Hyperglide freewheel noise under load
11-17-21, 03:49 PM
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Hyperglide freewheel noise under load
a question and maybe a theory:
I have just replaced an older (pre-HG: one of the mf-tz 6 speeds) freewheel with a NOS hg-mf-22 (singapore-made, 6s, 14-32), and found it to make an odd crunching/cracking sound in the middle few gears (while pedaling, not shifting), very similar to what is being described in several other very old threads ("Hyperglide freewheel trouble" and "Shimano freewheel, SRAM chain" – I would link them but don't have enough posts)
In both there is speculation that the problem has to do with chain compatibility w/ the hyperglide ramps, chamfers, etc – maybe SRAM chains don't work well, but then it doesn't seem that KMC work perfectly either. (I have a KMC chain, and haven't tried swapping it out). But my understanding is that the ramps, chamfering, etc, are identical to those used on the cogs of the HG *cassettes* – the problem seems specific to freewheels, and to the HG freewheels in particular (hg-mf32, hg-mf20, hg-mf22, etc).
I am curious whether the actual source of this problem is the concatenation of ramps, chamfering, etc, on the HG cogs, with a (known) liability of freewheel systems: the slight built-in wobble which (almost?) every freewheel has (an artifact of inconsistencies in the threading during manufacture, I'm told). That is: is it possible that the slight wobble of the freewheel system causes the chain (maybe worse on certain kinds) to move laterally, hence to rub (on the 'inside' of the links/plates) on the ramps and cut-outs of the hyperglide cogs? (If it were, it would help explain the worsening of the noise (for me) both in the middle cog + middle chain ring, its relative diminution when the chain-line removes lateral 'slack' (allowing motion, hence grinding) from the chain.)
(My particular hg-mf22 has a noticeable wobble – not otherwise a big deal, but am curious if it's causing this noise.)
Thoughts? similar experiences? I had not seen the problem diagnosed as such; curious if it's plausible, hoping it might somehow help someone down the line.
I have just replaced an older (pre-HG: one of the mf-tz 6 speeds) freewheel with a NOS hg-mf-22 (singapore-made, 6s, 14-32), and found it to make an odd crunching/cracking sound in the middle few gears (while pedaling, not shifting), very similar to what is being described in several other very old threads ("Hyperglide freewheel trouble" and "Shimano freewheel, SRAM chain" – I would link them but don't have enough posts)
In both there is speculation that the problem has to do with chain compatibility w/ the hyperglide ramps, chamfers, etc – maybe SRAM chains don't work well, but then it doesn't seem that KMC work perfectly either. (I have a KMC chain, and haven't tried swapping it out). But my understanding is that the ramps, chamfering, etc, are identical to those used on the cogs of the HG *cassettes* – the problem seems specific to freewheels, and to the HG freewheels in particular (hg-mf32, hg-mf20, hg-mf22, etc).
I am curious whether the actual source of this problem is the concatenation of ramps, chamfering, etc, on the HG cogs, with a (known) liability of freewheel systems: the slight built-in wobble which (almost?) every freewheel has (an artifact of inconsistencies in the threading during manufacture, I'm told). That is: is it possible that the slight wobble of the freewheel system causes the chain (maybe worse on certain kinds) to move laterally, hence to rub (on the 'inside' of the links/plates) on the ramps and cut-outs of the hyperglide cogs? (If it were, it would help explain the worsening of the noise (for me) both in the middle cog + middle chain ring, its relative diminution when the chain-line removes lateral 'slack' (allowing motion, hence grinding) from the chain.)
(My particular hg-mf22 has a noticeable wobble – not otherwise a big deal, but am curious if it's causing this noise.)
Thoughts? similar experiences? I had not seen the problem diagnosed as such; curious if it's plausible, hoping it might somehow help someone down the line.
11-18-21, 03:02 PM
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It's hard to use words to describe sounds so when I read "grinding" I don't think of the noise that is usually made when a cog set has enough orbital/wobble in it to allow for the chain to contact an adjacent cog's teeth. To me "grinding" is more like what dry and rough bearings sound like when coasting.
If there is enough orbital cog movement to get chain grabbing on adjacent cog teeth it should be easy to see it when the bike is on the stand. BTW the larger the tooth count differences are, between the cog the chain is on and the one next to it ,the greater the chance of contact when the cog set moves about.
Not mentioned is the chain's condition. A worn chain will not mesh smoothly with a new cog's teeth.
Pretty much all name branded chains made these days are HG compatible. I believe KMC is still Shimano's chain source. Andy
If there is enough orbital cog movement to get chain grabbing on adjacent cog teeth it should be easy to see it when the bike is on the stand. BTW the larger the tooth count differences are, between the cog the chain is on and the one next to it ,the greater the chance of contact when the cog set moves about.
Not mentioned is the chain's condition. A worn chain will not mesh smoothly with a new cog's teeth.
Pretty much all name branded chains made these days are HG compatible. I believe KMC is still Shimano's chain source. Andy
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