Front wheel 18" or 19"

I have a alloy D.I.D rear wheel and want a matching alloy front. Lots of people telling me to ditch the 19" and go with a 18". Big differance in handling. any noticable differance..

Yes to the big difference in handling...

If this is on a Z1, don't do it.

You'll change the effective steering geometry and cause the bike to be unstable at speed.

Kawasaki actually did this on the 1978 Z1R and that bike was notoriously bad handling - the 1980 Z1R went back to a 19" front.

Jeff:what caused the handling issue,what about runnin 17s on front and rear ?:blink:

are you using stock forks and brakes

My 2 cents: The 18" will somewhat quicken a notoriously slow steering bike. This has been done ad infinitum - ad nausium by using the 18" (afore mentioned) Z1R front wheel. The Z1R wheel is a mag, if you're going spoke you'll need to source the appropriate rim and have it laced to your hub. Racers have done it on drag strip, road racing, and street bikes.
Z1R instability may have been caused by the front fairing as it was fork mounted and directed wind-forces directly to the steering head; to wit: the 80 Z1R wasn't much more stable than the '78 and occassionaly a '78 was a decent handler at any rate. I've had two '78s, one was totally evil and NEVER felt planted and my keeper has always felt really good.
More evidence that the quarter fairings caused instability is that Japanese teams that raced (and currently race today) the Z1R have mounted the fairing to the frame; also, anyone who ever raced quarter-faired bikes back-in-the-day did so by either removing the fairing all together (ala ELR S1) or frame mounted the fairings (Cooley reps) solidly thereby eliminating the effects of wind-force on the front steering.
I have never heard anyone who converted a Z1 to an 18" front complain about handling; I have known a guy for over 25 years who has been running an 18" spoke on the front (and back, for that matter) of his '77 KZ1000 and it's got a hard hitting 1105cc motor. He put the 18" on in 1989.
If you want Dan's number or email address, drop me a line and I'll connect you guys.

I'm not trying to piss anyone off; but I'm about as certain as I can be that if you go to an 18" front and experience anything except positive results, it's not the wheel's fault.

-KR

i have a 18" front and 18" rear both are made by dymag i beleave, and i can say steering is a litle faster on my kz1000r i noticed it straight away 18 years ago when i did the mod.

bike in question in signature.

If other changes are made to the bike at the same time, the handling MAY be OK - I stress may...

I've had a couple of Z1's with 18" fronts and the bike is certainly less steady at speed - noticeably skittish.

If the rear is lowered a corresponding amount, there shouldn't be the instability issue. Any changes to the wheelbase (long swing arm), different length shocks, even different handlebars impact how the bike performs at speed. The Z1 isn't a slow steering bike - it's really a fairly neutral to light handling bike at speed.

The later KZ's had a mix of chassis configurations - some handled better than others. The 1978 Z1R was the worst handling of the bunch.

handerling is a very subjective mater.
wouldn't call any of the z range quick steering bikes compeared to modern race reps. would run rings round any z with a rs250.
just bear in mind that any change will alter how the bike reacts, its up to you to decide if that chage feels better for you.
you can allways fit a steering damper to stop the shakes.

Jeff.Saunders wrote:

If other changes are made to the bike at the same time, the handling MAY be OK - I stress may...

I've had a couple of Z1's with 18" fronts and the bike is certainly less steady at speed - noticeably skittish.

yeah jeffs right back when i live in Essex i could open the old girl up and i remember a bit of a tank slap at full speed round the motorway's like the m25.
hence 2 steering dampers.
i did lower the rear the same as the front though when wheels went on.
but here on this tiny island 45 is max speed limit so i really don't have this issue anymore.

I replaced the stock rims on my '73 Z1-900 with wider DID 19" and 18" rims and SS spokes years ago -- I added a number of frame strengthening improvements at the same time as well. All of this helped the bike's handling nicely.

Then in 2006 I upgraded the rims to even wider 17" Excel rims with SS spokes and Avon radial tires. I really like the handling even more now. The bike is much more planted at speed.

BohicaBob: your bike is a thing of beauty! Nicely done.
-KR

Thanks. I've owned it since 1974 and I am still interested in making improvements.