Larger chainring and freewheel crank question..

[Fumesucker]

My bikeE recumbent has a 20" rear wheel, a SRAM three speed hub, an 11 tooth small sprocket and a 44 tooth chainring. To make a powerful ebike with the kind of top speed I'm looking for (~35 mph) and still drive through the chain and gears will require a freewheel crank and a larger chainring.

Given the setup I have (see pics), what is going to be the easiest/cheapest way for me to accomplish a large chainring and a freewheel crank on my bike? I also think I would like to go to somewhat shorter cranks, what options are available to me on that?

Keep in mind that I haven't done much with bicycles in over thirty years, so my knowledge is pretty out of date.

 

[Miles]

Echo do a 160mm trials crank (threaded 1.37" x 24 tpi) for sq. taper or ISIS fitting: http://www.webcyclery.com/product.php?productid=16644&cat=306&page=1 You will probably have to replace the BB anyway, though...

A good 18t freewheel - Tensile or, less expensively, Shimano [WI ENO 22t would be the best].

Fabricate an adapter between the freewheel and your choice of chainring size/BCD.

 

[RevDon]

For what it's worth, here's a thread on the subject:

http://endless-sphere.com/forums/viewtopic.php?f=2&t=5607

Good Luck!
Don

 

[Fumesucker]

Hi Miles,

I saw you had Echo cranks on your immaculate build.

Are you aware of any directions for fabbing a freewheel for the chainring/crank? I need pictures because I tend to think visually and I don't recall ever having a freewheel apart to see how it's made.

Fabbing parts is not a problem as long as I know what they need to look like.

 

[Miles]

The trials cranks are threaded - you just screw the freewheel on

Here's why you need a high quality freewheel......
http://www.endless-sphere.com/forums/viewtopic.php?f=3&t=1926&p=89524#p89524

 

[docnjoj]

Also be sure to read the Bike-e tales from their former website and Easystreet Recumbents! I vaguely remember their chainwheel assembly was quite non-standard. Those folks used to have some replacement parts etc. This may not be necessary, but could save U some fabrication efforts!
otherDoc