Zongshen RX3: 21-inch Front Wheel
 

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.

http://i442.photobucket.com/albums/q...psvo4m1kua.jpg

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.

http://i442.photobucket.com/albums/q...ps4c1eozxn.jpg

http://i442.photobucket.com/albums/q...psd2im6gdo.jpg

http://i442.photobucket.com/albums/q...psrljtl749.jpg

http://i442.photobucket.com/albums/q...psgowwxy5n.jpg

http://i442.photobucket.com/albums/q...psykko0xnx.jpg

http://i442.photobucket.com/albums/q...ps6yqijuwr.jpg

http://i442.photobucket.com/albums/q...pse6xnejpd.jpg

http://i442.photobucket.com/albums/q...pshmgfbtnu.jpg

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.

http://i442.photobucket.com/albums/q...psnmbln2zm.jpg

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. :tup: 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. :tup: 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. ;)

http://i442.photobucket.com/albums/q...pssmmskhzc.jpg

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. ;)

http://i442.photobucket.com/albums/q...psoqk1rkrh.jpg

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

http://i442.photobucket.com/albums/q...psavpv45el.jpg

https://www.youtube.com/watch?v=2cl_cVlimB0

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

http://i442.photobucket.com/albums/q...pswmdckj0n.jpg

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. :tup: My previous, Shinko 244 tires perform poorly in very muddy conditions, so the new tires are a welcome improvement. ;)

http://i442.photobucket.com/albums/q...psjrnv1jho.jpg

http://i442.photobucket.com/albums/q...psssgtbq2i.jpg

http://i442.photobucket.com/albums/q...ps4prh2dja.jpg

http://i442.photobucket.com/albums/q...pstabphlej.jpg

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.

http://i442.photobucket.com/albums/q...psrc7w6ukr.jpg

http://i442.photobucket.com/albums/q...ps26ozjsvg.jpg

http://i442.photobucket.com/albums/q...pshkc6sx7d.jpg

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

http://i442.photobucket.com/albums/q...psfjmzgc0f.jpg

http://i442.photobucket.com/albums/q...psc0cdhkwm.jpg

http://i442.photobucket.com/albums/q...psilityebl.jpg

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

http://i442.photobucket.com/albums/q...chWheel025.jpg

did yer lose much braking with the bigger wheel..



...

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.

http://i442.photobucket.com/albums/q...pscawvt1lf.jpg

Great to see more posts again, Spud!

And well done on the front wheel upgrade! :clap: 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. :tup:

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.

http://i442.photobucket.com/albums/q...psvjaruffi.jpg

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.

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

Ditto!

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.

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.

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.

http://i442.photobucket.com/albums/q...pszk5asizh.jpg

http://i442.photobucket.com/albums/q...pszennbdcv.jpg

http://i442.photobucket.com/albums/q...pspsiss94p.jpg

http://i442.photobucket.com/albums/q...psh4hfipoi.jpg

http://i442.photobucket.com/albums/q...ps1shtmnmm.jpg

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. :tup:

http://i442.photobucket.com/albums/q...pso3a0c9q9.jpg

When you wash your bike, you should remove the Shock Sox, and clean them separately. After the Shock Sox dry, you can re-install them on the fork tubes. Removing the Shock Sox requires you to remove the lower fork guards (chevrons). ;)

https://www.youtube.com/watch?v=2cl_cVlimB0

That looks good, Spud. Nicely done and a great report.

Joe, can you confirm if the TT wheel will swap to the RX?

The CSC tutorial for changing the front tire of the TT250 is located at the following link.

https://www.cscmotorcycles.com/Articles.asp?ID=292

Looking at the photographs, the front wheel of the TT250 appears to be the same as the front wheel of my Zongshen ZS200GY-2. If so, the brake rotor is different. Also, the right side of the hub, which connects to the speedometer drive gear, is also different.

https://www.cscmotorcycles.com/v/vsp...ontWheel11.jpg

https://www.cscmotorcycles.com/v/vsp...ontWheel10.jpg

I would be remiss if I did not mention the CSC Cyclone RX3 has retained the original wheel geometry with the stock tires. CSC made certain the size 130/70-17, C6017 tire installed on the Cyclone RX3 was actually a little smaller in diameter than the original, 15-inch rear tire. :tup: Measuring the stock tires delivered with my CSC Cyclone RX3, I see the front tire is about 1-inch larger in diameter than the rear tire.

I introduced an imbalance in the wheel geometry when I installed a knobby tire with a more aggressive tread on the rear wheel of my RX3. In general, knobby tires are larger in diameter than the stock tires. For example, the size 5.10-17, Shinko, 244 rear tire has a diameter of 25.63 inches, as specified at the Shinko website.

http://www.shinkotireusa.com/tire/244-series

However, if you examine the Shinko 244 tires which will commonly be chosen for the 18-inch front wheel, they have the following diameters.

Shinko 244 Tires

Size 3.00-18 Tire: Diameter = 24.69 inches
Size 3.50-18 Tire: Diameter = 25.55 inches
Size 4.10-18 Tire: Diameter = 25.16 inches

All of these tires are actually smaller in diameter than the size 5.10-17, rear tire. In fact, the size 3.00-18 tire is almost one inch shorter. Given the knobby tires I prefer to mount, it's easy to introduce an imbalance in the original wheel geometry.

In contrast, here are the diameters of the tires I have currently mounted with the 21-inch front wheel.

Michelin T63 Rear Tire (Size 130/80-17): Diameter = 26.14 inches

https://www.denniskirk.com/michelin/...prd/643293.sku

Cheng Shin C858 Front Tire (Size 2.75-21): Diameter = 27.4 inches

http://www.csttires.com/int/moto/dual-spor/c858/

In this case, the front tire is approximately 1.25 inches larger in diameter than the rear tire, which allows me to re-establish the original wheel geometry supplied by Zongshen and CSC.

Based upon your tire preferences, and whether you have a 19-inch front wheel, you might not have any changes in wheel geometry. However, given my tire preferences, I can retain the original wheel geometry with a wider selection of tires after switching to the 21-inch front wheel. ;)

Thank you, Joe.

I went for a ride yesterday on an unimproved road which can become a quagmire in the rainy season. I could not have completed this ride with the Shinko 244 tires. Here are some photographs from two muddy sections of the road.

http://i442.photobucket.com/albums/q...psyk8d4njv.jpg

http://i442.photobucket.com/albums/q...psxhgyrqwg.jpg

http://i442.photobucket.com/albums/q...psydesfmey.jpg

http://i442.photobucket.com/albums/q...psbnupfjhd.jpg

http://i442.photobucket.com/albums/q...pswl4chijo.jpg

http://i442.photobucket.com/albums/q...psxgf6gqwd.jpg

http://i442.photobucket.com/albums/q...psap6sxubj.jpg

http://i442.photobucket.com/albums/q...pst9pbtn1j.jpg

After riding through the sloppy areas, these tires shed the mud very well.

http://i442.photobucket.com/albums/q...psu7nav6xv.jpg

http://i442.photobucket.com/albums/q...psow7zzmhe.jpg

http://i442.photobucket.com/albums/q...pstznm0qi9.jpg

http://i442.photobucket.com/albums/q...psnwdprktn.jpg

The Shock Sox do a good job keeping the fork tubes clean.

http://i442.photobucket.com/albums/q...psv8b0p0t4.jpg

Here a several photographs taken after I was heading home on the pavement.

http://i442.photobucket.com/albums/q...psm5qgwxpo.jpg

http://i442.photobucket.com/albums/q...ps5n3cxalv.jpg

Nice thanks for the pics. Makes me want to take a ride.

Nice to see you in action, Spud!!! :-)

I hate that pasty type glue-mud. Every tire is a slick in one revolution.

Great to see your pics again Spud!...and wow.....those tires do seem to shed mud very quickly.

Brave man, I think would been bypassing in the weeds. Looks like fun.

Lookin' good, Spud! And I agree - brave man! I would not ride through that mud unless I absolutely had to. I won't take a mud bath even at a spa! (not that I've been to such a spa...but I digress.) :hehe:

BTW, does the center stand work with the 21" wheel? Or are both wheels now touching the ground?

I did bypass the mud, where possible. ;) However, the elevated, rough terrain by the side of the road sometimes makes it mandatory to traverse the mud. I frequently ride over muddy roads in the spring and fall, so I have a pretty good idea when I can trust the tires, and when I cannot. ;)

The center stand works with the 21-inch front wheel, but you must place a board beneath the two legs of the center stand. If you do this, the center stand still lofts the rear wheel, and performs the same as it did with the 18-inch front wheel. I am going to weld two steel pads to the legs of the center stand.

Thank you, gentlemen.

Indeed, the "greasy" mud is the worst. If you drop the bike, you can't even stand, so you must kneel in the mud to wrestle the bike back up on two wheels. :wtf:

Here are a few photographs from today's ride. I am very much continuing to enjoy the 21-inch front wheel. :tup:

http://i442.photobucket.com/albums/q...pskqdi6qzb.jpg

http://i442.photobucket.com/albums/q...psdoixn4gu.jpg

http://i442.photobucket.com/albums/q...psymbllfrg.jpg

It's unfortunate the C858 tires are no longer sold in the United States. Fortunately, I stocked up on them for about $27/tire as the inventory was disappearing. ;) The C858 tire tread is aggressive enough to handle very muddy terrain, yet the tread doesn't reduce your cruising speed on the highways. Here are some more photographs from my last several days of riding.

http://i442.photobucket.com/albums/q...psfjzhcyxd.jpg

http://i442.photobucket.com/albums/q...psupxxtgnb.jpg

http://i442.photobucket.com/albums/q...psyhdr3ggy.jpg

http://i442.photobucket.com/albums/q...pseumlithf.jpg

http://i442.photobucket.com/albums/q...psgz1zlowp.jpg

http://i442.photobucket.com/albums/q...psvzvnjwth.jpg

http://i442.photobucket.com/albums/q...psvfitdkbk.jpg

After my stock of C858 tires is depleted, I would like to try the IRC, TR8 front tire, in size 3.00-21.

http://www.irc-tire.com/en/mc/produc...l/tr8/tire.jpg

http://www.irc-tire.com/en/mc/products/dual/tr8/

I have mounted the following front tires on several of my motorcycles, and they also perform very well.

Shinko 524: size 80/100-21

http://shinkotireusa.s3.amazonaws.co...5-soft-int.jpg

http://www.shinkotireusa.com/tire/524-525-series

Shinko 520: size 80/100-21

http://shinkotireusa.s3.amazonaws.co...es/520-int.jpg

http://www.shinkotireusa.com/tire/520

CST Surge I (C7209): size 80/100-21

http://www.csttires.com/int/wp-conte..._F-211x592.png

http://www.csttires.com/int/moto/off...c7209-surge-i/

Spud,

What did you use for spokes? After my ride a few weeks ago I want to get a little more ground clearance and the 21" swap sounds like the ticket.

I ordered custom spokes from Buchanan's Spoke & Rim.

http://www.buchananspokes.com/catego...spoke_sets.asp

After the 21-inch, custom spokes arrived, I disassembled the front wheel. Then I laced a size 1.60-21, Warp9 rim to the front hub with the custom spokes. I trued the wheel with my Park Tool, TS-7M truing stand.

http://www.parktoolmotorcycle.com/as.../TS-7M_002.jpg

I continue to enjoy riding with the 21-inch front wheel. Here are a few photographs from my last two rides.

http://i442.photobucket.com/albums/q...pslhdrwapu.jpg

http://i442.photobucket.com/albums/q...pslvyum59a.jpg

http://i442.photobucket.com/albums/q...psskhnkciq.jpg

http://i442.photobucket.com/albums/q...psvbhslc1t.jpg

http://i442.photobucket.com/albums/q...pshbxcemda.jpg

http://i442.photobucket.com/albums/q...psuurfynqr.jpg

I'm glad that 21" is working out for you as hoped, Spud!...and truth be told, visually it looks really neat on the RX3. If I did much more dirt, I'd like this upgrade. 90% of my riding is paved twisties and I've found the stock rim along with the stock tire is a very capable combo in our situation.....but not near as cool looking! ;-)

great work. i also want to raise my bikes height. can you please tell me how did u raise ur rear shock ? and how much did it rise?

Thanks