extended swing arm and fat tire

[alexhawaii20]

want to possibly buy some swing arm extenders, and was wondering if anyone has done this. my purpose is to possibly fit a bigger rim and tire. its my wife's bike but i love to ride the 250r, they're so much of fun. so the only reason i am doing this is for fun, a project i guess.
i don't want to extend it much. just want maybe 3 inches, and try to get a 160 tire ? btw i have a 2010 ninja 250r 2010 ninja 250r

and please remember this is my wife's bike so performance is not an issue, just want it to look cool with a fat tire. so please don't go off subject telling me this is wrong and serves no purpose . if i want more speed or performance i will simply just ride my 600cc, just doing this for fun.

btw i still ride my wife's 250r all the time even thought i have a 600. the 250r is an amazing bike

[Somchai]

Welcome Alex

To answer your question, for a 160 tire there normally is no need to extend the swing arm, but you would need a 4.5 inch rim for the 160 tire.
By the way some guys put the 160 on a 4.0 inch rim also.
The 300 is using a 4.0 inch rear rim, so this could help.
Only take care about the chain not to touch the tire.
In the Land of Smiles the guys put a 180 with a 5.5 inch rim at the rear without changing the swing arm (they use the standard swing arm).
Good luck

[ninjamunky85]

V-Rossi makes a wide rear wheel for the ninja250. Might help if you speak Indonesian. https://www.facebook.com/V-Rossi-1473225729557056/

[adouglas]

This is wrong and serves no purpose.

[SLOWn60]

Beauty is in the eye of the beholder, Alex. No judgement from me.

I'm not saying it's wrong what you want to do. You say how much fun it is to ride your wife's bike as is. Here are some facts to consider that the longer swing arm and fat tire will change:

Both the longer swing arm and the fat tire will raise the rear geometry significantly. This will decrease the rake & trail geometry of the front end. It may not make it outright dangerous but it will make the front end want to turn in and tend to tuck much faster than it does now. A fat rear tire resists turning more than a narrower profile. You add these geometry changes together and you have a completely different animal than you have currently!

You say it's your wife's bike so performance is not an issue and perhaps she never rides it in a way that would reveal performance issues. That may be true but be aware you are creating a potentially much more closer to dangerous machine for her to ride if you do make those changes.

Cool can be fun too but you may find the fun you get on it now may not be as much fun after the changes.

[accumack]

Do it to your bike and let your wife have fun on her's.

[thisisbenji]

Originally Posted by alexhawaii20

and please remember this is my wife's bike so performance is not an issue, just want it to look cool with a fat tire. so please don't go off subject telling me this is wrong and serves no purpose . if i want more speed or performance i will simply just ride my 600cc, just doing this for fun.

This sounds incredibly sexist, just saying.

[Motofool]

Originally Posted by alexhawaii20

want to possibly buy some swing arm extenders, and was wondering if anyone has done this.........

I have not done it, but I may be able to help you with some mechanical suggestions.

Do you have any extending kit that is available in your area?

Do you plan on replacing the rear wheel?



[IMG][/IMG]

[csmith12]

Welcome Alex!

I have no opinion on the swingarm aside of it's your $$$ spend it as you see fit and farkles need not have any purpose other than to bring a smile. Have you considered a 150 rear tire? Some members here have installed them with success on the stock bits.

[choneofakind]

Originally Posted by SLOWn60

Both the longer swing arm and the fat tire will raise the rear geometry significantly. This will decrease the rake & trail geometry of the front end. It may not make it outright dangerous but it will make the front end want to turn in and tend to tuck much faster than it does now. A fat rear tire resists turning more than a narrower profile. You add these geometry changes together and you have a completely different animal than you have currently!

You say it's your wife's bike so performance is not an issue and perhaps she never rides it in a way that would reveal performance issues. That may be true but be aware you are creating a potentially much more closer to dangerous machine for her to ride if you do make those changes.

ehhhh I disagree with your statement that it will raise the tail and change the angle of the head tube. Can you explain your thoughts here?

[SLOWn60]

Will do later. Gotta drive about 6 hours then get loaded tonight for a track day tomorrow!

[thisisbenji]

Originally Posted by choneofakind

ehhhh I disagree with your statement that it will raise the tail and change the angle of the head tube. Can you explain your thoughts here?

It's because the swing arm to tail angle stays the same.

When you extend the swing arm the distance between the axel and the tail section increase.

You have to lower the bike and extend the swingers at the same time to maintain stock ride height.

[choneofakind]

Originally Posted by thisisbenji

It's because the swing arm to tail angle stays the same.

There it is. That's what I was waiting for someone to say. That's the assumption I disagree with. I just wanted to make sure that was the thought before I went all, "nuh uhhhhhh" on it and assumed I knew what he was thinking.

The angle won't stay the same. A sum of the moments about the swingarm pivots tells us that with a longer moment arm from lengthening the swingarm, the shock/linkage combination will have to provide more force than with a stock setup, given that the mounting point on the swingarm does not change. Since the only thing providing force in that direction is the spring on the shock and F_spring=k*x, where k is the spring rate and x is the distance the spring has been compressed, the only way for this to be true is to compress the spring more than with stock, therefore the assumption of a constant angle is not valid. Now, with the unitrak linkage and dogbones, I'm not sure how the force vs shock displacement curve looks, so it may not be the same linear relationship as lengthening the swingarm. That means it may be higher than stock, it may be lower than stock. I'd bet this new sag point is determined by how much longer the swingarm is than stock.

But from what I've read about stretching bikes, typically preload has to go up because the back end sags when you lengthen it. This makes the bike ride like a dump truck on stock shock compared with a shock that is valved and sprung for this application.

Even in possibility where the rear IS higher than stock, the ninjette has a long way to go before it becomes unstable. Look at how many racers loft the tail up in the air. Mine is 1.25" taller in back and 0.25" dropped in front. No stability issues even braking on the track. It does get a little light in the back and walks around if you're really on the brakes, but that's because you're on the brakes and shifting weight around and tipping in; it never flirts with unstable. Saying that lengthening the bike makes it more dangerous is silly IMHO. If anything, it will make the bike happier to go straight and it will take minimally more effort to throw around on curvy roads. But it will still be a 250 so it will still be a hoot and not take itself seriously.

[thisisbenji]

Maybe it depends on the bike?

The only bike is really know anything about stretching is my Honda Grom.

Mine isn't stretched, but a lot of my friends have stretched Groms.

I can assure you, that bike increases in height with just the stretch.

However, you had mentioned something about shock linkage.

The Grom has it's shocked mounted directly to the swingarm.

I believe the Ninja 250 uses some sort of dog bone system?

[choneofakind]

Yeah, it's a 4-bar linkage setup between 1) frame 2) dogbones 3) unitrak linkage 4) swingarm


maybe I'm wrong. That's a definite possibility and I'm willing to admit it as an option. but I've never heard of a 250 that's been extended and sitting higher than stock. In my mind, the angle should be different. Like I said above, whether that's higher or lower depends on the geometry of the linkages and the spring rate being linear vs progressive.

[Motofool]

Originally Posted by thisisbenji

.........
I believe the Ninja 250 uses some sort of dog bone system?

Chris is correct about the torque being higher as the wheel axle gets further from the pivot of the swingarm.
However, the load on the rear tire also decreases, as more weight goes onto the front contact patch.

It may get a little higher due to the natural angle of the swingarm and the increased profile of the bigger tire.
Adjusting any difference in height is what the regulation of the rear shock of the OP's 2010 Ninja is for, if so desired.

[Somchai]

Alex here's a link where you can see a 180 rear wheel with the oem swing arm http://www.ninja250thailand.com/boar...?topic=44218.0
The front fork looks like from the ER6.

[corksil]

Originally Posted by adouglas

This is wrong and serves no purpose.

listen to chris, hernan, chris, alex, mike, steve, and benji along with somchai.

Stupid hurts.

What bothers me most is that you're trying to hurt someone else instead of yourself.

[cbinker]

Putting a larger diameter tire will raise the bike. I still do not believe extending the swing arm will raise the bike significantly, unless your extending it out by 6 feet.

[InvisiBill]

A 150 should fit fine without any mods. A 160 may or may not fit, depending on the brand, sprocket changes, etc. You'll want a wider wheel to avoid pinching the wider tire (resulting in a distorted profile).

As others have said, extending the swingarm will affect how the suspension operates, and if it sits differently, the steering too. Plus it looks stupid. It's completely unnecessary for a 150 or 160, so don't bother.

I have a Pilot Power 150/60 on a VRossi wheel in a 250 swingarm on my 500.