Paralever to Monolever conversion a.k.a. Spoked wheels on MOnolever

[StephenB]

Spoked wheels on a 1985-1995 Monolever rear drive



Full recognition for the idea and KUDOS go the the Bauer brothers in Germany who performed and published this procedure first (here is their website, only few pics)




You arrived here for one of the following reasons:

1. You don't like the y-shaped cast wheels that BMW introduced with the 1985-onwards streetbike monolever Airheads
2. You would like to convert your 1988-on GS/R to a monolever rear drive and continue to use your 17in rear wheel with a 130/80-17
3. You want different final drive ratios for your GS/R (37/11 and 33/11)

Since case 2 and 3 apply for me, I did not have to deal with the front end conversion as I have a spoked wheel front end already. However, it is quite straight forward: the 19" front wheel off the R100R fits onto a 1985-on monolever and only requires some different size sleeves to be correctly aligned, so is not entirely "plug 'n play".

The easiest way to approach the rear wheel conversion is using a 1988-1995 paralever (R80GS, R100GS, R80R, R100R) rear wheel.






I have marked the area of concern with the red arrow. How does that show when you mount the GS/R rear hub to the monolever rear drive:







In my case, 21.5mm of the inner hub had to come off. I gave the job to my local machinist Rich, and he took excellent care of it. I won't bore you with any details, just because I don't have any:












Now, in order to be able to use this wheel again on a paralever hub, I had Rich machine a spacer:











That took care of just the hub fitting to the final drive. The second before last thing you need are the 4 monolever wheel bolts (should you not already have them).


Now, the most important part is to make sure, that whatever tire size you're going to use is not rubbing at the swing arm. For a "standard" say 1987 R80 Monolever conversion, the rim has to be laced approx. 10mm off center.

My case is the conversion of a Paralever GS to a monolever. I would like to use 130-80/17 street tires or 50/50 to 70/30 knobbies, so I had some fellow riders check on tire width:

Tire size	Make/Model	Tire Width [mm]
140/80-17	Bridgestone BT45	140.00
140/80-18	Metzeler Enduro Sahara 3	140.00
130/80-17	Avon Gripster am24	143.00
130/80-17	Metzeler Enduro Sahara 3	125.00
130/80-17	Kenda 761 Dual Sport	127.00
130/80-17	Metzeler Tourance	130.00
130/80-17	Michelin Anakee	130.00
130/80-17	Metzeler Karoo 2	130.00
4.00-18	Metzeler Enduro Sahara 3	113.00

I took a couple of measurements of the new hub when installed. Assuming a safe 2-3mm clearance between rubber and swingarm, I have assumed a 140mm wide tire as maximun and therefore have the rim laced 15mm off-center to the left. I had Richard fabricate a 2mm shim, just in case the tires vary in width. But one can always use a knife to cut some rubber off.


I will consider a 30-50mm swingarm extension to the monolever swingarm as the paralever swingarm is 30mm (measured from swingarm pivot bolts to final drive center) longer than the monolever: 420mm vs. 450mm. I have collected some more measurements associated with the difference between Monolever and Paralever: http://www.stephenbottcher.net/BMW/R...dimensions.xls.

[Stagehand]

Excellent, thorough write up. Great visual aides. I give it an 8.5 or a 9. Whats it look like all ftted up?

I really like the idea of making the paralever into a monolever. Bulletproof rear diff, and easier to make longer, correct?

[StephenB]

Stagehand,
I won't have it all together before next year's riding season. Just imagine a completely refurbished Woody Y-laced GS wheel on a monolever final drive. It'll look as if it was designed that way!

Extending a monolever looks easier, I have an "appointment " with my machinist tomorrow to have initial discussions and to bounce some ideas off each other.

Stephen

[shawn]

Hi guys! can any other wire spoked wheel be used on a Mono bevel drive like this one. I can see why you have used a paralever wheel because you had one but as I haven't is there anything I can get that will fit straight on?

[StephenB]

You'd need the 4-bolt GS/R hub no matter what and whatever Woody or Buchanans can lace to it.

[Wirespokes]

What a great idea! I just wish there was another way to do this without offsetting the rim. If 1/2" less were machined off the hub the brake shoes wouldn't mate up. Had you looked into other solutions to that problem?

[StephenB]

No, I haven't looked and there are only so many BMW spoked wheels/hubs out there. I don't think you can solve it differently. Jon-Lars did the same on his converted GS with the original 3-bolt hub.

[Alexander Bauer]

Hi!

Originally Posted by Stagehand

Excellent, thorough write up. Great visual aides. I give it an 8.5 or a 9. Whats it look like all ftted up?

On a Monolever the wheels look like this:



Alexander

[Wirespokes]

Originally Posted by StephenB

No, I haven't looked and there are only so many BMW spoked wheels/hubs out there. I don't think you can solve it differently. Jon-Lars did the same on his converted GS with the original 3-bolt hub.

I think the R100GS (& 80GS) and R are the only ones with a drum rear hub in the four lug design. Are there others? I was wondering if there was a way to locate the brake shoes a half inch farther out. Still, lacing the hub a half inch off center shouldn't be a big deal.

[shawn]

I've been asking on my local bike forums about wheel lacing and its a lost art over here in the UK. Mag wheels have been out for 30 years and no one wanted spokes. Might be different in the USA with Harleys being so popular.

[StephenB]

Hi Alex,

nice of you to chime in. After all it was your idea!

Originally Posted by Alexander Bauer

Hi!


On a Monolever the wheels look like this:



Alexander

[Baffo]

Originally Posted by StephenB

Spoked wheels on a 1985-1995 Monolver rear drive
You arrived here for one of the following reasons:

1. You don't like the y-shaped cast wheels that BMW introduced with the 1985-onwards streetbike monolever Airheads
2. You would like to convert your 1988-on GS/R to a monolever rear drive and continue to use your 17in rear wheel with a 130/80-17
3. You want different final drive ratios for your GS/R (37/11 and 33/11)

Why not use an R65G/S or R80G/S hub (3 bolt holes) and a R80GS/R100GS rim respoked to each other? Or any other 40 spoke rim. (I want a 4.25x17 rear...)

[StephenB]

Originally Posted by Baffo

Why not use an R65G/S or R80G/S hub (3 bolt holes) and a R80GS/R100GS rim respoked to each other? Or any other 40 spoke rim. (I want a 3.25x17 rear...)

Because you would have the additional expense of buying a 3-bolt final drive in case you are aiming for the described 4-bolt monolever cast to spoked wheel conversion.

If you had a G/S already you can lace almost anything to that hub ... within reason that is. 3.25x17 doesn't seem excessive.

[Alexander Bauer]

Hi!

Originally Posted by Baffo

Why not use an R65G/S or R80G/S hub (3 bolt holes) and a R80GS/R100GS rim respoked to each other? Or any other 40 spoke rim. (I want a 3.25x17 rear...)

The 80 G/S had two version 10:32 and 11:37. 10:32 is rarely seen (most of them on ST). IMHO not the thing you are looking for a 100cc BMW.

I did the conversion because I wanted spokes. Cast Y-wheels IMHO look wrong on such a bike:



OK, it needs paint ....


Alexander

[indianscot]

To utilise the stiffness of a mono arm and use spokes, how about turning the arm into a twinshock type arm, ie. Double sided but single shocked. This way you could use various twinshock bevels, easier wheel finding.
Downside is loosing easy wheel removal and extra weight. Someone said that HPN does this for strength.
The offset of r100r wheel, how does the alignment with the front work out?