Can you still use your shifters?

[pprwngs]

Hello all! I'm new to the idea of building a gas bike. I'm looking to set it up on a mountain bike, but I would still like to use it without the motor at times. I'm wanting to keep my 21 speed twist shifters. Can someone point me towards some info on how to achieve this? Build threads are also welcomed.

Thanks!

 

[KB_UK]

Yeah you can do this no problem, adding an engine doesn't mess with the bicycle gears.

The only problem is that twist shifters are horrible! You won't have anywhere to put them on your bike. Some people throw away the front shifter and but the rear shifter upside down on the left side of the handlebar. It's much better to change to thumb shifters instead.

 

[FurryOnTheInside]

I still use the front and rear gears, allowing me to pedal along with the engine from start-up to very nearly it's top speed, and have a 30T granny ring so that I can get up hills even if the engine breaks down or runs out of fuel.
However the chain and some of the clutch parts will be turning any time the rear wheel is turning because of the fact that the left hand sprocket on the rear wheel is fixed not freewheeling. This isn't too bad, especially if you have a smooth running chain, no tight angle around the tensioner pulley whatsit, and a comparatively small rear sprocket (mine is currently 42T).

Now, personally, since the twist throttle is a bit chunky I decided to put both the shifters on the left hand side. I changed the front shifter to a SRAM one that uses two thumb buttons rather than thumb and forefinger, and I changed the rear shifter to a Shimano compatible gripshift (inverted) so that I can operate both with the same hand.

Left side controls

• FurryOnTheInside
• Sep 25, 2017

I have my controls hooked up now. Left hand does the front and rear SRAM indexed shifters for...

Left side controls, again

• FurryOnTheInside
• Sep 25, 2017

Just a view from the other side. The SRAM front gear shifter is rotated around a bit but that's...

Big triple chainset

• FurryOnTheInside
• Sep 26, 2017

Truvative Touro, a damn decent chainset on any bike. Lightweight but strong crank arms and the...

Wide straight bars

• FurryOnTheInside
• Sep 25, 2017

720mm bars, little sweep. The grips I got actually overhang the ends of the bars a bit so it...

 

[Frankenstein]

Those double levers are just killing me.

 

[crassius]

I like cruisers for comfort, but I replaced bars to get them higher and shorter - used a dogbone for shifter even though I have only shifted gears maybe once in 5 years.

on a mntn bike I built, there was room for both used for 21 speed

 

[KCvale]

I like cruisers for comfort, but I replaced bars to get them higher and shorter - used a dogbone for shifter even though I have only shifted gears maybe once in 5 years.

on a mntn bike I built, there was room for both used for 21 speed

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Just because there is room for a front derailleur doesn't mean you should install one.
I remove it to free up space and UN-complicate the bars.
Just put the front chain on the sprocket you want.

 

[FurryOnTheInside]

Just because there is room for a front derailleur doesn't mean you should install one.
I remove it to free up space and UN-complicate the bars.
Just put the front chain on the sprocket you want.

What happens when you get beyond the speed where you can pedal effectively using that gear? Do you have to pull over, stop, get off the bike and manually move the chain up onto the next gear? Doesn't that make it difficult to get going again?

 

[Frankenstein]

What happens when you get beyond the speed where you can pedal effectively using that gear? Do you have to pull over, stop, get off the bike and manually move the chain up onto the next gear? Doesn't that make it difficult to get going again?

Nobody does that, you are one of the few that will care about the front derailleur on this site. Personally I left mine on the smallest cog for max torque for initial starting, the engine handles er'thang else! With a jackshaft you don't even get that option, you don't keep the chainring.

 

[FurryOnTheInside]

Nobody does that, you are one of the few that will care about the front derailleur on this site. Personally I left mine on the smallest cog for max torque for initial starting, the engine handles er'thang else! With a jackshaft you don't even get that option, you don't keep the chainring.

Well, you don't; but the OP said he wants to keep the functionality of his mountain bike. He asked for some pointers on how to do this.

I would expect its more trouble to remove the existing front derailleur than it is to just leave the derailleur exactly where it is. A mountain bike needs something there to prevent dropping the chain.

 

[gary55]

The one problem I have found with front derailleurs is it gets in the way of mounting the engine. I'm sure this would vary form frame to frame. Once you jack shaft to a Nuvinci you'll never go back. Seamless shifting at full throttle. Run at a idle smoothly without jerking or dying, This is not a light bike but with a little tug on the bars and gassing it you can pull a respectable wheely. I finally grew a pair and tried it out, and it really puts a smile on your face. Effortless cruising at 35 mph. Worth every penny even though it was a lot of them. Oh and Jake I remember you saying you lost the plastic ring that goes between the grip and the shifter. I wound up making one from the plastic top of a spray paint can. Works perfect.View media item 61261View media item 61260