Trials Australia Forums

Yes, thx Alastair, although the sprockets may not actually be dished, but use a packer. (But maybe I missed the dished ones and need to look further).
(Jeez they know how to charge though eh? - I just bought a set of points from a UK retail outlet for less than a half of what they're charging).
Eagle, that's useful info, thanks for going to the trouble of measuring yours, I'll measure up my setup in the morning.
Cheers boys.

I bought a gold-anodised dished aluminium 428 chain TY250 twinshock sprocket from B&J Racing in the early 2000s and it is still going well.

Those shock mounts on TY250s are pretty strong, but they have a limit.
On one derelict TY250 I bought, the shock mounts top and bottom were bent, but it had been flogged around by teenagers with shocks that had no damping and no bottoming cushions. The mounts straightened nicely using an oxy torch and a piece of pipe slid over the mount.

You can also use a '' straight '' sprocket as I did, but you need a spacer between the sprocket and the hub plus you have to countersink the bolt hole so the head doesn't hit the swingarm.
Guy

Good tip Guy, ta. At least I have the 51T dished steel sprocket I can use initially.

David one of the top shock mounts on my frame was broken clean off, so some PO trauma there I guess. It's vulnerability isn't helped by the thread in it eh? Not too hard a fix, -drilled the old one out and brazed in a replacement that I knocked up on the rattly old lathe.
NJB have no stock of trials shocks at the mo' unfortunately. Patience. What about (modern) Betors? any opinions?

Jools wrote:Good tip Guy, ta. At least I have the 51T dished steel sprocket I can use initially.

David one of the top shock mounts on my frame was broken clean off, so some PO trauma there I guess. It's vulnerability isn't helped by the thread in it eh? Not too hard a fix, -drilled the old one out and brazed in a replacement that I knocked up on the rattly old lathe.
NJB have no stock of trials shocks at the mo' unfortunately. Patience. What about (modern) Betors? any opinions?

Modern design Betors don't cost much and work well for trail riding. They have too much damping on the compression stroke for competition trials work.

Although they weren't cheap, I bought a pair of Rockshocks from The Hell Team and had them on my doorstep in a few days. Paul had them on the shelf and they seem to work fine. I have Falcons on my other TY but can't comment yet on their performance.

Re: my TY250B. -I would like to get a 'feel' for the gearing / sprockets. -Opinions...
(I'm using 428 chain).

I have a 13T front sprocket. And I have a dished 51T rear, which will do initially to get the box of bits going, but I'd like to replace this steel 51T one with an alloy one. My personal preference has always been towards lower gearing. Is the standard 53T rear sprocket nice and low for slow-speed plonking? or maybe I should try to find a 55T, even if it's not dished I can easily make a packer based on my old worn TY175 sprocket to align it.

Other option of course is to go down a tooth on the front sprocket and stick with the (new but heavy steel) 51T that I have.
(Yes I know obviously, that 1 tooth on the front is worth 3 or 4 on the rear).

Whaddaya reckon?

Gearing is a personal preference. Why not just ride it and judge from how it feels which way you want to go.
By the way it's better for the way the rear suspension works to use the smallest rear sprocket you can get away with.

Next: front sprocket. Having briefly ridden the bike, I've confirmed that I need a 12T front sprocket. I've found a couple online but they specify fitting for TY250E model, mine is a 250B. Did they alter the front sprockets between the B and E models?

I have received the NJB rear shocks, ('Ultimate' model) which are pretty impressive. Beautifully made, very nice looking alloy bodies, -they easily clear the rear sprocket so no worries there. These shocks are adjustable for length as well as preload, so could be useful for fine-tuning the 'attitude' of the bike in conjunction with fork/yoke 'drop'.

The shocks feel beautifully supple operating them by hand, I've yet to feel them on the bike. Cost delivered to Oz was just under $400.

Another thing: I'm considering extending the engine end clutch lever by 25mm, (Was it Stanm who has done this?) - but obviously doing that using the original handlebar lever will result in some lost cable motion at the engine lever end. Is there enough leeway in the system that it will work okay, or will I need a different handlebar lever?

What about that front sprocket?