OzVMX Forum

Clubroom => Tech Talk => Topic started by: D project on November 14, 2014, 01:07:50 pm

Title: 18 V 19 rear wheels?
Post by: D project on November 14, 2014, 01:07:50 pm

Another one of my questions that has been bugging me ::).
Whith dunlop not making their MX32 in an 18" rear is there any benefit in going from an 18" to 19" rear wheel? How does it affect gearing and suspension?

Title: Re: 18 V 19 rear wheels?
Post by: Nathan S on November 14, 2014, 01:26:06 pm

19s run a lower profile sidewall, which is meant to cancel out the bigger rim diameter: It shouldn't affect gearing.

I've not done controlled testing, but my general impression is that 19s reward well set-up suspension more, and punish poorly set-up suspension more.
I wouldn't consider running a 19" rear on a pre-78 bike, but if I was building new wheels for an Evo+ race bike, I'd go for the 19 every time.

Title: Re: 18 V 19 rear wheels?
Post by: John Orchard on November 14, 2014, 01:43:21 pm

My take on it is...  the 18's tend to be higher profile, having more spinning & reciprocating mass with their increased weight.  I prefer the extra cushioning effect of the higher sidewall.  I think tyre fitting is a touch more difficult with less flex from a lower profile sidewall.

If I was a fit Supercross rider I think the 19" would be an advantage but I'd rather have an 18 on everything I ride  :-)

Title: Re: 18 V 19 rear wheels?
Post by: JohnnyO on November 14, 2014, 02:45:11 pm

I prefer an 18" rear on Evo and earlier bikes for the extra 'suspension' in the higher profile tyre..
As has been said the gearing shouldn't change with the tyre OD being roughly the same

Title: Re: 18 V 19 rear wheels?
Post by: KTM47 on November 14, 2014, 04:29:49 pm

I have had a 19" rear wheel on my Maico for over three years now.  I think it is better.  Better choice of tyres etc.  Enduro riders prefer 18" for better puncture protection.

Lets face it Motocross bikes have been fitted with 19" standard for almost 25 years now.

I feel my bikes corners better and drives better out of the corners.  Yes it's a Maico and it is even better than it was. 

Title: Re: 18 V 19 rear wheels?
Post by: Brian Watson on November 15, 2014, 01:20:46 am

So..does the same go ..should you fit a 17" tyre  to a pre 75 bike..more "travel" with the extra sidewall..??..the limited choice of tyres is hard to argue.... I know i fitted  a pair of MX31's to my pre 75 HVA and was very impressed..great tyres..

Title: Re: 18 V 19 rear wheels?
Post by: evo550 on November 15, 2014, 11:58:07 am

19 inch tyres also reduce flex in the sidewall creating a more solid ride.
Going from a 17 inch to a 19 inch tyre with the same psi, the 17 inch feels like its half flat.