A forum for owners of Yamaha TTR250 trail and enduro bikes!

barra8 · Guru

Chain length for 14-52 and 14-44?

TTRfan · Super Guru

Chain length for different sprocket combinations

TTRfan · Super Guru

RE: Chain length for 14-52 and 14-44?

brindabella · Senior Member

I'm afraid that list of chain link counts (above) appears to be wrong.

According to my logic, the ROUGH rule of thumb is:

** add half as many links as teeth **

if you add x teeth to the drive sprocket and y teeth to the driven sprocket,
you need APPROXIMATELY (x+y)/2 extra links to the chain.

to put it another way:

add 1 link for every 2 teeth added to the sprocket combination
subtract 1 link for every 2 teeth removed from the sprocket combination

so, for example, I personally chose to go from 14/44 to 13/46.
this is plus 2 on the main sprocket and minus 1 on counter-shaft sprocket.
that is (adding) a combined addition of 1 tooth, meaning HALF a link.
so I could just scrape by with the original chain.

The "reason" for half as many links as tooth count difference is that the chain
only covers half of each sprocket (approximately).

And the reason it is only approximate is that with different size sprockets, the chain feeds in at an angle.

By the way, adding one tooth to the rear, and NOT changing the chain,
should move the axle forward by about 4mm, when chain slack is re-adjusted.

I hope this helps someone.

barra8 · Guru

Cubber wrote:
Sounds like it may be likely that a bit of rocket science is needed then????
Martyn

Hhahahaha yeah wink I still cannot see how brindabella's thoery works confuse Time to ring a mechanic i think as it's been too long for me to remember the correct way to judge this & i do not have a bike to tell whether 14/52 is perfectly 110L.

...........................

EDITED: I know see how it works as 1 tooth counts for two links as two sets of rollers are needed for one tooth.

Jarrah.

-- Edited by barra8 on Tuesday 13th of November 2012 01:37:41 AM

barra8 · Guru

I checked my 51T sprocket against my 48. Results:

51T links around sprockets= 26

48T=25

..........................

It does seem like brindabella is correct in this case.Not saying your wrong brindabella just making sure as it's been ages since i have thought of this. Now come to think of it i'm pretty sure that is how it would go but still unsure on this. If i'm wrong i take full responsibility for being wrong wink

...................

Jarrah.

-- Edited by barra8 on Tuesday 13th of November 2012 01:30:54 AM

barra8 · Guru

It has all come back to me now.....Brindabella is right 100%. Just like to say thanks to Brindabella for reminding me as it has been awhile since i have thought of this & sorry for doubting you. If anyone can confirm that 14/52 is 110L exactly the chart above will become usefull. I cannot do this as i do not have a bike together to check so i can't say for sure. I do know one thing though......Chains should be even links so my first chart was wrong!! How embarrasing (atleast i can admit it :)

I must refrain from posting when i'm drunk or tired

..............

Jarrah

-- Edited by barra8 on Tuesday 13th of November 2012 12:42:14 AM

barra8 · Guru

brindabella wrote:
I'm afraid that list of chain link counts (above) appears to be wrong.

According to my logic, the ROUGH rule of thumb is:

** add half as many links as teeth **

if you add x teeth to the drive sprocket and y teeth to the driven sprocket,
you need APPROXIMATELY (x+y)/2 extra links to the chain.

to put it another way:

add 1 link for every 2 teeth added to the sprocket combination
subtract 1 link for every 2 teeth removed from the sprocket combination

so, for example, I personally chose to go from 14/44 to 13/46.
this is plus 2 on the main sprocket and minus 1 on counter-shaft sprocket.
that is (adding) a combined addition of 1 tooth, meaning HALF a link.
so I could just scrape by with the original chain.

The "reason" for half as many links as tooth count difference is that the chain
only covers half of each sprocket (approximately).

And the reason it is only approximate is that with different size sprockets, the chain feeds in at an angle.

By the way, adding one tooth to the rear, and NOT changing the chain,
should move the axle forward by about 4mm, when chain slack is re-adjusted.

I hope this helps someone.

This jogs my memory on this but i will now have to do more research. I thought it was if you change one tooth at the front it would be the same as changing two at the back but the chain lenght only changed one. I don't have a bike together to check this. It has been along time since i have thought of this so maybe i am wrong? confuse

Will let people know when i know more on this.

..................................

Jarrah confuse .

Cubber · Super Guru

Sounds like it may be likely that a bit of rocket science is needed then???? biggrin biggrin biggrin

Martyn

brindabella · Senior Member

just a little update..

my bike (13/46) has the same chain as the original standard (14/44).
so the definitive answer, by simply counting, is that 14/44 needs 106 links.

just for interest, the online parts manual says that a US 2005 TTR
which is geared 13/52 has a 110 link chain.

applying the "rule of thumb" starting from 13/52 would mean dropping 8
teeth from the back and adding 1 to the front giving 7, so 3.5 links less,
so you could try removing 3 or 4 links.

like I said, the rule of thumb is only approximate, and a more precise
formula taking into account distance between sprockets as well
(which I won't bore you with), gives 3.9 links less.
which (thank heavens) accords very nicely with physical reality!

BTW there is another rule of thumb with gearing (just to confuse
the issue and muddy the waters), that taking one tooth off the
counter-shaft sprocket is usually ROUGHLY as good at gaining off road grunt
as adding between 3 and 4 teeth to the rear wheel sprocket.

Andy_C · Veteran Member

Hi
I be very interested in knowing the number of chain links also,as I'm just about to fit 14/52 sprockets and a new chain with 116 links which I know has to be shortened.

Is the stated 14/52 - 110 link 100% correct? Not that I disbelieve you Jarra its I need to be 100% sure about the shortening of my new chain,be great if someone else could also confirm this.

Be much appreciated if any member with this sprocket combination could actually count the links in their chain and post the result, I'd like to get this right before I go cutting links out.

Thanks
Andy

-- Edited by Andy_C on Tuesday 13th of November 2012 06:23:03 PM

colin13846 · Senior Member

I would cut one link out at a time and then do a trial fit. Also try to get the longest length possible so the tyre sits furthest from the shocker rubber flap, otherwise the tyre will shread it.

barra8 · Guru

Andy_C wrote:
Hi
I be very interested in knowing the number of chain links also,as I'm just about to fit 14/52 sprockets and a new chain with 116 links which I know has to be shortened.

Is the stated 14/52 - 110 link 100% correct? Not that I disbelieve you Jarra its I need to be 100% sure about the shortening of my new chain,be great if someone else could also confirm this.

Be much appreciated if any member with this sprocket combination could actually count the links in their chain and post the result, I'd like to get this right before I go cutting links out.

Thanks
Andy

-- Edited by Andy_C on Tuesday 13th of November 2012 06:23:03 PM

14/52 is definetely 110L but i'm unsure if its spot on. This won't matter aslong as you have 110L but it makes working out sizes hard.

...............

Jarrah.

brindabella · Senior Member

110 links is surely right for 13/52 as this is the US setup.
by my calculations 14/52 will require the axle to be moved 3mm forward from the 13/52 position,
so it *should* fit, but initial axle adjustment will be pretty much fully forward.

your other choice is 112 links (as you cannot buy cranked links for 0-ring chain).
but this will position the axle about 13mm back from the standard new chain position.

the TTR has a range of axle position adjustment that seems to be about 22mm.
and 22mm is the equivalent of 2 links plus less than 1% chain stretch allowance.
so with 112 links you *might* not be able to get full wear out of the chain,
unless you subsequently shorten it by 2 links to 110 links.

seeing as you have the chain, and you have to cut it, why not just suck it and see?
put the axle fully forward, temporarily put on the new chain, fold back a link on the back
of the sprocket, and judge whether (with the addition of the joining link) it will fit.
actually that saves the bother of counting - just mark the cutting spot, or count the unused links.

but anyway, please count the actual final number of links as fitted and then tell us the results,
so the rest of us can take advantage of your pioneering, and just go to the bike shop
and ask them to cut it for 110 links (or 112?) if we happen to want to use that 14/52 sprocket combo.

Cubber · Super Guru

I did this way back in January, at the beginning of this year and posted this thread:-

CLICKY THINGY

I used 14/52 with a chain link count of 114 and the wheel well back.

It works OK. Still does. biggrin

Martyn

Andy_C · Veteran Member

Chain length for 14/52 sprocket change...

brindabella · Senior Member

thanks for that practical feedback.
it seems to be consistent with my theoretical calculations, which is nice to know.

and it looks like you have also confirmed that the diameter of a 120/80 knobby tyre is the absolute maximum limit.

something that now needs explaining is that Cubber is running the same sprocket combo but is somehow using 114 chain links.
that should be impossible - could there be variations of swing arms or adjusters between TTR250 models, or maybe a miss-count by Martyn?

Cubber · Super Guru

The rear rubber on my TTR is Pirelli MT43 and the rear wheel snail adjuster is as the latter of Andy's adjuster shots. aww

It's all this view shows. (I adjusted the guide fixing slots lower to obviate the chain catching)

I have just recently had a re-count of chain links and admit that I mislead you- there are only 112 links (including split link) but I must have had a senior moment back in April and added the split link in twice! confuse

Since fitting (Feb-2012) it's done OK. It's been no bother; no flap catching, chain adjustment or performance loss. smile

Martyn

brindabella · Senior Member

ah, that's all good to know.
nice looking bike!

actually there MUST be some slight swing arm variations, even between "blue" models - as the US model, which has the 52T sprocket standard, seems to have a different chain guide, with different number and position of mounting bolts.

I guess that explains why many people apparently modify (lower) the non-US guide which was designed for 44T.
To me, it seems a miracle that a guide could accommodate an 8 tooth variation while still doing its "guiding" properly.

I would love to see a photo of a successful guide modification for 52T.
ideally, it should be lower, a bit forward, and maybe at a slightly different angle (without compromising strength).

Cubber · Super Guru

To save me dashing into the garage with my camera, now that the bike's all tucked up for the night, here is a shot of my TTR before changing chain, sprockets and guide adjustment:-

Before changing sprockets & chain

and here is a shot of it shortly after changing sprockets, chain, etc:-

After changing sprockets & chain

Really there is nothing to notice, but in actual fact the holes of the chain guide have been deepened by a round file about 5mm - or slightly more.
The difference is just enough to miss major chain smack - but it obviously does catch because the orange guide has been worn away a little. (The original guide was completely goosed before the alterations)

Look carefully and you can see the different positions of the snail cam adjuster. smile

Martyn