Hello all,
I have been reading the posts on this forum and have found it very helpful in deciding what to do with my specific application. I really think I came up with a good combo and wanted to share with you all.
I found this link buried in a thread and was able to decide the best plan of action.
http://gearingcommander.com/
So a little background first. I have a 2009 WRX and recently purchased 21/18 wheels on X-hubs from wheelingcyclesupply.com. I want to do a quick swap, without messing with my speedhealer everytime, while keeping a similar overall preformance profile. it currently has 12/45 (top speed 81) which I very much like, but there is extra vibration, wear, and noise that can be prevented. What I came up with is the following:
For street/SM: ContiForce supermoto rear 150/60-17. gearing will be 13/47 with a 112 link chain
For dualsport/mx: Dunlop D606 120/90-18. Gearing will be 12/47 on 112 links
Because the overall diameter of the offroad wheel with tire is larger than the SM wheel with tire, I will need to drop one tooth on the fron sprocket when I put on the dirt wheels to maintain the overall gearing and speedo accuracy.
By doing it this way my top speed is 80.9 for SM and 82.1 for offroad. I should not see any real change in preformance, but should expect some in ride quality, and a ton in reliability and wear.
The distance between sprockets only changes by .14", which means chain adjustment is minimized. Furthermore, based on the number of links to teeth, chain and sprocket life will be maximized for the street application. For offroad, the front sprocket (12T) will be same-tooth/same-chain once every 3 rotations, which is not bad, but not optimum. I suspect I will spend more time onroad than off, so this is acceptable.
So when it is all said and done, I should be able to change the wheels and front sprocket alone. I may have to do minor chain adjustment (not sure if .14" is in the relm of acceptable tolerances), but will not need to break links ever. My speedo will remain accurate (with a one-time speedohealer adjustment), and I will have peppy stunt bike performance onroad, and a slightly mellow, but WAY improved over stock offroad ride.
I would have preferred to keep the front sprocket 13T for both applications, but to keep the performance close, or to have the offroad more responsive and the onroad more top speed oriented...I would have to change out links in the chain everytime. I"m open for critique. I have not yet made any purchases.
It's really a trade off. Either you have to adjust the chain and speedo healer everytime, or you have to sacrifice offroad preformance, or you have issues with dependability and wear. I am looking for an easy swap, with improved performance offroad, and the ability to do 70mph comfortably onroad. I want to ride around town getting good mileage during the week, and ride around trails getting TERRIBLE gas mileag on the weekends :)
What is everyone else doing? Does anyone here actually swap their SM and MX wheels often on their WRX/R, or do most find they like it one way and just stare at a spare set of wheels collecting dust?
p@
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