View Full Version : x seam

10-14-2013, 09:32 AM
I think im going to weld my bottom bracket to the main boom. Ill measure my x seam, and set the BB to me. Im 6'4" , so if someone else wants to ride my trike ill make the seat movable. Besides ill be the one riding it 99.99999% of the time. At this point i dont know ill make it movable. I mite make a frame with mesh cloth for the seat. That would make moving it forward easer for short peeps. No im not talking marshmellow chicks. I can use the seat plans from my LWB plans i got from another source.

I can understand the movable BB on trikes with short owners, but for taller riders i can see a problem with having too much slack in the return side of the chain letting the S part of the rear derailer going up, and and hitting the cassette. That would be bad. Id think just a 2" bifferance could spell trouble.

Please correct me if im wrong. You can google x seam. Its simple to do.

10-14-2013, 10:28 AM
The issue with they bikes is the center of gravity can be shift if the weight is moved too far in one direction or another. That can really mess up to ride. The Streetfox COG is right at the pivot having the seat move forward may - and I STRESS MAY- have some undesirable steering effects.
The adjustable bottom bracket is not just to adjust for shorter riders. It is for new recumbent rider to adjust for their knees.
New to recumbent riding you may have to move it for proper peddaling position. Moving the seat does not move the steering arm either. So while moving the seat may seem like a good idea you may end up with an uncomfortable ride because the seat to steering is not in the right place.
A suggestion: build it with the adjustable bb. Ride it for a week or two to ensure it is in the right place. Then weld in place and forget about adjusting it for others as the steering won't be right for them anyways. The adjustable seats on commercial trikes only changes seating angle not the to move forwards or back- they use an extendable tube instead for the COG issues. Good luck.

10-14-2013, 10:36 AM
DTD has good ideas in his post. I've a Spirit I've been riding off and on for about 6 months and I am going to weld the BB to the boom to save weight. I've also found that if I change the seat angle it has been necessary to change the X-seam seat position. I have a Barnett Williams style seat as you've suggested for yours. Just make sure that you make it adjustable a few inches back and forth in case you want to change the seat angle.

10-14-2013, 03:11 PM
Tell anybody shorter to bring some platform shoes with 'em http://ccs.infospace.com/ClickHandler.ashx?du=http%3a%2f%2f28.media.tumblr. com%2ftumblr_l4twmtWMFx1qabwixo1_400.jpg%23elton%2 520John%2520tommy&ru=http%3a%2f%2f28.media.tumblr.com%2ftumblr_l4twm tWMFx1qabwixo1_400.jpg%23elton%2520John%2520tommy&ld=20131014&ap=3&app=1&c=avgtbavg&s=avgtb&coi=772&cop=main-title&euip= d&hash=C7FB481333C6A46CC8F5BAA71836F529:rolleyes4: