19" to 18"?

Technical articles, tips, tricks and advice from the experts (and there are plenty of you!) on jetting, suspension, riding techniques, muffler bearings, powerband installation or anything dirt.

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LC4CARL
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19" to 18"?

Postby LC4CARL » Tue Apr 28, 2015 3:21 pm

Racing a motocross bike in GP's. Occasional woods riding and even more occasional MX riding.

Thinking about putting a smaller hoop on the rear wheel. Wondering if it's worth the cost: Does one notice better bump absorption with the resultant increase in speed potential? Is there improved traction from greater potential tread to obstacle conformity? Is there a down side for this application? Other?

Thx.
2015 GP 250AM 3rd, 2014 GP 250AM 2nd, 2012 GP 40AM 7th

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dlharte
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Re: 19" to 18"?

Postby dlharte » Tue Apr 28, 2015 7:08 pm

There are reasons most Enduro guys run 18" and they are standard on non MX targeted off road scooters.

But for me with Max's bike it's not worth making the switch. We do run mousses so flats are not a problem and running old mousses gives really good traction at more technical events. If I had to run tubes I would probably lace up a 18" hoop.

19's are lighter an turn better according to people sensitive enough to feel that kind of thing.

If you can get away with running 12 psi without getting flats I would say keep running the 19. If you taco a rim then replace with 18".
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edgy
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Re: 19" to 18"?

Postby edgy » Wed Apr 29, 2015 12:05 pm

From my recent experience with my Yz... Going to an 18" with a radial TT and a uhd tube, the motor spins up slower and has more flywheel effect torque which is what I want for the riding I do. May just feels like the motor is smoother because the tire bites versus spins though. For technical Tsf it's a great set up, GP's on a 250 4t is another matter I would think.

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Naeve44
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Re: 19" to 18"?

Postby Naeve44 » Thu Apr 30, 2015 9:19 am

I'm having the same ordeal. I've had a 18 for 6yrs and now I have a 19 on my rm250. In 3 rides I e had 2 flats and I run around 12 psi and my 18's I never had a problem with flags. Could be bad luck I don't know. But I did order a 18 and will be lacing it up this weekend. Also finding a 19 tube at a race very hard in Ktm country lol.
2015 KTM 350xcf
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2003 RM 250 10e
1999 Honda Valkyrie

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LC4CARL
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Re: 19" to 18"?

Postby LC4CARL » Fri May 01, 2015 2:23 pm

Interesting. I've been running 13 psi (according to my super accurate pen gauge) with good luck. Perhaps when I wear out my 19" I'll try an 18". Of course a larger fuel tank or Rekluse clutch would be nice...
2015 GP 250AM 3rd, 2014 GP 250AM 2nd, 2012 GP 40AM 7th

Luke
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Re: 19" to 18"?

Postby Luke » Fri May 01, 2015 4:23 pm

I switched from 19 to 18 on my YZ. For the woods it's nice, since I like to run really low pressure (8psi) For track (and track like) riding I can't tell the difference.

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Naeve44
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Re: 19" to 18"?

Postby Naeve44 » Sat May 09, 2015 7:22 pm

http://www.thumpertalk.com/index.php?/t ... m-today%3F
See if I did the link right?
I laced up my 18 and put some case covers on.
Didn't work that good. It's on the last page.
2015 KTM 350xcf
2008 RM 250 44U
2003 RM 250 10e
1999 Honda Valkyrie

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LC4CARL
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Re: 19" to 18"?

Postby LC4CARL » Wed Jun 10, 2015 4:15 pm

That looks sweet!
2015 GP 250AM 3rd, 2014 GP 250AM 2nd, 2012 GP 40AM 7th


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