Bair

Does a 3 have a single chainring and a back 3? And why is there no derailleur?
Have trouble comprehending this.

Thanks!

cb400bill

Three-speed bicycle - Wikipedia, the free encyclopedia

The three-speed bicycle is a bicycle that uses internal hub gears at the rear wheel hub to provide three gear ratios. Typically, in low gear, the rear sprocket turns faster than the wheel; in middle gear, the rear sprocket turns at the same speed as the wheel; in high gear, the rear wheel turns faster than the sprocket.

Chrome Molly

This has animated explanation of a 3 speed hub.
https://www.youtube.com/watch?v=K3QJTTcDXJo

iab

For Italians, a single chain ring up front (trust me, there is only 1)

Bianchi Sport 111 by iabisdb, on Flickr


and a 3-speed freewheel in back

Bianchi Sport 149 by iabisdb, on Flickr

Another example,

Torpado_Crank by iabisdb, on Flickr

Torpado_RD by iabisdb, on Flickr

Bair

thanks those pics helped!

noglider 

@iab is pulling your leg, because while he showed an example of a three-speed bike, it is not what a typical three-speed is. Look at it this way. A three-speed hub is one where the sprocket does not necessarily turn at the same rate as the hub. This is due to magic that occurs inside the hub. You can't see inside, so it seems like magic. The magic is explained here. If you want more information, see @Dan Burkhardt's youtube channel.

Here is my Rudge three-speed. It looks typical, except for the seat bag and the bottle cage on the handlebar. There is no derailleur. The shifter is on the handlebar, and it pulls a cable which goes into the right end of the axle of the rear hub. The cable works on the internals of the hub to activate the magic. 2nd gear makes the hub act like a regular one-speed hub. 1st gear makes the hub spin at 3/4 of the speed of the sprocket. 3rd gear makes the hub spin at 4/3 the speed of the sprocket.

noglider 

Oh, and there are internally geared hubs that offer more than three speeds. Here on BF, we refer to them as IGH's. There is even one that is continuously variable.

CroMo Mike 

iab has the coolest stuff, no doubt about it.

iab

I'm pulling no legs.

I posted what an Italian 3-speed is. I am in full agreement that it is not what an English 3-speed is. While the sun may never set on the English empire, the world does not revolve around the English 3-speed. I happen to prefer the Italian "sport" bike over the English. Even though I am sure the IGH shifts better than that pos Campagnolo Sport.

Boo. Ya.

Bianchi Sport 101 by iabisdb, on Flickr

nlerner

I suppose someone out there is running a triple crankset with a single rear cog and a singulator. Because they can.

noglider 

Don't tempt me, Neal. You know my International is still being planned.

@iab, it's gorgeous, but it doesn't answer @Bair's question.

Sixty Fiver

Three speed.. needs a derailleur to maintain tension when you shift the front triple.

Sixty Fiver

Triple cog sets were more common in the early days of derailleur equipped bicycles and were very common on Japanese children's bicycles... when one refers to a three speed we usually assume it is an internal hub gear although we can see there are exceptions.

sykerocker 

A quick explanation regarding 3-speed internally geared hubs vs. 3-speed derailleur (aka, Iab's Italian bikes): It's very nationalistic.

The three speed internally geared hub is a British invention, done around the turn of the previous century. Because of this, the British wedded themselves to this kind of mechanism. The big advantages are weatherproof, you can change gears when stopped or in motion, and if the bike goes down of the right side there's a good chance you won't take any mechanism damage. Plus the Sturmey Archer hubs are incredibly overbuilt. It's been at least 40 years since I last had to tear one down.

Since the IGH was a British invention, the Italians (and French) were loath to use it. They went with derailleur setups with fewer gears, but otherwise the same mechanics as the drop bar road bikes. Advantages are light weight and fast action. Disadvantages are you have to be pedaling to shift (which means if you stop at a traffic light in high gear, you're restarting in high gear), and if you go down on the right side, you could take a degree of mechanism damage bad enough to keep you from shifting until its repaired.

Both systems are terrific. The IGH has shown itself to be more convenient in urban riding because of the ability to change gear anytime in any situation, and overall ruggedness. Usually, when someone says "3-speed" they're talking an IGH. Although I know of 2, 3, 4, 5, 8, 11 and 14 speed IGH's. Fully 90% of what's out there, however is the classic Sturmey Archer AW or Shimano 333. Both are 3-speed mechanisms with either a toggle lever or a twist grip shifter.

Late thought: On the derailleur three speeds - if you can put a triple cluster on the rear wheel, it's just as easy to put a five speed cluster in its place, giving you either one lower and one higher, or (better yet for hilly terrain) two lower cogs. This is why you don't see many three speed derailleur bikes - since the late 1960's a five speed setup is usually the minimum.

nlerner

That's why I referred to a singulator.

nlerner

I'll check back in a decade or so given your current rate of progress.

Sixty Fiver

A singulator would not have the proper amount of take up and chain wrap for a 3 by 1 drive.

iab

Rear spacing for a 3-speed was 115. It used a 1/8 chain and was easy to upgrade to a 4-speed with a 3/32 chain as the spacing remained 115. A 5-speed using a 3/32 chain requires a 120 spacing. I would not consider that an easy change.

Also, back in the 50s, many plunger type derailleurs were specific for 3 and 4 speeds as their chain travel was limited and could not accommodate 5 gears. Although I have never tried it, I suspect that Campagnolo Sport derailleur cannot accommodate 5 gears either.