Rear Pivoting "Hardtail" Anyone????

cncron

I am building a daily rider chop/bob and would like to include a pivoting rear swingarm that looks like a hardtail.....kinda like the Harley Rocker Tail. Has anyone seen/built or be interested in one. I am looking at about a 2" travel in the swingarm with fender attached and also a sping mounted seat. The roads are super bad here in Ontario where I live and I just can't imagine riding full rigid. Any thoughts on this????

sure · Full Member Joined: May 07, 2008 Posts: 195

take a look at a harley soft tail frame.. you should be able to make a similar frame just set up for an xs motor..like this one...

cncron

Yes thanks....I am actually copying my Vstar frame....very similar. Know anyone that has done this with an XS650????

newxs650 · Full Member Joined: Jul 31, 2006 Posts: 62

cncron wrote:

Yes thanks....I am actually copying my Vstar frame....very similar. Know anyone that has done this with an XS650????

here's one using the stock HD frame.

kenb

cncron wrote:

I am building a daily rider chop/bob and would like to include a pivoting rear swingarm that looks like a hardtail.....kinda like the Harley Rocker Tail. Has anyone seen/built or be interested in one. I am looking at about a 2" travel in the swingarm with fender attached and also a sping mounted seat. The roads are super bad here in Ontario where I live and I just can't imagine riding full rigid. Any thoughts on this????

I know about those roads you're talking about, and I feel the same way about riding a hard tail around here. I'm pushing 50 with a previously damaged spine as it is, so I too have been looking at alternate rear suspension ideas for an XS650. My goal is to achieve the neat and tidy hardtail look, while still having some springs back there somewhere so I can keep riding for a few hours at a time.

I've looked over the Harley softtail notion on the back of an XS650 frame myself (even knocked off a few test drawings), but I've found a couple of issues that make the idea a bit less than straightforward than it appears at first glance.
First, the shock placement under the bike was a problem, as there isn't really much room under or behind the engine for them in the stock Harley layout without stretching the length of the bike considerably. This could be resolved by using standard coilovers mounted on top instead, if you wanted to explore installing the shocks under the seat like the old Vincents.
The second problem is the excessive distance between the center of the drive sprocket shaft at the rear of the engine to the center of the swingarm pivot shaft. On the stock XS650, these shafts are only 6" or so apart, resulting in minimal drive chain interference as the chain passes through the pivot area. Unfortunately, the best scenario softtail arrangement I could come up with had them spaced at least twice that distance, which would cause considerable drive chain interference with the swingarm pivot shaft tube. Dealing with chain slop and interference at this point will require a system of idlers or guides, or alternately, a jackshaft just in front of the swingarm pivot, just ahead of the back wheel as shown in the picture below.

Not to say the idea isn't worth looking at, it's just got some details that need working out. I've also looked at some monoshock ideas as well, but I'm a little hesistant to go that way because of possible difficulties getting it dialed in right. In the meantime, I've been boning up on lots of details about spring preloads and dampening rates and all that other neat stuff, so I'll have the best shot at making the right decisions when I settle on the final design.

Ken

thorshammer · Full Member Joined: Dec 12, 2008 Posts: 58

Three other options on rear suspensions is leaf spring running vertical, coil spring in tension rather than in compression like most bikes or even rubber block I suppose you could also run torsion suspension. I have found out that if the hardtail is stretched far enough and the back tire fat enough and you find good springs for arealy nice old saddle that that had springs under the cover you can live with it. You may want to see if you can copy a plunger frame or find an old savior frame. If any one wants Email me and I can probably find pics of all this stuff in my old book stash. Good luck on whatever you decide. bh_hammer @ hotmail.com

Julian · New Member Joined: Jan 25, 2009 Posts: 5

There is a group in England that produces a mono shock type softail frame for the sportster that is quite cool. I thought this would be close due to the unit construction of the engine and the fact that I also ride a Kawasaki vulcan 800 with the same basic rear end. I'll need to look at my computer at home for the web site. I seem to remember a few metric builds as well.

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