Definition please: "Splined"

Forgive my ignorance. Still learning. Could do research. You guys are quicker/easier.

What means “splined”? :thinking:

Quick/easy dictionary lookup says:

From the Norwegian splindra, a large flat splinter:

2 a) a flat key or strip that fits into a groove or slot between parts
b) the groove or slot into which it fits

Thanks for asking… I had wondered myself.

Wonderful etymology, guaranteed to make us all ride faster. :0)

I guess the original question was in connection with splined hubs/cranks.

A conventional (cotterless) crank as found on most ‘off the shelf’ unicycles works like this:

The hub has an axle running through it. The axle has a square section taper at each end. The end of the taper has either a threaded socket (for a bolt to go in) or a threaded sticky out thing (for a nut to go on).

The crank has a square hole in the fat end. The square hole slots over the tapered square end of the axle. It’s tapped lightly into place, then drawn firmly on by tightening the bolt (or nut).

The advantages are it’s simple, and reasonably cheap to make.

The disadvantage is that the power of the pedal stroke is applied to the flat surfaces of the taper but near to the corners. Any looseness, and these corners can start to wear away. Imagine how a spanner can take the corners off a square nut or bolt head if it slips. Something similar happens here.

One answer to this problem is to use splined hubs. These are more expensive to make. Instead of a tapered square end, they have an end which looks a bit like a cog. It has splines, which are ridges running parallel to the axis of the axle. I don’t know how many ridges/grooves there are on a typical splined unicycle hub, but the basic rule from an engineering point of view would be (up to a point) more splines = better, but more expensive to produce.

The fat end of the crank doesn’t have a square socket. It has a socket which has splines which match the splines on the axle. Imagine the socket in the crank as a ‘female’ cog.

So the splined crank fits snugly onto the splined hub, and the drive is transmitted through each of the splines. So if the hub has 48 ridges, and the crank has 48 grooves (say) then there are 48 points of contact, and there is less danger of movement and wear.

A conventional tapered square axle gives you 4 possible positions for the crank, so one way of evening out tyre wear is to move the cranks a 1/4 turn round now and again. A splined hub might offer (say) 36 or 48 (or whatever) positions!

Mike, thank you for this very clear explanation.

Raphael Lasar
Matawan, NJ

In an unusual move, I’ll come to my own defence. I assumed that Memphis Mud knew what a splined hub was ( I still do), but was wondering why a splined hub was called that.

If I was right, that makes all your wonderful words superfluous (so there!). If I was wrong, the definition was still helpful to me (so there!). In neither case was I being flippantly useless.

But Mikefule’s explanation was clear. Thanks, Mike.

Raphael, time for you to go practice for the Unithon.


There is no need to defend yourself. You weren’t being attacked.:slight_smile:

<spoken in the manner of Middle-Age Man from Saturday Night Live />Hey, I’m working on it!.

Raphael Lasar
Matawan, NJ

Thank you. If I understand, this drawing comes close.

splined explained.bmp (352 KB)

Shucks… need a different diversion… looks around helplessly

Most excellent.

Groovy! :roll_eyes:

A picture paints a thousand words. Why didn’t I think of that? :o

Incidentally, at a rough guestimate, that’s about a 35 mm crank you drew… where can I buy some? :smiley:

I do best when a picture ACCOMPANIES a thousand words.:slight_smile:

Re: Definition please: “Splined”

On Wed, 2 Apr 2003 12:42:46 -0600, Mikefule
<> wrote:

>A picture paints a thousand words. Why didn’t I think of that? :o
Just for the fun of it, I pasted your post in Word and the word count
showed 430. That’s including your signature and everything.

Both your description and Memphis Mud’s picture are very clear. To be
fair, MM’s pic has an additional 27 words to it, giving it a total
worth of 1027 words. :slight_smile:

Klaas Bil - Newsgroup Addict

"Before Ontario’s provincial parliament buildings opened in 1896, that site was home to the University Lunatic Asylum. "

Re: Re: Definition please: “Splined”


Personally I’m entranced with U-Turn’s quick, easy definition. How was he able to get it that quick and easy?


OT (but since its my thread, I feel I’m entitled)

U, why keep the sunfish and sell that Laser? In my sailing club (in Memphis believe it or not), I routinely trounce the sunfish in races. I finish minutes and minutes ahead of them. Even with the Portsmouth Handicap they lose. While I’m up front challenging the JY15s with my Laser, they’re poking around the rear.

Is the answer: “good Sunfish, busted Laser”?

Well Mud I rarely race because I live a ways from the ocean and am usually solo. So for practical and safety matters I’m usually on the pond here where they’ll know where to look for the body. The pond is quite constricting now that I have the skill and I’ve been up and down it (it’s quite long) many many times.

Since I’m not racing I don’t really need all the control that the Laser has. The cockpit is less comfortable and the boat takes a lot longer to get set up.

It’s actually a quite nice boat; I don’t really deserve it because I’m not taking care of it the way I should.

I’ve tried to get family interested enough to go to a larger boat but nobody is. The canoe is the same way; kind of disappointing because we did a lot of canoeing when I was a kid. So I’ve drifted away from all three.

Last year I upgraded all the Sunfish hardware and bought a new sail and have used it once since.

The one thing that has sort of worked is unicycling. So I’ve been working on that.

At least I learned to sail. It was very very interesting. Another excellent balance sport. Maybe someday it will come back to me; there will always be boats out there to start up again.

There were some good moments racing; it’s like chess but much more fun. I spent quite a lot of time out on the water.

That’s cool that you race; you must have a long season down there.

We have two seasons. Spring and Fall. In the summer, its doldrummy. The only wind is created by mosquitos beating they little wings.

Check out Tornado Alley Sailing Club

I’m Tom. Check the race results. I’m currently #1. (But I’ve only raced twice.) My 30 yr old Laser is called “YeeeHaa!” We race this Saturday. Wind forecast in the upper teens. (YeeeHaa loves the heavy air)

I tried to get the family into sailing too. The Laser is clearly a one-man boat.

Funny that the thing that we all do together is Unicycle. My two kids (8 and 12) are getting pretty good. Just bought the wife her very own Black Torker 20". She’s gone 2-3 cranks without touching the wall. She’s just about ready to solo across the room.

Hey nice, Tom. Same here with the seasons. There are polar bear clubs though, say Boston, where they sail their Lasers whenever they can break through the ice. Sheesh!

Right now my priorities are unicycling and hiking. But someday…

The Sailfish is big enough for an adult and a kid. Especially if the kid likes to jump off the front and have you rescue him! The Laser really isn’t.

bringing home the bouys after a race.

tom's laser little version.jpg