Recumbents and all feet forward machines
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My Mango came with 52 -39-30 rings and an 11 -28 cassette to a 26 tooth mid drive sprocket and standard 18 tooth final.
That gave a lowest gear of about 30.8 GI and a high of 136 GI assuming a tyre diameter of 19.92" for the Big Apple.
Speed range 11.8 kmh to 52.1 kmh at cadence of 80.
That was OK until I developed a bit of a heath problem and have, for the moment, to take the riding easy and has kept me from riding my Velo. Time to lower the gearing.
I finally received the new 22 tooth mid drive and swapped out the 26 tooth.
The new range is from 26.1 GI to115 GI. Speed range 10 kmh to 44.1 kmh at cadence of 80
Now I have replaced the 11 -28 with an 11 -32.
The range is now 22.8 GI to 115 GI. Speed range 8.7 to 44.1 kmh at cadence of 80
According to the spreadsheet anyway. The only time I might miss the higher gearing is to crank up the speed on a downhill.
It was a devil of a job to get the rear shifting to work. It kept derailing on the inside even though the limit screws were correct and also had trouble with interference between the 32 tooth sprocket and the deraileur cog.
Fortunately lots of ways to adjust because of the way it is all attached.
It's not yet quite right and there is a clunk noise on each change that echoes through the body and sounds worse than it is. You also feel it. A bit more fine tuning should see it right though. Wish I had some rollers instead of having to take it out and ride after each adjustment.
Build your own.
Regarding gearing, I was wondering if a 26 on the front (52/30/26) would give the lower gearing you are searching for?
Optima Baron Raptor
Low Racer - Recumbent
Yes I've been contemplating building one. I though a couple of front hubs in a frame would be sufficient for what I want.
I Looked at getting a 44-33-22 ( think it was.) ring set. Unfortunately it wont fit. the way the deraileur post is made wont allow you to lower the deraileur. The frame would get in the way if you lowered it anyway. As the said 30 is the minimum ring size. I think I could get around that though.
I was going to put on that ring set and also a Sram DualDrive in the mid drive. That would have given me from about I think 15 GI to about 140. Something like that anyway.
The Mango tour uses a 42/32/24 Shimano Deore XT Crankset. Ask Harry how they set up the FD.
http://www.sinnerbikes.com/wordpress/wp ... o-Tour.pdf
Thanks Ben. I notice the deraileur post on the tour appears to be different to ours. It is a round ali rod and quite thin in the photos I've seen. Looks the same as the Quest.
I guess I could buy the whole assembly and just swap it over.
I did finally get the shifting sorted out and it seems fairly smooth now.
I have a new SRAM Dual Drive here. Pity its not a disk brake version or I could try it out.
Hijacking your thread; hope you don't mind, but this may be of interest to you as well. Twilwel made a suggestion of a Alfine 11 hub at BROL as one option to get a better gearing range.
I have played with his suggestion in combination with a 34t Schlumpf High Speed Drive which on paper I think looks good but not sure if this will push the limits of the Alfine 11. Anyone have any thoughts on this?
Playing with HPV Drivetrain Analyzer I have come up with following tables which I think are pretty close based on my best estimates of wheel sizes.
Red Edition with Marathon Race 406-40:
Mango Tour with Schwalbe Big Apple 406-60:
Great minds and all that.
I played with that Soulbikes spreadsheet the other day before I had to go to the city and I looked at the gearing with the Alfine.
My current setup gives 22.8 to 115 GI which is 8.7 to 44.1 kmh at cadence of 80RPM. I need a lower low ad a higher high. I'd like say 12 to 120 GI like my trike.
Might be moot anyway as I mentioned in my email.
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