It is occasionally useful to remove a cassette (cluster of gears) to replace a spoke or unjam a chain from between sprockets and spoke. A light and compact lockring tool makes it possible to remove the cassette during a ride.
Originally, the Pamir Hypercracker was the only such tool. However, it is no longer available. More recently, new tools have been introduced, and several non-commercial units were developed as well. This page reviews at least some of the tools developed as of 2008/01, including both commercial and non-commercial units.
Note some hubs can be taken apart and the splined driver separated from the hub shell, all with e.g., a pair of 5mm Allen-head wrenches. Although the sprockets remain connected to the splined driver, the driver separates from the hub, making it possible to replace a spoke or free the chain without a lockring tool.
Circa 200, the Pamir Hypercracker was available as a road service tool. The Hypercracker fit between the lockring and frame, and a "finger" rested on the frame to hold the lockring while the cassette was turned.
The tool is no longer available. It is unclear why, and thus unclear whether buying a used one is a good idea. (There are some reports it broke occasionally; there are also rumors the owner retired and closed the business; it is relatively uncommon to need to remove the cassette, so sales of even a perfect tool will probably be modest.)
From http://www.bikepro.com/products/freewheels/fw_cas_tools.html as of 2008/01:
PAMIR ENGINEERING HYPER-CRACKER
The Hyper-Cracker breaks free the outer lockring on inner threaded HyperGlide cassette hubs. Neither bench vise or adjustable wrench is required for its use. With the rear wheel removed, it slides into the twelve sided lockring star, then the rear wheel is re-installed. Pressure on the cranks revolves the wheel, until a vinyl lever contacts the seatstay, at which point added pressure backs off the lockring. The Hyper-Cracker has a 14 and 15 gauge spoke wrench cut into it, for roadside spoke repairs. Weighs 41 grams.
Another picture, from http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=230354236842 as of 2009/07/05:
M-gineering (under "Hard to finds", as of 2008/01) offers the "Next Best Thing", which is a one-piece cast tool that fits between lockring and frame, much like the Hypercracker, but which has a "finger" going in the dropout slot rather than resting on the frame tube.
The shorter arm means higher forces. The dropout may be more robust than the frame (thus able to accept higher forces), but M-gineering warns of possible damage from using the tool.
In the pictures below, note the "block" to engage the frame hangs inboard of the hole, with at least two effects. First, depending on the dropout shape, it may cause frame engagement only at a small radius and thus high force, which may dent the dropout. Second, the tool cannot be slipped over the QR.
M-gineering's liability insurance excludes the United States, so it is only available in all other countries.
From http://www.m-gineering.nl/indexg.htm as of 2008/01:
With the NBT2 you can pull the cassette from your freehub on the road without other -heavy- tools. Invaluable if you need to replace a spoke on a rear hub. Thus it has the same function as the predecessor NBT (and the Pamir Hypercracker of old), but apart from that it is completely different. It's lighter (26 grams), investment cast in stainless steel, extremely compact, it will not damage your paintwork and it's cheaper to boot. The NBT2 has no small parts to loose along the roadside, no fine threads to cause problems and the high strength stainless steel will ensure it will survive years of neglect in your tool bag and still come up shining!
From http://www.m-gineering.nl/nbtg.htm as of 2008/01:
The Next Best Thing mk2 removes cassettes on the road without extra tools, eg to replace a broken spoke. The NBT2 is designed to fit Shimano compatible lockrings (not Capreo). 8 speed Campagnolo lockrings are slightly different, but for occasional use the NBT should work just fine. The NBT cannot be used with conventional freewheelhubs. And the NBT2 shouldn't be used with extremely lightweight aluminium (Stupid-lite[tm]) racingframes: these have enough problems of their own.
Prior to first time use it is recommended to check with conventional tools that the lockring hasn't been tightened way over the recommended torque by some hamfisted mechanic.
- Open the rearbrake.
- Engage first gear, eg engage the largest cog and smallest chainring. put the cranks horizontal.
- Release the QR skewer, and remove the endnut and conical spring.
- Fit the NBT2 in the lockring and put the axle back in the dropouts.
- Replace the skewernut (no need for the spring) and do up the QR tight. [Note: see below Comparison And Notes why tight is important.]
- Ensure that the axle is fully home.
- Grab the cranks with both hands, and unscrew the lockring one turn. If the bike is standing on it's wheels, it will want to ride forward.
- The face of the lockring is serrated, a load ratcheting sound is normal.
- Remove the wheel from the bike and remove the lockring by hand.
- Take care when replacing the cogset that all cogs are fitted with the wide spline engaging the corresponding groove in the freehubbody. It is very easy to disturb the position of the endcog when tightening the lockring, and this could seriously damage the freehub. With the lockring handtight, the cogs shouldn't wobble when spinning the freehub.
- To properly tighten the lockring, put the wheel back into the frame. Gently (the wheel is a large lever) rotate the wheel backwards to tighten the lockring. If you start with the lockring handtight, 10' (45°-60°) is sufficient.
- Remove the NBT2, and replace the QR (the smallest diameter of the conical spring goes against the axle).
- Check the rear brake.
Also fit between lockring and frame, the Stein has a short arm and cylinder that rests on the outside of the dropout, rather than the inside slot (as with the NBT2) or on the frame (as with the Hypercracker). It uses a second plate held by the quick release, evidently to resist twisting. Again, a short lever means high forces.
The earlier model is made of a spline pressed in a flat plate, and Stein notes it sometimes failed. Sometime in 2007, a new design was introduced in which the spline and flat plate are machined from one piece of metal. It is more reliable, but more expensive.
From http://sheldonbrown.com/harris/tools/cassette.html as of 2008/01
Jim Stein came to the touring cyclist's rescue with the new Stein Mini Cassette Lock tool.
Although this tool is a bit more expensive than the original Hypercracker, it is lighter, smaller and made with more precision. USA
Now also available in Campagnolo-compatible model!
I was occasionally having a problem with them coming apart under repeated loading so I have redesigned them. (it is miserable to have such a tool fail just when it is needed!) They are now milled from one piece of steel instead of using a pressed in insert. I increased the price a bit as it is much more expensive to make.--Jim Stein, September 2007
From http://sheldonbrown.com/harris/stein-mini-lock as of 2008/01:
Since the original Pamir "Hypercracker" went out of production a couple of years ago, there has been no small, portable tool available that would allow on-the-road cassette removal.
Such a tool is of vital importance to the touring cyclist, because it's the only way to be able to replace a broken spoke on the right side of the rear wheel, the most common spot for spokes to break.
Jim Stein has come to the touring cyclist's rescue with the new Stein Mini Cassette Lock tool.
Although this tool is a bit more expensive than the original Hypercracker, it is lighter, smaller and made with more precision.
The Unior 1659 (formerly EDLI) again fits between lockring and frame. It has a short finger that rests on the outside of the dropout (as with the Stein).
As with the earlier Stein, it appears to be of 2-piece construction and may be prone to similar failures.
From http://sheldonbrown.com/harris/tools/cassette.html as of 2008/01
This pocket lockring tool from Unior is even smaller and simpler, though it might not be quite as gentle on your frame's paint.
This handy tool also includes a 3-cornered emergency spoke wrench (fits European size spokes.)
Jeff Ackerman made a tool like an NBT2 but with less material. It is constructed by first removing nearly all but the spline from a non-portable tool, then welding on a nub to fit the dropout.
From http://ohmelovelo.dnsalias.org/tools/tools.html as of 2008/01:
This tool contributed by Jeff Ackerman. Jeff's description from T@H slightly edited: Started with a regular Shimano cassette tool and ground the large portion down so that it just fits between the cassette lock ring and the dropout. Welded on a metal block that just fits into the bottom of the dropout under the axle.
To use: remove the rear wheel, install the tool in the cassette lock ring, reinstall the wheel with the metal block in the dropout slot, and push the bike backwards now that the lock ring is linked to the dropout. [Note: backwards tightens the lockring; instead, pedal forward, see NBT2 instructions, above.] Stop as soon as the lockring loosens so as not to wedge the tool against the dropout.
The tool weighs a fraction of an ounce, smaller than 1" square, is much stronger than the original Hypercracker, and has no arm (like the original Hypercracker) that goes over the chainstay to mar the paint. It must be tailored to fit your specific dropout.
Jobst Brandt had a tool custom-made when he switched from freewheels to freehubs (mid 2007). Again, it fits between lockring and frame. It uses a longer arm, though probably not as long as the Pamir, and a Delrin cylinder rests on the frame.
Jobst notes the hole in the middle is large enough to fit over a quick-release nut.
Mark and Juliette McLean made a tool like an NBT2 but with less material, and like Jeff Ackerman's but with no welding. Like Jeff's, they start with a conventional cassette remover, but unlike Jeff's the nub is made by simply not grinding away material.
They warn dropout damage is possible.
The Hypercracker is a tool for removing the lock-ring that secures Shimano cassette sprockets. This is necessary if a spoke breaks on the cassette side of the rear wheel, or if the freehub needs to be removed for maintenance. The 'official' tools for the job are a Shimano cassette lock-ring remover, a big spanner and a chain whip - not the most practical toolset for an extended tour!
Hypercrackers were invented by Pamir Engineering, who used to make them. Sadly they no longer do, indeed I think the company was wound up when its founder retired. To use a Hypercracker you remove the rear wheel and fit the Hypercracker into the spline of the lock-ring. Then you replace the rear wheel in such a way that the frame or dropout prevents the Hypercracker rotating. All it takes then is a pull on the pedals (by hand should be sufficient) which rotates the cassette and rear wheel while the Hypercracker and lock-ring remain stationary. Voila! the lock-ring is loosened and when you remove the wheel from the bike you will be able to unscrew the lock-ring by hand and remove the cassette.
I first saw the idea of making your own Hypercracker on another cycle touring website: Ed and Jeanne Downing's. Their version involves some welding which mine doesn't, but then mine puts more load on the dropout and I did bend Juliette's dropout trying to release a very tight lock ring. I was not popular until it had been hammered and bent back into shape!
I took a standard Shimano cassette lock-ring remover and ground most of it away so this much was left: [See image above]
The stub sits against the dropout. I should think that if the lock-ring was really tight there is a risk of bending the dropout. It fits onto the lock-ring like this: [See image above]
In use it looks like this: [See image above]
The Stein has several small parts which are easy to lose, especially out on the road —two black metal "plates", a thumbscrew, an aluminum barrel, and a small washer. Also, it is always desirable to save weight and packing space, especially for a tool which is used only rarely: the value of anything you bring might be seen as (frequency-of-use)/(weight × space), so the greater the weight and space, the more sensible it is to leave it behind or carry something more useful else instead.
A Stein was modified by discarding the outer support plate, griding away some of the material on the spline plate, and replacing the thumbscrew, barrel, and washer with a single piece consisting of an Allen-head (hex socket) bolt (with threads that match the Stein), a barrel that is threaded and screwed tight to the bolt so that it cannot be separated, and a piece of rubber tubing to better protect the paint.
Discarding and grinding away parts of the support weakens the tool and places eccentric loads on the screw threads. However, the tool appears adequately strong for this use, and using an Allen-head bolt allows the barrel to be tightened fast, which allows all of the threads in the plate to share the load. (In contrast to the Stein shown on Sheldon Brown's site, this one has a threaded insert; for this purpose, the effect is the same.)
The rubber tubing was conveniently at hand, but may be too thick to fit all frames.
The Allen-head bolt and barrel can be reversed for stowing, allowing the unit to lie flat in a tool case.
Note some tools will not work on some bikes. Be sure to try it before you rely on it.
The Next Best Thing/NBT2 instructions emphasize the quick release should be tight. Clamping tight serves at least two purposes. First, it keeps the tool where it is least likely to damage the dropout. Second, a tight QR increases dropout support, so it is better able to handle loads caused by the remover, thus reduceing risk of dropout damage (for any NBT2-style remover). However, on bicycles where the tool is a tight fit between lockring and frame, clamping tight increases the force required to unscrew the lockring, and it is unclear in general when the increased load outweighs the increased support and thus what is the best practice for all situations. but note clamping tight is not simply for convenience. Note also the Stein rests differently during use.
With all of these tools, as the lockring unscrews it forces the tool in to the dropout. Thus, once the lockring is freed, approximately 1/8 turn, the quick release should be loosened to avoid damage to bicycle and tool.
On tools with the spline pressed in to the rest of the tool, the spline may separate. An example from http://www.vwvagabonds.com/Bike/BikeSuccessFailure.html as of 2008/01:
A chain whip and cog wrench are heavy tools to carry on a bike tour, but we had to have some way to remove the cassette in case we broke a few spokes on the rear wheel or broke some teeth on the cassette. So we purchased a Stein Mini-Cassette removal tool.
One morning Rich tried to remove the cassette from my bike. I heard a lot of grumbling, and finally a loud crunch from my bike and a "Oh no." from Rich. Fortunately the tool—not my bike—broke.
While it is a beautiful design, it just didn't work for us.
The above mentions the value of a tool for replacing sprockets. Odds are good a shop with sprockets also has a tool and will install sprockets cheaply. There may be situations where sprockets are needed, available, and a tool is not, but these situations are very rare. Further, it is often possible to ride with broken sprocket teeth, so the relative inconvenience is small. Thus, if your hub disassembles easily, there is little additional value to carrying a lockring tool just to replace sprockets.
The following table briefly compares the tools. Dropout notes whether force is applied so it tends to spread the dropout. Commerical indicates commercial availability as of 2008/01. Flat stow indicates whether the tool stows flat, which may be an issue if tools are carried in a small case. Press fail indicates tools where the spline is pressed in and may fall out in use. QR Clearance indicates whether the tool can be used without removing the QR, a slight convenience (depends also on the QR). Weight is approximate. Notes are below.
|Tool||Commerial||Dropout||Flat Stow||Press Fail||QR Clearance||Weight||Notes|
The "Cassette Cracker" was the predecessor of the Hypercracker, used to unscew the smallest sprocket on earlier freehubs which used a thread-on sprocket rather than the later splined sprocket and lockring.
From http://www.bikepro.com/products/freewheels/fw_cas_tools.html as of 2009/07/05:
PAMIR ENGINEERING CASSETTE-CRACKER
The Cassette Cracker is a miniature chain whip for freeing up and removal of the first position cog on freehubs where no outer lockring is used to hold all the cogs on. Neither bench vise or adjustable wrench is required for its use. It is an aid in cog removal for spoke changes. With the bicycle chain on the smallest chainring and the largest rear cog, and the right crank arm at the three o'clock position, a vinyl coated steel hook grips the bike from the upper-inside of the right chainstay.
A four link length of Sedis chain is then looped under and over the top of the smallest rear cog. With forceful downward pressure on the right crank arm, the small cog spins off, then take the wheel off to remove the others. It's small enough to carry on the road and weighs 51 grams.
From http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=330342363132 as of 2009/07/05: