uncle

This is a 23" frame (give or take) so when I get a chance to weigh it, we will see how it compares... I just went out to the garage, and the fork has stamped dropouts, with unthreaded eyelets (so two strikes against it for being made of some upscale steel). The eyelet positioning leads me to believe the fork is 1970's, or earlier, vintage.

uncle uncle

Thanks for the info Piff... see my response above (I meant to link my response, but failed to do so...)

barnfind

I didn't have any 23" frames here but I do have quite a few 25.5" frames.

1977 Raleigh Super Course - 1 lb 14.7oz
1978 Raleigh Super Course - 2 lb .02 oz
1977 Raleigh Professional Mk V - 1 lb 15.8 oz
1975 Nishiki International - 2 lb 2.7 oz
1980 Nishiki Sport - 1lb 14.7 oz
1981 Nishiki International 1 lb 13.5 oz
1981 Nishiki Comp II - 1 lb 15 oz
1981 Lotus Legend - 1 lb 14.2 oz

1980 Nishiki Sport - 2lb (21" frame)

The Raleigh Pro is the only one that's supposed to be chromoly, being marked Reynolds 531.
The Nishiki Comp II and Lotus Legend both have Tange decals on their forks but they say nothing about being chromoly.
Each Raleigh bike is a 25.5" frame, all others were billed as 25" frames.
The steer tube on the Nishiki Sport is about 1/2" shorter than that of the other two Nishiki forks.

beicster 

I am surprised at the small difference in those.

barnfind

I have my suspicions that fork tubing isn't always as advertised, whether for structural or strength issues of monetary ones.
I was told more than once by both a few frame builders and by salesmen that the larger size bikes are generally not made of the thinnest tubing both because many tubesets didn't come in long enough lengths and for strength or liability issues.

The lightest forks I've got here are uncut universal Tange replacement forks, they're fully chrome plated and have 'Tange" and a number on the steer tube, and on a few I can make out part of a Tange logo on the inside of a few fork blades through the plating. A few have stamped crowns, a few have tapered or forged crowns.
Most came from a variety different clean outs of old inventories over the years. Somewhere I've got a few smaller Peugeot forks, including a few 531 models from a PX10 but a quick look didn't spot any. They may be put away separately as I normally separate anything with French threading.

I've seen a few cases that even with chromoly fork blades, the cast or forged crown can make up any weight saved in the tubes to the point the chromoly fork is actually equal to or heavier than the plain steel with stamped crown models. Blade length also affects weight, so a 27" wheel fork is usually a bit heavier than a 700c fork of the same tubing simply because there's more of it. The amount of brazing on the crown can also make a difference, a fork built a bit heavy on the brass can be noticeably heavier as well. I've got one fork here with Huret dropouts and no tubing decals that looks like its got grapes hanging inside the bottom of the steer tube where the brass dripped out during manufacture. That fork I believe came from a mid range Gitane or Lejuene. It was just tagged 'French' when we found it. It weighs 2 lb 8.2 oz. and it for a small likely 21" frame. It also appears to be full of cosmoline or some sort of grease, its oozing out of the vent holes in the blades. It was wrapped up in the stuff with brown crepe paper wrapping all over. I suppose to get a real weight it'll need to be soaked in solvent to get it all cleaned out. It looks to me like they wrapped it up, then dipped it in cosmoline. (The one I weighed was unwrapped and just wiped down with mineral spirits externally). We found boxes of old Gitane and Lejeune receipts from the late 60's so we concluded that's likely what the fork came from.

The weight difference would really only be a good tell as to what tubing it is if you had an identical fork with the same steer tube length and same crown to compare it too.

The two Nishiki Sport forks are a good example of that, the fork from a 21" frame weighs more than the one from the 25" frame of the same year. Both use the same style crown and appear the same other than color from the crown downward. One would expect the fork with the much longer steer tube to weigh more but its not the case.

samkl 

Whoa. For reference my 4130 Surly Cross Check fork weighs 2.3lbs (uncut). Half a pound more than a Super Course.

P!N20

I only ride with my forks tuned to drop D.

Sluggo

Re spark test: This is a destructive test and I assume that you are not planning to sacrifice your fork to find out what it is made of, but if you were to try this (maybe with an unusable fork), you would need some reference materials to be able to observe the difference in sparks and calibrate your eyeballs. To the extent that spark patterns are driven by carbon content, the difference in sparks would be very subtle between hi-ten (about 0.2 to 0.4% carbon) and 4130 (0.3% carbon). There is probably enough chro and mo in chro-mo to change the spark patterns, but it would require experiments to discern.