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Author Topic: converting bike with gears to single speed?  (Read 787 times)

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Offline paranoidmexican

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converting bike with gears to single speed?
« on: July 26, 2019, 09:05:36 AM »
Does anyone have any experience doing this? I got some free bikes, but the rear shifter doesn't work properly on either bike. Could I just remove all shifters/derailers and shorten the chain, or is getting a new rear wheel absolutely mandatory for safety reasons? These are wal-mart grade bikes that will only see leisurely neighborhood cruises, nothing long distance. (less than 5 miles a day). One bike would have a little trailer my kids could sit in.





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Offline amishrob

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Re: converting bike with gears to single speed?
« Reply #1 on: July 28, 2019, 01:43:18 AM »
just remove all unnecessary parts then find the straightest chainline and shorten to fit there. chain tension may be hard to get right though.

Offline joelite44

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Re: converting bike with gears to single speed?
« Reply #2 on: July 28, 2019, 02:21:43 PM »
If your going to carry a trailer you might as well have gears.

Watch some youtube videos and get these derraileurs going its nothing a few years of experience won't fix.

Offline ediotism

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Re: converting bike with gears to single speed?
« Reply #3 on: July 28, 2019, 08:56:17 PM »
do you mean the whole derailleur is fucked? or just out of maintainence/ adjustments?

the easiest way to learn how to adjust/tune the deraileur to work 'good enough' is just to open a youtube video.

a basic cleaning and some appropriate lubrication, along with some basic adjustments, may make it work well enough depending on condition

Offline paranoidmexican

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Re: converting bike with gears to single speed?
« Reply #4 on: July 29, 2019, 08:43:03 AM »
do you mean the whole derailleur is fucked? or just out of maintainence/ adjustments?

the easiest way to learn how to adjust/tune the deraileur to work 'good enough' is just to open a youtube video.

a basic cleaning and some appropriate lubrication, along with some basic adjustments, may make it work well enough depending on condition

out of the three bikes I have only one has drop outs that let me run single speed. I saw some videos on how to change the cables out, I'm going to give the other 2 bikes a try. believe it or not, this is my first time messing with bikes other than bmx lol
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Offline paranoidmexican

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Re: converting bike with gears to single speed?
« Reply #5 on: July 29, 2019, 03:29:31 PM »
do you mean the whole derailleur is fucked? or just out of maintainence/ adjustments?

the easiest way to learn how to adjust/tune the deraileur to work 'good enough' is just to open a youtube video.

a basic cleaning and some appropriate lubrication, along with some basic adjustments, may make it work well enough depending on condition

so I just changed the cables on one bike, and it wasn't that bad haha.
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Offline ediotism

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Re: converting bike with gears to single speed?
« Reply #6 on: July 30, 2019, 07:16:40 AM »
there are basically 3 screws on a derailleur for adjustments:

a tiny one to set the inward movement limit, i.e. stopping the derailleur being able to move the chain closer towards the hub once it's on the largest cog

another tiny one next to it, to set the outer movement limit, i.e. stopping the derailleur being able to move the chain closer towards the inside of dropout once the chain is on the smallest cog

once you've got those set the chain/cog/transmission change should work regardless of how ghetto it is

Offline paranoidmexican

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Re: converting bike with gears to single speed?
« Reply #7 on: July 30, 2019, 10:54:05 AM »
there are basically 3 screws on a derailleur for adjustments:

a tiny one to set the inward movement limit, i.e. stopping the derailleur being able to move the chain closer towards the hub once it's on the largest cog

another tiny one next to it, to set the outer movement limit, i.e. stopping the derailleur being able to move the chain closer towards the inside of dropout once the chain is on the smallest cog

once you've got those set the chain/cog/transmission change should work regardless of how ghetto it is

aside from some surface rust, the bikes are in better condition than i realized. derailleur didn't need any adjustment, I was having a hard time getting the linear v-brake to work properly, i cleaned and greased the posts but the brake will not hold even tension on both arms or center itself properly.
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Offline ediotism

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Re: converting bike with gears to single speed?
« Reply #8 on: July 31, 2019, 10:52:50 AM »
i cleaned and greased the posts but the brake will not hold even tension on both arms or center itself properly.

for a conventional V-brake, there should be 3 tiny holes on the frame right next to the v-brake lug, and you should see that the coil spring 'slots' into one of the three. they are for you to adjust tension. by slotting the coil spring into different holes you can get different amount of absolute tension, or tension relative to the opposite brake arm. that should give you a set up that works good enough for the arms/ brakepads to stay away from the rim when you're not pulling the brake lever

Offline joelite44

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Re: converting bike with gears to single speed?
« Reply #9 on: August 01, 2019, 05:39:55 PM »
i cleaned and greased the posts but the brake will not hold even tension on both arms or center itself properly.

for a conventional V-brake, there should be 3 tiny holes on the frame right next to the v-brake lug, and you should see that the coil spring 'slots' into one of the three. they are for you to adjust tension. by slotting the coil spring into different holes you can get different amount of absolute tension, or tension relative to the opposite brake arm. that should give you a set up that works good enough for the arms/ brakepads to stay away from the rim when you're not pulling the brake lever

Place the brakes on the middle hole and bolt it to the frame. undo the little screw that tensions the v brake spring and stretch it out.

This is the same spring that is held to the middle hole. Do this so the v brake can have more tension.

Lastly tighten the screw in slightly and which ever brake  (Left or right) needs more tension, undo the contrary screw to carry it in or out.

Sorry for sounding retarded.

Offline ediotism

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Re: converting bike with gears to single speed?
« Reply #10 on: August 04, 2019, 12:05:20 AM »
maybe he should just do footjam nosepicks to stop

Offline paranoidmexican

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Re: converting bike with gears to single speed?
« Reply #11 on: August 05, 2019, 10:48:50 AM »
maybe he should just do footjam nosepicks to stop

got the brakes worked out. funny enough, i really only use my front brake to stop lol
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Offline jonathan

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Re: converting bike with gears to single speed?
« Reply #12 on: August 09, 2019, 08:28:35 PM »
are you still interested in converting to single speed? if the dropout does not allow room to move the axle, you can do one of two things:
find a "magic gear". play around with the cogs on the rear wheel until you find one that works with the front chainring and keeps the chain tight. this is a ghetto, temporary solution. it only works a chain that is worn to exactly the degree to which the current chain is. when the chain wears more or you replace it, it won't work anymore.
chain tensioner. there are a ton of these on the market. A Shimano Aline tensioner might work, but if you remove the cable from a derailer and adjust it such that it cannot move laterally, you've made a ghetto tensioner that will work just fine.

the front rings and rear cogs on a bike that was designed to shift won't hold the chain in one place very well, especially if the chainline is not spot-on.

adjusting shifters and derailers is not difficult. you just have to take a few minutes to understand how to set the two limit screws, set the cable tension so it effectively pulls the derailer across all the gears, and set the b-screw so it spaces the jockey pulleys from the cassette. this is all very simple after a few Park Tool videos.

if the drivetrain is old or out of whack in any way, things won't work so smoothly. you might need to replace cables, housing, or drivetrain parts- a worn out cassette, chain, or chainring won't shift well. make sure the derailer hanger is straight and perpendicular to the center of the bike.

you might be able to remove the left shifter and lock out the front derailleur by cinching down the limit screws on it until the derailer stays in one place, keeping the chain there, probably on the center ring.

all this trouble with front triple chainrings is why most modern mountain bikes have only one front chainring and very few other bikes have more than two chainrings.

for an old road bike with a thread-on freewheel, you can get the chainline close enough to work by rebuilding the rear wheel. replace the freewheel with a single-speed freewheel and swap the axle around so the drive side spacers are on the opposite side of the hub. this will throw the rim off-center, so you'll need to dish the wheel. you might be able to pull this off by adjusting the spoke tension, but you might end up with too much nipple engagement on the right side and not enough on the left. the answer to that is to rebuild the wheel with the spokes on the opposite side of the hub. this is time consuming, but if you're used to building wheels, its no big deal.

if your rear wheel has a freehub designed for a multi-speed cassette, you should buy a single-speed cog (Surly!) and some spacers to line it up with the front chainring. if you can get a hold of some old cassette spacers from a worn out cassette, you can use those too. in a pinch, a carefully selected range of PVC pipesegments will do most of the spacing.

Bikeguide.org - Bike maintenance for BMX'ers

Re: converting bike with gears to single speed?
« Reply #12 on: August 09, 2019, 08:28:35 PM »

 

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