Replacing 3 Cog Sprocket For A Smaller Single Freewheel

[The Mighty Volt]

Hi all.

As some of you may know, I am planning to build my A123 packs into the frame of my Raleigh Chinook Bike.

Unfortunately this means I have to reach a compromise for space. The derailleur and 3 cog sprocket must go, being replaced by a smaller single front freewheel.

Does anyone have any suggestions as to how I should go about this, what tools I will need and what freewheel I should get to replace the 3-cogs?

The theory behind removing the derailleur and large 3-cog is that they, basically, are in the way and are preventing me from utilizing the maximum frame-space available.

I have been tempted to rip the lot of it out, but that's a bust. It defeats the purpose. I want an electric bicycle, so I need some pedal propulsion at least.

I figure 8 gears are better than none.

 

[jdcburg]

MV - If you are in the US, SickBikeParts http://sickbikeparts.com/catalog/catalog.php has everything you need to replace your front chainrings with a freewheel one. You'll have to shop through the catalog for parts for their shift kit. They can also sell you a longer BB spindle if you need width in the frame. Jim@sickbikeparts.com is a great resource if you need him - jd
ps - If you can get the rpms low enough, you could even drive the bike through the chain and rear derailleur. I did it with my mtb and I've been happy with it. Lots of power for the hills and speed on the flats. All from 24V 350W

 

[amberwolf]

The derailleur and 3 cog sprocket must go, being replaced by a smaller single front freewheel.

Keep in mind that if you use a *smaller* front chainring than the size of the ring you typically pedal with (or intend to ride with using the motor), you will only have pedal-assist up to the speed you are willing to windmill your feet at to keep up. Assuming that you dont' change anything on the rear cassette to give smaller rings back there, of course.

Let's say you usually use the middle ring, and it's 38T. If you were to use a (common size) 18T freewheel (on a crankshaft adapter), then the max speed you will be able to pedal at with the same cadence will be less than half of the speed you formerly did so with the 38T.

If you usually rode with the big ring, say a 48T, you would then only get about 1/3 (0.375x) the speed you used to at the same cadence.

Just some food for thought when considering what size ring to put on there.

Do you *need* a freewheel at the cranks? There is already one at the rear cassette, so unless you are driving the chainring with the motor as well as the pedals, there's no need to freewheel the pedals too.

what tools I will need

Usually the only specialty tool needed, assuming you have to take the cranks off, is a crank remover. I think I bought mine for $10 or $15 a year or two ago, and it has been invaluable in salvaging stuff from bikes, as well as customizing my own.

Allen wrenches, usually 5mm, are typically needed to get the chainrings off a spider, but some use other fasteners.

Channellocks or similar can be used to remove the BB lockrings and nuts and bearing cups if you must do so to change out the BB crankshaft for a longer one. Some bikes won't work with that method and require a splined tool to remove them, but I've found on several that a standard cassette-removal (freewheeling type) tool fit their BB cup splines well enough to remove them! So if you have one of those, it might work fine without buying another tool.

The theory behind removing the derailleur and large 3-cog is that they, basically, are in the way and are preventing me from utilizing the maximum frame-space available.

If you only remove the derailer and the left and center rings, leaving the outer one, would that give you the space you need? If not, you could get just the long crankshaft from SBP above, and use that to put your large ring farther right to give more clearance; maybe that would give you the space without taking away your ability to assist at higher speeds?

 

[The Mighty Volt]

MV - If you are in the US, SickBikeParts http://sickbikeparts.com/catalog/catalog.php has everything you need to replace your front chainrings with a freewheel one. You'll have to shop through the catalog for parts for their shift kit. They can also sell you a longer BB spindle if you need width in the frame. Jim@sickbikeparts.com is a great resource if you need him - jd
ps - If you can get the rpms low enough, you could even drive the bike through the chain and rear derailleur. I did it with my mtb and I've been happy with it. Lots of power for the hills and speed on the flats. All from 24V 350W

That's pretty much what I intend to do- widen the arrangement at the bottom to take account for the filling-out I will be doing in the middle of the frame, so I don't wind up like a cowboy on a pregnant horse, trying to bow my legs onto the pedals!

Thanks for the link, I will check them out.

 

[jdcburg]

Also Cyclone-tw sells an offset BB spindle that is 156mm if that would work better for you. For the Cyclone they want the offset on the left but I flipped it over so the offset is on the right and it works fine. That gave me enough room to put 2 freewheels on the chainrings - 1 for the motor and 1 for the cranks - jd

 

[The Mighty Volt]

Also Cyclone-tw sells an offset BB spindle that is 156mm if that would work better for you. For the Cyclone they want the offset on the left but I flipped it over so the offset is on the right and it works fine. That gave me enough room to put 2 freewheels on the chainrings - 1 for the motor and 1 for the cranks - jd

Thanks for that.

I basically just want one rear cog and one front cog.

It's important I want to be able to make it look like I am pedalling when I am in the public view.

Also I need something to rest my feet on when giving it revs.

 

[jdcburg]

MV - I see SBP now has their own 156mm BB spindle and a 206(!)mm cartridge BB if you really need some width. Did you figure out what else you will need for the conversion? It depends on what type of BB you have now. If you have a cartridge, you can buy the 153 or 206 replacement cartridge if you think they might work for you. You can also replace the cartridge with cups, bearings and a spindle using their kit if you want to go with the 134, 135 or 156 spindle. If you already have cups and bearings, you can probably just buy a spindle. One other thing you will need to know is if you have a 68 or 73mm BB. That's the width of the BB. I'm sorry I can't remember how to measure it (what points to measure between) but your LBS or probably Sheldon Brown's pages will tell you.

I don't think you will need the HD freewheel. The 2 smoker guys do because they have to stand on the crank to kick over the engine. You should get the crank tool as AW said. If you are going to use a cartridge, then get the cartridge tool, otherwise your LBS can take the cartridge out for you. You don't need special tools for cups and bearings. Check out Sheldon Brown's pages for instructions on removing/installing/adjusting the BB spindle. You need to use SBP's cranks, freewheel (FW) and chainring. They have different size chainrings. I use the 44T and can comfortably keep up pedaling to about 30 mph with a 33 to 11 rear cassette and 26" tires. You won't want the chainring hardware kit as the bolts are too long (sized to bolt 2 chainrings together) but you might want to go with nyloc nuts or loctite when you bolt the FW to the chainring. The FW lube is probably worth it. Keep us posted and send in the questions as they come up - jd

ps you'll probably need a FW tool as well

 

[The Mighty Volt]

MV - I see SBP now has their own 156mm BB spindle and a 206(!)mm cartridge BB if you really need some width. Did you figure out what else you will need for the conversion? It depends on what type of BB you have now. If you have a cartridge, you can buy the 153 or 206 replacement cartridge if you think they might work for you. You can also replace the cartridge with cups, bearings and a spindle using their kit if you want to go with the 134, 135 or 156 spindle. If you already have cups and bearings, you can probably just buy a spindle. One other thing you will need to know is if you have a 68 or 73mm BB. That's the width of the BB. I'm sorry I can't remember how to measure it (what points to measure between) but your LBS or probably Sheldon Brown's pages will tell you.

I don't think you will need the HD freewheel. The 2 smoker guys do because they have to stand on the crank to kick over the engine. You should get the crank tool as AW said. If you are going to use a cartridge, then get the cartridge tool, otherwise your LBS can take the cartridge out for you. You don't need special tools for cups and bearings. Check out Sheldon Brown's pages for instructions on removing/installing/adjusting the BB spindle. You need to use SBP's cranks, freewheel (FW) and chainring. They have different size chainrings. I use the 44T and can comfortably keep up pedaling to about 30 mph with a 33 to 11 rear cassette and 26" tires. You won't want the chainring hardware kit as the bolts are too long (sized to bolt 2 chainrings together) but you might want to go with nyloc nuts or loctite when you bolt the FW to the chainring. The FW lube is probably worth it. Keep us posted and send in the questions as they come up - jd

ps you'll probably need a FW tool as well

Wow, thanks for all that. Thanks to Amberwolf too!

Here is what I have decided to do: I will remove the existing set up, and photograph everything.

Then I will report back and we can see what stuff would best suit the bike. I like the extra wide spindle a lot and it seems cheap.

 

[The Mighty Volt]

Hello again Gents....here is my latest progress report on this matter.

I have persevered with the frame build, I now nearly have all the A123 I need, just waiting for a delivery.

I bought this off Ebay, and used it today, with success, it is a cheapo crank puller. I soaked the crank bolt overnight in WD40/Plus-Gas and then bust a nut today to get it to come off.

This is what I was faced with once the crank came off

I see the flat, rusty plate has some sort of a "shape" to it....two flat sides and two rounded sides.

I am guessing that this needs to come off now to reveal the next part of the puzzle, or does it?

I wouldn't say the Spindle in it is any bigger than 135mm, which is standard I'll bet.

The sickbikeparts.com spindle seems to be different to mine, and they warn that it will not work with a "HD Freewheel"...the ends of the spindle have a collar on them whereas mine are straight/flush.

So anyways...what should be my next step? Thanks!

 

[The Mighty Volt]

This, by the way, is the freewheel I took off.

One idea I did have was to mount it in a clamp and use a hack-saw blade to take off the two smaller cogs, as these are the really offensive ones, in that they get in the way of any completed build.

Does anyone see anything which would alert me as to any issues I might have when choosing a spindle from sickbikeparts.com?

Do the front freewheel and the rear cassette always need to be in a perfect straight line with each other?

Also, if I go for a single front-freewheel, I am guessing it is safe to now remove the front derailleur, and still have the use of the rear cassette gears which are built into the X5304

Thanks again for all your help.

 

[jdcburg]

That looks like a cup-and-cone bottom bracket (BB). The spindle should spin easily but not have any side to side play or a grinding feel. If you are putting on a new chainring and cranks you can check now and see if they will fit. If you need to replace the spindle with a longer one or if you think the bearings are bad or need grease, you should do that now. You should be able to put an adjustable wrench on the flats of those outer parts (cups) and turn them out quite easily. IIRC the right hand one (with the bike right side up) will be LH thread. In any case, they should be independent of each other so you don't need to hold one to turn the other. On my bike the left one looks smaller because it has no flange. The bearings will probably not be loose in there but contained in a ring, but if not they will all come out onto the floor. Once you get one side out you can slide the spindle out and then remove the other side along with its bearings. At some point you should measure the width of the BB between the cups. It will be either 68 or 73mm. If you are replacing the spindle you will need to know that. Don't be afraid to get a new cup & bearing set. They are pretty cheap and it's easier to do it now. You can get one from SBP or your LBS. Keep everything clean and grease it well. You can clean the inside of the BB with mineral spirits then dry it well. Putting it back together is the opposite. Getting it the right tightness is something of an art. I tighten the side with the flange on it with a wrench, then tighten the other side down by hand and then with a wrench until you can just feel the bearings being squeezed a little too tightly. Then I back off a frog's freckle. It should spin freely but not have any side to side play. You can also read about it at Sheldon Brown's BB page. Then attach the FW to the chainring and thread that assembly onto the right crank. Mount them on the spindle and tighten the bejesus out of 'em. Recheck the feel of the spindle in the cups. If it feels loose or tight you may have to remove the crank on the non-flanged side (it's the left on my bike) and adjust it again, then replace the crank and recheck it. Good luck and keep us posted - jd

ps you need to remove the other crank as well. Also you will need a chainring from SBP to attach to the freewheel. You won't be able to attach the old chainring to the freewheel

 

[jdcburg]

You need to maintain alignment to keep the chain from coming off the front chainring, like it is trying to shift to a smaller sprocket. You may be able to use the front derailleur for that. I used a roller (see image below) when I put the wide spindle on mine. It's only in contact with the chain in the bottom 3-4 gears - jd

 

[jdcburg]

Also from the measurement of the BB in one of your images, you have a 68mm BB - jd

 

[jdcburg]

Also you need the SBP cranks, as they are threaded for the freewheel to attach to. So to reiterate, you need a crank set, chainring (specify size), freewheel, BB spindle for 68mm BB (158mm long), and maybe a cup and bearing set. Also some grease, the right tools and some time. I'll try to answer the questions as they come up - jd

 

[jdcburg]

Wait, what you are referring to as a "freewheel" in your images is really a chainring and right crank. There is no freewheel there. A freewheel will allow the chainring to spin in a forward direction without the crank(s) turning. There is also a freewheel in the rear cassette so the spinning rear tire/wheel will not turn the chain. Do you really need a freewheel in the front, at the cranks?

 

[The Mighty Volt]

Wait, what you are referring to as a "freewheel" in your images is really a chainring and right crank. There is no freewheel there. A freewheel will allow the chainring to spin in a forward direction without the crank(s) turning. There is also a freewheel in the rear cassette so the spinning rear tire/wheel will not turn the chain. Do you really need a freewheel in the front, at the cranks?

Hi there, yes, you are correct, I am using the wrong terminology, sorry. I want to take the crank+ chainring and cut the two smaller-diameter rings off with a hacksaw blade. This frees up space between the existing, remaining chain ring and frame, get's the derailleur out of the way {eliminated totally} and clears up room on the handlebars, now that there is no need to change gear at the front chainring.

Then I want to fit a better and bigger spindle, one which allows the pedals and crank arms to clear the new box/body I am building into the frame of my bike. At the moment the current spindle offers less width than is necessary, and it also rocks a lot in the housing, too much play.

Thanks for your very helpful posts, right now I am just trying to digest them and make it all make sense.

Thanks again! I will keep you updated!

 

[amberwolf]

Hi there, yes, you are correct, I am using the wrong terminology, sorry. I want to take the crank+ chainring and cut the two smaller-diameter rings off with a hacksaw blade.

Ah...you might want to check carefully before doing that: Those two smaller rings are usually what the bigger one is bolted, riveted, or welded to.

It may be possible to remove the rings of teeth on them, but it is unlikely to be possible to remove the entire disc of those two chainrings. Typically with swaged-on types like in your pic, the smallest two rings are riveted or welded together, (sometimes bolted but rarely), and then swaged thru both of them to hold them onto the crank. Then the largest outer ring (usually not a full disc but really just a ring of teeth with mounting tabs) is riveted/welded/bolted to the middle ring's disc.

So if you remove either of the smaller rings' disc portion, then none of them are attached to the crank anymore.

Worse, if you were to cut thru the crank itself between rings to remove them, then you also remove part of the square-taper mating surfaces, and that reduces the amount of force-transfer area, making the crank weaker, inviting potential breakage of the crank if you really had to stand on it to pedal sometime.


If you find some regular spider-style triple chainring cranks, then you can leave off the smaller ring, but often the largest ring is *still* bolted to the middle one, so you may still have to leave it on there. Sometimes it's not bolted directly to it but may require it to be present to fully engage the entire length of the bolts for the large ring to spider connection (or else you have to use different bolts).

 

[The Mighty Volt]

@amberwolf

That's brilliant. Sounds like I have to go out and buy a dedicated chainring now!

Eitherways I am determined to see this thru.

I want 72v of A123 built into the frame, hell or high water.

I was going to go for 100v+ but it's pointless....I lose the capacity that I was hoping for {20Ah+} and I have also been reading some threads around here, especially this thread http://endless-sphere.com/forums/viewtopic.php?f=3&t=6615 and also I have taken on board comments about the type of Fet's in the controller of my choice.

Initially I thought the 4115's were the business, now I have been given reason to believe that the 4110's offer the same degree of usefulness with improvements in efficiency.

Ironically, when it is all said and done, I will probably end up back using the same old generic Crystalyte controller, though I hope not.

 

[jdcburg]

Is it possible with the wider spindle (156 or 206) that you could leave the other chainrings on, even if you don't use them? - jd

 

[The Mighty Volt]

Is it possible with the wider spindle (156 or 206) that you could leave the other chainrings on, even if you don't use them? - jd

Well this is the issue I was wondering about....{no pun intended}

If I use the wider spindle and the wider spindle causes the chainring to be pushed "wide".........then the {front} chain ring is no longer in line with the rear cassette and this can be problematic.

I had this ideal notion that the chainring could be left in it's original position with the pedals/crank forced wider of the frame than they hitherto had been, but basically the pedal, chainring and crank are all one and the same on the drive-side.

Force the crank/pedal wide, and you force the chainring wide with it. Force the chainring wide, and you are out of line with the rear cassette.

:?

 

[amberwolf]

Right. This is part of the problem I had with CrazyBike2's drivetrain (on the left side, with the motor and pedals input to the jackshaft side of the main drivetrain), and why I wanted to make that adapter that Thud did make for me, so I wouldn't have to deal with all the stuff that you're pondering right now. The way Thud made it, I can also move the chainrings wherever I want them on the right side, although I have to make my own chainring adapter to the jackshaft itself, since it isn't a square-taper (in this case, an advantage to not be, as you are finding).

Now, in the case of a spider, you do actually have one more option. You could make an adapter ring, out of the flat bottom of a saucepan if necessary, and stick the largest chainring where either of the smaller ones normally bolts to.

 

[jdcburg]

I got the 158 from Cyclone because SBP didn't have them at the time. It is offset, designed to have the offset on the left. I needed the extra space for 2 freewheels on the right so I flipped it over. Because of my interlocking freewheel design, the main drive chain has to be the outboard one so I need the roller to maintain alignment in the granny gears. Anyway, I just went out and measured the spindle protruding (without removing the cranks). On one side of the BB it's about 25mm (1 inch) and about 60mm (2.25 inches) on the other. If you put the offset on the left, the one inch would be on the right, That looks close to what yours is so there may not be a problem at all. BTW, I barely noticed the wider spindle or the offset and I pedal all the time.

I think the SBP spindle is the same. You could email jim@sickbikeparts.com if you have questions. He is a partner but also a bike mechanic, so he knows about bikes. You could also check with him about the measurements of your BB (68 or 73) so you get the correct spindle. When I was building mine, he was very helpful and answered my questions the same day - jd