I've a Challenge Hurricane and have had to alter the boom length. That went well (measure 10 times - cut once !) but I've now had to reduce the chain length.
I've done this slowly, link at a time, but there seems to be a point where you have to compromise. I'm used to a df, where the derailleur keeps the chain in constant tension on both the power and return run. This doesn’t seem possible on the recumbent due to the large 60t large chain. As can be seen from the photos you are constrained by the large front/large rear combination. This means the small/small combination leads to the return chain sagging. Is this usual ? I assume a front ring smaller than 60t would improve the situation - is that the way to go ? Any advice appreciated.
http://i1268.photobucket.com/albums/jj577/kearnss/largefrontlargerear.jpg
http://i1268.photobucket.com/albums/jj577/kearnss/largefrontlargereardetail.jpg
http://i1268.photobucket.com/albums/jj577/kearnss/smallfrontsmallrear.jpg
http://i1268.photobucket.com/albums/jj577/kearnss/smallfrontsmallrearchainsag.jpg
http://i1268.photobucket.com/albums/jj577/kearnss/smallfrontmidrear.jpg
http://i1268.photobucket.com/albums/jj577/kearnss/smallfrontmidrearchainrub.jpg
I've done this slowly, link at a time, but there seems to be a point where you have to compromise. I'm used to a df, where the derailleur keeps the chain in constant tension on both the power and return run. This doesn’t seem possible on the recumbent due to the large 60t large chain. As can be seen from the photos you are constrained by the large front/large rear combination. This means the small/small combination leads to the return chain sagging. Is this usual ? I assume a front ring smaller than 60t would improve the situation - is that the way to go ? Any advice appreciated.
http://i1268.photobucket.com/albums/jj577/kearnss/largefrontlargerear.jpg
http://i1268.photobucket.com/albums/jj577/kearnss/largefrontlargereardetail.jpg
http://i1268.photobucket.com/albums/jj577/kearnss/smallfrontsmallrear.jpg
http://i1268.photobucket.com/albums/jj577/kearnss/smallfrontsmallrearchainsag.jpg
http://i1268.photobucket.com/albums/jj577/kearnss/smallfrontmidrear.jpg
http://i1268.photobucket.com/albums/jj577/kearnss/smallfrontmidrearchainrub.jpg