Going Where I've Never Gone: Need basic background info on "single speed" and related components

[RTIII]

Hi All,

I'm not a novice and I'm not an expert on what I'm asking about - obviously! I'm ignorant but not stupid! So you get where I'm coming from, etc, a little bit of background:

WAY back in, oh, late 2016... I think, I got hit by a car while bicycling and kept injuring myself (and making it much worse) while healing - for example, trying to lift a leg over the cross bar on my bike (which survived but for a bent wheel) - and it got bad... SO, I built this e-bike, described here on Endless-Sphere, and seen here:

(The Endless-Sphere page linked to above has nearly all the details about it, if you are curious.)

I got asked about it so often I created Bad Knee Bikes to make them (all e-bikes, of course!) for others... But, I was focused on a particular path... I'm not writing to spam the place, but it's maybe fair to say I tried a standardized product but instead they're all time-consuming, custom one-offs, but, still, they've all been of a "more normal" design like you see above.

So, "that's where I've been."

Now, I want / need to build something very different. Nevermind the details of that for now, I'm a good engineer, good fabricator, just profoundly ignorant of what's out there, since the kinds of parts I am interested in now are nothing I've used before.

I've come here to get insight, please... I used to have someone at BikeWagon to talk to and get advice from, but they've been absorbed by L9 sports and, well, sure, they sell components, but they' don't seem to care about that much, it's hard to hunt their selection, the selection is WAY down, and, worst of all, there's NO real purchasing help available. (If someone knows a well stocked place to buy a wide variety of bike components, like the old BikeWagon used to do, I'd be appreciative for the tip! Where do I get cheap components anymore?!)

Down To Brass Tacks:

I'm asked to make something more or less "from scratch" (damned versatile stuff, that scratch!), and, regarding only the stuff I don't know about, I need to know about crank spindles with, as I see it now, single, small diameter gears, and driven (rear) axles with "fixed" gears, and I'd like to know a little more beyond the minimums here.

So, just the basics, first:

I don't even know the proper nomenclature - the names of the parts - to ask for these fixed gear parts (the kid who answered the phone for L9, who bought or merged with BikeWagon gave TWO DIFFERENT NAMES for the crank spindle assembly, neither of which was I able to use to successfully find the parts!), or how they're constructed or anything - surely the driven gear is not a "cassette!" Does whatever the rear part is or parts are mount to the rear wheel the same way? Etc. ... Pointers of all sorts entirely welcome! Just remember, my blind spot is on

Beyond that, are there gear wheels that just spin or, maybe like a cassette with one gear, only lock in in one direction? The latter seems likely, the former? Not sure! Any gears that afix directly to an axle shaft? Etc.

Thank you very much for any responses.

 

[offGridDownUnder]

Beyond that, are there gear wheels that just spin or, maybe like a cassette with one gear, only lock in in one direction? The latter seems likely, the former? Not sure! Any gears that afix directly to an axle shaft? Etc.

Thank you very much for any responses.

I am not very knowledgeable, but I am playing in this space a bit these days. This search phrase will give you some terms:
Novatec D236SBT Sealed Dirt Jump Single Speed

 

[E-HP]

I need to know about crank spindles with, as I see it now, single, small diameter gears, and driven (rear) axles with "fixed" gears, and I'd like to know a little more beyond the minimums here.

surely the driven gear is not a "cassette!" Does whatever the rear part is or parts are mount to the rear wheel the same way?

Beyond that, are there gear wheels that just spin or, maybe like a cassette with one gear, only lock in in one direction? The latter seems likely, the former? Not sure! Any gears that afix directly to an axle shaft? Etc.

First, just to clarify between fixed gear and single speed, and what you're looking for.

Fixed gear bikes have a rear cog/gear that is directly attached/fixed to the hub. So a "fixie" bike can be pedaled forward, backward, or stop, but can't coast, and sometimes don't have brakes. The ones I see in SF have a tiny caliper brake, because of the hills, but are mainly used for track racing.

Single speed bikes have one rear cog/gear, with a ratcheting mechanism built in (freewheel), plus the cog. The assembly attaches to the hub. A freewheel bike can only be pedaled forward. Pedaling backwards disengages the cog from the rear hub, which allows the bike to coast when not pedaling or pedaling backwards. You can get freewheels with one speed, or with a stack of cogs/gears, up to 7. Note: for multi-gear bikes, in addition to freewheels, there are cassettes. The cassette type of hub similarly have a stack of cogs/gears, but the ratchetting mechanism is built into the hub, and the gear stack/cassette (up to 11 gears) slides on to that mechanism.

From what you said in your last sentence, it seems like a single speed freewheel and freewheel hub may be close to what you're looking for, however I can also see how a fixed gear setup might be used in some applications, so eager to hear more.

 

[RTIII]

Thanks E-HP... I'm in the SF Bay area, too, by the way. ...I've never thought too much of hub motors, but your description sounds enticing! ... If you don't mind my asking, what scale of $$ was your "econo" model?

...THANKS for the help with the nomenclature!

Fixed gear vs single speed. Got it...

Using your tips in a web search (Note, I NEVER "Google!") and found a Sheldon Brown article on the subject! I'd forgotten about him - fantastic information source! ... I first learned of him / his writings some 5 years ago or so - I think Chalo pointed him out to me, IIRC.

That article doesn't cover all I was asking about, at least I don't think so - still have to read it; it's titled, "Fixed Gear Conversions."

I'll take it a full assembly, minus gears, is similar to this - this with a "free hub" for cassetes, of course: I gather that the "single speed" takes something like this for a rear hub, but with shorter splines?

I've seen some of the splined regions without the rest as in this - but it's obviously far from a complete assembly, and I haven't found gears that look like they'd fit yet:

or this:

Of course, these last two images have no spindle for the wheel like that first Shimano unit above. And, I take it that these inner splines seen here engage on whatever the actual wheel hub assembly is, with axle down the middle? ... I don't recall seeing those before! (or this, for that matter!)

Thanks again for the tip! I'm sure I'll be back!

 

[RTIII]

OK, found this!

Given Sheldon's comments, I soon knew EXACTLY what I was after! YAY! And thanks Sheldon and THANKS CHALO for pointing me to his stuff long ago! ...When I saw the name "sheldombrown.com" in the search results I KNEW that's where I could find a wealth of info!

Looks like just the thing, but I'll need the lock-rings and gears, etc. ...It's a start! BTW

Now, it's about the crank assemble - "bottom bracket", I guess, and I'm intrigued by Sheldon's mention of tandems and their "sync chain." ... WAY back in, oh, 1969, my mom brought home a tandem bicycle one day to ride with my father - they never rode it, even once that I can recall, but my sister and I rode it and we with our friends sometimes... BUT I don't remember it well enough to recall if the sync chain was on the opposite side of the drive chain or not! However, I think I want to see what those look like... Hmmm... I'm enjoying the education!

 

[amberwolf]

Note the hub you're showing is a fixie hub (or flip-flop track hub), and has no freewheeling mechanism, so whatever drives the wheel will always be spinning while the wheel spins, and vice-versa, in either forward or reverse directly.

Regarding tandems: The typical way I've seen them is the captain's chain runs on the left side back to the stoker's BB, then drives that BB, along with tthe stoker's input, to output on the right side back to the right side of the rear wheel (making the rear drivetrain from stoker to wheel "normal"). There are other methods, but that is the "simple" one. THere are variations on this one, too, depending on the usage and needs.

SheldonBrown has something to say about these, too:

Tandem Bicycles

An introduction to tandem bicycles.

www.sheldonbrown.com

Tandem Bicycles - Details and Tech Stuff

An introduction to tandem bicycles.

www.sheldonbrown.com

Some thoughts:
--it often matters what the intended usage is for a bike as to what the best way to set it up is. Sometimes someone asks for a type of bike (or assist system) that isn't actually ideal (or even workable) for their usage...but they don't know about other options, and/or may not even have defined their usage, but want something for stylistic or other non-functionality reasons.

Can you get the end-user of this one to provide you with their usage and other parameters, so you can verify that this is really the path they want to go down?

There are advantages to the fixie and/or singlespeed approach, but also some disadvantages that make it less usable, or even unusable (or unsafe), in certain applications.

FWIW, if it's a singlespeed drive, then there's less reason to go with a middrive vs a hubmotor.

A geared hubmotor may be about as light as a middrive, and be as effective since there's no gear changing to make a middrive more efficient under changing circumstances. It won't directly put any wear on the drivetrain, unlike a middrive. (if it's a fixed gear bike it does still wear the chain and sprockets and pedal bearings a bit by forcing them to spin regardless, but it's not putting a load thru them like a middrive would, if that matters to the end-user.

A DD hubmotor might be heavier but simpler, if the reason for the singlespeed / fixie approach is simplicity and reliability (less stuff to break)

If you use a rear hubmotor, and the bike does not have disk brakes (at least on the rear), then you can flip the motor over and use a bolt-on cog (maybe a track cog) back there on the rotor mount, which would then be on the right side.

A front hubmotor doesn't interact with the drivetrain, so that could be any type that works with the fork of the bike.

 

[amberwolf]

I've seen some of the splined regions without the rest as in this - but it's obviously far from a complete assembly, and I haven't found gears that look like they'd fit yet:


or this:

Of course, these last two images have no spindle for the wheel like that first Shimano unit above. And, I take it that these inner splines seen here engage on whatever the actual wheel hub assembly is, with axle down the middle? ... I don't recall seeing those before! (or this, for that matter!)

FWIW, the two images you show there are the two parts of a freehub mechanism (not necessarily the same freehub). The silver one is the internal part that mounts inside the wheel hub (or hubmotor) and drives the hub. The black one is the external part that drives the three ratchets that stick out on the largest-diameter part of the silver one. The sprockets mount on the black one, on it's splines (the threads can be for a lock ring for a single sprocket, etc).

So there aren't any sprockets for the silver item, as it's not intended for them.

The two parts of the freehub together mate to a wheel hub designed for that kind of freehub. It's probably simpler to buy the whole hub together with the freehub, based on the frame size / width of dropouts and the gearing desired, and the type of wheel to be built around it.

 

[RTIII]

HEY Amber! It's been a few years! (I'll write you privately on on why.) ...Always appreciated your comments! (Remember the TS DZ2 motor? I've taken care of my two units, and, with the brass - maybe bronze? - gears swapped for the nylon originals, STILL get maybe 40 miles out of the battery, or even more!)

Yes, I agree, buying the whole spindle and hub assembly is a better call, if you can get what you want. And, I can!

This is a weird build - I'm making the frame myself, from "scratch," and so I get to pick ALL the details. So far I've selected (not yet bought) what I gather is quite an odd selection!

I'm having trouble finding various specifications as I definitely expect as available data in other areas of my work. For example, what's the width of the Shimano Y10416120, fixed gear 16T at the hub? That's just one example. As an engineer, I want to know this stuff as I design, and as this is "uncharted territory" for me... Well?! ... Anyway, I'm getting there, and I'm enjoying the journey - isn't that the best way to go through life?

While I'm doing the fabrication and build, the customer doesn't want me to make details public, such as posting a build-thread here (or elsewhere), but I MIGHT give something of a parts list, of at least the parts that are involved in what I've learned and decided from this thread... I guess that's OK here? ...I'll have a couple of the cranksets used in tandem bikes, for example, but... -eh- ... Would anyone care? IDK.

Anyway, I'm glad to get your input.

 

[tomjasz]

Times flies!

A lousy photo with a MAC motor mounted on a Marin frame. A one-speed, but the spacer for a single-speed freewheel was hard to find and expensive! I actually found a NOS suspension fork on an obscure parts site. Sadly health issues stalled that and several other builds for a couple of years. I believe I've found a motivated 40-something to help me sort the somewhat massive collection of new and unused parts and motors.

 

[RTIII]

Hey Tom, I SURE recognize that frame! What size is it? It looks kinda small. And your seat tube high and stem, too! You'got a build page for it? I'm curious about details.

Meanwhile, my FIRST Marin, the purpleish blue one now has disks AND rim brakes, plus I built-out the electrical system a lot so it COULD be confused for a moped in darker lighting conditions because it even has TURN SIGNALS! ...It's got a flat right now and is in the back of the shed waiting for these f-ing atmospheric rivers to be over with for the season!

And speaking of rain: Just barely more than 24 hours ago ended 27 straight hours of rain in which we got a full 30% of our normal ANNUAL rainfall, this month has brought us 800% ON THE DOT more rain (that is to say EXACTLY 8 times more) than normal for the month, and so far we are at 643.27% of normal annual rainfall for the rainy season (September to June)! WTF?! ...And we're not done yet! There's another Atmospheric River headed this way starting next Monday and is forecast to bring almost exactly an inch of rain more! ...Then, of course April!

This wouldn't be so bad were it not for the fact that the roof has leaks that have been getting worse for the last 20 years and the landlord wouldn't fix them, and now, his widow wants to but is BROKE!

 

[Chalo]

Note the hub you're showing is a fixie hub (or flip-flop track hub), and has no freewheeling mechanism, so whatever drives the wheel will always be spinning while the wheel spins, and vice-versa, in either forward or reverse directly.

Actually, that one isn't for fixed gears. It's a BMX "flip flop" hub designed for a 1.37"-24 threaded freewheel on one side (16t minimum) and an M30x1 threaded freewheel on the other side (13t minimum).

Fixed gear hubs have a stepped thread with 1.37"-24 RH threading at the root, for the cog, and 1.29"-24 LH threads on the outer end, for the lockring. Without these opposing threads, applying reverse torque to the sprocket risks unscrewing it from the hub.

As for the original question, there are two easy ways to set up a multi-speed hub for single speed use. One is to remove the multi-speed freewheel and install a single speed threaded freewheel. The other is to remove the multi-speed cassette and replace it with a single cassette cog and spacers to take up the extra width.

BMX world offers us single-speed "cassette" hubs that use replaceable 8t to 13t drivers that incorporate both the sprocket teeth and part of the ratchet mechanism.

There are also MTB single speed hubs that use a shortened version of a normal multi-speed freehub body. These work the same as an ordinary cassette hub with a single cog and spacers, but the short freehub body allows the hub flanges to be wider apart and make the wheel stronger.

It's possible to mount multiple sprockets on this last kind, up to the limit of however many will fit on the shortened spline.

 

[amberwolf]

Actually, that one isn't for fixed gears. It's a BMX "flip flop" hub designed for a 1.37"-24 threaded freewheel on one side (16t minimum) and an M30x1 threaded freewheel on the other side (13t minimum).

Fixed gear hubs have a stepped thread with 1.37"-24 RH threading at the root, for the cog, and 1.29"-24 LH threads on the outer end, for the lockring. Without these opposing threads, applying reverse torque to the sprocket risks unscrewing it from the hub.

I forgot about that. Thanks for reminding me.

 

[calab]

Fixed Gear Conversions

Fixed gear bicycles are usually associated with track cycling, but many riders enjoy riding them on the road. How to set up and ride a fixed-gear bicycle for road use.

sheldonbrown.com

Its under the Flip-flop Hubs sections about 1/3 down from the top.​

Note, there are two types of hubs called "flip-flop":

• Fixed/free, this is the type I speak of above, with a "track" side and a freewheel side.
• BMX type...BMX flip-flop hubs have two different freewheel threads, a standard one on one side, and a special smaller-diameter freewheel thread on the other, designed to work with special small freewheels (14, 15 teeth.) These are now quite rare, but if you are calling around looking for "flip-flop" hubs, make sure you get the right kind.

Sheldon Brown is a great website.

Have you ever seen a cassette freehub on one side and threads on the other side of the hub, I'd assume for a single speed thread on style. It might be a custom hack job, but it didnt look like it. I am going back in a few hrs and I will snap a picture and look at it more closely. Its a 29/700 rim, like I said the hub looks "not hacked" at all, looks stock, but no markings. Used wheel it is, straight, axle doesnt wobble like the last one that bit the dust last night.
The freehub/cassette side of the hub looks to be the normal width for 6/7/8 gears.
I put a 7 speed freewheel on it and it threaded on a few turns, 2 or 3 times full around.
I do need a better look at it.


The only thing I could find was this, cassette hub meant for spacers for s/s gears on cassette hub. I was going to use it for a 7 speed and not touch the threaded side of hub.

VeloSolo - Anodized Singlespeed Cassette Hub Spacers

VeloSolo - Anodized Singlespeed Cassette Hub Spacers

www.velosolo.co.uk

Going along the lines of this from Sheldon website.

Cassette Hubs​

It is easy to convert a Shimano cassette Freehub ® for singlespeed use. The simplest way is just to remove the derailers, shorten the chain and thread it onto the chainwheel and rear sprocket of your choice. This is less than ideal, however, because you've got the extra weight of the unused sprockets to deal with, and the chainline will probably be crooked. The sprockets used on multi-speed cassettes are designed for easy shifting, which is not a good thing on a bike that isn't supposed to shift! The teeth are short, increasing the risk of cropping the chain.

The better way to convert a cassette Freehub ® is to remove the 7-, 8- or 9-speed cassette and replace it with a single sprocket. You will also need a bunch of spacer washers to hold the single sprocket in place. You can often get a suitable number of spacers by taking apart a couple of discarded, worn-out cassettes.

Having a single sprocket sandwiched in a stack of spacers makes it easy to get the sprocket properly aligned for perfect chainline with whichever chainwheel you choose to use in front.

You can use one of the old sprockets from your taken-apart cassette, but it you are less likely to have accidental derailment if you use sprockets made for single-gear us, with longer teeth. BMX cassette sprockets are best. These sprockets are quite inexpensive, and are available in a range of sizes.

edit
Found lots of info now that I know its tandem hub for drum

Hubs & Cassettes | Tandems East

tandemseast.com

Tandem wheels. — Cognoscenti Cycles

Tandems can be a lot of fun, especially if the two riders are quite compatible. But a tandem is a very specialised bike and it's subjected to significant and unique stresses. This demands a proper design and specific materials. Having worked in the past in a bike shop that hand made custom

www.cognoscenti-cycles.com

 

[Chalo]

The only thing I could find was this, cassette hub meant for spacers for s/s gears on cassette hub.

VeloSolo - Anodized Singlespeed Cassette Hub Spacers

VeloSolo - Anodized Singlespeed Cassette Hub Spacers

www.velosolo.co.uk

Hubs like that aren't for cassette + single speed; they're for a cassette on the right and a drum or band brake on the left. They're for tandems more often than not.

There are similar-looking hubs (all for multi-speed freewheels rather than cassettes as far as I know) that have LH threads on the left. Those are for Currie e-bikes that use pedal drive on the right and motor drive on the left.