Chain-Suck :
see Main Article : Chain-Suck in a NUTSHELL

by Jonathan Levy


So, you are intending to enter a cross-country race ! You expect muddy conditions, and are worried that your bike might get chain-suck which will end your chances in the race. You once experienced chain-suck a long time ago ..... and some of your friends have been getting it badly over the past month. You would like to check whether you have a problem before it happens during a race.

OK, you could just go for a muddy ride and hope that absence of a problem is indicative. With this approach, the particular ride you do might not place mud and grit in the critical places, nor perhaps in sufficient quantity, nor perhaps before steep locations on your route where chain-suck is brought on by high pedalling loads. If it doesn't, how will you be sure that the problem won't occur when least wanted ?

The method described below will give a far more reliable confirmation as to whether chain-suck is likely on your bike, or not. It has been developed to ensure conditions which are acceptably constant, repeatable, certain, and realistic, to lessen these as issues of contention; it also reduces the time which might otherwise be needed to reach a conclusive result (+ve or -ve).

The test only takes about 1 hour.   Neither you nor bike need get very dirty. Anyone watching will think you've gone crazy.   They're probably right !!

  1. Ensure that the bike has all the actual drive-train components which you intend using later, especially the granny-ring and chain; beware of changing anything afterwards unless you test it. This may mean doing a second chain-suck test if changes are found to be necessary.

  2. Do NOT LUBRICATE your chain before setting out. Instead you must CLEAN the CHAIN and SPROCKETS to REMOVE ALL the LUBRICATION by any suitable method, before setting out. The aim of the test is to see how your drive-train performs after lubrication has been stripped out by mud; this can happen quite fast in practice. You need to be sure that you don't get chain-suck even in this situation.

  3. Select a route with mud known to cause chain-suck ; not all muds are equal, and if they have low friction, they may not cause the problem. The route must also have puddles of suitable consistency mud along its length or in a few critical locations, to make it easy to apply the mud for testing purposes. The route should have sections of fairly level ground to allow the mud/grit to be worked into the sprockets and chain. It should also have sections of steep uphill to achieve high pedal forces and chain tension. There should be a mud puddle shortly before a steep uphill towards the end of the route for the final test. Sections of the route can be repeated to achieve the same thing.

  4. There is no need to make a special effort to ride through mud puddles, unless you want to get dirty.

  5. Select puddles which have at least a few places with suitable consistency mud. The mud should be soft to slightly runny but not too runny; if it is too stiff, you can mix water to taste !! The mud should have a fairly fine sticky matrix with a range of fine and courser sand and grit particles included. You should avoid rubbing any larger gravelly particles into the chain because they are less likely to get there in practice, can damage the chain and sprockets, and if they become jammed between chain and teeth will affect the test unrealistically.

  6. Stop at the first suitable mud puddle and pack mud into the chain along its inner surface (easiest on the lower section of the chain), using your fingers. Keep rotating the chain until the complete chain is packed with mud. Then slap some additional mud over both rear and front sprockets.

  7. Reverse pedal to start working the mud into the drive-train and to dislodge any large gravelly particles or small stones which may have been placed, before they can cause problems.

  8. Carefully ride the bike some distance to work the mud into the drive-train (say 0.5km to 1km); rear sprocket "skipping" may occur, caused by any gravelly-particles/stones until they are dislodged.

  9. At the next mud puddle splash the drive-train with muddy water while reverse pedalling to wash off the surface mud. This will have a dual effect: it will remove residual lubrication, and wash mud particles into the chain interior. Then repeat the process of re-packing the chain with mud. The purpose of these actions is to simulate the conditions of a longer ride where mud is alternatively removed by water puddles and rain and then replenished, stripping out lubrication all the while.

  10. Ride flatter sections to work mud into the drive-train, and then steep sections to test for chain-suck; then repeat the mud washing and re-packing operation.

  11. I have found that if chain-suck does not occur after 5 repetitions of the cycle of hand-packing the mud then washing it into the chain with muddy water, interspersed along about 5 km of total riding distance on hilly terrain, then it is most unlikely to occur at all, even without any lubrication.

  12. If chain-suck occurred, follow recommendations in the main article to resolve it ; then repeat the test if you want to check.

  13. After returning from a successful test with complete absence of chain-suck, thoroughly clean all parts of the bike's drive-train, and particularly the chain. Lubricate the chain.

This test is aimed primarily at detecting 1-ring suck, and identifying its causes by successive testing. It can be used for 2-ring suck if mud happens to be the immediate precipitating cause of this alternative form of chain-suck, rather than its more usual cause, namely adverse rotational alignment of adjacent chain-rings.

Copyright Jonathan Levy, 2000. All rights reserved.

For the related articles, follow the links below ...
Chain-Suck : in a NUTSHELL ...comprehensive summary and solutions
Chain-Suck : the OVERALL picture ...details of mechanisms & solutions
Chain-Suck : the DETAILED Investigations ...field & workshop testing
Chain-Suck : the FIELD TEST ...a field testing method for identifying causes
Chain-Suck : Restoring Worn Tooth Pressure-Faces filing them
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