13T & 46T sprocket review
 

If you read my thread on how I broke in my RX3, you'll know that I found it insufficient for hilly terrain and mountains. It was anemic. Poky.

Well, I'm headed back to the mountains, and I'm taking the RX3. In an attempt to alleviate the concerns of being underpowered, I am experimenting with different sprockets.

The set I just installed are a 13T front, and a 46T rear, as endorsed by SpudRider. That does represent a substantial change in gearing, about 11%. That seems like too much for highway riding, but probably just right for the hills and mountains. I might go back to the stock 14T in the front for the highway journey to the mountains, and then swap in the 13T for the hilly terrain.

I just installed them both to make a test run, and HOLY COW. This is the shot of adrenaline the RX3 needed so badly. It's terrific. It went from poky to perky. It feels much stronger everywhere.

The biggest surprise was highway performance -- this thing moves now! It is running 65 mph (GPS) at 8,000 RPM, and 73 mph at 9000. And that is sitting up - you don't have to shlump over the gas tank crouching behind the windscreen to get those speeds. And it can HOLD those speeds up a hill. And when you're going 73 mph at 9000 RPM, you have plenty in reserve. Smack the throttle wide open and it will accelerate noticeably, on up to at least 80 GPS mph at 10,000 RPM. (Acknowledging that that requires a trip into the red zone on the tach, of course).

This is behavior previously unknown to me on the RX3. On the highways before it would hold 72 on flat ground, but at the first incline that would drop to 65 quickly. Not anymore -- this 13/46 rig will pull 72 up a hill, and accelerate up that hill if you ask it to.

Yes the engine is spinning faster. And MPG will probably suffer. But practical speed hasn't, and responsiveness and the fun factor are massively improved.

This mod may not be for everyone, but I can say that I am much more optimistic about how the RX3 will be able to handle my return to Colorado.

Several of us had the same reaction when we upgraded.... It opened the bike up.

Doing ONLY the 13t front gave me those benefits, without a major noticeable MPG change (but I'd only had a few tanks through it before then). It's become usable around town including highway time, where before I was constantly fighting it.

Drove halfway across Texas today, and I have to say I LOVE the 13/46 combination. It makes the bike so much more practical. It can easily hit 72 and hold it on hills, and I got it up to 87 indicated on the speedo, about 79 GPS. So there's really no downside, other than the engine spinning about a thousand RPMs faster.

I drove 460 miles today, mostly at 72 to 78 mph (GPS). It was so much less stressful I can't even describe the difference. I brought along the 14t as I thought I might change it out for the highway portion of the trip, but I can't see why I would do that when the 13/46 is working so well.

MPG is awful at about 40, but that's what happens when you push 72+ mph for hours on end, and is comparable to the MPG I was getting from the stock 14/44 combination the last time I crossed Texas. The RPMs are higher but the overall load on the engine is the same.

I did the 13.....then did the 13/46.....then did the 14/46 and that's still what I'm running. I found it the perfect combo for where we live and my riding style.

Yep, it all depends, that's for sure.

I ran into a sign today out in the desert between Carlsbad and El Paso. It said "no services for the next 111 miles." And I had already gone 40 miles on that tank. And was getting a steady 40 mpg. So it looked like I may not make it. I wasn't worried, I carry a spare gallon, but it's a bit of a pain in the butt to unhook all the gear to get to the gas can, so...

I decided to slow way down and see what kind of MPG increase I can get. I rode those 111 miles at 55 mph, at 7,000 RPM, and made it with a gallon to spare. That tank delivered an average of 57 mpg.

That's pretty much as good as I was getting from the 14/44 combo, so it was very nice to see that going 13/46 didn't sentence me to always have low mpg.

Interesting difference. I haven't done long rides on the RX3, so my riding consists of a lot of 50 MPH riding with about 20% done at 70. I'm averaging a little over 50.

Climbed my first mountain today with the 13/46, a long gradual slope up to 6,000 feet. The little 250 struggled, but nothing like before, I could comfortably maintain about 60. Not bad!

I have been pushing the RX3 quite a bit the past couple of weeks. Today I rode for 650 miles, that's a pretty long day. And I have to say again, I am loving this 13T/46T combo. Today was 11 hours of constant highway riding, and it was such a massive improvement over the stock gearing! Last time I rode this way, with the stock gearing, I had to avoid highways to avoid bogging down and slowing everyone down, and riding in the emergency lane to let them pass and all that.

This time, I took the Interstate the whole way. I was generally able to hold the 75 mph speed limit, and this time I was the one doing the passing.

I also set what I think has to be the speed record for an RX3 with a stock engine: down one long hill the GPS hit 87.2 mph, and the speedo showed 94!

This sprocket change has transformed the bike. It isn't 100% yet, it still can't hold the speed limit up long hills, but it's getting very close to being able to handle all expected situations. I'm optimistic the 298cc kit will give it that last bit.