Gearing

[gphil]

Going to pass this out because you fellas are quick to respond and the ideas and comments are always useful. I am attempting a build of a DeltaRunner and starting to get down to gearing. What type or how many shifts would you suggest. I have seen 18 , 10 , and others and which one would be the best for this project. Could get so high that you could not push the pedals. Give an idea of what to look for. Gonna hit the thirft stores after this post anyway. Thanks lots. Gphil

[GregLWB]

Going to pass this out because you fellas are quick to respond and the ideas and comments are always useful. I am attempting a build of a DeltaRunner and starting to get down to gearing. What type or how many shifts would you suggest. I have seen 18 , 10 , and others and which one would be the best for this project. Could get so high that you could not push the pedals. Give an idea of what to look for. Gonna hit the thirft stores after this post anyway. Thanks lots. Gphil

What type of terrain do you ride in? How fast do you want to ride? How fit are you? What kinds of load (trailer, gear, etc.)?

Greg

[John Lewis]

Really need to know where you ride. As a first suggestion I used the following on my DeltaWolf. Remember though that the Wolf has 26" rear wheel. Also on a bent it is better to have a lower gear and spin the pedals around 80 rpm if you don't want to end up with knee problems.

In my moderately hilly area I used 48/38/28 rings and a 7 speed 13/32 sprocket. Might have been 14/32. On the steeper hills I could maybe go a bit lower but it's not too bad. I spin out pedaling at about 45kmh say 26 or so mph but only manage that on a downhill or with a good tail wind.

There's a good calculator on the Sheldon Brown site for looking at various gear combinations.

Hope this helps,

John Lewis

[gphil]

Greg, In answer to your questions I must say , all the above. I exercise twice a week and push a stationary bike fourteen miles a week. So I am in fairly good shape for a old guy. So living here in Atlanta the lay of the land is hilly , hot and all that. I want to go fast as I can when not pumping up a hill and be able to pull my grandson behind once in a while. I think bikes have saved me to tell the truth. A couple stints ago and a lot heaver they got rid of all that. So there ya go. New to gears and such I have a pedal forward recumbent I bought and it has 26 gears or something like that. I just see all these hulks and really do not know what to look for. A all around gearing would work. Thanks for the comeback. Just saw your post and thanks John. gphil

[TheKid]

The DR also has 26" wheels, so John's gearing will work well with it. Using John's gearing @ 80 RPM, your low gear would be 22 gear inches at a speed of 5 MPH. Your high gear would be 96 gear inches with a speed of 22 mph. If you use a mega freewheel, 7 speed 11-34 with a 24-34-42 crankset, your low gear would be 18 gear inches, which would be good for hills or carrying a heavy load, and your second gear would be 22 gear inches. Your high gear would be 99 gear inches at a speed of 23 mph. If you don't mind spending extra bucks or are lucky enough to find a donor with custom gearing, you could go higher.
I chose simplicity, because I don't care about speed. I was also lucky enough to run into a 5 speed freewheel, 14-28. I have a single 34 tooth chainring up front. My range is 26 gear inches in low, which is fine for the small hills I encounter, to 63 gear inches in high gear. At 80 RPM, which is what I also strive for, the speed range is 6 - 14 MPH. I usually spin in high gear a little faster, because my average speed is 15.1 mph according to the computer. Bear in mind I have disabilities and my reflexes have slowed, which is why I chose the higher seat of the DR and the simplicity of having only one shifter.

[GregLWB]

gphil - John and the Kid have given you some good info. The Sheldon Brown site gearing calculator is really good. I don't have a trike yet, so take this with a grain of salt. On my LWB commuter I run a 54, 43, 30 triple on the front and a 7 speed 11-32 on the back. I live in Oregon (so lots of hills) and I now have a motor assist on it (mainly for the speed, but also so I can ride more and further):scooter:. BM (before motor) I had a top pedaling speed of 27 mph on the flats with no wind and could sustain ~19. The hills were pretty good with the 30 on the front and the 32 in the back (heavy bike and at the time I was ~320 lbs). I have a 26" rear wheel also.

I woud recommend that you use a crankset on the front that has bolted rings instead of the riveted ones (although you can drill out rivets and put bolts) because as you start riding you can change out your ratios as you find what works best for you.

The advantage you have on a trike is that on the hills you can go as slow as feels comfortable and you won't get wobbly.

I hope that helps.

Greg

[TheKid]

Drilling out the riveted rings is a great idea.

[gphil]

Thanks guys, that was some good stuff to study. I did not know so much went into a bike etc. Appears like I am gonna have to do a little reading in Sheldons book. ghil