suzuki250 Posted August 13, 2014 Report Share Posted August 13, 2014 What would be a reasonable amount of ground clearance for a pre65 bike I’ve just measured my frame and I’m getting about 10 to 11” with 360mm shocks Quote Link to comment Share on other sites More sharing options...
naichuff Posted August 13, 2014 Report Share Posted August 13, 2014 Just measured my cub and the Bultaco is 13" but the Beta is only 12" The cub uses 360mm rear shocks Quote Link to comment Share on other sites More sharing options...
jon v8 Posted August 13, 2014 Report Share Posted August 13, 2014 I've had a few conversations about this recently.Alot depends on the type of bike,with a lightweight 2 stroke engine plenty of clearance is good - 12-13" is fine. But with a pre unit 4 stroke motor it can be better to have a lot less.Because the engine is so heavy and tall having plenty of clearance can make the bike top heavy and want to fall over making them handle badly.My AJS has little clearance,(I'll measure it if I remember) but handles and steers incredibly well.Wheras my alleged mate has jacked up and tweaked his 500T Norton to make it more competitive - with the result that it steers quicker.The downside is that it feels very top heavy and needs lots more energy/fight to keep it upright. Our conclusion is that its probably better to have less clearance and lift the front wheel over an obstacle,rather than fight a top heavy monster. We are most likely wrong,but my AJS seems to work... 2 Quote Link to comment Share on other sites More sharing options...
sparks2 Posted August 13, 2014 Report Share Posted August 13, 2014 Hi Couldn't agree more with Jon. In my opinion, raising the ground clearance destroys the handling and stability (on any bike). You will probably see that modern bikes do not have a great amount of clearance. As Jon says, lift the front wheel over obstacles. 1 Quote Link to comment Share on other sites More sharing options...
suzuki250 Posted August 13, 2014 Author Report Share Posted August 13, 2014 I’ve altered the rear suspension mounts slightly and this is giving me 11” clearance with 360mm shocks With what Jon's said above I think I’m happy with this amount The bike is a bantam with a cub sub-frame and a Villiers 32a engine! Quote Link to comment Share on other sites More sharing options...
laird387 Posted August 13, 2014 Report Share Posted August 13, 2014 (edited) Hi, An 1963 AJS 16C left the factory with 10.5" ground clearance - and they did handle well, in ORR we did a comparative test with various models of fourstroke pre-unit bikes - with everybody riding all the other bikes - then comparing notes. The universal agreement was that in any normal riders hands about 10" clearance was right - and even better if you could keep the bulk of the weight as low as possible - typical comments on one of the bikes that had just over a foot clearance was that it handled like a pregnant camel.......... Maybe I'll put that test in the new digital magazine if enough people wuld be interested? Enjoy, Deryk Edited August 13, 2014 by laird387 1 Quote Link to comment Share on other sites More sharing options...
jon v8 Posted August 14, 2014 Report Share Posted August 14, 2014 I just measured my AJS,its only 9 1/2" of clearance unladen... With my lardy frame on it I guess it squashes down a bit on the soft IRC tyres and the forks give a bit too.Being a rigid I have to bear in mind how cruel I'm being to the rear tyre which limits speed of attack over obstacles during hillclimbs on muddy banks - but its not often a problem. Quote Link to comment Share on other sites More sharing options...
laird387 Posted August 14, 2014 Report Share Posted August 14, 2014 (edited) I just measured my AJS,its only 9 1/2" of clearance unladen... With my lardy frame on it I guess it squashes down a bit on the soft IRC tyres and the forks give a bit too.Being a rigid I have to bear in mind how cruel I'm being to the rear tyre which limits speed of attack over obstacles during hillclimbs on muddy banks - but its not often a problem. Hi Jon, I'll bet you are using a 4.00 x 18 rear (whatever the modern equivalent is), whereas we always used 4.00 x 19............?????????? Deryk Edited August 14, 2014 by laird387 Quote Link to comment Share on other sites More sharing options...
jon v8 Posted August 14, 2014 Report Share Posted August 14, 2014 Yep, you are right Deryk... its a modern 4.00x18 IRC tyre,very soft - they even grip when the sharp edge has worn off.In fact the knobbles are starting to rip off where the torque of the motor makes the tyre fight for grip. Quote Link to comment Share on other sites More sharing options...
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