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ROD¹ said :-
Ian, do you have a large carpark local to yourself which is empty at weekends.
If you do that would probably be the safest option to set up the outfit.
09/04/2026 17:25:45 UTC
Ian Soady¹ said :-
Good point Rod, and I have identified such a car park which I will use to explore sharp left and right turns. However to get to it needs a couple of miles on fairly busy roads including a couple of roundabouts.
But now the good(ish) news. I filled in a query form on the Avon (now Goodyear) website and was very surprised to get a phone call in return from a very helpful chap. He stressed that he was calling rather than emailing as nothing he would say could be construed as "advice" for obvious legal reasons. Anyway, he was very helpful regarding tyre pressure / load combinations and it's clear that I've had the front tyre overinflated - and it still is, probably, at 28 psi. The unladen weight on the front wheel is 86kg - let's say that increases to 120 fully laden. According to my chap, this would correspond to a pressure of 21 psi (the lower limit to stop the tyre coming off the rim). I'd be very uncomfortable at that so will try the effect of 25.
I have been trying to work out the effect of front tyre pressures and it has struck me that lower pressure equates to a bigger footprint which would act to increase effort required to rotate around the steering axis - exactly the same as the effect of a steering damper. Like trying to steer a car with flat front tyres and no power steering. So I think I'm eventually on the right tack(!). Hopefully I'll have another short test today at 25.
I must say I've never bothered much about tyre pressures on solos, taking a starting point for most as 28 front, 32 back although these are for bikes weighing 180 kg or so. I seem to remember the Tiger liked 42 at the back but it was a big heavy beast.
10/04/2026 10:08:45 UTC
Upt'North ¹ said :-
Well done Avon/Goodyear. Good customer service is underrated. I had a similar experience at Doves Builder Merchants at Berwick-upon-the-Tweed this morning. There's some nice folk out there.
You included Ian....of course.
Upt.
10/04/2026 11:20:31 UTC
Ian Soady¹ said :-
I've just had another very short run and a great improvement. 25 psi in the front: much much better especially on smooth road surfaces. A biggish bump still knocks the bars but at least they don't start oscillating. I got up to about 20mph and felt relatively safe.... I may try even lower pressure but won't go below 23. Another long conversation with a passing couple who used to have bikes in their youth, and the postman who said he could do with something like the outfit to do his round. I did offer to sell it to him but he said he preferred to remain married.......
I have started to wonder about the back and sidecar tyre pressures - currently 30 and 25 respectively.
10/04/2026 11:54:11 UTC
ROD¹ said :-
Ian, Did you ask Avon if they still make the speed master rear tyre? These were the preferred front tyre for an outfit back in the day.
I believe some tyre manufacturers make small batches of retro tyres, like the TT100 from Dunlop ect.
The square section of the speed master rear would give the same properties as lowering the tyre pressure, giving a greater contact area.
10/04/2026 12:07:50 UTC
ROD¹ said :-
I have just checked the web but the speed master does not seem to be available.
The best I can find in an 18" is the Heidenau K28.
10/04/2026 12:15:35 UTC
Ian Soady¹ said :-
I think the rear was called the Safety Master (popularly known as the skidmaster)? As I remember the front (ribbed) was the Speedmaster. I have one on my Norton Electra with a TT100 on the back....
I've been having a chat with an ex aircraft engineer on a BSA forum and he tells me that nose wheel shimmy is a problem on aircraft. They had a special tyre to counteract it:
10/04/2026 12:24:51 UTC
ROD¹ said :-
Then this popped up!
https://www.aceclassics.co.uk/products/avon-sm-mkii-400-18-rear-tyre/...
10/04/2026 12:18:36 UTC
Ian Soady¹ said :-
Well spotted. A bit pricy though! And showing as out of stock.......
10/04/2026 12:21:28 UTC
Ian Soady¹ said :-
I can't see any availability on the Avon. However, I've used Mitas tyres successfully on other bikes and in fact have one on the sidecar wheel. The H-03 looks like a possibility and at £50 good value:
10/04/2026 12:39:17 UTC
nab301 said :-
Ian that's interesting re the tyre pressures , is the 21psi recommendation related directly to the unladen weight or just as you say the minimum pressure to keep the tyre on the rim ? I have a road rider front on my solo Enfield and the bars can flap about a bit when slowing down.. I better get out the weighing scales. Roadriders have fairly stiff side walls compared to some "classic" type tyres which could also be part of the problem , either way if you don't hear from me again you'll know lower front tyre pressure isn't a good idea! (currently 30psi approx)
Nigel
10/04/2026 14:38:22 UTC
Ian Soady¹ said :-
Interestingly, looking at the workshop manual the front pressure is 16 psi! Of course tyres used to be much stiffer then. I think I'll probably go for the Mitas although am feeling a little more confident now. Maybe a slightly longer test run at 24 psi is in the offing? I'm also still considering adapting the BSA steering damper.
Given the amount the outfit veers on acceleration / braking with 42 bhp I wonder how those with Gold Wings etc manage?
I have found a graph / spreadsheet showing weight / pressure relationships courtesy of Claude that I'll try to post.
10/04/2026 14:50:40 UTC
Ian Soady¹ said :-
Here you are:
10/04/2026 14:49:50 UTC
Ian Soady¹ said :-
I've ordered the Mitas from Demon Tweeks in 3.50x18 size. Meanwhile have taken the old Roadrider off the front wheel. What a struggle! I had to use my home made bead breaker for the first time since making my Tiger wheels tubeless (below). The tyre was like iron, which is not surprising - when I looked at the date code it's 16 years old. I think it would have held the bike up with no air at all it was so stiff, and this probably contributed a lot to the shimmy problems. The task wasn't helped by the Akront flanged alloy rim, which seems to be deeper than the chrome rims I'm used to. Fortunately managed without nipping the tube or damaging the rim so am just waiting for the postie with my new tyre. I think there's room under the mudguard for it.....
I suppose I should now check the date code on the back tyre although it (and the front) wer performing fine when the bike was a solo. Although only in the dry of course. And I don't want to repeat that fight any time soon.
14/04/2026 10:23:02 UTC
nab301 said :-
Just for the record, my foray into lower front wheel tyre pressures on my solo Enfield didn't appear to improve anything , it is possibly a little more stable with the higher pressure..
Ian, how on earth does that bead breaker operate?!
Nigel
14/04/2026 13:21:09 UTC
Ian Soady¹ said :-
I'm glad you saked Nigel - shows someone's paying attention. I think I did post about it years ago - it must be nearly 20 years since I made it. Essentially it's a square made out of 4x4 timber with the dimensions such that the rim rests on the square and the hub, disc etc drop through. One of the arms of the square is elongated - to the upper right in the pic. Then it's a simple matter of taking another 3 foot length of 4x4 and loosely attaching that to the extended arm with a strap. A short length of - wait for it - 4x4 is then positioned on the tyre wall. If the far end of this long length is pushed down, the block pushes down on the tyre wall breaking the seal on the rim. The whole lot sits on a workmate to bring it to working height.
That picture shows it in use on the Tiger's front wheel, removing a tubeless tyre (although fitted with a tube). I sealed up the spoke nipples with a heavy duty aircraft fuel tank sealer to allow the use of tubeless tyres which was a great success. The Tiger was still on the road last year so despite the dire warnings from "experts" it hasn't killed anyone.
14/04/2026 16:19:07 UTC
Ian Soady¹ said :-
Of course the main use for the frame is to act as a support when fitting / removing tyres as the rim sits on the frame while the spindle / sprocket / whatever drops through.
Anyway, successfully fitted the Mitas this morning although the flanged rim was a bit of a tussle even with the softer tyre. This picture shows another weapon in my tyre / wheel armoury: a jig for adjusting spokes and balancing wheels which is what I'm doing now. It's not perfect for this job as it depends on the wheel bearings being very free, and most sealed bearings offfer slight resistance. This pic makes the tyre look huge - it's not.....
The jig is made from 1/2" MDF (which I had to buy, shock horror) and various bits of scrap wood. It and the tyre fitting frame have been in my shed for 20 years or so. I have a pair of Dunlop tyre levers that are about a foot long and 1.5" wide so help preserve the rims from damage. Both are perforated with a series of holes where I've used them to make impromptu pullers at various times.
15/04/2026 12:04:12 UTC
Ian Soady¹ said :-
....a dn now the wheel is back on the bike, fortunately without fouling anything although it's a little closer to the mudguard than ideal. Will it have the desired effect? Will I come back and tell you if it does? Is the moon made of green cheese? All these and others will be answered in due course.
15/04/2026 16:28:46 UTC
Upt'North ¹ said :-
Green Cheese, I prefer a nice Cheddar or maybe a brie if the mood takes me.
15/04/2026 18:01:00 UTC
ROD¹ said :-
Red Leicester for myself, but I did develop a strong preference for Mimolette when I was in France last year.
15/04/2026 19:05:09 UTC
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