Biposto conversion - shock repurpose doable?

[petrole]

Didn't want to necropost on this older thread: Biposto Swing Arm Conversion but didn't see that the question got answered, so bringing it up here.

I have heard that you could just install a stiffer spring on one of the shocks from the bip and use that as the mono shock is that possible or is what I heard totally wrong and not do able?

Basically, I'm in middle of doing conversion from an '07 Biposto rear to an '06 Monoposto rear. I have all the parts except for monoshock (ATM is broken or something, keeps saying NSF...), so was wondering if can reuse one of the bip's shock (as stand-in)

Just FYI - current setup has both shocks with zero preload (I barely make a dent), so my thinking is to use one of the shock and crank up the preload to compensate for the non-shared setup. As well as rebound/dampening.

-Pete

[YellowDuck]

I haven't done this (I have a mono), but I have an opinion on it....

I think you might get away with it but only if you change the spring. Cranking up the preload is not going to cut it, even if you are a featherweight - it wouldn't be enough spring even if you weighed nothing and the suspension was only supporting the bike. You don't change the spring rate by increasing the preload, or make the suspension more "stiff", unless you crank in so much preload that you are riding around with the suspension completely topped out (you don't want to do that). Unfortunately, buying an appropriate rate spring that would fit would be money wasted once you get the monoshock, since I doubt they are the same dimensions (ID and length).

Of course, it would be underdamped as well, but probably with some knob twiddling you could make that part work halfway acceptably.

Are you looking to eventually use an OEM monoshock, or something aftermarket? I think getting a used OEM one would not be that expensive, given the number of people who have upgraded to Ohlins, Penske etc. I might be convinced to part with mine, which is in good shape. Or, I could even lend it to you for a few months while you scrape together cash for whatever you are looking to evenutally buy. PM me if either option interests you.

[arbakken]

I bought a used monoshock with a hyperpro spring for $50 here on the forums. If you were to try and re-purpose a biposto shock, I'd throw a hyperpro spring on there and try it. Even if the shock doesn't do a good job, the spring is an AMAZING upgrade over stock, so you could still reuse it on the proper mono shock if you ever found one.

[petrole]

Yeah, after completing the conversion yesterday and reading up here on the forum, decided to go with YSS mono-shock (most bang for $$). Plus ATM (read wifey) has allowed for funds again.

Thanks again to YellowDuck for the generous offer.

[Skandarn]

Keep an eye on this one.
Ducati Sport 1000 / Paul Smart Ohlins Rear Shock | eBay

[petrole]

So completed my conversion from Biposto to Mono. I'm sure you guys have seen conversions before but figured why not another one
Btw, I'm not really good with write ups, so bear with me.

So it all started with a picture of a Paul Smart with a Zard exhaust system. I just had to have that system on my bike.

First thing needed was the mono-swingarm in order to accept the lower exhaust. After searching and searching, landed a great deal from eBay.
Couple weeks later, it arrived - 90 euros ($114 USD):

The black paint was kinda in bad shape, so it needed a repaint. I wanted to spend my money on the important stuff first, so I just rattle-canned it. I found that Ford Motors - Cardinal Red matched the closest. so after sanding, primer, 5 coats of red and 4 coats of clear, I'd say not bad....



Next, read that the biposto rearsets wouldn't work with the new swingarm config, so off to a little more searching. For me, the stock '06 rearsets were enough. They were about 25mm back and 25mm up. Perfect for me. I've bought adjustable rearsets before and the thing is, once I set it, I never change it (so, all that adjustibility just goes to waste).
Found that a member was selling a set here (pretty much complete, just missing all the bolts/springs/etc) for $140. Snatched it up quickly.



Once they came in, I gave them a nice polish.

Then I tracked down all the various bolts/etc that I would need to fit the rearsets on. Boy was I surprised to find that the brake lever/bracket mount bolt was (cough) $30. Stupid little bolt. anyways, all these little odds and ends totaled $55 (brake lever spring, bolts).

I then ordered the exhaust with the help of Stephano.

So while that was coming in, I figured I had enough to start the conversion.

Being as how I was going to take off the swingarm, I needed something to hold up the bike, so I remembered a member here constructing a trellis to hold up his bike. so off to hardware store, picked up some 1 inch inner diameter steel piping and built one. It's pretty strong too!


(Yes, my garage is a mess. I've since cleaned it up)

Removal of the rear wheel, brakes, exhaust, and rearsets was very straightforward.
Next came the shocks and finally the swingarm itself.

Hard to believe that a little cir-clip and set screw is all that's holding in the swingarm pivot shaft.


Expensive wheelbarrel

[petrole]

Putting on the new swingarm was also straightforward. Just had to shim it.
I realized that using the stock biposto shims in the same order (two thin ones on the right, and one thick one on the left) worked well.

Also routed the brake line and speed sensor according to how I saw it was done on other mono's.


At this time, I ordered the YSS shock (initial purpose of this thread) since the biposto cannot be substituted for the mono setup. While that was coming in, I just propped up the bike with one of the biposto's shocks so that I could take it off the trellis contraption.

Next, I proceeded to install the "new" rearsets and quickly realized two things.

1st, on the shifter side, using the stock biposto sidestand interfered with the shifting lever. Meaning my toe would hit the spring on the sidestand on upshifts. Biposto's have it on the outside, mono's on the inside. So off again to find a mono side stand. Easy enough and after nice deal with Rubberside Down, score a complete set (bracket and all) for $80


After quick polish and install, this provided the proper "toe" clearance:

(Looks really close in this pic but is actually far apart, you with mono's know what I'm talking about).

2nd, on the brake side, I reused the rear master cylinder and thought I could reuse the stock biposto plunger pin. Wrong.
The Biposto's pin is much longer than the mono's:

Another $25 bucks (sigh, stupid little parts).

Then last Friday, Klaus (as in Klaus Huenecke, not Santa) came through and delivered me my YSS shock - G366-TRCL ($589).

So quick install later, she now has that spring in her step again:

[petrole]

And now here she is, waiting to get her "voice".



Come on...Marco, I'm dying here...LOL


ETA: Note from Marco says I'll be getting this in by next week....yaaahooo!!
Also wanted to say that if it weren't for this forum, I'd have a lot more difficult time sourcing parts, information, and confidence to do this myself. Great group of folks here!

[1duckyboy]

Super write-up, Pete, good picturess and lots of detailed information. Looking forward to completed project pics. I've checked out several adjustable rearsets and none go as low as the stock mono ones are.

[JCPakBikes]

Good stuff!!
These bike are so much Fun to work on as well as watching people work on them.

Cheers!!