Convert 21 speed to 1 gear

[Keith Pegg]

What parts do I need to convert my 21 speed E 29" bike to one speed. Or is there a kit to do so. I live in an area that has no hills so I use my PAS in high gear only. Maybe a link or company to help getting ready to service my two year old bike and set up for spring again.

Old man on the Beach

 

[motomech]

You probably have a screw-on free wheel mounted on your motor and although there are screw-on single speed's that attach, the smallest gear avail. is a 16 T. Too small to be useful to pedal along unless you mount a really large "roadie" sprocket on the frt. But, most often, they won't mount on mountain bikes because of clearance issues. Also you need to rig up some sort of chain tensioner and probably a different length chain. All in all, not worth the trouble.
For my rear hub motor system, I(like most here)use a DNP free wheel which has the smallest small gear(11T) w/ a 48T frt. This combo allows useful pedal input into the low/middle 20's mph.
What I have done in this pic, is to cut off the largest gear, although in the past I have cut off as many as 3 gears. It lightens it up a little bit and looks kinda cool.

The free wheel is still heavy, but then again, the motor is more so and the free whl. weight probably isn't much of a factor.

 

[boogieBeats]

Hello,

I'm assuming you can do the math to figure out if your gear ratios will work out. If not, I'll be happy to explain.

If you want to do a single speed, you'll need a way to tension the chain. From the picture I believe you have vertical dropouts.
You'll need something like this.

http://surlybikes.com/parts/drivetrain/singleator

Many friends of mine use this racing their MTB's. It works well. $50 seems to be the going rate.

You can also use a derailure as shown above as a single speed tensioner. It certainly works. You can set the limit screws to lock its posistion, or use a small piece of cable to get the position right. The surly has one less pulley, and in my mind, one less thing that needs cleaning and lubricating. Depends on budget really.

It also looks like you have a free wheel. I just looked at the quality bikes catalogue at my local bike shop last night. 16, 17, 18 tooth freewheels are available. Also, consider centering the hub and re-dishing the wheel to get a better chainline. Otherwise, you'll have a bunch of rack in your your chain.

If do you have a cassette free hub, you have more choice for gears and can get the chainline right with spacers. The surly sprockets cost more money, but I've found they hold the chain much better than old cassette cogs cut apart.

 

[2old]

The reason the single speed sprockets have better chain retention is they don't have shifting ramps like geared ones. I've had at least three bikes (vertical dropouts) with a "magic ratio", that is the chain was perfectly tight without a tension device. There are some freewheels which can be dissembled and some of the gears replaced with spacers if your system has a freewheel.

 

[amberwolf]

You probably have a screw-on free wheel mounted on your motor and although there are screw-on single speed's that attach, the smallest gear avail. is a 16 T.

I have a 12T that came on an MXUS from Neptronix; I think originally it came from Kinaye? If so I'm sure you can find it in his for-sale thread(s) on ES.
https://endless-sphere.com/forums/viewtopic.php?f=2&t=67833&p=1237062&hilit=12t#p1237062

 

[wesnewell]

What parts do I need to convert my 21 speed E 29" bike to one speed.

You don't need any parts. Just leave it in the gear you want.

 

[dogman dan]

You need two short pieces of baling wire. As said above, just leave the bike in the gear you like best.

You can ditch the cables and shifters though. Replace the cable with 4" of baling wire. Put the shifter in the gear you like by hand, then bend over the wire to lock it there. This way, the front derailleur remains as a chain guide, and you won't have to have it drop to low on a bump from time to time, and you get to keep the rear one, as a chain tensioner.

The rear gear can do this in the highest gear without the wire, but put one on in case you find you want a lower gear in the case of a breakdown.

Now your bike is clean, and the bars empty of all but brake levers.

 

[Keith Pegg]

Thanks for the help, I have some ideas now and a lot to think about, My bike is fun and built two years ago I keep adding and changing things as I go, Drives my wife crazy.

Old man on the beach

 

[boogieBeats]

You need two short pieces of baling wire. As said above, just leave the bike in the gear you like best.

You can ditch the cables and shifters though. Replace the cable with 4" of baling wire. Put the shifter in the gear you like by hand, then bend over the wire to lock it there. This way, the front derailleur remains as a chain guide, and you won't have to have it drop to low on a bump from time to time, and you get to keep the rear one, as a chain tensioner.

The rear gear can do this in the highest gear without the wire, but put one on in case you find you want a lower gear in the case of a breakdown.

Now your bike is clean, and the bars empty of all but brake levers.

Good idea!

I just realized you could use the adjustment barrel to catch the ball end of a shortened shifter cable. One could tension the derailleur it as needed for the gear, then fine tune the chain line with the barrel.

 

[dogman dan]

Ahh,,, that's another good idea. Old junk cables still fine for that use.

You could still change the gears with a wrench then. I just have that desert rat mentality, baling wire fixes nearly everything.

 

[Ykick]

Sorry to play Debbie Downer here but sooner or later, if you do any meaningful pedaling through the smaller cogs on threaded freewheels you’ll eventually discover the inherent weakness of a freewheel hanging on the side cover of hub motors.

I’ve broken 2 9C/clone side covers recently. Reason being there’s no bearing supporting the outer cog of a threaded freewheel. So whenever you pedal aggressively (standing on the pedals for example) you’re applying a helluva large amount of leverage force to the side cover where the freewheel threads attach to the motor.

Like any sort of metal fatigue - do it enough and it will fail.

These recent events shattered my previously held belief that DD motors were so “reliable”. Pros and cons to everything, I suppose?

Cassette freewheels use a bearing supporting the outermost cogs of the gear cluster. But unfortunately, there’s not too many hub motors that provide cassette freewheel option.

Hallomotor found on eBay seems to offer some DD cassette motors but I’m still researching their quality/performance?