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Geared to the moon?

56K views 174 replies 38 participants last post by  NoEasy8 
#1 ·
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.
 
#50 ·
Everyone likes something different, but I would say the 16t sprocket is a must-do. The stock bike is not "slow" with the stock gearing, but it is certainly lazy, often feeling like it's lugging a bit. Rolling on the throttle at highway speeds (70+) doesn't shoot away from traffic in a way I'd expect it to. My 865cc Bonneville is quicker, though its RPMs are well over 4k while the Bobber dawdles just over 3k.

Had I not owned a Thruxton R before, I would not have a point of reference for how I'd like the bike to perform.

I am also planning on stepping up to the 40t in the rear, mudguard gap be damned.
 
#51 ·
Everyone likes something different, but I would say the 16t sprocket is a must-do. The stock bike is not "slow" with the stock gearing, but it is certainly lazy, often feeling like it's lugging a bit. Rolling on the throttle at highway speeds (70+) doesn't shoot away from traffic in a way I'd expect it to. My 865cc Bonneville is quicker, though its RPMs are well over 4k while the Bobber dawdles just over 3k.

Had I not owned a Thruxton R before, I would not have a point of reference for how I'd like the bike to perform.

I am also planning on stepping up to the 40t in the rear, mudguard gap be damned.



I don't necessarily agree with beatle on this one . From my own personnel experience my stock BB was no slouch certainly not lazy and never experienced any lugging , It performed well when ever I wanted It to , getting on a highway at say 40 mph then up to 90 just left everything else behind , yeah Its not sports bike quick but for what It Is for me It has plenty of get up and go . You cant compare a Thruxton R with the BB Its a totally different beast the Thruxton Is at home on the track with the HP motor were the Bobber Is not HT motor . Is a 16t sprocket a must have , Its the cheapest mod = performance you can make and my bike Is even better for It , but imo nothings a must have . Just sayin :|
 
#55 ·
I often feel like the Boober is either lugging or engine breaking, compared to previous bikes I’ve owned. I’ve attributed it to the bore/stroke ratio I guess. But maybe that’s not right. Wondering if the 16t mod would make it easier to hit the “sweet spot” between lugging and engine breaking, at lower to middle speeds.. (I do a lot of city riding, constantly between 2nd and 3rd.)
 
#60 ·
Completely agree, Gary. I only bought the stupidly dumb expensive Supersprox (although I do like the aluminum carrier idea) because I couldn’t find a (reputable) available steel 39T sprocket. With the Bobber engine (and non-race application) I’d rather use steel sprockets.

Mike
 
#61 ·
The bobber feels a good bit different with a 16t front, revs are most definatley higher than before but i'm up at 50/60 before I know it and the tcs lamp flashes a bit more than it used to lol.
 
#62 ·
Dang, I've never had the TCS lamp flash at me on the Bobber. On the Thruxton, it'll come on in 2nd gear if I really twist the wick. Though the shorter wheelbase, more horsepower, and lower gearing contribute to that. In 1st gear, the Thruxton feels like it's going to rip my arms out of their sockets if I really whack the throttle.
 
#72 ·
I just called to order one. It was around $45 plus shipping, though he couldn't tell me how much shipping would be. Probably less than $15. Nice person (Steve) taking my order. Was a little more than I thought it would be, but no more than it should be for a black steel sprocket. I think I spent more on the aluminum one for my Bonnie, so not outrageous.

Vortex makes a 525 black aluminum sprocket with 39 teeth: 526zk-39. They're a little more than $60 on ebay.
 
#77 ·
Just got around to installing my new sprockets. Wow, what a difference! I used to feather the clutch a lot at low speeds. Now don’t have to. Take off from stop is very smooth with no judder.

I used a Thruxton 16T front sprocket and 39T Supersprox Stealth sprocket (hybrid steel/auminium).

The install was easy and only took me 2hrs. Keep bike on ground and in gear. Remove front sprocket cover. Undo the outer two coolant reservoir nuts and pull reservoir away from chain guard. Remove the two bolts holding the guard in place. Flatten front sprocket nut retaining washer so nut but will turn. Use 36mm socket with breaker bar to loosen nut while depressing rear brake. Put bike in Neutral. Put bike on paddock stand. Remove rear wheel and swap out rear sprocket (pretty straightforward) using blue Loctite and torque to 55Nm. Return attention to front sprocket. Remove chain from front sprocket. Remove nut, washer (can reuse or get new one), and old sprocket. WATCH ORIENTATION OF NUT, WASHER, and SPROCKET! Reinstall in reverse order but just hand tighten. Reinstall chain over front sprocket. Reinstall rear wheel and adjust rear wheel alignment and chain tension. Tighten rear wheel axle to 110Nm. Lower bike to ground. Put back in gear. Tighten front sprocket nut to 180Nm while depressing rear brake. Bend washer to retain nut. Refasten the two chain guard bolts. Refasten two reservoir nuts. Torque four front sprocket cover bolts to 9Nm. Check wheel alignment. Done!
 

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#78 · (Edited)
Had this mod done for a while so thought I'd give a quick update. I went out for a fast run with a friend on his 1050 Speed Triple the other day and one point to note when considering dropping a tooth at the front was, that it did feel like I lost a little room in each gear. It also makes the bike a little more jumpy which can take some extra getting used to in the corners.

I still would 100% recommend the mod over all but it makes the bike much less lazy. You do need to work the gears about 5% more and control the throttle a little more when leaned over. Neither are a bad thing but means you have to work a bit more which can be new if you're used to high reving bikes.

If you're mostly around town and 0-40 riding it's perfect but I think if you are a fast track rider then you may not benefit as much. I'm not judging how you want to use your Bobber, so long as you ride one!
 
#79 ·
Had this mod done for a while so thought I'd give a quick update. I went out for a fast run with a friend on his 1050 Speed Triple the other day and one point to note when considering dropping a tooth at the front was, that it did feel like I lost a little room in each gear. It also makes the bike a little more jumpy which can take some extra getting used to in the corners.

I still would 100% recommend the mod over all but it makes the bike much less lazy. You do need to work the gears about 5% more and control the throttle a little more when leaned over. Neither are a bad thing but means you have to work a bit more which can be new if you're used to high reving bikes.

If you're mostly around town and 0-40 riding it's perfect but I think if you are a fast track rider then you may not benefit as much. I'm not judging how you want to use your Bobber, so long as you ride one!
Sounds like the perfect mod for where I live, we're only officially allowed up to 40mph (coughs:wink2:) on the island and it can be congested like most towns would be. I'll have to look to get it back on my to do list.
 
#88 ·
Hey Chico,
Yeah I've emailed my local Triumph dealer. They don't list any real parts on their website and neither do any other bike shops in Australia from what I can see. I'm hoping they can send one out to me - I'm laid up at home recuperating and all I can do is buy parts from the couch. It awful ?
 
#89 ·
Well I just heard back from the dealer - $51.45, on back order, 3 week wait. I swear no one stocks anything any more, they just wait until someone needs a part then orders it in from the manufacturer. ? Prompt reply though - emailed at 2200 last night, reply 0900 this morning ??
I have found I can get an AFAM sprocket from the UK for $40 incl postage. Anyone else used an AFAM sprocket?
 
#99 ·
I have found I can get an AFAM sprocket from the UK for $40 incl postage. Anyone else used an AFAM sprocket?
The only advantage, if it is one, is the rubber applique on the OEM sprocket.
I agree with Chico. The rubber dampener is supposed to help reduce chain noise. I’ve never had an issue with chain noise when I used non-dampened front sprockets on other bikes.
 
#100 ·
Between kid and work, my 16 tooth Thruxton sprocket has been on a shelf for a few months, until today.

The bike looks mean with the sprocket cover off, and I wish there was a simple kit to relocate the coolant.

Instantly, love it. This is another one if those mods that feels like it should have come this way. I’ll do a larger rear sprocket when I need a new chain, but already have much better 6th gear pull on the highway, and better power down low.
 
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