Possibly Stupid Question on Front Sprockets

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handyandy1100

handyandy1100

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Had a crazy idea the other day about adding extra speeds to a single speed bike. I know the common method is to change the rear wheel or perhaps just the hub to one with multiple gears.My thought was what if you added a 3 sprocket front sprocket set like from a 15 speed bike and used a chain tensioner or perhaps a rear derailleur to take up the needed slack in the chain to allow a front derailleur to shift the chain over the three sprockets. So you get a very crude 3 speed bike.

I figure it must not work or I would have seen it done before. LOL
 
Rule number one is that there are no stupid questions... :)

Yes, that would work as long as you use a freewheel and not a coaster brake. You'll need a 3/32" chain and a freewheel sized for the narrow chain but it should work fine.

There were a few BMX bikes that tried that setup with a double chainring. The Huffy Z-2 was one of the more popular ones.
 
kingsting said:
The Huffy Z-2 was one of the more popular ones.
Click to expand...
...and the Murray Street Machine...
008_zps5b64bf52.jpg

Jason
 
kingsting said:
Rule number one is that there are no stupid questions... :)

Yes, that would work as long as you use a freewheel and not a coaster brake. You'll need a 3/32" chain and a freewheel sized for the narrow chain but it should work fine.

There were a few BMX bikes that tried that setup with a double chainring. The Huffy Z-2 was one of the more popular ones.
Click to expand...


Oh, okay. I was thinking of using the coaster brake rear wheel that is usually used on one speed bikes. Would the issue just be the differences in the sprockets/chain, or some deeper reason due to the nature of the coaster brake hub?
 
I believe you would truly need a free wheel hub and 3 speed freewheel sprocket to make it work correctly.

I had tried to make 3 speed bmx bike using some odd ball Japanese 3 speed sprocket and derailleur that just happen to fit on a cheapo BMX coaster brake wheel. Unfortunately It didn't work out very well, because every time I went to jam on the brakes the chain would jam up the derailleur, or fall off. Luckily I found a freewheel OGK mag set and used a regular 3 speed freewheel sprocket to make my 3 speed bmx bike run. Although the 3 speeds worked great for leisure cruising, having the chain bounce off after sticking a big jump only to have a bear claw pedal mutilate your leg like a cheese shredder makes you remember why having freewheel gears on a BMX bike without some sort of spring tensioner was one of my worst ideas ever.
 
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clouseau said:
I believe you would truly need a free wheel hub and 3 speed freewheel sprocket to make it work correctly.

I had tried to make 3 speed bmx bike using some odd ball Japanese 3 speed sprocket and derailleur that just happen to fit on a cheapo BMX coaster brake wheel. Unfortunately It didn't work out very well, because every time i went to jam on the brakes the chain would either get jammed up, or just come completely off. Luckily I found a freewheel OGK mag set and used a regular 3 speed freewheel sprocket to make my 3 speed bmx bike run. Although the 3 speeds worked great for leisure cruising, having the chain bounce off after sticking a big jump only to have a bear claw pedal mutilate your leg like a cheese shredder makes you remember why having freewheel gears on a BMX bike without some sort of spring tensioner was one of my worst ideas ever.
Click to expand...


Ouch! Sounds like more fun than I care to have.

I figured there were reasons why I never see this done! LOL
 
I tried that with a walmart Mongoose Beast.

I used an old derailleur as a tensioner and had 3 sprockets up front from another walmart bike with a single speed coaster in the rear. To engage the brakes, the tensioner has to take up all the slack first and then hold the weight of braking. That will bend the tensioner unless it's made very heavy. But the slack in the chain amounted to half a turn on the cranks, so it wouldn't be feasible for brakes.

A freewheel with handbrakes would have worked. My fat bike didn't pan out because there was no way to put handbrakes on it, so I left the chain on one of the chain wheels full time.
 
:doh: I believe I misunderstood your question. Now If you added a three speed crankset to your current bottom bracket with a front derailleur and chain tensioner there's no reason why that shouldn't work. There are a many special needs hand pedal bicycles set up this way so that the person doesn't have to take his hand off the pedals/steering to stop.
 
3 speed frontend, 1 speed rear end with coaster brakes will work?

Sent from my SM-G920V using Tapatalk
 
Nope, it won´t work. Wildcat pretty much explains it all above. Every multipeed handcycle i´ve ever seen with a CB was running planetary gear systems, not a deraileur. You could run an FSA Patterson crank, but that´d cost you far more than a multipseed rear wheel would...
 
What I wound up doing was using the middle chain wheel for an easy cruising gear. I could switch to the next larger chain wheel by adjusting the rear wheel so there would be enough chain. A very manual 2 speed. I couldn't adjust the wheel in the dropouts enough to use the 3rd chain wheel, I would have to add a couple links to the chain, but then the smallest chain wheel wouldn't work, too much chain to adjust for.
If you could use handbrakes, then all 3 speeds with a tensioner would work.
 
I did this years ago, i had to mod a deraileur for the rear so that it would let the chain go straight to apply the brake and then had to mount a spring tensioner on top to take up the slack that was created when pedaled back to apply the brake. it was wanky but it worked..
 
I have been tempted to run a Surly Single cog on a Velosteel hub with a White double-double crank set up, just to do it.... But that's a lot of expense to achieve a range similar to a regular 3 speed hub. Just rocking the Dingle might make sense though.
 

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