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Need a bit of help to get my head around steering mods on a twinshock. I've read about people fitting parallel yokes to alter the steering angle, rather than cutting and re welding frames. Does that not just shorten the wheel base and leave the fork angle the same? Just wondering whats needed to improve steering is it about the rake on the forks or the wheel base? Cheers.

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Buy a twinshock with good steering geometry, like a 200 Montesa or Fantic. They were built for competition and don't need any cutting and welding!

Bikes like Honda Tlr's were designed to be trail bikes or at best dual purpose and hence need modifications.

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Parallel yokes do shorten the wheelbase if the originals were not parallel like on TYs, parallel yokes will also steepen the angle by a certain amount depending on how much the originals were offset by

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It's a TLR200 I'm looking at. Think I'm needing the basic info on offset and parallel yokes. Do these terms refer to the angle of the fork tubes in relation to the head stock? I was thinking parallel yokes meant the stanchions were back in line with the steering head rather than forward of the stem in a v configuration.

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You are right. Parallel yokes means that the tubes and the steering stem are parallel. If the tubes are in the same plane as the steering stem, that is called zero offset clamps. Zero offset clamps may also be parallel clamps.

Angular offset clamps add another degree of complexity/sophistication because they can keep the steering geometry closer to ideal through the suspension travel. In my opinion, Bultaco Sherpa T and Yamaha TY twinshock clamps have a very well chosen amount of angular offset.

The total offset of a front end includes the amount the axle is forwards of the fork tubes centre line, as well as whatever offset is built into the triple clamps, and the length of the forks from top clamp to axle.

It is possible to reduce the steering rake without modifying the frame. The most common method is to lower the front (slide the tubes upwards) or raise the back of the bike (increase the spring preload, or fit longer shockies). Another way is to use eccentric sleeves on the steering head bearings.

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Thanks! That helps a lot. So in the case of the TLR does it start life with off set yokes and steeting that can be altered by fitting parralel yokes or by modifying the head stock angle? Am I right in thinking that if it's done right the frame mod is better as it retains the original off set?

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Tlr200's sit low at the rear so move the bottom shock mounts forward to raise back end. 

Cut frame top tube and pull back front wheel. Fit a 6mm spacer into the top tube gap.

Extend swinging arm 25mm to put wheel base back to what it was before you pulled back the front wheel.

The steering will now be as quick as you could ever need it to be!

 

I did all of the above and it transformed the bike........but it still doesn't steer as well as my cota200 or seeley!!

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Feet up Fun: I never thought of eccentric sleeves, clever.

Check out the below reference link and do note this thread has some good points from others. I have also included two links, reading that will really get you thinking.

The one missing term in the above is trail. The yokes or triple clamps having no offset will negatively affect trail (according to the articles). Changing the rake (cutting the frame) gets a lot of credit for a "transformation", but after reading the articles you may think twice? There are just too many factors. You might look for someone with a bike having these mods already done that you could try?

Check this tread out in the Honda forum:

 

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I've never ridden a cut 'n shut that rode any good....they tuck under or fall into corners in my experience. 

Good friend of mine has a very modified TY175 on mark 5 frame, nothing on that bike is std bar steering geometry. He has tried various head angles but feels Yamaha got it right back in the day. 

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2 hours ago, iconic558 said:

PS I should add original as left factory, some bikes head angles 'fatten out' with use so I'm told? 

It can go the other way if the bike has a head-on crash into something!

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Being quite tall, I always thought the handlebars on my Majesty were too far back. so I cut the bar clamps off the top yoke and machined and welded them back on inline with the fork legs, and it steered a lot better 

 

 

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