IthaDan 

Old news: Murray did that in the 80s-

hairnet

cannot be unseen or unheard

bloodfont

I know this is an old thread, but I'm building a double chainring fixed gear myself and I've been pondering a solution to switching chainrings without removing the rear wheel or changing chain length (2 master links) and then I found the following chainstay, hight adjustable pulley (like a springless tensioner)

So keep the chain (tightly tensioned) on the big chainring and then, when moving it to the small chainring, lift it up on the pulley wheel (remove it from the pulley wheel when on the big chainring).

I will be testing this, but I believe it's possible to do all this using your foot, without dismounting your bike (might need a chainring guide though as I don't believe the foot has the finesse required)

seau grateau

Please take video.

Flatulentfox

You might want to check out this relatively new technology. It seems to have promise as far as changing gears while riding.

Zoroman

Okay. Hear me out:


You will ONLY be in the easy-pedal-gear when you are actually climbing UP hills. The rest of the time you will be I the "standard gear".


Why not just FLIP the HUB and have one small sprocket on one side of the hub (standard gear) and one larger sprocket on the other side of the hub (easy-pedal-gear).


Yes it will take a minute to dismount and quick release hub your rea tire and flip it but why not do this?


I did it and it works great. And I have enough length in my rear wheel drops outs and they are HORIZONTAL so I do not even need a chain tensioner or 2 different chains. One chain works for BOTH sizes of rear sprockets just fine!

bloodfont

I understand your sarcasm but you need a springloaded chain tensioner to use and FD and that is not possible on a fixed gear, it'll rip it of.
Initialy I thought you gave me a link to the Schlumpf 2 speed crankset, which is an option, but expensive

I know the flip-flop hub is an option, but it's a bother in group rides with people with derailleurs. Also it wears out the drouputs (especialy since it's a conversion to fixed, not a track-specific frame).

I am interested though, in what you said regarding the QR, do you use a QR on a fixed gear rear hub? How's it holding out? Have you had any issues?

Zoroman

I love it! I will try to get pictures this evening after work but while still light out. I bought wheels from Wabi, it has freewheel ability on BOTH sides. So I put a 16 tooth freewheel on the normal side and a 22 tooth freewheel on my climbing side. It is a breeze to switch. If you are trying to ride with people who all have gears/ derailers why wouldn't you be riding a geared / derailer? I have both types and enjoy both bikes but a single speed even with a flip flop hub is never going to be a geared/derailer bike and I would not expect it to be, yet it seems you are trying for that. A really, really implausible aspiration.

Flatulentfox

The chain tension that will rip off a derailleur if used with a fixed drive train will also rip off that little chain tensioner you linked to. If you want a variable gear drive train with the convienece of a single/fixed, either get an internally geared hub or crank. Otherwise, just ride it fixed/single. If neither of those work out for you, get a bike with a derailleur drive train.

I don't understand why people are always trying to reinvent the wheel with a single/fixed drive train. The whole point of it is its simplicity and reliability.

Zoroman

Indeed, I share your befuddlement.

ThermionicScott 

Bicycles in particular seem to attract tinkerers that are undaunted by past failures. Once in a while, a person (or company) truly does come up with a better mousetrap, and that is what each bike tinkerer aspires to.

Zoroman

As indicated above it has worked great and been bullet proof. Its a single speed (with flip flop hub) which was successfully used since 1890-ish. It has been ridden around the world by more than a few people.

Zoroman

I just want to add that while my setup is NOT a QR, it loosens with a simple allen wrench (lightweight and small).... and it is FAST!

bloodfont

The pulley I mentioned is not a chain tensioner i.e. it has no spring and no cog, it's just a pulley/chain guide. The chain cannot pull/push it because it has nothing to grab on to.

I do not want to reinvent the wheel but to keep simplicity. It seems simpler to have a double crank and a pulley than to flip-flop a wheel.

Unfortunately my fixie conversion project has changed to a restoration. So I won't be able to test my theory.

true. To grow old making money by doing what you love. It's a nice dream

Zoroman

So a double crank will require a way to shift (i.e., gearing), thus you introduce a derailleur ....Isn't that a multi-geared bike then with at least one half of the complications of the conventional multispeed bike with a front derailleur and a rear derailer?

bloodfont

No, it's just a double crank and a chain guide (pulley wheel), nothing else requried. It's like your 2 cog setup but without having to remove the wheel to switch between them, no extra tools, no turning screws, no derailleurs, no spliting the chain

Zoroman

So to switch "gears" you get off the bike and pull on the chain with your fingers to lift it off a setting to change the chain location from one crank (sprocket size) in the front to the other crank (sprocket size) in the front???

bloodfont

Either that or use your foot, while pedaling, without dismounting

JeremyLC

Just get one of these and mount the shifter somewhere discreet.

bloodfont

Yes, but an IGH costs a lot compared to a pulley which costs next to nothing (can even be DIY)

Zoroman

What???? Now that I have to see!

Zoroman

I really must insist this be put in a different section of this forum.


This whole section is a single speed & fixed gear section. It is NOT a 3 speed section.

JeremyLC

The S3X IS fixed gear. No freewheel. It happens to also have 3 gear ratios.

ThermionicScott 

I have an undying love for @f1xedgear's implementation.

Zoroman

I guess I need my head examined. I have no idea how 3 gears in a 3 speed hub belongs in a single speed section.

I feel like I am in a room with Sean Spicer or Kellyann Conway right now.