I keep running across references to a 39-tooth sprocket. I'm getting my '03 750 ACE ready for a long (10,000 mile) road trip in the spring. What's the deal with this sprocket? How will it effect my performance?
A 39 tooth sprocket will lower your rpms on the highway making for a much more pleasant ride. You will lose a bit of low end. It's hardly noticable with a 39. From what I've seen a 38 tooth seems most popular. It will lower your rpms a bit more than a 39. Many on this forum use a 37 tooth.
The smaller your rear sprocket, the lower your rpms will be on the highway. The smaller your rear sprocket, the less off the line acceleration you'll have. You may have to slip your clutch a bit more taking off from a standing start with a smaller rear sprocket.
I'm running a 38t rear sprocket, love it! As DynoBobSlick said, it's primary benefit is lower engine rpm's at highway speed. The engine is not nearly so busy-sounding. You do lose some off-the-line power, but it's acceptable.
I've been running a 36 for almost 6 months now. About 4K miles. I have a 2000 ACE with pipes, Bean box mod, 4 degree timing mod and Barnett clutch springs. I only ride solo and can say with my bike's improved performance the 36t is the best choise for me. I commute 40 miles 1 way on 2 lane back roads as well as numerous 200+ milers on weekends. I can cruise easily at 70-80 with adequate passing power and when in town I'm never beyond 3d gear. In fact if I'm cruising around 55-65 and need to get going I can drop to fourth as I can accelerate through 80 easily in fourth. And the best news is they're always " in stock".
I dropped from a 42 to a 39 on my 2002 750 spirit, and ride mostly 2-up.
I really like the drop in rpm at my typical cruise of 70-80, and any loss in acceleration, or pulling away from a stop hasn't bothered me enough to prevent me from considering even a further drop to a 36 tooth.
I used to look for a "6th gear", but now sometimes find myself feeling the shifter and being pleased to find there is one more left.
I also dropped to a 39 rear ( from a 41) and find it ideal.
I do a fair amount of 2 up riding, and feel that the loss of any torque at the low end is negligble.
The bike no longer feels like it needs another gear, and I can cruise comfortably at 75 to 85 with no problem.
It is probablyone of the best 'mods' I have done, (along with the Mustang seat).
Thanks, everyone, for the replies. Based on that, I'm going to look for a 36 or 37 rather than a 39. I ride alone, and only weigh 145, and low end acceleration that isn't important to me. Thanks again.
Roger on the 20 year absence from riding ... It was about 18 for me until September when I got the 2002 Spirit.
If you're gonna do a major roadtrip this spring and still have the stock seat, you might very seriously consider what harryco, myself, and a bunch of other folks on this forum say about the Mustang seat being a worthwhile mod.
If I had to choose between a sleeping bag and tent, or the Mustang seat, it might be a difficult choice
Thanks for the suggestion Kermit. I've been thinking about a Mustang seat, even though my stock seat seems perfectly comfortable so far. I've got a fancy 2-position backrest which I love, and I wonder if a Mustang seat will be compatable with it. If that turns out to be a problem, I'm thinking I might go with one of those gel seat covers. Any thoughts on that item?
A funny aside about my 20 year absence from riding. The guy I bought my ACE from was selling it because he'd just turned 50 and his wife had convinced him he was now too old to ride. When I arrived to buy the bike, the wife looked like she'd just swallowed a pine cone, and the guy looked like he might take up wife-beating. That's because I'm about to turn 70, and 30 years at sea has left me with a face that looks a lot like Keith Richards on a Monday morning.
I'll have to bow out to others who may have experience with the gel or other stock seat modifications since I don't.
My seat choice was mostly to improve passenger comfort for the wife when she complained that 50 miles was about the limit for the "wedgie" stock passenger seat. As a bonus, it worked out great for me as well because the deeper bucket seems to help my lower back, and the padding, which at first I thought was too firm, eliminated my hot spots. As it turned out, the foam density for us is perfect, and I like that I feel like I'm sitting IN the seat instead of ON it.
The bike was my 60th birthday present from my wife. I wasn't even really shopping, but we stopped to admire it one Sunday when a friend had ridden it to church and he mentioned that he was thinking of moving up to a larger bike. A week later she came home and said "Marty's bike is for sale ... maybe it would be fun to ride again", so that's all the encouragement I needed.