twistgrip

A common complaint is that the sharp action of the hall switch twistgrip throttle makes it difficult to hold intermediate throttle settings, especially on bumpy roads where it becomes almost impossible. Here is a quite simple alteration I've made to my Torq which makes control very much easier. On a bumpy level road where it was formerly impossible to hold a steady intermediate setting, the throttle involuntarily snatching the power up and down, an exact unassisted intermediate speed like 15, 16, 17 or 18 mph is easily held constant now. Many of you will be familiar with the two part twistgrip gearchange used by Shimano, SRAM and others for gearchanging on both derailleur and hub gears, and it's this same idea I've used for an entirely different purpose. The photograph shows the modified twistgrip in which only the inner part operates the throttle. You can see that the thumb and forefinger part of the hand turns the throttle, while the remainder of the palm can hold the static outer grip and provide exact registration of the chosen position.

The throttle spring tension is now held only by part of the hand and it can become a little tiring to hold it at full throttle all the time, so there's an incentive to relax a bit and use lesser throttle openings whenever possible. That should automatically help to maximise the range in many circumstances.   In use I find the better control a great improvement, but in case some might feel differently, I've made the mod reversible.

Here's the instructions, which you should follow closely if you want to be certain of easy reversibility.   Tools you will need are an allen key for removing the throttle, a thin bladed screwdriver with blade at least the length of the twistgrip rubber, a hacksaw, some scissors and a small craft knife. Materials needed are twistgrip rubbers about which more later, and some insulating tape, preferably self amalgamating as here.   To start the job, first carefully cut away the outer insulating layer from around the throttle connecting plug, then press on the latch and release the connector. Now use the allen key to remove the throttle from the handlebars.

Use the craft knife or small scissors to carefully cut out the end disc of the twistgrip rubber, cutting from the end internally by following the inside of the handlebar. Retain the circle you cut out. Now insert the thin screwdriver blade under the twistgrip rubber and carefully work it through to the end, taking care not to pierce the rubber. With the blade through, run just a little soapy water down alongside the blade, you won't harm any electrics, then rotate the screwdriver so that the blade gradually revolves around the twistgrip and breaks the rubber's grip on the surface. Withdraw the screwdriver blade and you will now be able to work off the twistgrip rubber by twisting it.

Now take the twistgrip and measure 45 millimetres along the plastic handle tube from the edge of the control head of the twistgrip and mark it. This will be the twisting section as seen in the photograph. Use the hacksaw to cut through the tube at this point, taking care to keep the cut exactly at right angles. Clean up the end of the cut, and keep the offcut piece of plastic tube which will also be about 45 mm, you'll need it if you want to revert to the standard twistgrip.

Now to add a section of twistgrip rubber to the cut off short twistgrip tube, but it can't be the old rubber which we need intact for now. I've used a piece from an old short twistgrip, but if you're starting with a new standard 22 mm rubber grip, it needs to be a flexible one since it needs to expand to the 30 mm diameter of the twistgrip. If in difficulties with this, a motorcycle dealer may have a more suitable rubber. Once the rubber's fitted and trimmed to length, put aside the short twistgrip for the moment. On the bike's handlebars, move the left hand brake lever inwards by 25 mm, also shifting anything else that might be against it, like the bell.   Now fit the short twistgrip up against the brake lever in it's new position, reconnect it's plug and insulate it, preferably with self amalgamating tape as mentioned above

Offer this up to the handlebar with the blind end correctly oriented, then mark the point at which it needs to be cut. Carefully cut it at right angles, slightly moisten it internally and slide the grip onto the handlebar so that it's up against the twistgrip section but not binding it's action. Now the finishing touch. Take the original handgrip rubber, offer it up and cut it to the length of the outer grip rubber, then fit it over the rubber, it will fit on easily and will soon grip the inner rubber. Keep the short piece that you just cut off. Now take the end circle that you cut out of the original rubber grip right at the beginning, apply some rubber solution to the edges and face of that, and also to the edges of the fitted end section. When the rubber solution has dried to tacky, register the disc and press it back on. When it's set, take the bike out and revel in the new degree of controllability you now have.

If you decide you want to revert to standard, remove all the twistgrip rubbers and reposition the short twistgrip to it's original point. Fit the short cutoff of the original rubber grip that you kept onto the inner end of the short twistgrip Take the cut off hard plastic twistgrip tube that you kept and slide it onto the handlebar end, then join it to the inner tube section with a single turn of pvc insulating tape without any overlap. Finally take the long section of the original rubber grip, moisten it internally slightly and slide it on, butting it to it's original section. The longer section of rubber grip will overlap the cut in the plastic tube and the twistgrip will feel and act as it did originally.