Framebuilders - Offset Rear Triangle

Bikeforums.net is a forum about nothing but bikes. Our community can help you find information about hard-to-find and localized information like bicycle tours, specialties like where in your area to have your recumbent bike serviced, or what are the best bicycle tires and seats for the activities you use your bike for.



PDA

View Full Version : Offset Rear Triangle

Little Darwin
09-18-06, 03:50 PM
I have no aspirations of becoming a frame builder, but I am curious if anyone has any opinions on the pros and cons of an offset rear triangle.

I am thinking that to eliminate dishing, a rear wheel could be moved to the right in order to allow the building of the rear wheel with symmetrical lacing and tension...

I suspect there may be chain line issues to resolve, but it would seem that with the chainrings outside the BB and chainstays that moving the wheel that way could actually make for a better chain line on a derailleur equipped bike.

I suspect that there may also be strength related issues related to bends in or angles of the chain stays and seat stays.

I suspect there could be issues with chainring clearance.

I also suspect issues with "That's not how it is done"

Any comments? Has anyone ever seen or tried something like this?

MnHPVA Guy
09-18-06, 07:57 PM
I've been building with offset rear triangles for 27 years. I've never broken a rear spoke on a frame I've built. The rear wheel on our LWB recumbent tandem carries 250-275 lbs when were touring, and has gone 25k + miles with only 36 - 14ga spokes.

Some people say it could be a problem if you trashed a wheel on tour and have to get a replacement. But you are unlikely to have problems with a dishless wheel, (I never have) and it's easy to undish a replacement wheel.

The only downside I've ever found is that when you finally outgrow "train wreck" shifting, you end up putting reverse dish in a hub geared wheel.

You do have to use cantilever brake bosses with different offsets left and right.