1.6 versus 1.85 Rim for front wheel

[tony27]

What effect would running a 1.85x21 rim have in place of a 1.60x21 on the front of my CZ?
I'm finally getting round to ditching the steel wheels & it's not that easy to get undrilled rims here in NZ, the local wheelbuilder has managed to find undrilled Akront rims but the front is 1.85 section rather than the normal 1.6.
Most new rims seem to come into the country drilled for disc brake hubs with 8mm diameter nipples which need re-angling to suit & oversize nipples used which adds quite a bit more to the cost of the wheel than getting a blank rim drilled to match the hub

[matcho mick]

just measured CZ spoke set from buchanans,nipples are 7mm anyway,so 8mm's no biggie,can't help with rim size,all my fronts are 1.60's too!,

[tony27]

The rear I got done last year was a rim from Torpedo7 which was drilled for 8mm nipples & larger nipples than in the buchanans kit were needed
I have the matching front rim which is 1.60 & it seems a pity to not use the stainless nipples that came in the kit

[matcho mick]

it's not like they're elle mcphersons' nipples mate,just get some bigger ones to suit topedo 7's rim??,problem solved?,

[Matador107]

Wish you'd broken that sentence up into two paragraphs, anyways Chivo's at Granville for responding in my opinion.

[Matador107]

Respoking, see what happens when women get involved!!!!!!

[Lozza]

What effect would running a 1.85x21 rim have in place of a 1.60x21 on the front of my CZ?
I'm finally getting round to ditching the steel wheels & it's not that easy to get undrilled rims here in NZ, the local wheelbuilder has managed to find undrilled Akront rims but the front is 1.85 section rather than the normal 1.6.
Most new rims seem to come into the country drilled for disc brake hubs with 8mm diameter nipples which need re-angling to suit & oversize nipples used which adds quite a bit more to the cost of the wheel than getting a blank rim drilled to match the hub

I'm not sure about a knobby tyre but a road tyre will have more a triangular section on a wider rim than a semi circular section on a narrower rim. The wider rim gives more side grip due to it being flatter, at the expense of side to side 'flickabilty' the narrower rim is the opposite. Again not sure if that transposes over to knobbies

[John Orchard]

Loz I don't know if you accidently said "wider" instead of 'narrower' but on either a road or knobby tyre, a wider rim will pull the beads apart causing a wider footprint when the bikes is vertical (causing weaving & tankslappers on a roadbike) and reduced footprint when cranked-over.

On dirtbikes the wider footprint gives more stability on sand as the tyre rides up higher 'on' the sand, rather than sinking in it.  A narrower rim will give more steering precision, unless you only ride in deep sand, stay with the 1.60 rim, 1.85 rims are for 125 rear wheels.

On a roadbike to make the tyre more 'triangular', to give more mid-corner grip (at full lean) you would use a narrower rim. Although at a point too narrow you lose side contact with the ground as the tyre is pulled in so far that you can't get to the edge of the tread.

On superbike rears back 10 years ago, they were making 190/50-17 size tyres for a 6" rim, the 6" rim flattened the contact patch when the bikes was vertical, causing atrocious handing (high speed weave, tankslappers & no side grip?, now the manufacturers are making 190/55-17's or 190/60-17 which are higher in the middle to make the shape more 'triangular', reducing the contact patch width when the bike is vertical, and increasing the contact patch size when cranked-over.

Having to wider contact patch when the bike is vertical allows the roads 'self steer' forces to have more effect on the bike because the contact patch is further away from the bikes centreline.

[Lozza]

I'll defer to your knowledge there John , all I know is a wider (up from 2.15 to 2.75in) on a bucket racer made the side grip just enormous, same going from 4.5 to 5.5in on RGV/RS 250's. It was a trade off even on the bucket it was noticeable going through say the flip flop at Oran Pk. Superbikes would be x100 on that I suppose

[Mick D]

I'll defer to your knowledge there John , all I know is a wider (up from 2.15 to 2.75in) on a bucket racer made the side grip just enormous, same going from 4.5 to 5.5in on RGV/RS 250's. It was a trade off even on the bucket it was noticeable going through say the flip flop at Oran Pk. Superbikes would be x100 on that I suppose

When I saw your original post Lozza, I concluded that the above was what you based your reply on.

The thing is Lozza on that case, the tyres they are using on buckets now are actually designed for the more modern machines and the inadequate outdated bucket rim sizes addressed by fitting buckets with wider rims. To get closer to the modern tyre fitting specs. unfortunately VM3? is the max width allowed on Buckets and the minimum advised by all tyre fitters and sellers.

FWIW, My education and opinion, completely agrees with John Orchards Knowledge and more than adequately explains the answers he has given to the original question. Which in actual fact was asked about a motocross application.