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Discussion Starter #1
Hey all! So, I've done some reading and searching on the forum about chains and sprockets.. I'm sure I'll be going with a D.I.D chain, however I am contemplating a sprocket change too, as I'm an expert at "while you're in there" syndrome....

My bike, a '95 Thunderbird, could use some more "legs" on the highway.. So, I'm thinking an 18T could be ok.. But maybe I should go 19T?

Has anyone done anything different, and what was the outcome?

I would love to hear about your experience and opinions here!

As usual, thanks in advance!!

Jim


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I usually like to gear a bike up when I get it, and that would help with the fact that the gear ratios are a bit closer than I prefer, but my first gear launches are already about as difficult as I can tolerate so I guess I will leave it as it is. I've got a '99 though, which I think already has 18T up front as stock? I can never remember off the top of my head...
 

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I've tried 19t but settled back to an 18t as best compromise for me. But note a Tbird is already about 3.5% higher geared with a 150/80/16 tyre over the Legend 160/60/17.
 

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On my 96 Adventurer, I went to a 18 as soon as I got it home. Ended up changing again to a 19. Feels much better on the highway.

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Discussion Starter #5
Super helpful thanks guys.. still not sure on 18T or 19T however.. keep the opinions coming! :)

It is interesting to see how many have switched.. i.e. pretty much everyone.
 

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I wonder if there is a way to tell how many teeth there are on the countersprocket without removing the cover?

Perhaps a person could put the bike on a stand, then position a marked pin on the chain just going into the cavity, then turn the wheel and count chain pins until it appears again on the way back out. For different sized sprockets, that number will be different. You'd have to get it down to the half-pin interval though, because a one tooth difference will yield only a half-pin difference on the chain (chain wraps around only half of the sprocket).
 

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Here's another gearing calculator, an MS Excel spreadsheet I downloaded from here originally.
 

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Thunderbird (five speed ) for the U.S. market had a 17 front and 43 rear. U.K. was 18 front and 43 rear. My best result is a 18 front and a 40 rear. I tried putting a 19 on the front but the standard chain was too short, better to get a smaller rear and take some out. It also makes the chain shorter, which is nice.
 

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i put a 19T in my Legend a while back (like 6 years ago). Best decision i ever made. It was the closest thing i could do to make the gears taller besides add a 6th gear, which ain't happening.

Ended up needing a new gasket for the engine seal that was installed a year later. Never understood why they would make the front sprocket cover part of the crankcase.

The 17T that came stock with it (i think?) was WAY to low. first gear was so low that second gear takeoffs were almost the norm, unless you really wanted to blast off. You had to almost immediately shift into second, because it was so short that it topped out at about 40mph. Made cruising on the interstate UNBEARABLE. Did i mention i have slash-cut megaphone pipes w/ the baffles drilled out? My bike is generally obnoxious, but this was over the top.

Now it cruises at 70mph at 4000 rpm. Much more quiet than 5500rpm. Still very capable of burnouts, draggin' and other tomfoolery. I would love to have a 6th gear though to get out and cruise on the interstate, but then again it can already easily get to 125mph, so what is need of 6th gear? I have to remind myself sometimes it's not a vtwin and it likes to stay around 4000 rpm at cruise, and doesn't like dropping to 2000 or lower.
 

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Hey Cloud9, did you keep your rear sprocket stock?
I didn't change it out and i know my dad didn't (he gave it to me), but the original owner may have. i don't think that it is non-stock. would be hard to tell from just looking though. from the feel he may have upped the rear to get more torque, but i can't imagine that his intent would be to eliminate the need for 1st and make it unbelievably loud at interstate speeds.

also, from what i read it was a little short in first gear and seemed to want another gear and this is exactly the experience i had when riding before i swapped the front out.

So lets make my answer a tentative YES. i will check tonight.

ps: don't hate because he gave it to me. i spent a lot of my own money, time, blood, sweat, and tears keeping it running well. i just wasn't ready to keep it before, because it was too much MC for a learner. but now, he's done with it and i get to cherish a piece of history. hell even my insurance agent told me not to get rid of it.
 

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Discussion Starter #15
HAHA.. I would never hate on you for that. In fact, when I moved to NYC I traded my old jeep to my friend who owned my Triumph.. so.. it was kinda free.
 
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