Author Topic: Wheel options - spokes with disc brakes  (Read 6217 times)

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Offline tvholstein

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Re: Wheel options - spokes with disc brakes
« Reply #15 on: February 07, 2014, 11:07:47 PM »
Nigel, is that a straight fit or are there modifications needed?

Offline nigecollier

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Re: Wheel options - spokes with disc brakes
« Reply #16 on: February 07, 2014, 11:37:52 PM »
had to turn a few mm off sprocket side to line up & fit wheel bearings to take xs spindle, also spacers, ive a small lathe so pretty easy

Offline Joffa1

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Re: Wheel options - spokes with disc brakes
« Reply #17 on: March 21, 2018, 06:54:17 AM »
Have been thinking about wheel and tyre options for my newly acquired XS500c and came across this thread. I guess Iím looking for weight loss and better handling but still with authentic old school looks.

Am I correct in thinking if I can source an XS650 front hub and a SR500 rear hub then I can lace up new alloy rims with spokes and this will give me a significant weight loss over the stock cast wheels?

I would be looking to run the standard twin disc up front and single disc rear. Thoughts? Problems? Advice?

Much appreciated. 

Offline guylr

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Re: Wheel options - spokes with disc brakes
« Reply #18 on: March 22, 2018, 07:43:03 PM »
Wheel choice for the 2nd generation XS500 is an interesting subject and one I'd like to share what I've learned about so far. First though it's also interesting to look at what was going on in Yamaha design and marketing when these bikes came out. 1976 was the year that the first cast wheel Yamahas came onto the market outside Japan. Here in the US we got the RD400, XS500C and XS750C that year that came with the new, unpainted, seven spoke cast wheels. They were stiff and massively overbuilt for the job. Back in Japan, those new models still got spoked wheels which is curious but my strong suspicion is that production by Enkei and Asahi Malleable Iron Works was limited and they reserved them for the export bikes. These same models became available with the cast wheels on "Premium" versions the next year. Note: the bikes we knew as XS500 and XS750 were called GX500 and GX750 along with GX250 and GX400 models. All came with disc brake, spoke type hubs on the rear wheels. We never got the rear disc brake spoke wheel hubs only the cast wheel versions.

In '77 the XS500 cast wheels were were still the heavyweight version and still unpainted. For 1978 though, the factory saw the advantage of weight and cost reduction of making the wheels lighter by thinning the spokes and reducing mass in the hub area. The SR500 cast wheels also made their appearance in 1978 and received are also the lighter weight design. 1980 saw the last versions of the original seven spoke cast wheel that finally were intended to be run tubeless. These rims are only different by the small bead retention lip machined into the flat area in the bottom of the rim that is intended to help keep the tire on the rim when deflated. Many people, including myself, run tires tubeless in all years of the seven spoke cast wheels. The bead sealing area on them is exactly the same as on the rims marked as suitable for tubeless tires so that they hold air and stay on the rim just fine. Doing this will save from 1/2 to over a full pound of unsprung weight depending on the tube size and thickness.

OK, so what wheels to use? I believe the XS500C and later 500s look right with the cast wheels. That's probably because that's how I first saw them 40 plus years ago. To see if you agree just Google "1976 GX500". I did see one GX500 model that someone in Japan had put SR500 bodywork on with spoked wheels and it looked great. I just think the square tank and fenders looks better with the cast wheels.

Cast Wheels
For cast wheels the easiest swap is just use XS500E wheels front and rear and run them tubeless. About 1lb. lighter front and 2lbs. rear.
For a lighter Rear wheel you can use an XS400D, E or F cast wheel. About 3-1/4 lbs. lighter than stock XS500C.
SR500 rear wheel is about 1-1/4 pounds lighter abut also about 3/8" wider so may not fit the stock rear arm. I was going to use one of those with an SRX600 swingarm but the arm is so wide it would hit my mufflers.
For an even lighter front wheel you can use an 18" RD400 (single disc only) or and XS400D/E/F wheel for dual disc (must swap bearings).

Spoked wheels have the advantage of being able to lace up some wider rims for more modern rubber. In practice though they are not a lot lighter if any than cast assemblies.
Early TX/XS500, TX750, early XV535 and all 1972 to 1979 XS650 front hubs and wheels are a bolt on fit and allow for dual discs. The RD250/350 hubs will work but are single disc.
Rear wheels are tougher because we never got the GX wheels from Japan that are made for a rear disc. The GX500 hubs should be an easy bolt on if you can source them from a salvage breaker in Japan. Otherwise I'm at a loss to come up with a good Yamaha rear spoked disc hub. You could convert to drum brakes in which case an early TX/XS500 would be a good choice.
If you were into some work a rear hub/brake assembly from an XT600E might work as might the hub/brake from a TDR250. Those might need a wider swingarm though. 
 
My bike currently has a 1980 XS850 front wheel (requires wider XS650 fork underbracket and crown) and a 1979 XS400F rear wheel. I run both tubless and run 5mm thick discs front and rear along with 520 chain and sprockets.

Here's how the rear wheel weights compare stock to modified so you can see how a little parts swapping can make a big difference. The bike handles noticeably better. 
XS500C Rear Wheel, 110/90-18 Avon AM26 with Tube, Steel 39T 530 Sprocket (1J3-25439-20-00), 7mm Stock Disc rotor = 40 lbs. (18.14 kg)
vs.
XS400F Rear Wheel, 110/90-18 Avon AM26 (no tube), Alloy 40T 520 Sprocket (Spocket Specialists), 5mm 1L9 Disc rotor = 33.4 lbs. (15.15 kg)
 
I hope that helps some. if you have questions just ask.

Guy

PS for spoke rear hubs. I forgot to mention that TZ250/350 and 750 hubs will work if you don't mind running without a cush hub. A lot of those bikes got converted to cast wheels and the rear wheel assemblies will work on the XS500 with a little axle and spacer work. I ran a slightly narrowed magnesium TZ750 hub on my DS7 racebike for year without problems. The TZ250/350 should fit without modifcation.

 
       
« Last Edit: March 22, 2018, 08:06:27 PM by guylr »
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