Thruxton R Gearing for Acceleration - Triumph Forum: Triumph Rat Motorcycle Forums
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post #1 of 41 (permalink) Old 08-01-2019, 11:07 PM Thread Starter
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Thruxton R Gearing for Acceleration

I'm thinking about changing the gearing to something more aggressive, want to get more low end acceleration. I know I need to go bigger on the rear sprocket, or smaller on the front. Was looking at Renthal, and they make 47, 48 and 50t sprockets that seem to fit.

What do you folks suggest that will give me more acceleration and won't throw things out of whack?
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post #2 of 41 (permalink) Old 08-02-2019, 12:09 AM
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Originally Posted by drainyoo View Post
I'm thinking about changing the gearing to something more aggressive, want to get more low end acceleration. I know I need to go bigger on the rear sprocket, or smaller on the front. Was looking at Renthal, and they make 47, 48 and 50t sprockets that seem to fit.

What do you folks suggest that will give me more acceleration and won't throw things out of whack?
Gearing changes are one of my favorite subjects, I have nine different gearing combinations for my Thruxton R.

Your stock is 16T/42T. People calculate it a two ways I use the rear divided by the front to get 2.625 in this case, this method means the higher the number the lower (more low end).

The T120 stock is 17T/37T or 2.1764 which is quite high by comparison.

Quite frankly the internal gearing on the Thruxton R when combined with the 16T/42T gearing is already so low it almost takes a magician to go from 1st to 2nd without hitting the rev limiter on the drag strip.

Now if your want a little more low grunt from a roll on then getting a bigger rear sprocket would better than going smaller than the 16T.

I would not going in larger than a 44T on the bike, and if your in sport mode with the traction control off the bike may try to throw you off with a 1st gear roll on.

The 44T would probably slow you down at the drag strip... from my experience. You lose about .1 to .3 when you bounce off the rev limiter depending how long it takes you realize it.

P.s. You may need a longer chain for a 44T if your chain is new.
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Last edited by retjustdad53; 08-02-2019 at 12:30 AM.
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post #3 of 41 (permalink) Old 08-02-2019, 12:14 AM Thread Starter
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Gearing changes are one of my favorite subjects, I have nine different gearing combinations for my Thruxton R.
Haha nice. What do you suggest?
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post #4 of 41 (permalink) Old 08-02-2019, 12:39 AM
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Haha nice. What do you suggest?
Sorry had to stop and help the wife in mid reply.
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post #5 of 41 (permalink) Old 08-02-2019, 03:51 AM
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I thought the purpose of the standard gearing on an R (for roadwork not dragging) was to stop me looking for 7th gear?

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post #6 of 41 (permalink) Old 08-02-2019, 01:19 PM Thread Starter
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Originally Posted by retjustdad53 View Post
Gearing changes are one of my favorite subjects, I have nine different gearing combinations for my Thruxton R.

Your stock is 16T/42T. People calculate it a two ways I use the rear divided by the front to get 2.625 in this case, this method means the higher the number the lower (more low end).

The T120 stock is 17T/37T or 2.1764 which is quite high by comparison.

Quite frankly the internal gearing on the Thruxton R when combined with the 16T/42T gearing is already so low it almost takes a magician to go from 1st to 2nd without hitting the rev limiter on the drag strip.

Now if your want a little more low grunt from a roll on then getting a bigger rear sprocket would better than going smaller than the 16T.

I would not going in larger than a 44T on the bike, and if your in sport mode with the traction control off the bike may try to throw you off with a 1st gear roll on.

The 44T would probably slow you down at the drag strip... from my experience. You lose about .1 to .3 when you bounce off the rev limiter depending how long it takes you realize it.

P.s. You may need a longer chain for a 44T if your chain is new.


Thanks. So a 43 would probably do it. If I did go up to a 47 on the rear, couldnít I balance it out by going 17 in the front?

Iím going to replace my chain with the sprocket, so Iíll be able to size it right.
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post #7 of 41 (permalink) Old 08-02-2019, 02:22 PM
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Thanks. So a 43 would probably do it. If I did go up to a 47 on the rear, couldnít I balance it out by going 17 in the front?

Iím going to replace my chain with the sprocket, so Iíll be able to size it right.
Can you tell how what to do with bike? You will notice the change two teeth on back on one tooth on the front.

I think 99.9% of Thruxton R owners would not go lower on the gearing, quite a few have gone with higher gearing.

In the last three years you are the only rider who I have heard who wanted lower gearing so that makes you unique.

I do drag race my bike 3 or 4 times a year and find the stock gearing about as low I would go, I might try a 16/43 combination but to be honest I could not recommend anything lower than a 43T.

Since I do also do land speed racing I have more experience with higher gearing, so maybe you might be the guy to pioneer the lower gearing area.

Good luck and remember traction control can be a friend.
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post #8 of 41 (permalink) Old 08-02-2019, 11:35 PM Thread Starter
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Can you tell how what to do with bike? You will notice the change two teeth on back on one tooth on the front.

I think 99.9% of Thruxton R owners would not go lower on the gearing, quite a few have gone with higher gearing.

In the last three years you are the only rider who I have heard who wanted lower gearing so that makes you unique.

I do drag race my bike 3 or 4 times a year and find the stock gearing about as low I would go, I might try a 16/43 combination but to be honest I could not recommend anything lower than a 43T.

Since I do also do land speed racing I have more experience with higher gearing, so maybe you might be the guy to pioneer the lower gearing area.

Good luck and remember traction control can be a friend.
Thanks for all the advice. I'm definitely different than the other R owners, I'm not interested in taming the beast.

I think I'm going to give 43t a try and see how that works. You think I will need a longer chain? Stock is 110L, right?
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post #9 of 41 (permalink) Old 08-03-2019, 12:28 AM
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Thanks for all the advice. I'm definitely different than the other R owners, I'm not interested in taming the beast.

I think I'm going to give 43t a try and see how that works. You think I will need a longer chain? Stock is 110L, right?
I believe the stock chain is 100 links, but it should work if you have made any chain adjustments.

I admire your enthusiasm. Short story if you don't mind.

I was road racing when I was about 19 and wild as hell. In one race I passed on old guy (28 yrs old) at least 4 times.

After the race I went over to this old guy with a better bike, nice leathers, etc. So I asked him why with all of the good stuff why he was slow?

He calmly looked up at me and said I finished ahead of you. You see I was fast but I kept running off the track and he did beat me. I didn't really get it until years later.

Sometimes you can be wild ass fast and still slow.
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post #10 of 41 (permalink) Old 08-03-2019, 12:40 AM Thread Starter
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I believe the stock chain is 100 links, but it should work if you have made any chain adjustments.

I admire your enthusiasm. Short story if you don't mind.

I was road racing when I was about 19 and wild as hell. In one race I passed on old guy (28 yrs old) at least 4 times.

After the race I went over to this old guy with a better bike, nice leathers, etc. So I asked him why with all of the good stuff why he was slow?

He calmly looked up at me and said I finished ahead of you. You see I was fast but I kept running off the track and he did beat me. I didn't really get it until years later.

Sometimes you can be wild ass fast and still slow.
I'm definitely not wild-ass fast, or young. Just having fun with my bike and customizing it to make it my own. Even better that no one has tried to go bigger on the rear sprocket.
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