Permobil F5/F3 shaft size & offset.

[Burgerman]

From the inner surface of the rim where the bolt hole is, to the inner edge of the tyre is 39mm

Thats the one. Thats all thats required.

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Why? Because we know the stock tyre width is a nominal 3.00 inches in size.
So we now calculate how thick the spacer should be to fit x wheel (many wheels are all different offsets so we just measure a wheel that we want to use) to put the inner tyre edge the same distance from everything that it is as stock.

Now this usually works out great with around a 10 to 12mm thick spacer on the rims/120 tyres I use. Much nmore difficult on skinnyer tyres. Because it can mean an impossibly thin or minus thickness spacer... Which then means finding a wheel with a bigger offset.

[LROBBINS]

The 8.8 on the bolt in the photo is a metric grade designation. It is the most common grade of steel (not stainless) here and is roughly like U.S. grad 5. It is a mildly hardened steel. If the socket is larger than 6 mm, it is probably 8 mm.

[shirley_hkg]

I can't make that triangular taper hubs. Dare not to.

Take a easy way. Get 2 hubs. Put it on lathe to trim off sprocket. Weld a new flange to the barrel to fit new tubeless rims.

[Burgerman]

You wont need to do that. A simple spacer ring, with a few extra threaded holes in it works with the 120/70-8 tyres and 3.5J rims.

[shirley_hkg]

I don't think Jefferso aims at 120/70, but 3.00-8 instead, 3.50-8 at most.

Another thing is we cannot put spacer on a taper axle, can we ?

[Burgerman]

You dont need to.
You just make a spacer that goes between the existing hub, and the new wheel.

Fitting the 120/70 tyre, or the 110/80 tyre, is FAR superior to all the 3.50 tyres. Try one and you will throw away all the others. And it means a simple flat adapter ring.

3.50 x 8 too tall, and are generally weak construction compared to duro 120/70 8. Or 110/80 duro. They are not really much wider, just look better, stronger, easier to fit wider rim.

Countersunk holes in spacer ring to bolt to existing hub. With countersunk bolts. Leaves a flush surface. Then drill / tap new holes for 3.5J rim.

[Marcelo]

If you really need a measured drawing after seeing that video, ask me again and I'll pull a wheel off and try to get you enough measurements. But I think it would be lots easier to just use the stock hub.

All my chairs use an adapter bolted to an existing hub apart from 1 of them. This works OK on wider rims as theres enough space to do that. If you are swapping rims for narrow ones just to go tubeless then its not so easy. But I always use wider rims. Looks better, works better, rides better, so why go narrow?

Generally use 120/70 - 8 tyres (duro) on 3.5J x 8 rims on modern chairs now. Strong, tubeless, wear extremely well, better ride, never a puncture, shirley gets rims (or ebay super cheap) tyres are not cheap And they look good too!

Pugman sorry to interrupt the topic I would like to know your opinion, is it worth putting an f 3 tire on my f 5 to reduce friction when cornering indoors?

[Burgerman]

Tyre?

I wasnt aware there was any difference.

But if a chair is programmed correctly it doesent make any difference what tyres are used.

[Marcelo]

Thank.