robf Posted September 4, 2012 Report Share Posted September 4, 2012 Hi guys From what I can see many twin shock bikes came with tiller style yokes as standard and most modern bikes do not. It also seems quite popular to either mod or change the top yoke to get rid of the tiller system. So what was the original thinking behind them and what has changed now that makes them a bad idea ? Quote Link to comment Share on other sites More sharing options...
goudrons Posted September 4, 2012 Report Share Posted September 4, 2012 Most old twinshocks were what were considered parts bin specials, that is, manufacturers used existing parts off other bikes to make a trials bike. Most were based of trail type bikes and shared a lot of their parts, particularly the Japanese ones, though go back a little further and you'll find they were based on old British road bikes!! This was up until the likes of Fantic who were one of the first to mass produce a purpose built machine. The tiller style top yoke is better for a "sit down" or more relaxed style of riding, the bars come back towards the rider so there's less of a reach to the handlebars. Stand up and this tiller leaves less room to ride behind, less weight on the front (when needed) and a less direct feel to the steering as the front pivot point (head stock) is further forward than your grip on the bars. What's changed? Us really. We know it's not always the best arrangement, other manufacturers have shown us the light, directer steering helps turning tighter and give a better feel of the front wheel, room behind the bars helps us move our weight around the bike better, makes an older bike feel a little more modern. Quote Link to comment Share on other sites More sharing options...
cvgmmartin Posted September 4, 2012 Report Share Posted September 4, 2012 Any tiller action is due to the relative position of the handlebar grips and the steering pivot and not to the position of the bar clamps on the yokes. By rotating the handlebars forward it is possible with some high rise bars to position the grips over the steering pivot and hence there should be no "tiller" feel. Quote Link to comment Share on other sites More sharing options...
woody Posted September 4, 2012 Report Share Posted September 4, 2012 For my 340 Bultaco I have a standard top yolk and a modified one with normal clamps. Can't tell any difference in the steering whatsoever. The advantage of the modified yokes is that it allows bar risers to get the bars a little higher and a more comfortable riding position. Bear in mind that the highest bars are now 6" whereas the bars fitted to the bikes in the 70s were a lot higher, therefore the riding position was more comfortable. The 'tiller' affect is in the mind, the bars on Bultos, Yam, Kwawsaki etc are only just behind the steering stem and as already mentioned, rotate the bars forward and they are over the axis of the yokes. It has more affect on the comfort of the riding position than the actual steering. The positioning or style of the clamps didn't necessarily evolve with bike design. MP and Rickman forks, Montesa and Ossa all had conventional clamps on 60s and 70s designs. Fantic, on the 240 and 300 (and early monos I think) went back to rear set clamps, as did Armstrong on their later models. Some Grippers have the bars rear set too. Personally, I think it is something else that has been overblown and helped sell aftermarket parts and conversions - but that is just my opinion. If you want a real tiller affect, ride a 50s British pre-unit rigid which has about a 3" fork offset and clamps set about 3" rearwards... 1 Quote Link to comment Share on other sites More sharing options...
sparks2 Posted September 6, 2012 Report Share Posted September 6, 2012 Well said Woody Quote Link to comment Share on other sites More sharing options...
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