smokey125 Posted October 30, 2015 Report Share Posted October 30, 2015 Having seen a bit of the Manx classic/twinshock while I've been at the Manx Grand Prix I'm interested in what basics constitute a twinshock. Other than having two shocks! What brakes, frames, engines etc are allowed, size (as in fork diameter) or age limits. Anything else that should be considered before I start to make something that's not allowed. Even more interested after seeing some of the pit bike engine specials people have made which look very similar to the first bike I ever rode in a schoolboy competition. The rules for classic and twinshocks seem to be even more liberal than those for classic racing. Which I didn't think was possible! Quote Link to comment Share on other sites More sharing options...
collyolly Posted October 30, 2015 Report Share Posted October 30, 2015 I would suggest the twin shock class is for "original" bikes with drum brakes built prior to 1985 ( end date will be disputed no doubt but that will give you the idea) Anything else will be seen as a special and classified accordingly. The pre65 scene has it's own set (lots of sets and depends where you are in the world) and lots can be found by trawling the net for sites of clubs that specialise in that class. Why would you want to build a bike and class it as a twin shock other than to gain an advantage ? There are plenty of good original bikes around just search fleabay 1 Quote Link to comment Share on other sites More sharing options...
smokey125 Posted October 30, 2015 Author Report Share Posted October 30, 2015 (edited) Why would you want to build a bike and class it as a twin shock other than to gain an advantage ? There already seem to be plenty of people radically modifying original twin shocks at what can't be anything less than great expense! To gain an advantage. Have to say I've seen a lot that are about as original as Trigger's broom. There also seem to be plenty of people who have already built a twin shock machine for nothing more that the pleasure of doing so and having something a bit different! I'm an engineer and I love building things. I've got lots of parts around me already if the main criteria is it has to be pre 85 and drum brakes then I have a start for a fun/cheap project. There are plenty of good original bikes around just search fleabay I search fleabay and all I see is bikes with price tags that I think are far too big or basket cases with build cost that will run out of control. The moment you are constrained to something that is either desirable or in relatively short supply cost jump out of all proportion. Start with a cheap plentiful road bike and see where it takes you. If that's not in the spirit of the class or outside of the rules then I'll build something different. Edited October 30, 2015 by smokey125 1 Quote Link to comment Share on other sites More sharing options...
b40rt Posted October 30, 2015 Report Share Posted October 30, 2015 Look out for a decent 240 / 280 SWM or Gori, very good in standard form, or with a few minor mods can be easily tailored to your size. Check their history, they won virtually everything late 70's early 80's. 1 Quote Link to comment Share on other sites More sharing options...
2stroke4stroke Posted October 30, 2015 Report Share Posted October 30, 2015 Why would you want to build a bike and class it as a twin shock other than to gain an advantage ? There are plenty of good original bikes around just search fleabay Not everybody wants the problems of owning a 40 year old bike, perhaps. 1 Quote Link to comment Share on other sites More sharing options...
collyolly Posted October 30, 2015 Report Share Posted October 30, 2015 But I think that for some, is the attraction of owning an old bike. Yes they are often hard to get to run right and spares are often like hens teeth but that is all part of the classic bike scene. Build a special by all means I think they are fantastic, but ride your creation against the modern bikes to show you are as good as today's factories not against an early seventies Bultaco but with modern experience. The sport has moved on so much since the twin shock days, even in fact since early mono days and by building a special you no doubt build in advantages which will seem unfair. Quote Link to comment Share on other sites More sharing options...
jon v8 Posted October 30, 2015 Report Share Posted October 30, 2015 Not everybody wants the problems of owning a 40 year old bike, perhaps. I have to say there does not have to be lots of problems in running a twinshock bike,esp if you buy one in good shape in the first place. A TY175/250 for instance requires very little to keep it going well,there is plenty in the way of info and spares to keep them running. As long as they are put together properly they are just as reliable as a modern bike. I ran my last TY250 from 2006 to last year with no problems at all,and is still running fine with its new owner. Even points ignition on them works fine with almost zero upkeep. Honda TLR's,Beamish Suzuki's,Bultaco's,Mont's and Fantics - can and are just as good,there are plenty to choose from. 3 Quote Link to comment Share on other sites More sharing options...
2stroke4stroke Posted October 30, 2015 Report Share Posted October 30, 2015 The sport has moved on so much since the twin shock days, even in fact since early mono days and by building a special you no doubt build in advantages which will seem unfair.[/quote Assuming they stick to drum brakes it's hard to think what advantages could be built in that are not seen on many Fantics that have been recently put together. By the way, I run a bog standard SWM. Quote Link to comment Share on other sites More sharing options...
old trials fanatic Posted October 30, 2015 Report Share Posted October 30, 2015 There already seem to be plenty of people radically modifying original twin shocks at what can't be anything less than great expense! To gain an advantage. Have to say I've seen a lot that are about as original as Trigger's broom. There also seem to be plenty of people who have already built a twin shock machine for nothing more that the pleasure of doing so and having something a bit different! I'm an engineer and I love building things. I've got lots of parts around me already if the main criteria is it has to be pre 85 and drum brakes then I have a start for a fun/cheap project. I search fleabay and all I see is bikes with price tags that I think are far too big or basket cases with build cost that will run out of control. The moment you are constrained to something that is either desirable or in relatively short supply cost jump out of all proportion. Start with a cheap plentiful road bike and see where it takes you. If that's not in the spirit of the class or outside of the rules then I'll build something different. So you are going to build a special great. Use your engineering skills and create something really special and enjoy the process and riding your special. Sounds great to me just enter it as a special. After all its not about the winning just the fact that you are out enjoying yourself on your home brewed special. The fact that you wont be competing for Championship points doesnt matter does it 3 Quote Link to comment Share on other sites More sharing options...
lineaway Posted October 31, 2015 Report Share Posted October 31, 2015 Myself, it is just satisfying to take a bone stock 40 year old bike and clean section after section that modern riders have to stop in. That is what vintage is to me, no price tag involved. 7 Quote Link to comment Share on other sites More sharing options...
b40rt Posted October 31, 2015 Report Share Posted October 31, 2015 Hi smokey125, there are very few twin shocks that are standard, even the one's that look it. Most have electronic ignition, which is generally an acceptable mod'. Frame chops and footrest repositioning is not always obvious, modified top yokes are also common. Lightening flywheel, revised porting or engine's from later models are also common. You here stories of "original" bikes winning, if they don't have pirrelli' s or Dunlop trials champion's, and gas girlings or equivalent, they aren't standard. Modern tyres and shocks are a world away from 80's offerings. Bottom line is your bikes modified even by fitting current tyres, cables, levers, bars, levers, footrests, units etc. What's acceptable, depends who you ask ! Quote Link to comment Share on other sites More sharing options...
smokey125 Posted October 31, 2015 Author Report Share Posted October 31, 2015 b40rt I aware of the sort of arguments people have about what's original after 23 years of road racing classic bikes! I'm not interested in building something that will be way better than something that was genuinely available. I've seen that happen with racing and costs have gone through the roof and in my opinion largely ruined it. It's more about what can be done on a budget with a little imagination and thought but still keep the spirit of a class. If money was no object i'd search for a Whitehawk TY175. 1 Quote Link to comment Share on other sites More sharing options...
collyolly Posted October 31, 2015 Report Share Posted October 31, 2015 Do you seriously think you can build your own bike for less than a Whitehawk ty175 ? If you can then you have a ready market for an entry level trials bike 1 Quote Link to comment Share on other sites More sharing options...
collyolly Posted October 31, 2015 Report Share Posted October 31, 2015 Hi smokey125 Love your posted picture on the twinshock thread, if you can build something similar for less than a ty175 then you just need to productionise it and hey presto the schoolboy market will be re born. How many parents want to spend £3500 on a Beta ? Back in the day (1970's ) you had to put your name down to join Surrey schoolboys trials club it was so large they could not cope with the entries. Good luck Quote Link to comment Share on other sites More sharing options...
still trying Posted November 2, 2015 Report Share Posted November 2, 2015 Hi Smokey, I'm in a similar position as you, an engineer wanting to build a special.But without spending a huge amount and not quite having the resources couldn't compete with the ultra modern bikes. I have chosen to build to an older technology class. Hence I have aimed at "Twin Shock" As such I avoided any progression in the mounting of the rear shocks, They are mounted directly from the frame to the swing arm. I used knowledge that has been around before me to design it. Light as possible (using period available materials, NO carbon fiber etc) Skinny as possible As much ground clearance with as low as possible C of G As low a seat height as possible This was a bucket list kind of project for me and as such I have chosen that if there is too much upset when I ride they are quite welcome to not count my score. With building from scratch (80% kept old engine, forks and wheels) you end up with a huge setup / development risk that the factory built bikes don't have. They have had years and hundreds of people developing the setup knowledge (Even building lightweight frames!). Personally I think that if you stick to the guts of the "Twin shock" meaning, (period engine,forks,breaks,& twin non linkage rear shocks) then people would be pretty unfair if they disallow your creation from competing. After all the Big para dine shifts; mono shock linkage systems, disc breaks, water cooling are what made all previous machines obsolete. But as I Don't live in your end of the world, how the locals react, I have no say, I hope you enjoy the build as much as I have. Cheers and good luck . Quote Link to comment Share on other sites More sharing options...
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