do shift kits make you go faster?

happyjourney

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I know they deal with hills better but due to the fact that there are so few teeth on the smallest rear sprocket does that equate to faster top speeds?
 
Top speed is the Holy Grail among a lot of people. Top speed is limited by incline of the road, how much wind resistance you encounter, altitude, and the displacement of the engine. When the torque out of the engine equals the resistance of these four factors, your speed goes no faster, regardless of the number of teeth utilized in the rear sprocket.

Like a four-wheel vehicle, with a downhill, strong tail wind, or big engine, you can go faster in higher gears. In lower gears, the engine becomes the resistance. You have seen big trucks go down long inclines (well, maybe not in Florida). In Colorado, engine braking is mandatory to avoid runaway trucks. (Lets see.... a 9,000 gallon gasoline tanker with no engine brake nor friction brakes doing 120 mph equals.... a lot of excitement.)

There are all kinds of fun comments from some writers how fast their bicycle went, like one who claimed 65mph (while it was strapped to the back of his pickup truck on the interstate.)
 
They can make you go faster but my shifter kit allows me to climb any hill that Colorado Springs has to offer and I am geared to max out at 25mph in 7th gear.
 
In my experience with my ht shift kit bike, yes top speed is much higher. I have yet to go wot in 6th gear until it stops accelerating. It just feels toooo fast for an old huffy style bike. I think a Hawaii member does 50mph on his!

The biggest advantage is hill climbing and a lower cruising rpm that draws less attention and vibrations on the unbalanced ht.

What speed do you feel is ideal for you?
 
I know they deal with hills better but due to the fact that there are so few teeth on the smallest rear sprocket does that equate to faster top speeds?

The smallest sprocket is like overdrive. Mine is 12:1, which is like a 29-tooth rear sprocket for Happy Time engines.

My first gear is 37.09:1, akin to an 89-tooth rear sprocket for HT.

Second gear is 28.36:1, like a 68-tooth sprocket.

Acceleration is very quick, which gets you to the same top speed as a single 29-tooth sprocket, only faster.

JMO, there are very few engines with 76mm clutches or Happy Time engines which can produce enough torque to make use of 12:1 gearing.
 
Hi guys, my expeariance with a shift kit is that they do give a little more speed, but not heaps. These motors just aint got enough torque. I have 66cc mild port widening/ramping, rocksolid head, sbp chamber, vm 16 mikuni, homemade cdi (thankyou Jaguar), sbp jackshaft & shimano hyperglide 32(?) thru to 11 & I use 11 tooth of the jackshaft for less angle of the chain. The motor has 4 & 1/2 tanks of fuel thru it since I put all new bearings except big end & piston & rings so it'll loosen up more yet, but I can get 67kph max at the moment, til I hit a headwind or incline. And that aint maintained speed. I use 6th of 8 gears as top. Cheers
 
The others have answered quite well and it's a question we get all the time.

Just throwing a shifter kit on does not mean your top speed will automatically increase. For example, if your engine is running poorly before, it certainly won't improve with a shifter kit. If your engine is running well and you have a small bolt on sprocket with gears higher than than your bike sprockets, then you PROBABLY* won't have a higher top speed, but you will certainly accelerate much faster.

It bears repeating - there is a LOT more to speed than just a small rear gear!

*even here it depends - if a lower gears gets your engine into the power band, then you could go faster!
 
A shift kit makes my bike MUCH faster going uphill! As for straightaways, I'm a little slower then folks who run small single speed sprockets in the rear.

My riding is mostly on dirt trails with some hills so a shift kit is a lifesaver.
 
question- Why doesn't any of the successful motorized bicycle racers have it on their bikes? Are they just dumb? NO. More sprockets/bearings/chain means more resistance to forward motion. They select the gearing they need for the track they will race at and just go with it.
The advantage for us non-racers is being able to climb hills better and achieve a good top speed. I myself don't need it because my motor is maximized in every way and it achieves a good power range without the crutch of a shift kit. But if you need it then buy it!
 
Jag,
A shifter kit is not a crutch and while you probably didn't mean to be insulting, it can be taken that way.

There is no way even your maxmized machine would be able to climb steep hills up to 12,000 feet and cruise comfortably 25 mph on flat terrain at 6600 feet. Yes, I road my MB climbing from 8000 feet (Almont, CO) feet to 12,000 onto the top of Cottonwood pass. I fell just shy of the summit of the pass when my freewheel failed. It was my fault, my standard freewheel was acting up for a while and I didn't have the desire to replace it with my HD once just yet.

For racing, i agree...a single speed in its simplicity is probably best.
 
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