AJS & Matchless Owners Club

Hi all,

Been around the traps but getting enthused again. Covid sure knocked the fun out of all things two wheeled in the last 2 years!

I have a '55 US model G80CS pretty original condition that I ride regularily in Historic bike club rallies and rides. I have been doing modern trials for a year now, and feel like my skills are at the point where I can trust myself on an 'old bike' without the fear of trashing it too much.

So, I am starting the thought process of deciding on what bike to buy, build or find!

A friend of mine has an original G3LC trials, believed to be '56, which has the same full width hubs as my G80CS, seemingly correct rear subframe, and gerling shocks. That said, he'd never let me ride it in a trial, however, I've ridden it more than he has!

Finding an original Matchless trials bike here in OZ, would be all but impossible - and as such, I may be forced to convert a road bike or, build one from scratch.

My question really is, is there any documentation or , can anyone point me in the direction of information on the differences between factory rigid and sprung frame geometry?

A modern trials bike has a wheelbase of around 1320mm (52") and a head angle around 26 deg, though unspecified by manufacturers.

Wondering if I'd be better served weight and wheelbase wise (and money wise!) with a rigid matchless frame? I know the front end on my G80CS is very 'slack' and it is hard to steer on the road, suspect it would be hard to steer off road in a trials environment?

IS there any comparisons between wheelbase and head angle on the early rigid vs later 50's sprung frames?
Pic for attention.

Hi Marty, can’t speak reference frame dimensions, wheelbase etc but can confirm that my single seat G80 rigid feels substantially more trials-like versus my sprung ‘54 G80CS. I was lucky to be able to spend many hours in the family’s field on my Bultaco Sherpa 250 and a Greeves in my youth and the G80 rigid, albeit way heavier, has a real trials ‘feel’ on the road. Very easy to keep my feet on the pegs approaching traffic lights at speeds substantially below walking pace. I definitely prefer the two 19” wheels on the G80 rigid and a much lower feeling c of g even if just imagined. Rigid would be my way forward.

Iron Head

Matchymarty wrote: ↑Tue Oct 19, 2021 10:27 pm
My question really is, is there any documentation or , can anyone point me in the direction of information on the differences between factory rigid and sprung frame geometry?

A modern trials bike has a wheelbase of around 1320mm (52") and a head angle around 26 deg, though unspecified by manufacturers.

Article here about modding a frame for trials use includes mention of changing the headstock angle to 25 deg.

https://www.jampot.com/article_read.asp?id=167

There's a section in Christians Archive for trials bikes with articles that may have some info, here:

http://archives.jampot.dk/editorial/Trials/

Nice bike good subject. I'm in....


They can be converted.

Rigid to sprung frame etc but makes it so heavy.


I looked and looked for information but found very little. I was wanting to compare the frames pictures etc.

Shame there is not a post on the subject ! )

REf ; Part no's in general its very complicated has there been an updated set (computerised sort of thing rather than black magic system)
(being dyslexic does not help I think there's a partfinder some where,? That must be some, where on another list ? ? ))



Good luck with your project.

kind regards to all.

db133 wrote: ↑Sat Dec 10, 2022 11:48 am I looked and looked for information but found very little. I was wanting to compare the frames pictures etc.

Shame there is not a post on the subject ! )

REf ; Part no's in general its very complicated has there been an updated set (computerised sort of thing rather than black magic system)
(being dyslexic does not help I think there's a partfinder some where,? That must be some, where on another list ? ? ))

Not sure where you've looked but there are illustrations of both the rigid and the sprung rear ends on pages 25 and 26 on the '54 Spares List here:

http://archives.jampot.dk/book/Spares_l ... ingles.pdf

The rigid rear was available as an option for competition models.
I only looked at 1954 as you haven't referred to any particular year and there's nothing on your Profile, although the frames didn't change much (if at all, depending upon model) in the 50's.

Hi

REF ; Not sure where you've looked but there are illustrations of both the rigid and the sprung rear ends on pages 25 and 26 on the '54 Spares List here:

http://archives.jampot.dk/book/Spares_l ... ingles.pdf

Yes thats all I found so far

regards