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TheObieOne3226
2005-02-15, 08:05 PM
There are 3 types of crank to hub interfaces used in unicycles. Cottered, Square Taper, and Splined.


Cottered:

This is the oldest type of crank/axle interface that is still used. The axles and crank holes are round. The axles have a groove in them. A wedge, called a cotter, slips in there to keep the crank still.

The cotters are thin little pieces of metal that taper. They wear out and have to be replaced. Sometimes they shear in half, causing the crank to spin freely about the axle, which can be fairly catastrophic for the rider.

Basically, this interface is obsolete. It is weak and requires a lot of maintenance.

TheObieOne3226
2005-02-15, 08:15 PM
Square Taper (aka Cotterless)

This was the standard in the bike industry for many years and is still the standard in the unicycle industry. Many bikes still use this as well. The axle is a square peice of metal that tapers (thinner on the outside). This allows you to press a crank (which has the same taper on the inside) on to the axle by using a bolt. This system is reasonably strong. Problems exist in the maintenance. The cranks cannot be removed very often, since each installation removes material from the axle. This will eventually wear down your axle. On bikes it screws up your chainline. Also, if someone rides on a loose crank, the axle and crank turn into round useless things never to be useful again. If installed properly the first time, this is a good system. Here is a quote from John Childs on his method of crank installation:

Originally posted by john_childs
My procedure for crank installation:

1. Buy a torque wrench. See my thread I'm torqued (http://www.unicyclist.com/forums/showthread.php?s=&threadid=31614) for a recommended $20 torque wrench.

2. Rub some grease on the hub tapers. Be careful not to get any grease on the hub threads because the threads are going to get Loctited. Grease and Loctite don't mix. The grease will prevent the Loctite from sticking correctly and doing its job.

3. Put the crank on the hub. There are three ways you can go about doing this. In most cases option "a" will be enough.
a) Press them on by hand with no mechanical aid. This should be adequate for most cranks. However, some cranks may not slide willingly all the way on to the taper. In these cases a little mechanical persuasion might be needed.
b) Pound the cranks on using a block of wood and a rubber mallet. Do not pound directly on the crank with a mallet or hammer. You may damage the crank. Place the block of wood on the crank and then use the rubber mallet or hammer to tap on the block of wood.
c) Use a large C-clamp or bar clamp to press the crank on the taper.

4. Put some red or blue Loctite on the crank nut. Either the red stuff or blue stuff will do the job. The red stuff is the high strength or permanent strength Loctite. The blue stuff is the medium strength Loctite.

5. Thread the crank nut on with your fingers.

6. Tighten the crank nut using a torque wrench. Tighten the nut to 35 to 40 foot-pounds. It is important that the nut be lubricated with Loctite to get a consistent and reliable torque reading. If the threads are dry you may get an unreliable torque reading.

7. Install the dust caps.

With this procedure the cranks should be tight and not loosen up on you during a ride.


If you don't want to buy a torque wrench, you should take the cranks and hub to a bike shop and let them do it. At the very least take it to someone who has a feel for installing them and can get close to the amount of torque needed.

This system will serve you very well if properly installed and maintained. However, even if maintained well, it has strength limits due to the narrow axle.

TheObieOne3226
2005-02-15, 08:29 PM
Splined:

A more recent development in the bike industry and even moreso in unicycles, splined axles are the best interface available. The axle has grooves on it. The inside of the crank has a matching pattern (although different companies make different patterns, because unicyclists are dumb and don't use ISIS yet) and they slide together. A nut pulls the crank onto the grooves, and the crank and axle sit together snugly. This system has numerous advantages:


Strength: Stronger than square taper designs. Splined cranks have larger diameter axles, which add strength.

Good interface: The crank and axle have much surface area contacting each other, so the interface is very strong.

Ease of maintenance/removal: Splined cranks are very easy to remove or replace, provided you have the right tools. Unlike square-taper designs, the crank does not draw further onto the axle with every installation, so, if maintained well, splined axles can last a very long time.


Some differences between various types of unicycle cranks:

Spline count: This is simply the number of grooves on the axle. Generally, the more the better, but a higher spline count does not ensure a better product.

Pinch bolts: Some splined cranks have a pinch bolt in addition to the main axle bolt. The pinch bolt makes the crank clamp onto the axle. This makes crank removal and installation very easy, and keeps axle wear minimal.


Splined cranks should remain lubricated on their axle. A liberal application of copper anti-sieze on occasion will fill the gaps between the crank and axle, preventing the annoying squeaking often assosciated with splined cranks.

brockfisher05
2005-02-26, 12:21 AM
I think i will put that copper anti-sieze on my cranks sonce they sometimes creak

forrestunifreak
2005-03-06, 08:17 PM
Originally posted by TheObieOne3226

Splined cranks should remain lubricated on their axle. A liberal application of copper anti-sieze on occasion will fill the gaps between the crank and axle, preventing the annoying squeaking often assosciated with splined cranks.

Dos it matter what lubricant I use?mine creak,and i put just regular grease on it,is that ok?


also,how tight can the pinch bolt be?i had to really crank it on with a cheater bar to get the crank not to wiggle.

TheObieOne3226
2005-03-14, 02:37 AM
Originally posted by forrestunifreak
Dos it matter what lubricant I use?mine creak,and i put just regular grease on it,is that ok?


also,how tight can the pinch bolt be?i had to really crank it on with a cheater bar to get the crank not to wiggle.


For the spline interface, it is best to use a lubricant with body to fill gaps. However, it is also important to use a lubricant that will not get sqeezed out of the splines when you tighten them. Anti-sieze fits both criteria, and is available at pep-boys for $2. A $2 tube will last you several years.


I always lube up my pinch bolt threads with anti-sieze and then tighten them as much as I can. I slip a pipe or something over the end to increase leverage. The lubricant prevents damage to the threads and allows you to get the bolt tighter.

this end up
2005-03-17, 08:19 PM
Originally posted by TheObieOne3226
[b]If you don't want to buy a torque wrench, you should take the cranks and hub to a bike shop and let them do it. Bike shops will usually do it for about $5.00. also its fun to watch the surprized looks on the cashiers face when you walk in with a uni.:D :p :D

weeble
2005-03-21, 05:50 AM
Originally posted by TheObieOne3226
Square Taper (aka Cotterless)
If you don't want to buy a torque wrench, you should take the cranks and hub to a bike shop and let them do it. At the very least take it to someone who has a feel for installing them and can get close to the amount of torque needed.

Is there a problem if the nuts are TOO tight? I always just haul on the wrench and get them as tight as I possibly can.

Unitik908
2005-03-25, 09:32 PM
Originally posted by weeble
Is there a problem if the nuts are TOO tight? I always just haul on the wrench and get them as tight as I possibly can.

Chase

TheObieOne3226
2005-03-26, 02:26 AM
Originally posted by weeble
Is there a problem if the nuts are TOO tight? I always just haul on the wrench and get them as tight as I possibly can.

At around 80 foot pounds you destroy the threads and need a new hub.

unicus
2005-04-29, 12:41 PM
Originally posted by TheObieOne3226
...because unicyclists are dumb and don't use ISIS yet
Koxx One use the ISIS crank interface - http://www.einradladen.net/catalog/product_info.php?cPath=6&products_id=296

And very nice it looks too.

UniTyler
2005-08-05, 05:39 PM
Wow, how long did it take you to write that Obie?

Evan Byrne
2005-08-05, 05:51 PM
Get profiles.

uni-matt
2005-08-06, 12:39 PM
wots profiles?

James_Potter
2005-08-09, 12:52 AM
Originally posted by uni-matt
wots profiles?

they're a brand of crank arms, that you don't really need unless you're really really good at unicycling. they're almost impossible to break, and have a lifetime warranty, and cost $100 for the crank arms and $320 with the hub.

theotherguy
2005-10-11, 02:05 AM
that sounds like it costs a lot. $$$

maxisback
2005-12-24, 05:33 AM
men.. dont say that forrest uni freak.. lotsa ppl bend there profile.. Im not that great at unicycling and mine are already starting to bend..

forrestunifreak
2005-12-24, 05:21 PM
men.. dont say that forrest uni freak.. lotsa ppl bend there profile.. Im not that great at unicycling and mine are already starting to bend..


What...the heck?

koebwil
2005-12-30, 07:58 PM
does anyone have advice for removing splined cranks, I have a qu-ax and they just won't come off.

skroboskim
2006-04-23, 06:22 AM
does anyone have advice for removing splined cranks, I have a qu-ax and they just won't come off.

i havn't messed w/ my splined cranks yt, but i know that getting a hammer , putting something that fits through the spokes and won't bend then knocking the crap out of it works tho and if you want to make it perty put a piece of wood between the something that fits in the spokes (a long bolt perhaps... or maybe an extension) and the crank arm itself

maestro8
2006-04-25, 10:54 PM
getting a hammer , putting something that fits through the spokes and won't bend then knocking the crap out of it..
this is very bad advice... you can end up damaging your cranks doing this... in their installation manual, Profile specifically mentions not to hammer on the cranks.

why is this bad? you're applying forces to the crank at an angle to the axle, which can deform the crank / axle interface. once the crank is deformed it will never have the same "fit" with the axle as it did when it came from the factory; the crank will develop a slight wobble which will wear down the splines over time. worn splines = premature failure!

the best method to remove splined cranks is using a bearing puller. search your local auto shop / auto parts supplier, search the forums, search the Internet, they're relatively cheap ($20-50 USD) and easy to come by.

the second best method is using a "crank removal bolt" and a rubber mallet. Profile supplies such a bolt with their hub & crankset. it's a big fat bolt that threads into the axle but is clear of the cranks (the cranks can slip off the axle with or without this bolt in place). place the wheel on a support so the axle is off the ground and whack the hell out of the bolt head. either the axle will push through the hub or the crank will start moving away from the hub (depending on how tight the axle fits in the hub) and you should be able to wiggle the crank off the axle from there.

to aid either of the above two methods you can heat up the crank (assuming it is not heat treated) with a torch. heating causes the metal to expand slightly, giving you a little "room" between the crank and axle. most good hub & cranksets are machined to very tight tolerances and once any grease, grime or grit gets between the crank and axle, you'll have one hell of a time getting the crank to budge.

good luck! feel free to PM me if you have any more questions...

picado
2006-07-03, 01:19 AM
Hello

I just got a new unicycle and it got splined cranks and hub


splined technology is very new to me..

i got a question


during a training i have to Tighten the crank... its is loosing with a day of training...

its is normal ? and why its happens ?

Jerrick
2006-07-03, 05:29 AM
On a new uni, it will loosen up pretty quickly, kinda like a new guitar string, you put it on, stretch it to the right note, play it, it will loosen up, so you have to tighten it back up a little.

On your uni, it will loosen up, just tighten it up, then it should stay pretty tight for a long time, but I take mine apart once a month and clean, re-grease, and tighten everything back up, so its like new.

picado
2006-07-03, 02:51 PM
so its normal ?

Jerrick
2006-07-03, 10:22 PM
Kinda, as long as they arent coming loose after every ride.

At first, when I got my uni, and put it together, It came loose after a couple of ride, I tightened it back up really tight, and it was fine. Every month I take it apart and then put it back together to keep things clean and tight.

If yours is coming loose after every ride, that should be happening, so really tighten up everything, check if any of the threading got stripped, if they are, replace those parts, and you can use some locktite to help.

picado
2006-07-23, 01:35 AM
iam talking about this one
http://www.unicyclist.com/gallery/?g2_itemId=222823

he always get out..
just like 4-6 times on a day training

and i have to tight this everytime..

but i noticed a thing..
when i ride fowards it become to loose.
and when i ride backwards its became to tighten up.

my cranks are the left on the left side and right on right side...

when you say its normal to happen... its so normal how is hapening to me ?

thanks

picado
2006-07-24, 01:50 AM
can some1 help me ?
now i am thinking in change the side of the wheel

and dont change the side of the cranks...

iam lossing it

Jerrick
2006-07-24, 05:22 AM
Hmm, I dont see why yours would loosen, but then tighten when going backwards.

If you can somehow make it so that when you flip some stuff, but make sure nothing gets stripped. Try that.

picado
2006-07-24, 11:58 AM
the uni is really new..

i dont think this should be happening...

iridemymuni
2006-07-24, 12:13 PM
i suggest loctiting you're threads there. that will keep the bugger in

picado
2006-07-24, 03:48 PM
but if i loctite i can take the threads off when i want ??

Jerrick
2006-07-24, 08:36 PM
Give up a call to where you bought it from, this may be a defect, probably can get a replacement part or something.

Also, if you go withlocktite, get a strong color, that way, it will be in there really tight, but when tacking it off, it may take a while, but it is still possable to get it off.

burjzyntski
2006-07-25, 02:31 AM
I suggest you try turning the seatpost around (180 degrees from the way it's currently facing).

That ought to do the trick.

picado
2006-07-25, 07:39 AM
i bought it from UDC.
and iam from Brazil..

i have to mail them... maybe they got the point

picado
2006-07-26, 07:33 PM
i already loctited and iam waiting for the 24 hours

i am going to ride to test if my thread is now locked

i did some searchs on the forum and my problem with the thread on the cranks looks like a normal problem..

i hope that the loctite help me :)

thanks for the help guys

picado
2006-08-08, 09:11 PM
yea... the thread locker worked for me

thanks for the help guys

picado
2006-08-08, 09:11 PM
yea... the thread locker worked for me

thanks for the help guys

andrewfif
2006-08-10, 04:50 PM
Can I use WD40, or Heavy Duty Silicone spray?

They seem like they would work fine.

maestro8
2006-08-14, 06:03 PM
Can I use WD40, or Heavy Duty Silicone spray?
WD40 is not a lubricant. It is a cleaner / degreaser... so applying WD40 will effectively remove any lubricant from the crank.

Silicone is intended for use with non-metallic surfaces. It won't provide the long term protection you'll need for your cranks.

Hit your local bike shop and ask for some metallic anti-sieze. If there's none there, go to your local auto parts store (Kragen, Pep Boys, etc.)... they'll definitely have it there as it's a popular lubricant for brake pistons. It's fairly cheap and very effective for lubricating any metal-to-metal interface. You should take care, however, to avoid getting any anti-sieze on your skin or clothing... it's not a very human-friendly substance.

Sponge
2006-08-18, 04:09 AM
To the rider from Brazil:

Did you use red loctite or blue loctite? Because the red loctite is dangerous stuff and its actually called studlock or something which holds threads in almost permanently. The blue stuff is what should have been used.

I hope you used the right stuff

picado
2006-08-19, 01:21 AM
hey sponge.
i used the red loctite..
but its is not locked permanent..
now i cant take off the thread but it is not taking off by a riding..

now it is taking off once a week..