old trials fanatic Posted October 24, 2011 Report Share Posted October 24, 2011 Just wondered cos i have a spare front end from an OSSA gripper languishing in the corner of the shed and one of the main things that puts me off riding the 199B is the orrible feel of the tiller steering so just wondered if anybody had tried non leading axle forks? Using the Ossa yokes as well would also get rid of the tiller effect which feels very strange. Funny thing is in their day i dont seem to remember it bothering me but it does now. Quote Link to comment Share on other sites More sharing options...
bogwheel Posted October 24, 2011 Report Share Posted October 24, 2011 Please be the lab rat and try it. Been wanting to do the same - but everyone says that the front wheel will hit the down tube? Front end is only orrible when you swap between a modern bike. (i too never noticed it years ago) Quote Link to comment Share on other sites More sharing options...
bullylover Posted October 25, 2011 Report Share Posted October 25, 2011 Hello all. OTF, just to side track your question a bit I have read somewhere, probably on here, that a good modification to Bultaco forks was to put Ossa damper rods in them and it stops them from topping out all of the time. As Bogwheel said just put them on and see what happens. As they say brute force and ignorance always works. Good luck. Bully Lover. Quote Link to comment Share on other sites More sharing options...
old trials fanatic Posted October 25, 2011 Author Report Share Posted October 25, 2011 Please be the lab rat and try it. Been wanting to do the same - but everyone says that the front wheel will hit the down tube? Front end is only orrible when you swap between a modern bike. (i too never noticed it years ago) I'm not swaping from a modern just from me Ossa and the James both of which feel "normal" just the 199B that feels like a barge. Perhaps thats why i never ride it ? Daft really i suppose cos loads of people do ride em and love em but it just dont feel "right" perhaps i'm just strange? just thought i'd include that before everybody else chips in LOL Quote Link to comment Share on other sites More sharing options...
noel063 Posted October 25, 2011 Report Share Posted October 25, 2011 Hi Guys, A while back Woody posted some info with regards to swapping Bultaco fork internals for Ossa internals. I have been toying with the idea myself. Quote Link to comment Share on other sites More sharing options...
woody Posted October 25, 2011 Report Share Posted October 25, 2011 Hi Guys, A while back Woody posted some info with regards to swapping Bultaco fork internals for Ossa internals. I have been toying with the idea myself. The Ossa and Bulto rods are pretty well identical, both being Betor, the only difference being the 'piston' part of the shuttle valve that sits just below the rebound spring. They seem to be the same on all Ossas, a round disc with slots in for oil flow but they can differ on Bultos. On the 199b it is a solid square shape where oil flows past the 4 sides, on earlier Bultos it is like the Ossa but with holes instead of slots. I tried Ossa rods in the Bulto forks and it actually mmade no difference in the end (no mods required as they are identical fitment, both being Betor) I also took the Ossa forks, removed the sliders and replaced them with the Bultaco sliders and fitted those to the 199b. The Ossa stanchions are about 1" shorter than the Bulto ones (early MAR, later MAR and Gripper will be about 2" longer) so I was also interested to see if it made any difference to the steering, being a bit lower on the front. Answer was no, and the damping was still no improvement and the forks still topped out... No idea why as the forks work well in the Ossa, so must be to do with geometry or whatever. The best improvement I have made to the Bulto is Magical fork springs. Much better and although they are stronger, the forks no longer top out.... Work that one out... Oil is the usual 180 - 200cc 10W The stuff about tiller steering - well, my opinion it's all B*****ks and I think people are being brainwashed by others. My Sherpa top yoke was modified to take conventional clamps. Having tried it, I've fitted a standard yoke again - couldn't tell any difference. The only reason I let it be done was so I could fit bar risers under them as I'm tall, but that actually messed up the steering by unweighting the front as I was too rearwards. Standard yoke back on. I think with old British yokes where the clamps are about 4" behind the stem and the forks are 4" in front of it, there is a case of 'delayed action' to answer, but Hondas, Fantic 240, Sherpa - not really. As OTF has said, they weren't a problem back in the day - why now? With the Bulto, much improvement can be made by getting the suspension to work right. It is probably the most overlooked aspect of set up next to budget tyres in preference to proper tyres. If the suspension is working correctly at both ends, noticeable differences will be felt with the steering. If the rear shocks are clapped out and /or too soft, they will sit the rear of the bike low, making an already long fork rake longer. If the front is too soft, it will tuck on turns, if too hard or full of oil to compensate for the soft springing/damping and it will push out, especially with the back sitting low. Fitting shocks about 1" max longer helps keep the stance of the bike neutral when the rider is on it and decent fork springs will keep the front sitting up but be compliant enough to let it compress the right amount on turns and help prevent tucking or pushing. Obviously, a bit of rider input is required as well... But the front and back has to work equally well and together to get any benefit. Springs and damping in rear shocks need to be right. Solid shocks, ATF oil, dodgy seals, fork springs from a road bike from the breakers yard - all 'cos they were cheap' ultimately mean your bike will handle like a sack of ***** or plank when the reality is, most of us need it to work as well as it can as we need all the help we can get... All very well polishing this or that, painting this or that or buying all the latest riding kit - false economy, bike set up comes first. The steering - unless you're doing really tight up your own backside sections, the like of which I haven't come across in any classic events, the standard Bulto steering should be fine. They still turn tight, but you have to be aware of where the front wheel is/will be in a turn, so plan for it when walking the section - almost a lost art... My 199b has been pulled in and I'm yet to be convinced it is a big improvement in muddy conditions where it doesn't feel so planted. Rocks and 'clutch in' tight turns probably, but very rarely do those. Up rock streams, it is maybe a bit more nervous, although I've yet to try it properly with the standard yoke back on as I'd only done a few sections with it when I broke my shoulder, so no decision yet. Classic Experts hopefully. Or you could try Alpina or Pursang yokes from around a 1975 bike which are parallel - I'm trying these on my stndard 199b when it's back together. Or if you're clever, modify the Sherpa yokes to parallel. Better than cutting a frame to alter the angle. The yokes are 'undo-able' mods - cutting the frame isn't so easy to reverse... If you fit later MAR or Gripper forks, you will have to modify the top yoke and dremel out the collars that the stanchions sit up against as they will be too long otherwise. They will need to sit at least 1" above the top yoke. If you fit them normally, up against the collar in the top yoke, it will be like a chopper. Earlier MK1 or 2 MAR forks will fit fine but a bit shorter than standard Sherpa. The front mudguard may be very close to the exhaust on turns with the forks comressed. Test it first by removing the springs and pulling the forks right up and turning from lock to lock to see if it hits exhaust or frame. I can't help with any thoughts on how it will steer with Ossa forks as I've never tried it. All the trail will be altered so it may not even feel right - steering geometry is a complicated business that is over my head. Quote Link to comment Share on other sites More sharing options...
old trials fanatic Posted October 25, 2011 Author Report Share Posted October 25, 2011 The Ossa and Bulto rods are pretty well identical, both being Betor, the only difference being the 'piston' part of the shuttle valve that sits just below the rebound spring. They seem to be the same on all Ossas, a round disc with slots in for oil flow but they can differ on Bultos. On the 199b it is a solid square shape where oil flows past the 4 sides, on earlier Bultos it is like the Ossa but with holes instead of slots. I tried Ossa rods in the Bulto forks and it actually mmade no difference in the end (no mods required as they are identical fitment, both being Betor) I also took the Ossa forks, removed the sliders and replaced them with the Bultaco sliders and fitted those to the 199b. The Ossa stanchions are about 1" shorter than the Bulto ones (early MAR, later MAR and Gripper will be about 2" longer) so I was also interested to see if it made any difference to the steering, being a bit lower on the front. Answer was no, and the damping was still no improvement and the forks still topped out... No idea why as the forks work well in the Ossa, so must be to do with geometry or whatever. The best improvement I have made to the Bulto is Magical fork springs. Much better and although they are stronger, the forks no longer top out.... Work that one out... Oil is the usual 180 - 200cc 10W The stuff about tiller steering - well, my opinion it's all B*****ks and I think people are being brainwashed by others. My Sherpa top yoke was modified to take conventional clamps. Having tried it, I've fitted a standard yoke again - couldn't tell any difference. The only reason I let it be done was so I could fit bar risers under them as I'm tall, but that actually messed up the steering by unweighting the front as I was too rearwards. Standard yoke back on. I think with old British yokes where the clamps are about 4" behind the stem and the forks are 4" in front of it, there is a case of 'delayed action' to answer, but Hondas, Fantic 240, Sherpa - not really. As OTF has said, they weren't a problem back in the day - why now? With the Bulto, much improvement can be made by getting the suspension to work right. It is probably the most overlooked aspect of set up next to budget tyres in preference to proper tyres. If the suspension is working correctly at both ends, noticeable differences will be felt with the steering. If the rear shocks are clapped out and /or too soft, they will sit the rear of the bike low, making an already long fork rake longer. If the front is too soft, it will tuck on turns, if too hard or full of oil to compensate for the soft springing/damping and it will push out, especially with the back sitting low. Fitting shocks about 1" max longer helps keep the stance of the bike neutral when the rider is on it and decent fork springs will keep the front sitting up but be compliant enough to let it compress the right amount on turns and help prevent tucking or pushing. Obviously, a bit of rider input is required as well... But the front and back has to work equally well and together to get any benefit. Springs and damping in rear shocks need to be right. Solid shocks, ATF oil, dodgy seals, fork springs from a road bike from the breakers yard - all 'cos they were cheap' ultimately mean your bike will handle like a sack of ***** or plank when the reality is, most of us need it to work as well as it can as we need all the help we can get... All very well polishing this or that, painting this or that or buying all the latest riding kit - false economy, bike set up comes first. The steering - unless you're doing really tight up your own backside sections, the like of which I haven't come across in any classic events, the standard Bulto steering should be fine. They still turn tight, but you have to be aware of where the front wheel is/will be in a turn, so plan for it when walking the section - almost a lost art... My 199b has been pulled in and I'm yet to be convinced it is a big improvement in muddy conditions where it doesn't feel so planted. Rocks and 'clutch in' tight turns probably, but very rarely do those. Up rock streams, it is maybe a bit more nervous, although I've yet to try it properly with the standard yoke back on as I'd only done a few sections with it when I broke my shoulder, so no decision yet. Classic Experts hopefully. Or you could try Alpina or Pursang yokes from around a 1975 bike which are parallel - I'm trying these on my stndard 199b when it's back together. Or if you're clever, modify the Sherpa yokes to parallel. Better than cutting a frame to alter the angle. The yokes are 'undo-able' mods - cutting the frame isn't so easy to reverse... If you fit later MAR or Gripper forks, you will have to modify the top yoke and dremel out the collars that the stanchions sit up against as they will be too long otherwise. They will need to sit at least 1" above the top yoke. If you fit them normally, up against the collar in the top yoke, it will be like a chopper. Earlier MK1 or 2 MAR forks will fit fine but a bit shorter than standard Sherpa. The front mudguard may be very close to the exhaust on turns with the forks comressed. Test it first by removing the springs and pulling the forks right up and turning from lock to lock to see if it hits exhaust or frame. I can't help with any thoughts on how it will steer with Ossa forks as I've never tried it. All the trail will be altered so it may not even feel right - steering geometry is a complicated business that is over my head. Thanks for all that Dave most informative. All i was trying to achieve was to get the 199B to steer like my Ossa and James which i have been able with very little effort to get to behave much alike, apart from the fact the Ossa feels so damn heavy which it is compared to the James although not so noticable when riding it, steering wise. That way when i swap from one to the other it only takes a section or so to recalibrate myself. Oh well looks like the 199B will stay in the back of the shed for a while longer as i find it too hard to readjust from it to the James which i dont with the Ossa. Am i the only person who has this problem ? sounds like it Quote Link to comment Share on other sites More sharing options...
pschrauber Posted October 25, 2011 Report Share Posted October 25, 2011 I don't really know what tiller effect* means, does it mean that the fork action is not smooth and more stuckering expecially in turns with additional fork action downwards or upwards or while breaking riding down a hill? And once again I must admit that my english ... is somehow limited. (BTW: tiller effect on www.dict.cc puts out the German word Ackerfr Quote Link to comment Share on other sites More sharing options...
woody Posted October 25, 2011 Report Share Posted October 25, 2011 All i was trying to achieve was to get the 199B to steer like my Ossa and James Ossa and Bulto like chalk and cheese, the Ossa really was a quick steering bike for it's day, especially the MK1 with the short swingarm Longer shocks on the 199b, get the suspension working well and it will feel much better. But never steer like the Ossa unless you pull the steering in and even then... The last James I rode made my Ossa feel like a chopper... Quote Link to comment Share on other sites More sharing options...
woody Posted October 25, 2011 Report Share Posted October 25, 2011 I don't really know what tiller effect* means, does it mean that the fork action is not smooth and more stuckering expecially in turns with additional fork action downwards or upwards or while breaking riding down a hill? And once again I must admit that my english ... is somehow limited. (BTW: tiller effect on www.dict.cc puts out the German word Ackerfr Quote Link to comment Share on other sites More sharing options...
toofasttim Posted October 26, 2011 Report Share Posted October 26, 2011 And this is an extreme example: Quote Link to comment Share on other sites More sharing options...
feetupfun Posted October 26, 2011 Report Share Posted October 26, 2011 I reckon the reason that the location of the handlebar clamps relative to the steering stem axis is unimportant is because it is the position of the handlebar grips (not the bar clamps)relative to the steering stem axis that determines the spatial relationship between your hands and the steering axis. Adjusting the handgrip position by rotating the bars in the clamps allows you to get the ideal fore-aft positioning of the grips. The reason why your Bultaco feels different to your OSSA in turns is mainly the steering trail difference and yes it is great fun to experiment with different front forks and triple clamps, but the Bultaco is quite limited for increasing the trail dimension by how close the mudguard already is to the exhaust pipe. I had a ball a couple of years ago swapping front end bits between a TY250 and a KT250, much as Woody did with his bikes, and while it was great fun and I did manage to make the KT to steer just like a TY250, it looked quite weird and the front mudguard got quite scratched up from rubbing against the exhaust pipe. I also agree with Woody that setting up the ride height and the action of the suspension properly at both ends makes a huge difference to the way the steering works in turns. It shouldn't be surprising because the front and rear heights and the way the suspension reacts to bumps and body movement affects the steering geometry. Quote Link to comment Share on other sites More sharing options...
brownee Posted October 26, 2011 Report Share Posted October 26, 2011 Not read this thread in full but just posting this on behalf of my Dad who wanted to show how it can be done.... Quote Link to comment Share on other sites More sharing options...
brownee Posted October 26, 2011 Report Share Posted October 26, 2011 Or should I say "Should be done" Quote Link to comment Share on other sites More sharing options...
feetupfun Posted October 26, 2011 Report Share Posted October 26, 2011 Or should I say "Should be done" It would be helpful to be able to see the triple clamps Quote Link to comment Share on other sites More sharing options...
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