wheel sizes

Restoring my 74 850 & it has always had a 18 inch rear & a 19 inch front & I have thought this was how its meant to be but the manual tells me they are both 19s , My rear wheel looks correct so what could it be off or were some bikes like this as Ive had this bike for many years & travelled many miles like this..thanks bill

All the Commandos had 19 inch rims. 1.85 inches wide. A previous owner has had an 18 inch rim laced up.

The 18" rear rim was a very common upgrade, the tire selection was better in 18"

Unclviny

Unclviny said:

The 18" rear rim was a very common upgrade, the tire selection was better in 18"

Unclviny

Click to expand...

What he really meant is that the 18 inch conversion is a downgrade, or a "retrograde".

I've also seen a few 19" to 18" wheel conversions. Sometimes involving both front and rear wheels. However, I've never had the opportunity to ask about it. I'm wondering what changes in handling the rider would experience should his 19" wheels be replaced by 18" hoops. Assuming, of course, that everything else remains the same.

I've switched out 19" to 18" rear rim-tires and back in same day d/t flats. All on WM3 rim. Main notice was the more sure footed respomsive ease to steer on 19" but a tendency to trip out leans and power sooner than 18" 18" could hold a dash more hook up but took more pilot throttle and effort to reach that point on or off road.
My personal preference now is go pure factory for everything but all out racing and risking, then 18" comes into its own with meatier tires available at more cost.
Its like difference of moving around in a T-shirt vs a long sleeve dress shirt, not really much difference in what you can do in them, just the ease to do so factor.
Oh yeah 19" narrower tires wear center out faster than slightly wider 18" profiles any where from 500-1000 mile more depending on operators mood.
Of course to if both ends same size then just move fronts to rear and carry on with a longer mileage advantage of 19".

I have 18" rims front and rear on my 850. The bike steers and handles well. I think that because the bike sits about 1/2" lower there is a reduction in ground clearance. Really there is not enough ground clearance. It is pretty easy to grind the bike on sharp bumpy corners. Even on big speed bumps the bike grinds underneath. I would not change the front to an 18 again. I only did that because the wheel I used was free. I think changing the rear only may not be as bad because then width of the tire can also be increased which means there may be no loss of hieght depending on which tire is chosen.

Yes sir there is much to be said for increasing non foul lean angle. Lowering the rear does not decrease lean clearance nearly as much as lowering the front.
Unless modifying engine significantly and intentions to really press limits, 19" on both ends is more pleasant and fun to me. Going by some hints of road riders reports and my own findings, I'm reducing hot rod Peel front tire to 100/90x19".
I've got two rear wheels on hand for factory Combat Trixie, one 19" one 18". That way can ride again sooner for tire repair issues and use up any size tires I find bargains on. The main issue on same day switching, is on crossing my cattle grate drive way exit, for first real lean with power enough to climb slope onto Gravel road way, can't get quite as spunky on 19" 110 as can on 18" 120 before squealing to recover the over sight.

@Hobot: Is the cows that make 18" wheels a better choice, or are there other factors?

Ain't no best choice for everyone. 19" in the 100-110 width sizes. feel to me easier to steer just tooling around and a bit more precise to react to fork or throttle inputs, with corresponding slightly more twitchyness to road texture-undulations.

An !8" rear in 100-110 widths feels about like 19" sizes to me. Only going to 120 width 18" rear made my two Combat feel a bit more sluggish to whip around or throttle up. Main daily advantage of the 120 size is on THE Gravel, as it tends to hold more side loads before skipping out and I can run a bit less PSI to get softer ride with tire conforming over rocks better than 19" size with less internal volume. Wear is the other 120 advantage. But for pure Commando delight of bicycle ease and gliding along on big twin torque I like the smaller tires on 19" rims.

The main reason to go 18" is more tire selection, from normal skinny sizes to fat 130 all out racer rubber plus better dual and single purpose tires. As was mentioned it you enjoy leaning to max now and then, don't put 18" on front, which also don't fill up the fender gap view as well either. I'm going to break in Peel on big fat rear race rubber then work up to beyond sport bike spanking turns in timed track days, but long term plan on dual purpose 18"x120 rear and 19"x100 front and not play too hard in public.