Over the last couple of weeks I’ve had several conversations with my son, David, about the difficulty of pedaling my recumbent trike up hills. Because of the extremely mild winter I’ve been able to put in many weeks of training but I’ve not been making the progress that I think I should. I know I am now 68 and have some heart issues and maybe 20 pounds overweight. I’m not using these as excuses, I’ve been very athletic all my life and should be able to overcome all of these issues within certain perimeters. I know I’ll not be able to reach some of the fitness levels that I’ve had at other points of my life, but I feel that I should be able to reach a level of fitness that will allow me to perform acceptably for bike touring. My goal is to have me and my equipment fit enough for 50 miles per day with 4 on and 1 off.
Right now I feel like back in my weight lifting days. Lifting more weight than I am ready for, burning my muscles at the beginning of the workout and toast for the balance of the workout. As soon as I pull out of my driveway it is uphill. By the time I make this climb, I am toast for the rest of the ride. I feel I would be better off doing more reps with lighter weights or a higher cadence in a lower gear.
So if not me, what then? It’s got to be the equipment. So let’s take a look at what I have and what can be changed to help reach my goals.
My trike at present is a homemade Atomic Zombie DeltaWolf with 26 inch rear wheels. Most commercial delta trikes have 20 inch rear wheels and that makes a big difference on the hills. Greenspeed’s new delta trike even has 16 inch wheels. I would like to keep the 26 inch wheels for ride comfort, looks and top end speeds. It has a front chain ring of 24 teeth and rear cog of 28 for it’s lowest gear. That gives me a 22 gear inch low gear. My other studies lead me to believe I need to be down around 18-19 gear inches. That is where some of the commercial delta trikes are also. I’ve even read of some trikes with mid-drives in the 11 gear inch range.
While surfing for other information I ran across this Human Power Load Calculator at Bikes At Work. This calculator told me that a reasonably fit person should be able pull 314 lbs up a 9% grade at 3.5 mph using .3 hp. This 314 lbs comes from my 195 lbs of body weight, 70 lb trike and 49 lbs of camping equipment, food and water. Reducing any of these weights would add to your speed. I’m trying to stay on the conservative side so there is no surprises later.
I’ve never been one for an extended fast cadence, so lets say at 70 rpm cadence what gears on a trike are necessary to maintain this 3.5 mph on a 9% grade. There are many gear inches/speed calculators on the internet. For convenience I used the one at Recumbents.com
Using my 26″ wheels and 24 tooth chain ring, the calculator tells me I need a 36 tooth rear cog. This would give me 17 gear inches and 3.6 mph with a cadence of 70. The only gear clusters with a 36 we could find are 10 speed. I don’t want the problems of the der for the 10 speed and I have a minimum amount of ground clearance for a long der.
I have 2 other options. Change the 26″ rear wheels to 20″ wheels and loose some top end but save some weight or install a mid-drive on the trike to get my granny gears.. In my mind, the mid-drive would give me the best of both worlds and it’s an easy install.
A check of the gear inch calculator tells me I will easily get an overkill of 11 gear inches and up from there. I think this is the direction we will go. We have a couple of 6 speed rear clusters to work with. As soon as I work out the details of the mid-drive I’ll post here. As soon as I have pics of the install I’ll post on Atomic Zombie.
At this point I’d like to inject a point. This mid-drive is just an easy way to get the gear range needed to climb hills and have gears needed for speed also. There are ways to custom build freewheels and chain rings that may cover your needed range of gears. If I was riding a lighter weight bike I would find another way other than a mid-drive. Mid-drives just make an easy installation on a heavy trike to get the gear range needed to climb hills.
I know that 3.5 mph is not very fast but it is a speed and will eventually get you there. I’ve heard it said that “I can walk that fast”. But can you walk that fast carrying 314 pounds up a 9% grade? I may be slow but I’ll still meet you on the other side. I read of some 13% and 14% grades also. Be prepared. I read of one person’s idea of putting a little red wagon tongue on the front for pulling his trike uphill. I’ve thought of a harness over my shoulders and a rope. Whatever it takes, right?
After I wrote the above post, I made a trip to my sons house to install the mid-drive. We started talking before working and made a decisions to try something else. From a LBS I picked up a megarange 6 speed freewheel with a 34 tooth low gear. That put me at about 18 gear inches. I’ll soon change out the BB and also put on a new triple chainring with a 20 tooth low gear. This will put me at about 14.6 gear inches. This approach made chain management much easier. I may later change out the the 6 speed freewheel with a 10 speed freewheel that has a 36 tooth low gear and a smoother spread of gears.
Sites of interest:
Bike and Trike Gearing and Gear Inches http://www.bikesatwork.com/hauling-cargo-by-bike/gearing-and-gear-inches.html
How Much Weight Can A Bike and Trailer or Cargo Trike Carry? http://www.bikesatwork.com/blog/how-much-weight-can-a-bicycle-carry
Gearing 101 Tutorial http://www.cyclingsite.com/lists_articles/gearing_101.htm
Sheldon “Gearhead” Brown Gear Theory for Bicyclists
Hope this help’s with your next project.