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Geared to the moon?

45815 Views 170 Replies 37 Participants Last post by  kilyung
I'm coming from a Thruxton R which I just didn't ride "hard" enough to keep it around. I loved the motor though, and the instant torque at any point in the rev range was welcome. I figured I'd like the Bobber's engine even more given the way I ride most of the time. That said, though it does have more torque in the range where I typically ride, it doesn't feel like it. I then looked up the gearing which really surprised me. The Thruxton uses 16/42 (2.625:1) and the Bobber is 17/37 (2.18:1). No wonder it feels so much different. Rather than swapping both out right away, I'm planning to start with a 16t front sprocket and go from there.

Has anyone else changed their gearing? I wonder why Triumph geared them so radically different. I also wonder what the ratios in the gearbox are, and if they differ between the various 1200 models.
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It's not that I wanted to make changes its that wanted to see what gearing they did..cause mine has the purge valve turned on in the map and we don't even have a purge valve.
Yeah, well you lost me on that one... I'll have to hook up the bike and take a look.
Even the Information section has sweet FA compared to earlier DNK maps....

Personally I don't think the map should be protected like they are it should be viewable but you cant copy or compare.
I hear you -- would be nice to be able to see and compare, even if you couldn't copy or alter the map. I understand the concept of intellectual property rights and therefore can't blame DNK for their policies. Too bad the implementation couldn't find some middle ground.
Yeah, well you lost me on that one... I'll have to hook up the bike and take a look.
Just mean I wanted to double check their work.
Sorry to dig up an old thread. I have a '23 bobber with cat delete and BC drag slips. I have a DNK tune for this setup, will I need a new map if I change gearing?

Thanks all!
Doesn’t look like it, can ask DNK anyway.

Sorry to dig up an old thread. I have a '23 bobber with cat delete and BC drag slips. I have a DNK tune for this setup, will I need a new map if I change gearing?

Thanks all!
I asked Danielle if gearing changes would require adjustments to the map parameters. Her response was no, fuelling was not affected by changes to drivetrain configuration.
Finally went to 16/42 on my '21 SM - have to say absolutely NO REGRETS - I struggle to understand the motivation for 17/37 - I feel that riding at 16/42 is much more chill in fact and suited to the "relaxed" MO of the SM/Bobber. Much less clutch babying, much more confident take offs, and easier speeding around traffic when needed/desired. Soundtrack is improved as well, hard to put a finger on it but the engine just sounds happier/less stressed.

Highly recommend! I feel like if it was stock, very few people would complain and fewer would even consider making the gearing taller from there.

16T Front sprocket T1182516 (Very cheap, dealer can order from Triumph. It's the Thruxton RS sprocket)
Replacement tab washer T1186601 (also very cheap and either in stock or can be ordered from your local dealer)
42T Rear sprocket RST-2012:42-BLK (Supersprox stealth in black, special order from Supersprox but just 56 Euros plus shipping. Email [email protected])
525 Black DID ZVMX Chain (For both SM/Bobber the stock chain is 108 links, I added one pair to make it 110 which resulted in very nearly identical to stock wheelbase and plenty of adjuster room in both directions)

Tools: 36 mm socket (Impact recommended for taking it off, or a very long breaker bar and a buddy to help). Torque wrench, blue locktite, wheel balancing stand, wheel weights, chain tool (motion pro PBR), tape measure or ruler, various sockets and torx for the front sprocket cover, axle nut, chain guard, rear sprocket nuts.
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How long did the whole job take to complete?

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I went with 16/39 and absolutely love it
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I went with 16/39 and absolutely love it
Recently did the same. The bike should have come this way.
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How long did the whole job take to complete?
I would budget 4-5 hours to be honest if you want to be relaxed.

-remove & fit front sprocket (remove and refit sprocket nut and cover)
-break & refit and re-tension chain
-remove & refit rear wheel and rear sprocket
-rebalance rear wheel

I forgot to mention before, needing to have a wheel balancing stand and weights handy as you should rebalance the rear after swapping the rear sprocket.
… you should rebalance the rear after swapping the rear sprocket.
Good point. I never thought of that! However after several years without issue, I’ll just save it for the tire change.
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