Thruxton Thruxton R Front Sprocket

No but I have put a T120 rear on my Thruxton and taken 2 links out of the chain.....One tooth on the front sprocket from a 16 to 17 is virtually unnoticeable....But, its inexpensive and easy to do, so why not give it a go and see how it works for you.
bellow is what you will get with the rear from a T120 (37) compared to the stock Thruxton (42)

 

You got that wrong!! 1tooth on the front sprocket is the equivalent of two or three teeth up/down on a rear sprocket !!! Smaller incremental changes are easier to make on rears ! Fronts make much more noticeable larger changes ! Do the maths = fronts are 16/17 teeth and rears 37/45 on all bikes excepting Moto-X and trail bikes where 14 & 15 tooth fronts can be found. Do division front into rear 45 divided by 15 = 3 or 37 by 16 = 2.4 , one front tooth is generally = to 2.5/3 rear sprocket teeth..!

 

Yes, 1 on the front is the equivalent of 3 on the rear. I have gone from 42 rear to 37 rear, to get a similar effect from the front you would need to go to 18 tooth from the stock 16 tooth, Triumph do not do an 18 tooth front sprocket to suit a 525 chain, so I went down five on the rear to get where I wanted to be. Which is as near as you can get to changing the front to 18, which is not enough
If you go from 16 stock front to a 17 (stock T120 front) it makes next to no difference on the bike.

I'm not sure where you get the "37/45 tooth on all bikes" rear thing from, the Thruxton R has a 42 tooth rear and the T120 has a 37 tooth rear....

The two charts that I posted above show the difference after my modification between a stock Thruxton R with a stock rear 42 tooth sprocket and 37 tooth rear sprocket. Look at the chart, their isn't a huge difference and if you put a 17 tooth on the front you end up being more or less in the middle of those two charts, and that was not enough. The bottom chart is the stock Thruxton and the top one is same bike with a 37 tooth rear.

With the 37 tooth rear I had to shorten the chain, if however I could have bought a 18 tooth front I would not have had to shorten the chain.

This question is about the 2016 Thruxton R gearing which is way to short and I'm not sure what part of my first post you are disagreeing with...Maybe I should have explained the part about not being able to get a 18 tooth front sprocket.
I have also told the OP to try the 17 tooth front first and see what they think, but as far as I'm concerned it made next to no difference.

Useful tool, link below, the Thruxton R is in the database, use it as stock and you can alter whatever you want to in the Current or Custom columns. Click on the ones you want it to display and it shows you where you will end up after whatever change you make. It even shows chain length and the amount of distance you need to move the rear axle one way or the other to suit your gearing choice.
great tool once you figure out how to use it....

http://www.gearingcommander.com/

By the way, this is what I do for a living......

 

Hi Midas, I have several observations to offer you :

First, 18t and 19t front sprockets are readily available available for the 865 & 955 engines, I have 1 of each in stock. This applies to 525 and 530 chain sizes; don't know from 'hands-on' experience of the Thruxton 1200 R but the same front sprocket design has applied to all Triumph models for the last 15 years.

Second, when I changed from 18t to 19t on my 2010 T100 I found the difference was clearly noticeable at cruising speeds between 60 & 80 mph I was losing 350 to 500 rpm using the 19t front sprocket. I also did the same on my Tiger 955i and found almost identical results.

I suppose it depends on how much change in gearing you are wanting to achieve, but I certainly wouldn't write-off 1 tooth up front as insignificant.

 

Hi mate, the sprockets are different or at least that's the way it looked for me at the time, I certainly couldn't find one to fit the Thruxton R, unless I missed something otherwise that is the way I would have gone. It would have saved me shortening the chain.
I also said that he should maybe try a 17 tooth front first to see what he thought, I did and it was not enough of a difference for me. The cruising speed/rpm wasn't really my number one priority, it was giving me a gearbox that suited the motors torque on UK A roads.
The tool (Gearing Commander) I posted a link to takes all the hard work out of working this out and lets you know exactly where you will end up after any sprocket changes you make.
The thing with the Thruxton R is that the red line is 7200rpm and with the light crank it spins up extremely quickly and this makes a huge difference to how useful the stock gearing is, first gear is relatively useless IMO. The T120 has a heavier crank and seems to take twice as long as the Thruxton R to get to that 7000rpm and even though the gearbox is virtually identical that heavier crank makes a big difference.

Below is a chart of the rpm changes at 80 mph from the "stock" gearing, the "current" is with the 17 tooth T120 sprocket and stock 42 tooth rear Thruxton sprocket and "custom" is with the stock front Thruxton 16 tooth sprocket and T120 37 tooth rear.....

Torque and engine characteristics change massively from bike to bike, your T00 has much less TQ than the Thruxton R and at a different RPM range and also had a heavier crank, the Tiger had less TQ and at higher rpm than the Thruxton R has and also another 2300rpm (9500rpm). You cant really compare different engines with different characteristics when it comes to gearing changes.....

But once again as I advised yesterday for the sake of £25 for a front 17 tooth T120 sprocket it would be sensible to try that first and see if it was enough for your needs.

 

Yes, there are a few places that will make rear sprockets but front not so many, and to tool up for front sprockets is expensive and really not worth while for a one off sprocket. Someone will probably start doing them for these bikes eventually..
The rear T120 37 tooth sprocket cost me around £45 from Triumph and a rivet link was £5, so not to bad...

 

I looked everywhere mate and came up with nothing, and yes as far as I can see they have changed the spline pattern with the new models..

 

I ha e been riding bikes and playing with performance of my bikes for 30 odd years, everything from carby & exhausts to gearing , and most manufacturers of bikes make their bikes with rear sprocket in the 37/45 teeth range and do sprockets up to 2 or 3 teeth larger or smaller than std, maybe you should have tried 1 tooth larger front and then a smaller rear up to 3 or 4 ?? Mix and match, the fronts are some what easier to do on most bikes rears can be very fiddly/complicated especially if like you found out the chain needs shortening !!
If you do this for a living ?? I am non plussed by your reply or thought processes, as mixing and matching front and rears together would have achieved what you are after without cutting chain ???

 

I ha e been riding bikes and playing with performance of my bikes for 30 odd years, everything from carby & exhausts to gearing , and most manufacturers of bikes make their bikes with rear sprocket in the 37/45 teeth range and do sprockets up to 2 or 3 teeth larger or smaller than std, maybe you should have tried 1 tooth larger front and then a smaller rear up to 3 or 4 ?? Mix and match, the fronts are some what easier to do on most bikes rears can be very fiddly/complicated especially if like you found out the chain needs shortening !!
If you do this for a living ?? I am non plussed by your reply or thought processes, as mixing and matching front and rears together would have achieved what you are after without cutting chain ???

 

To be honest I don't really care what you think about how I go about things.

I can put another 15 years on your 30 when it comes to bikes. I've been building and tuning engines for 40 years. (Meriden Triumph twins and Triples, BSA's, Norton, Norton rotary and Harley's)
I think I'm pretty well on the way to knowing what I'm talking about by now.

As this stands I was answering a question from another Thruxton R owner and from what i can see you do not have a Thruxton R (correct me if I am wrong)
So you probably don't understand the Thruxton gearing anyway. You also wouldn't have any idea of UK roads or how the stock gearing performs here never mind any gearing alterations.
Either way, removing a couple of links from a chain and riveting a link takes me five minutes, far easier, quicker and less expensive than removing and replacing the front sprocket as well as the rear especially when I can get where I want to be by just changing the rear. As I said if there was an 18 tooth front available I would have just changed that but their aint.

Another point to your idea of mixing different front and rear sprockets, is that 39 or 40 tooth rear sprockets are not an easy item to get hold of for the Thruxton R.....So, once again I don't know where you are coming from with that.
It's all well and good you sitting there coming up with your weird and wonderful ideas behind your keyboard but when it comes to actually doing the job and sourcing the parts it aint that easy.

So, to sum up, I removed a rear wheel and spun of six nuts to change a sprocket which took me around 10 minutes, I then proceeded to remove a couple of links from the chain that was already off the wheel due to changing the sprocket which took me another five minutes and bingo, job done and I'm where I wanted to be in 15 minutes...
You on the other hand would rather I buy two sprockets instead of one, go through the hassle of removing and replace both to get to the same end result..
Hmm, maybe not eh...

Let me just remind you what you said yesterday...

"and rears 37/45 on all bikes excepting Moto-X and trail bikes"

And today you say...

"and most manufacturers of bikes make their bikes with rear sprocket in the 37/45 teeth range"

Well you were wrong yesterday and you are trying to cover your arse today. You come back on here and tell me I'm not making sense and you know better....Again, maybe not eh!

This is part of the reason I don't really relish giving up time and trying to help people out on the internet, because there is always some smart arse that knows better who doesn't actually know as much as he thinks he does.....

That smart arse would be your good self.

 

While you two have been having a pissing contest I've been looking up factual Triumph part numbers which appears to imply that it is possible to purchase a Triumph 18T front sprocket that will fit on a Thruxton 1200 R :


Triumph 1200 (& others) engine front sprockets :

Thruxton R - PFKL2658710Sprocket, Front, 16T, 525 £23.40 http://www.worldoftriumph.com/trium...ck_01=&block_02=100075731-0-2&block_03=233370


Bonny T120 - PFKL2643946Sprocket, Front, 17T, 525
http://www.worldoftriumph.com/trium...ck_01=&block_02=100074494-0-2&block_03=611010


Bonny T100 (carb) - PFKL1198740SPROCKET.GEARBOX.18T 525
http://www.worldoftriumph.com/trium...lock_01=&block_02=100064707-0-2&block_03=3130

Looking the diagrams they all appear to be the same design.

 

Dave, that's like reading the instructions before assembling!! How dare you!!

 

Well I thought it made things perfectly clear...........................

There again, I don't have 1500 yrs of horse, horse and cart, steam engine and petrol engine experience ....................

 

I think the clue is in the "words appears to imply" and "appear"
Mate, these part numbers "appear to imply" you are wrong, they are different, probably the diameter of the output shaft. If they were the same both part numbers below would match, they dont because they are different.

I also find this all very amusing, none of the three of you seem to have one of these bikes yet you all are happy to tell me I'm wrong when I am the one that has done the work and researched all this months ago...
Oh well, that's forums for ya.


PFKL1198671 SPROCKET. G/BOX. 17T, 525 T100 (carb)
PFKL 2643946 Sprocket, Front, 17T, 525 T120

 

Setting up the Supercharger on the dyno...

 

Don't those flexible silencers affect the handling

 

and yet another example in "How to win friends and influence people".

 

Bloody hell mate ....I'm well impressed

 

I'm not here to win friends pal.
Someone asked a question and I tried to help him out but then other people that aint got a clue about the subject matter feel like they have to turn it into a shitstorm.
I stay away from other parts of this forum that center on bikes I don't own or have any knowledge about, how about you?

 

Seems I was right, see the next post dick!!

 

No pal, you were wrong and you know it. It would be spectacular for you to be relying on the next post when he was wrong too...

Thats the problem with people like you, ya think your clever then you get shown up to be the idiot you are you cant hold your hands up and admit it..

Big of you to call me a "dick" from the other side of the planet, I'm impressed with your outstanding bravery.....Get back in your box you fu*king hero...