Zongshen RX3: 21-inch Front Wheel

[SpudRider]

Several days ago I laced a Warp9, size 1.60-21 rim to the front hub of my Zongshen RX3, and mounted a size 2.75-21, Cheng Shin, C858 tire to the front wheel.



Prior to lacing the 21-inch rim, I had raised the front fender, and road tested the configuration to ensure I had adequate clearance between the front fender and the rest of the bike.

















I raised the front of the fender a distance of 1-9/16" by mounting the metal frame of the fender to the top point of the front mounting bracket. I added a short section of aluminum bar stock to raise the rear of the fender the same distance. I also trimmed the inside edges of the fender near the forks to allow the forks to descend without rubbing the fender. I discovered I also need to trim a little from the rear of the fender, because it contacts the exhaust header when the forks are fully compressed. Otherwise, the fender is very solid, and doesn't contact the rest of the motorcycle.

[SpudRider]

I have now test ridden the bike for about 200 miles, and I am very pleased with the performance of the 21-inch front wheel. I installed the larger front wheel to improve the off road handling of the bike, and to gain a wider choice of tires for the front wheel. However, I also discovered several additional benefits from this modification. The entire suspension now performs significantly better, both while riding on pavement, as well as riding off road. The forks absorb bumps, potholes, and trenches much better. In addition, raising the front of the bike has also improved the performance of the shock absorber. Also, the saddle seems to be more level, and more comfortable, now that the front of the bike has been raised about 1.5 inches. Finally, I also gained some additional ground clearance.

Installing the 21-inch front wheel has raised the saddle height a little. However, I can still get both feet flat on the ground, even with my 30-inch inseam.



The RX3 originally had a 15-inch rear wheel. Installing a 21-inch front wheel has more closely restored the original geometry of the bike to match the larger, 17-inch rear wheel. As a result, the bike seems to track a little more stably at highway speeds. In addition, the larger front wheel more easily surmounts off road obstacles, and also allows the bike to turn nimbly during slow speed maneuvers.

The original side stand is still usable, but the bike does lean quite a bit to the left. Therefore, I do plan to raise the side stand about 3/4-inch.

[SpudRider]

After raising the fender, the front of the forks still seem to be pretty well protected from rock impacts, which could damage the inner fork tubes. However, the inner fork tubes now do collect more mud and dust. Therefore, I installed a pair of 6" Shock Sox to help clean the forks, and protect the fork oil seals. I am going to trim a bit from the lower fork guards (chevrons) to prevent them from rubbing the Shock Sox.

http://bermmotorsports.com/products/...ular-shock-sox

[SpudRider]

After 8,000 miles, I also replaced my Shinko 244, rear tire, with a Michelin T63 tire, size 130/80-17.



I am very pleased with the performance of both the C858 front tire, and the T63 rear tire. Both tires perform well on pavement, and do a good job traversing muddy, off road terrain. My previous, Shinko 244 tires perform poorly in very muddy conditions, so the new tires are a welcome improvement.









Once you traverse the muddy terrain, both of these tires shed the mud very well. Here are some photos taken farther down the road, after I cleared the muddy area.

[SpudRider]

Here are a few more photographs of the 21-inch, Warp9 rim, C858 front tire, and the 6" Shock Sox.







I am very pleased with this modification, and I would never return to the smaller front wheel. I noticed similar improvements when I converted the 18-inch front wheel of my Zongshen ZS200GY-2 to a 21-inch wheel.

http://chinariders.net/showthread.php?t=6409

[pete]

did yer lose much braking with the bigger wheel..



...

[SpudRider]

No, I did not notice any loss of braking power with the front wheel. The front wheel brake is working as well now as it did before the modification. However, the rear wheel might be a little less prone to lock, now that the original wheel geometry has been regained, and a little more weight is placed on the rear wheel. I will continue to monitor the performance of both brakes, and I will report any differences I might notice. If possible, I plan to ride again this afternoon.

[rtking]

Great to see more posts again, Spud!

And well done on the front wheel upgrade! I am very curious about the weight difference in the Warp 9 rims (both front and rear) versus stock. Wondering if the lighter reciprocating mass results in noticeable performance (acceleration) change? I'm pleased with the RX3's stock acceleration, but a little more doesn't hurt!

Add one more project to be done on my RX3.

[SpudRider]

Originally Posted by rtking

Great to see more posts again, Spud!

And well done on the front wheel upgrade! I am very curious about the weight difference in the Warp 9 rims (both front and rear) versus stock. Wondering if the lighter reciprocating mass results in noticeable performance (acceleration) change? I'm pleased with the RX3's stock acceleration, but a little more doesn't hurt!

Add one more project to be done on my RX3.

Thanks for the kind words, RT. I will be posting more, now that the cold weather has arrived.

I did not remember to weigh the 1.60-21, alloy, Warp9 rim. However, I can weigh the 2.15-18, steel, Zongshen rim, and call Warp9 to determine the weight difference.



I'm confident the narrower, 21-inch front tire weighs less than most 18-inch rear tires, and 19-inch, front tires. Therefore, the unsprung mass of the front wheel should be significantly reduced, which aids handling, even though I can't report I noticed a significant "butt dyno" difference in acceleration.

Incidentally, I have built custom wheels in the past for Zongshen ZS200GY-2 owners. Therefore, I am considering doing the same for Zongshen RX3 owners.

[fjmartin]

That all looks great Spud! If you decide to build custom wheels, let us know. I may be interested in your offering!

[rtking]

Originally Posted by fjmartin

That all looks great Spud! If you decide to build custom wheels, let us know. I may be interested in your offering!

Ditto!

[pyoungbl]

The TT250 uses a 21" front wheel. CSC lists that as about $90 without the tire. I wonder if the RX3 could use the same wheel. If so, one could do the 21" conversion for cheap....my favorite course of action.

Peter Y.

[SpudRider]

Cheaper is always best. However, I suspect the TT250 front wheel is the standard, Chinese front wheel. If so, I am pretty confident it will not fit. The hub of any wheel from another mootorcycle must accomodate the RX3 speedometer sensor, brake rotor, et cetera, and this is very unlikely.

Formerly I would allow people to ship me their hubs, and I would build them custom wheels for $55, plus the actual cost of all other parts (rims, spokes, et cetera), plus shipping. However, if I decide to do this project, I would only build and ship complete wheels.

I estimate I could build a complete, 21-inch front wheel for about $325, plus actual shipping costs to the buyer. This wheel would include the following items.

New, complete Zongshen hub, including all bearings and seals
New, alloy, Warp9 rim (black, blue, orange, red, or silver)
New, custom, 21-inch, stainless steel spokes
New, stainless steel, spoke nipples

Actual shipping and packaging costs usually average around $45.

If anyone is interested, let me know, and I will research the matter further.

[SpudRider]

I went for another ride yesterday. I have now ridden about 300 miles on the new, 21-inch front wheel. Both brakes work great, and I have ridden over some sloppy fire roads where I would never have ventured with the Shinko 244 tires.

I adjusted my SpeedoDRD for accuracy. My previous setting was -11.1 percent. With the 21-inch wheel, the new setting is -3.1 percent. Therefore, the speedometer is pretty accurate with the 21-inch wheel, minus the SpeedoDRD.

Here are a few photographs from yesterday's ride.

[SpudRider]

I trimmed the lower fork guards (chevrons) a little to provide more clearance for the Shock Sox, and everything fits well. I might lower the Shock Sox a little bit, but they are doing a good job keeping the fork tubes clean in the current position.