Option #1: X-Class setup

I might have posted this before, I'm curious how my new options compare against the stock X-Class gear range. My cheapest option of getting lower gears would cost me $250 and these are the results. The chart looks like this:

This mod would give me one higher gear and three lower gears. The gears are significantly lower than my current setup and still even better than using the SRAM Dual Drive.

I can't help but to think what would happen if I combined the two. Hmmm, now that would be interesting. Best of two worlds? Let's see.

Combining both systems would give me a range of 8.9 - 97.1! That's insane! I could probably climb a wall with that setup! That would be pretty ideal, but it would cost me $650+ to get there. That's still less than the installed cost of the Schlumpf drive and would weigh less overall. Two points against getting the Schlumpf. I understand the Schlumpf drives weigh in excess of 10 extra lbs! Do I really want to carry around a 52lb trike? Uh, no!

38T chain ring on an SRAM Dual Drive?

I'm curious how swapping the 40T chain ring for a 38T would effect the lowest gear. How much lower gear inches will I get from the replacement? Would it be worth it? Let's take a look.

I saw the preliminary gear chart and thought, "Why stop here?" So I decided to tap on another couple chain ring sizes to see how low I could go and what the effects would be on the high end Here's the side by side comparison of a 36T, 38T and 40T chain ring on the SRAM Dual Drive setup.

Tough choice. I love the idea of being able to go under 15GI's, but that comes at the expense of one less high gear than my stock setup. I'm liking the 38T chainring.

SRAM Dual Drive

During my research for more options on getting lower gears in prep for climbing hills, I discovered the SRAM Dual Drive system. Utah Trike sells it and it happens to fall in between the two prices of my other options:

1. Add a 3 chainring setup at the front boom - $250
2. SRAM Dual Drive - $400
3. Schlumpf Mountain Drive - $700+50 (shipping/tax/blah)

Q: So what's the SRAM Dual Drive?

A: It combines a 3-speed hub with a 9-speed cassette. So what does that mean? It's a single unit that replaces the front chain ring as well as the rear cassette or in my case, a freewheel. It basically relocates the front would-be chain rings to the rear in the form of an internal hub. The cassette is added on. If installed, I'll get 3x9 = 27 gears instead of my current 7.

The cassette is actually a 9-speed with the following cogs:
11, 13, 15, 17, 20, 23, 26, 30, 34

This is how the gear chart looks like. The middle column shows my current range. It's not completely accurate b/c my current freewheel is only 7 speeds while the new cassette will be a 9-speed.Looking across the chart, I see that I'll be getting 3 lower gears! It's significantly lower - 16.1GI's instead of 22GI's.



Another effect of going from a 7-speed to a 9-speed is that the transitions between the gears will be a lot smoother. There's no jump from second lowest gear to lowest gear like there is now.

In addition to the lower granny gear, I get two higher gears for downhill speed! 78.3GI and 92.5GI is a big enough hop from the existing 67.9GI's. That gives me a 36% jump!

In my previous posts, I noted that 88GI's would be my ideal high end. Having a gear higher would be even better. What I'm most excited about though is the 16.1 lower gear.

Another advantage to this system is that less can go wrong. The system is definitely more complex, but there's less to mess around with. Everything is internal and gear changing is all done from the rear. Nothing happens up front.

The kit comes with a wheel! Since I need a back rear wheel anyway for backup, I won't have to buy an extra. The kit also comes w/the shifter, derailleur, cable, hardware, grips. Sounds really good! Hmmm.

Thank you donors!

I had promised to print out the names of all who are donating to the Aids Life Cycle on my behalf to be pasted on my trike. Here's how the collection looks like so far.

Thank you! To make a donation, please click here:

Donate to ALC on behalf of Brian

Typical road bike gearing

I'm curious what my companions will have on the ALC in terms of gearing. I'm reading that road bikes have something between 18-104GI's by utilizing a 11-34T cassette across a 22/32/44 chainring setup.

I did some further research and found a general idea of what different types of bikes can be expected to have:

Mountain Bike: 18-103GI's
Road Race Bike: 43-127GI's
All around: 20-90GI's

My KMX Tornado: 22-67.9GI's

Somehow I'm still a lot faster on the downhills than most DF bikes I've ridden with. They're not mashing down the hill though. I suspect my speed has something to do with my bent being more aerodynamic. I'm no physicist but theoretically, I would need less high end gear inches to achieve the same speed since I can take advantage of the momentum and aren't fighting as much resistance.

From experience, I think 2 extra gears up top would be ideal. Assuming there's a 15% increase in GI's per gear, that would put me at about 88GI's - far from the 100GI's that I original thought I may need/want.

This is good news. I can sacrifice quite a bit of high end gears to boost the low end. Calculating the same logic that I used for the high end gear to push the low end 2 gears down at 15%/each , I end up with around 15GI's on the low end.

A boom and chain ring setup from the old KMX X-Class satisfies the low end, but not the top end. The top end would pretty much remain unchanged whereas the low end is improved fairly drastically. My lowest gear inch will be 12.1 instead of 22.0. I'm certain I can climb any hill with that.







While the old KMX X-class gearing is supplied by a 42T chain ring, the newer setup from the KMX Cobra (mountain climbing version) is equipped with a 44T. I made this chart to decide whether it would be worth going for the newer Cobra setup or just stick with the available X-class one. I suspect the X-class one will be cheaper. It's priced at $250 shipped for the boom, derailleur, and chain rings.



I'm still considering the Schlumpf drive, an internal gearing system but that's priced at way over $250. It's more like $850-900 by the time it's completed. It involves not only acquiring the components, but customizing it and having it specially installed. The Schlumpf drive acts as a double or quadruple chain ring w/o a derailleur. It's typically used on geared unicycles. Who ever thought unicycles could be geared?? Well, they can and Schlumpfs technology makes it available....at a price - a steep one.

Looking at the numbers, this is pretty ideal! I would get virtually the same low end gears with high end topping out at 94.5GI's. If I got this setup, I wouldn't want to go further. I could commit to keeping it and not modding it any further.








The previous option of replacing the stock boom components with a new one from another KMX has an obvious price attraction, but I think I'd still have an urge to eventually increase the high end. With nothing else available, I'm topped out.

How practical would a higher top end be though? I think I've already gone 34mph. My goal had been 40mph, but I'm thinking that's just a ridiculous speed to go unless it's on a closed course, but even then it wouldn't be worth the extra cash it would cost to get there.

I'm still on the fence, but need to make a decision w/in the next month. I need time to get the components delivered, installed and tested before the ALC in June.

Riding urge

I got the urge to ride, but the weather lately has been horrible! Rain everywhere, mud, and dirt. Definitely not ideal riding conditions. Ugh. I only have a few more months of riding before the big event and I still don't have even half the funds I need to join the ALC. Ugh.

It's been a month

Wow, it's been awhile since I last rode. After just 3.75 miles I already felt like throwing up. It was probably b/c I didn't have much to eat for lunch and rode too hard. Lack of training made it a bit uncomfortable. But boy was it fun! I almost forgot how much fun it is to ride this thing!

Sped up to about 28 mph today on the asphalt. A couple slow moving cars ruined my speed though. Darn. Got the usual looks and kid's remarks,

"Wow, I haven't seen one of those bikes before!" shouted a little girl probably about 9 years old from her voice as I sped by.

Didn't see her face, but she was probably one of the most excited kids to ever comment on the trike. Sometimes I'm a bit hesitant to be too nice. Scared their parents might think I'm some guy from, "To catch a predator."

Just showered. Feels good.