Pushing skills and bike to the limit: Wobble turning at high speeds

[jogirob]

Hello all,
This last memorial day weekend I popped my group ADV ride cherry. These guys were leagues beyond my abilities on BMW's and KTM's but I managed to go places I would have never tried on my own. Going over gravel, ruts, rocks, up and downhill the RX3 with stock road biased tires helped me survive the day unscathed except for a few rattled nerves. If not for my expert rider training(on paved) I would've definitely wiped out though.
One thing I noticed about the RX3 is that I get a wobble on steady high speed turns (55-65ish) is this normal?

As a side note, be careful when group riding. Group riding pressure will get to you. Take it easy and ride within your abilities.

[2LZ]

Originally Posted by jogirob

Hello all,
This last memorial day weekend I popped my group ADV ride cherry. These guys were leagues beyond my abilities on BMW's and KTM's but I managed to go places I would have never tried on my own. Going over gravel, ruts, rocks, up and downhill the RX3 with stock road biased tires helped me survive the day unscathed except for a few rattled nerves. If not for my expert rider training(on paved) I would've definitely wiped out though.
One thing I noticed about the RX3 is that I get a wobble on steady high speed turns (55-65ish) is this normal?

As a side note, be careful when group riding. Group riding pressure will get to you. Take it easy and ride within your abilities.

Glad to hear it all went well and you had a great time.
From another Sac area guy, where did you go?

I've not had any wobble issues on either of my RX3's....not that I push them real hard but I have done corners at those speeds.

[Jay In Milpitas]

I used mine mostly for commuting until last month with half the trip being freeway, and I had a wobble one time, but that was corrected when I brought the tire pressure back up to where it should be. I was lax in checking it for a while and it had dropped to about 28 psi on the front.

I have occasionally had a *weave* start at speeds above 65 which is instantly resolved by getting my elbows out and relaxing my grip on the bars, rider induced "wobble".

[jogirob]

Originally Posted by 2LZ

Glad to hear it all went well and you had a great time.
From another Sac area guy, where did you go?

I've not had any wobble issues on either of my RX3's....not that I push them real hard but I have done corners at those speeds.

Here you go: https://ridewithgps.com/routes/18773508 It's a good route because it avoids freeways. There are a few 65mph sections. Lots of twisties, and blind curves. My favorite spot has been Latrobe Rd near Deer Creek Preserve. I was thinking about redoing this route on my own terms at a lax pace so I can enjoy it better.

[pete]

hell whats all that green area? on the map..
roads/tracks everywhere.... yer never get me out of the place
if I lived near it....

and I know what yer mean about group rides... you seem to
end up riding some ealse ride...


..

[2LZ]

Originally Posted by jogirob

Here you go: https://ridewithgps.com/routes/18773508 It's a good route because it avoids freeways. There are a few 65mph sections. Lots of twisties, and blind curves. My favorite spot has been Latrobe Rd near Deer Creek Preserve. I was thinking about redoing this route on my own terms at a lax pace so I can enjoy it better.

Ha ha! You were in my neck of the wood when you hit Fiddletown. I ride that area all the time. It's my backyard.

I know what you mean about Latrobe. When I worked at Hazel and 50, I'd take Latrobe twice a day. It was a ton of fun. I called it "The Latrobe Road Course and Grand Prix Challenge".

Your explanation is why I basically quit group riding. Now I just ride with Mrs. 2LZ. Not only was it usually a pace I didn't like but generally half the pack had riding habits I had to watch out for all day.

[jogirob]

I would guess the green stuff means forestry. Speaking of green stuff I just remembered that I'm using Slime in my tubes. I'm pretty sure that's what's causing an imbalance that's multiplied when I'm leaned over.

I heart Latrobe Rd. There are a few shaded spots with trees where I can have a picnic under and not be bothered by a single soul. It's sad that that's where adventuring has whittled down too with everything being fenced off and private property...around here at least.

What I wouldn't give to date a girl that ADV rides. I've tried getting this Rosie girl to marry me but she won't respond to my YouTube comments lol https://www.youtube.com/channel/UCgE...9muwYabeOaF3OA

[AdventureDad]

Rosie would be a great catch! [ATTACH]at 11:30[/ATTACH]

[sqwert]

RX3 originally had a 15-inch rear wheel. CSC did us a favor and went to 17. I expect 18 was always front, so 17 upgrade tipped the forks a little steeper. Benefit is quicker handling. Compromise is quicker handling beyond capabilities of some riders at high speed. Go to 19-inch front wheel to mod steering geometry to give up a little quick handling for inline stability at speed. Not really a design failure, but a well thought through choice leaning toward dualsport and rougher adventure type riding. It is all about choices. My RX3 is getting a 19, probably a 4.00 to increase height if rim wide enough and enough space between forks. The old school universal tread like on my XR750 collector bike will suit my rides. Available treads range from ribs to hard terrain knobbies. Rims not wide enough but room between forks aluminum rim will go on. No problem, just need time to get it all done.

[Juanro]

Originally Posted by sqwert

...so 17 upgrade tipped the forks a little steeper...

Outer diameter of the 130/90/15 is about the same of the 130/70/17, perhaphs a couple milimeters of diference. I don't think rear tyre size change made a difference in bike's handling.
On the other hand, a couple members here myself included had in fact changed tyre size, either back with a higher profile, or the front, I have a 19', Spud a 21', and I don't think I noted that much of a change in handling either.
The RX3 was always surpisingly stable, not only for a bike relatively tall, but even in absolute terms.

[vickytulla]

I was facing heavy wobble right after i put heavy offroad tires in my Rx3... bike will dive into wobble asa i go above 60mph...

so quick fix was to put front stock tire back and bike is fully stable again...

[2LZ]

I have the stock tires and when I get out on HWY 88 by our house, the traffic is RIPPIN' coming down the hill from Tahoe on a Sunday. 75 was a bit unnerving weaving that fast on a twisty two lane mountain highway, but it beat getting run over. I just have to remind myself, "It's just a 250". If I want to hold 75 all day, I'll take the heavy bike. I try to keep the RX3 on the back roads.....under 70. Very comfy and stable then.

[sqwert]

Originally Posted by Juanro

Outer diameter of the 130/90/15 is about the same of the 130/70/17, perhaphs a couple milimeters of diference. I don't think rear tyre size change made a difference in bike's handling.
On the other hand, a couple members here myself included had in fact changed tyre size, either back with a higher profile, or the front, I have a 19', Spud a 21', and I don't think I noted that much of a change in handling either.
The RX3 was always surpisingly stable, not only for a bike relatively tall, but even in absolute terms.

Yes, it would be very difficult to equal the RX3's handling potential, even stock, for the same investment in any other bike. When everything is right, it is a very comfortable bike for buzzing the back roads at somewhat sporty velocities. Perhaps a little short suspended for rough offroad, but that isn't why I bought it. I have other bikes more suited to that type of riding. Also, the seat sucks, but the accessory seat is significantly better.

All else being the same, rolling radius of a 130/90-15 isn't much less than a 130/70-17. However, when people change rims, they also usually change tire brands, types, models, etc. It's all those other changes that affect rolling radius that very few riders ever take into account. For instance, I've seen dozens of posts advocating narrower but taller rims and tires for improved handling, but virtually every one includes a significantly more aggressive tread pattern, so how can size differences be tested if other significant factors are not controlled? Very bad science. All else must be the same for a comparison to be valid.

Anywho, I've dealt with several RX3s that had high speed handling issues. A few just needed the tires properly inflated. A couple needed a bit of tightening of the triple tree. A couple needed both. All had stock 17/18 wheels except mine, which is fitted with a 19 on the front. Only a couple still had the OEM tires as several OEM tires were ruined prematurely from bad brake rotors. Mine suffered all three problems. Shame on me.

Replacement tires ranged from classic trials, universal, and rib treads to modern sport, touring, adventure, and knobbies. Tires were NEVER an issue unless worn spots from bad brakes or improperly inflated. What I did learn was the more aggressive the tread, the pickier the front end was about inflation when it came to hard surface/highway riding at speed. A few pounds of rear tire pressure didn't seem to make any difference. Therefore, I'd have to recommend first, check air pressure, second check triple tree tightness, then check tires for uneven wear from warped rotors.

Speaking of 19-inch fronts, I can't find any adventure tires (similar to stock) in 110/90-19. Lots of cruiser and rear knobby treads, but very little in the middle. I'm thinking of Duro's 4.00-19 trials or universal treads (OEM on Urals, so should stay available a while), 6-plies that should easily handle any load tossed on an RX3.

Not much available cheap (I go through lots of tires) in 130/70-17 other than cruiser treads. Tons of good choices in 130/80-17, though. No need to worry about messing with geometry with an 80 cross section rear with a 4.00-19 front, there will be plenty of rake for stability.

130/90-17 sees the Kenda K760 Trak Master II, one of the best ever DOT legal full knobbies that won't get you a ticket from some nasty ol' cop--says "DOT" right on the sidewall. 130 tires are about 5 inches wide, so that 20% difference in cross section will add an inch or so to the rolling radius over stock. Then, knobs are a lot thicker than stock treads, and I have no idea how much difference that will add. A matching front tire on a 19-inch rim would likely make a good companion. Same tire is available in 110/90-19 that might fit between the front forks, and 100/90-19 that will fit for sure, but it is a rear tread pattern that will probably wobble at speed on pavement without the weight of your hand on the bar (doesn't take much).

I've run the K760 rears on the front of other bikes and they never let me down off road. Amazing low traction performance on either end, just don't expect super straight line stability on hard surfaces. Just ignore the wiggles at speed and enjoy the glue in the mud, sand, and snow. Do not grab a hand full of brakes with someone following close behind. A fat K760 on the front makes grown men hitting the brakes in mud, sand, or gravel giggle like little girls. They are that good on the front offroad. If I ever take a RX3 on boonie rides, I'll have the K760s on both ends. I won't even consider any other tires. They are that good off road, and I've run 84mph with them on pavement, they were well behaved, and I still live! When the RX4 is available I'll get one off the first container, and K760s will go on my current RX3, no question.

The Pirelli MT21 is available in 130/90-17, if you want a top-of-the-line European tire with better street manners than the K760. Unfortunately, there is no appropriate size available to match the odd tread pattern on the front. Still a great tire, though.

The Shinko 705 (what I'm running now on the rear) is an adventure tread tire and works pretty well. It is nowhere near the K760 or MT-21 in the dirt, though, but is a very nice tire for paved and dirt roads. If I only rode pavement, I'd shop for real street tires, probably on the sporty side because I tend to go a little faster than legal on back roads.

Hope that helps with your next tire shopping experience.