Re: SPD pedal compendium
Posted: 25 Nov 2020, 4:19am
It isn't as simple as v1 and v2 concerning bindings. If you go back a few pages I have grouped the pedals according to which cleats they were originally specified to use. Group A contains PD-M737, PD-M525, PD-M323 pedals which were originally designed for SM-SH50 and SM-SH55 cleats, and there is a difference in the bindings in the next group of pedals which were designed to accept SM-SH51(v1) and SM-SH55 cleats, which included PD-A525, PD-M535, PD-M636, PD-M747. Even within each group there are variations in how the bindings operate, but there are major differences in pedal operation depending on which cleats they were originally designed to use.
You will note that I refer to SM-SH51 cleats with a v1 or v2 suffix. This is because there are two different cleats with the same part number. Currently you can only buy the second sort. Pedals work differently with each version of the SM-SH51 cleat.
Reshaped cleats provide a good way of customising the amount of float and release characteristics. Cleats wear anyway and shimano recommend a new set every year or so if you ride much. However the pedals wear too and this of course also influences how the bindings work. Float is usually 'easy' float, i.e. the jaw springs are still holding the cleat lengthwise. Once the cleat is twisted past a certain point the jaws start to be forced open and this may be considered to be the limit of the easy float. However if the jaws and/or the cleat are worn, the float may become both freer and greater in extent.
Zenitb's photos show there should be different amounts float in different directions; if the cleats are new, this is a sure sign of worn pedals; none are designed with asymmetric float (although some do have asymmetric release characteristics). Roger's PD-M737s could be worn too, perhaps. As i have commented previously, float is a very personal thing; as long as you have enough (for you) then pedals might feel 'about the same' in use. However if there is even one degree less float and you nudge into the limit whilst pedalling, the result can be excruciating pain which may develop over a period of time whilst riding.
Note that in some early pedals (with a flat front jaw) the float is limited by the width of the bottom of the cleat nose; a small scallop in the cleat here can increase the available float in that pedal type only.
Most cleats are nominally 34.0mm long (where the jaws hold them). Most SPD pedals have jaws which close to 33.0 to 33.5mm when they are new. Pedals which have gone though a few sets of cleats tend to have worn jaws; both the jaws themselves wear (when releasing and whilst pedalling if you use/need the float whilst pedalling) and the jaw stoppers wear too, because every time the cleat is released the moving jaw(s) slam(s) into the stopper. The former type of wear increases the jaw opening and the latter reduces it. Normally the jaws wear faster than the stopper, but this isn't guaranteed. With new cleats, worn pedals may feel 'normal' even when the jaws are worn such that the opening is between 33.5 and 34.0mm, but in the latter case the slightest cleat wear will soon change the feel of the pedal.
The jaws also wear in two other main ways; laterally (so as to influence the extent of float, and/or the release) and vertically (which affects how noisy the pedals may become and again the release characteristics. You can infer lateral wear by how much float there is each way and (in pedals which ought to have a symmetric release) how the release is in each direction.
Vertical jaw wear is much more difficult to characterise, since worn (worn to be thinner) cleats and worn shoes (e.g. worn where the jaws contact the sole) can also allow the cleats move vertically in use. However in extremis some pedals can measure within spec for jaw opening, and even with new shoes and new cleats, a SM-SH51 cleat can still move vertically and/or release more like a SM-SH56 cleat; this normally means the jaws are vertically worn. This form of wear limits the working life of SPD pedals for some riders.
Most forms of cleat and jaw wear make for more/easier float and an easier release. However there is one form that does not make release easier; if you use the float when pedalling the rear of the cleat may develop a groove where the jaw bears against it. This groove impedes the vertical movement of the cleat and if (through design, wear, or cleat compatibility) the pedal doesn't have functional 'kicker ramps' (which force the rear of the cleat upwards when twisted) the release can be impaired.
Anyway the bottom line is that if you fit current cleats to older pedals (which is probably more likely than older cleats in newer pedals) you may get reduced float, depending on the detail of the design/manufacture of the parts and how worn the pedals are. Few such combinations are inherently dangerous per se (an obvious exception being the use of SM-SH50 or SM-SH55 cleats in 'open' binding pedals) so have at it. If the amount of float is tolerable for you then great. If it is not, a few (usually simple) modifications to the cleat may sort it out.
cheers
You will note that I refer to SM-SH51 cleats with a v1 or v2 suffix. This is because there are two different cleats with the same part number. Currently you can only buy the second sort. Pedals work differently with each version of the SM-SH51 cleat.
Reshaped cleats provide a good way of customising the amount of float and release characteristics. Cleats wear anyway and shimano recommend a new set every year or so if you ride much. However the pedals wear too and this of course also influences how the bindings work. Float is usually 'easy' float, i.e. the jaw springs are still holding the cleat lengthwise. Once the cleat is twisted past a certain point the jaws start to be forced open and this may be considered to be the limit of the easy float. However if the jaws and/or the cleat are worn, the float may become both freer and greater in extent.
Zenitb's photos show there should be different amounts float in different directions; if the cleats are new, this is a sure sign of worn pedals; none are designed with asymmetric float (although some do have asymmetric release characteristics). Roger's PD-M737s could be worn too, perhaps. As i have commented previously, float is a very personal thing; as long as you have enough (for you) then pedals might feel 'about the same' in use. However if there is even one degree less float and you nudge into the limit whilst pedalling, the result can be excruciating pain which may develop over a period of time whilst riding.
Note that in some early pedals (with a flat front jaw) the float is limited by the width of the bottom of the cleat nose; a small scallop in the cleat here can increase the available float in that pedal type only.
Most cleats are nominally 34.0mm long (where the jaws hold them). Most SPD pedals have jaws which close to 33.0 to 33.5mm when they are new. Pedals which have gone though a few sets of cleats tend to have worn jaws; both the jaws themselves wear (when releasing and whilst pedalling if you use/need the float whilst pedalling) and the jaw stoppers wear too, because every time the cleat is released the moving jaw(s) slam(s) into the stopper. The former type of wear increases the jaw opening and the latter reduces it. Normally the jaws wear faster than the stopper, but this isn't guaranteed. With new cleats, worn pedals may feel 'normal' even when the jaws are worn such that the opening is between 33.5 and 34.0mm, but in the latter case the slightest cleat wear will soon change the feel of the pedal.
The jaws also wear in two other main ways; laterally (so as to influence the extent of float, and/or the release) and vertically (which affects how noisy the pedals may become and again the release characteristics. You can infer lateral wear by how much float there is each way and (in pedals which ought to have a symmetric release) how the release is in each direction.
Vertical jaw wear is much more difficult to characterise, since worn (worn to be thinner) cleats and worn shoes (e.g. worn where the jaws contact the sole) can also allow the cleats move vertically in use. However in extremis some pedals can measure within spec for jaw opening, and even with new shoes and new cleats, a SM-SH51 cleat can still move vertically and/or release more like a SM-SH56 cleat; this normally means the jaws are vertically worn. This form of wear limits the working life of SPD pedals for some riders.
Most forms of cleat and jaw wear make for more/easier float and an easier release. However there is one form that does not make release easier; if you use the float when pedalling the rear of the cleat may develop a groove where the jaw bears against it. This groove impedes the vertical movement of the cleat and if (through design, wear, or cleat compatibility) the pedal doesn't have functional 'kicker ramps' (which force the rear of the cleat upwards when twisted) the release can be impaired.
Anyway the bottom line is that if you fit current cleats to older pedals (which is probably more likely than older cleats in newer pedals) you may get reduced float, depending on the detail of the design/manufacture of the parts and how worn the pedals are. Few such combinations are inherently dangerous per se (an obvious exception being the use of SM-SH50 or SM-SH55 cleats in 'open' binding pedals) so have at it. If the amount of float is tolerable for you then great. If it is not, a few (usually simple) modifications to the cleat may sort it out.
cheers