Tyres/Wheels/Chain width issues - Confused

[Surfdeneige]

I can't get my head round this business of changing the swinging arm and
rear wheel to accommodate a far wider tyre. From my reckoning surely the
wider you go the less true the line is from front to rear sprocket and that
there becomes a point where the chain/guard will rub on the tyre. If the
chain isn't straight then that must cause big problems? Need a good explanation.

[rickman CRR]

Off-set front sprockets keep the chain in line.
Recently seen a tuned Zed engined Harris running a 190 section sports tyre. The off-set front sprocket wasn't off set enough and the chain had "fluted" the tyre edge!

reasons for doing this? Allows you to use the modern tyre technology and arguably looks good.

Check out the link pages to Debben or Klasmo for examples of off-set front sprockets.

(Edited by rickman CRR at 1:00 pm on Sep. 29, 2006)

[Surfdeneige]

Thanks, good info. What do you think to offsetting front and rear sprockets by 10mm to fit a 140/150 rear tyre? I have a KZ650 with no mods, totally original and don't want to butcher i but really think it would look better with a wider tyre. I have measured and think I could just about get away with a 130 as it is. More advice would be welcome. Cheers, Ken.

[london calling]

Ken,to fit a 140 rear tyre you need at least a 3.00 inch rim and a 3.50 or 4.00 for a 150 for the tyre footprint to be correct.
I've seen a 150/70 on a 2.50 GPz/J3/R2 rear wheel and it ruined the handling and cornering of the bike so only fit a tyre that your rear wheel can use properly.
Remember that thinner tyres make the bike more manouverable and responsive to changes in direction.

[Rich]

Thinner tyres also sap less ponies!

[Pigford]

Changing wheel size is due to either:
1: Want bike to look better/modern/chunkier....
2: Better selection of tyres....

If "1" then you'll probably want to go big as practicable, so its time to get the credit card ready!!! Off-set drive sprox will be esential (as already stated see Debbens) and maybe swingarm mod, depending on how large.
If "2" you can get tyres such as BT45's which are pretty good and will out perform the bike/frame anyway!!!
Pay's yer money, takes yer choice.. have fun!

[Surfdeneige]

I have a 3" on the back with a 110/90/18 and it looks a bit sorry for its self. I take it you guys know the max a no mods tyre change would be? is it 130/90 or 80 or does it not really matter? Is it a bit tight for size?

I know you will think me mental but I think and old modded z would look great with a single sided swinging arm and a 300 section on the back. I could never do it to the bike I have but if I ever had the time and money I would love to trick and old z, anyway that aside confirmation of the above would be great.

[Iain marshall]

what like this

[Surfdeneige]

saw one just like that today with a 180 on the back at re henderson garage, nairn.

I mean like this http://www.harley-davidson-choppers.com/fat_tire_kit_harley_DYNAl.htm

[Padders]

Nice bike shame about the engine.

[Iain marshall]

Ian thought you liked the Gixer motor

[Padders]

In the right place yes but I think too many people dumped the old Zed and GS motors for gixer's and spolit a lot of the bikes. I would love an early Spondon or Martek big tube framed Gixer for the garage. But an Early Harris must hace the aircooled motor. I saw a Rickman a while ago n one of the mags with a GSXR engine and it just did not look right. I wish I had kept my old JMC framed gixer as I reackon I could have fitted a Zed engine in to it. Similar to the old Wakisaki bike.

Ian.

[Steve R]

Pigford,
Reason number 3 you have a lot of horse power and want to drag it!
I think Steve Debbens Bike looks stunning and he is using a wide tyre to handle the gee gees.
One day I will build a zed like that, but not out of my Z1A I love it to much as it is.

[hanskloss]

[quote]Quote: from Surfdeneige on 9:55 pm on Sep. 29, 2006
I have a 3" on the back with a 110/90/18 and it looks a bit sorry for its self.

3.0" must feel sorry at the rear, the stock front is 3.25 and rear 4.0, I have 4.10 oldfashioned TT100 (it'll be about 130size I believe) fitted with plenty of space to the chainguard

[Big John]

Right a question. Z900A4 fitted with Dresda box section swingarm, want spoked alloy rims, does anyone know how wide I can go on the back with said setup?