FRANK CANNON

Seems like this was an innovation at one point?

Bandera

1" x 3/16" "skip tooth" was a standard pre-WWII like on this track bike.



Superseded by 1/2"X1/8"



-Bandera

ThermionicScott 

To work with block chain, of course:



The inch pitch block chain in 20th century track racing

FRANK CANNON

Nice Schwinns!

A less stupidly worded search shows me these were a development and then the modern chain came, but these were thought to be stronger so they hung on for quite a while.

FRANK CANNON

Ahhhhhhh!

So you could just replace your chain with a double roller. This is what I was looking for, I saw two bikes the other day probably 40 years apart and the older one had the modern chain.

Thank you.

FBinNY 

The block chain came first. Originally chains were made of identical plates inner and outer. 3-4 plates were placed together with a pin through them with 1 plate on each side riveted on. The sprockets of the time had a 1" pitch because the teeth couldn't engage the block.

Later the laminated block was replaced with a solid block which was less taxing on the sprockets, and later yet that in turn was replaced with a block that had rollers. But these 1" pitch roller chains still had the spacing of 1" block chains with 2 roller spaced closely on what was the block, then a larger gap between links.

The last innovation, was respacing the rollers to have the uniform spacing of modern 1/2" pitch chains, allowing 1/2" tooth intervals.

Like with everything mechanical, it's an evolutionary process. 1/2" pitch was a necessary step that made derailleurs possible (or at least practical), but the 1" pitch standard hung around for decades for single speed applications, probably because the sprockets were already tooled and change cost money.

FRANK CANNON

Thank you FBinNY, that was an excellent post.

Bill Kapaun

Thinking about this a bit and it seems the concept of our rings/cogs with an odd number of teeth couldn't exist with 1" spacing vs our 1/2" spacing.

FBinNY 

Why not? It's inch pitch, so why can't you have 1 inch pitch 25t (comparable to modern 50t ring).

However, you're right that it reduces gearing options because you can't have the equivalent of a 39t (for example). Then again mtn riders haven't used odd numbers from the beginning.

Al1943

My first bicycle had a chain like that, single speed tank. My father bought it for me used in 1951, paid $20 but that was more than it was worth.

FBinNY 

So, $20 in 1951 would have been worth about $187 these days. That would have to have been a very special tank.

Al1943

Yeah it was way too much for the old bike. Knowing my father, he was probably trying to help out the seller. In my 8 yo eyes he was paying too much and I was getting a rusty old bike.

FBinNY 

At 8yrs I doubt you were that worried about your father's finances, unless it was going to come out of your 0.50/week allowance. OTOH what 8yr old wants a rusty old clunker?

JonathanGennick 

Were there skip tooth cogs to go along with those skip tooth rings?

FBinNY 

Jonathan,

I'm surprised at you.

How else would it work, if BOTH sprockets didn't match the chain?

BTW- here's a link to a nice article on the subject, with photos showing the chain and sprockets. While there, take a look at the block chain pictured. Note the large gap for teeth compared to the block, and the uneven pin spacing. Later, when the block was replaced with a pair of rollers, the uneven spacing had to be maintained for sprocket compatibility.

So if you look at the blocks you can imagine them replaced with closely spaced rollers, and the tooth staying in the larger gap between the pairs. Respacing to uniformly spaced 1/2" pitch came later.

JonathanGennick 

Well, yes, FB, I was having a difficult time envisioning any other option. OTOH, I have not once seen nor heard mention of a skip-tooth cog. I've seen skip-tooth rings, but always with normal cogs in the back.

So I was just making sure XD.

JonathanGennick 

Btw, this has been a most interesting thread. I like the history in it.

Al1943

No allowance, ever. Just paper routes, etc.

Al1943

Back in the day the big boys told me that the skip tooth chains were "power chains" and the others (1/2" pitch) were "speed chains".

FBinNY 

here you go

JonathanGennick 

Thank you FB! My life is complete. (Well, let us hope not. Lol)

I'm guessing that either 8 or 7 teeth would have been the practical lower limit on such a cog.

FBinNY 

Same here, I had to save up nickles from deposit beer bottles collected from construction sites to buy my first bike. That allowed me to make the big time delivering drugs. Sounds better than it was, I delivered prescriptions for the local drug store, making minimum wage plus tips.

That got me to like bicycling in the rain because the tips were much greater when I showed up looking like something the cat dragged in.

FBinNY 

No, here's a 6t, which would correspond to a modern 12t sprocket.

I don't remember if Campagnolo ever offered a 12t track sprocket, but one (the only?) advantage of 1" pitch sprockets and chains, is that the chain plates didn't overhang as much, so they could work slightly closer to shoulders on hubs and sprockets than the 1/2" pitch chains of the period.

AlmostTrick

Will a modern 1/2" chain work on the skip tooth chainrings/cogs? Seems like it would.

FBinNY 

No it won't, for two reasons.

1- 1" pitch chains are 1x3/16" and so the teeth are too wide
2- the tooth profile and spacing is wrong. As I pointed out earlier, 1" pitch chains have 2 pins and rollers close together and then a wider gap, rather than uniform spacing. sort of like this O O . O O . O O vs. O O O O O. So the two consecutive rollers of a 1/2 pitch chain can't fit between the teeth and likewise the teeth can't fit between the rollers.

Do not confuse 1" pitch chains and sprockets with the skip tooth sprockets SunTour introduced on freewheels a few decades back.