Obscure SPD history question

[rogerzilla]

M737, the original "XT SPD" has moving front and rear bindings.  M525, the original "DX SPD", like all current SPDs, only had a moving rear part.

AIUI M535 superseded M525 and was in turn superseded by M536 - which has the double binding again.  Why did Shimano bother to bring it back, and when was it finally decided not to be a selling point (and excess weight)?

FWIW, I have some M536 pedals and, while they feel the same as all others to ride with, entry is a little more slick.

While I'm at it, how long did the original zero-float "black cleat" SM-SH50 last?  I think there was always a silver "sissy cleat", originally SM-SH55 but now SM-SH56.

[FifeingEejit]

I had a set with the old style bindings on a 2nd hand bike I bought;
I thought they were crap and sold them back to the guy I'd bought the bike off

Pink bike paid a bit of homage to the PD-M520
https://www.pinkbike.com/news/the-20-year-history-of-the-shimano-pd-m520.html

[Brucey]

FWIW Shimano appeared to have given up with the 'double jaw' pedal later on too, but up it popped again in the form of PD-M858; another relatively heavy, complicated expensive pedal that didn't sell well....


380g of mud-gobbling badness


The SM-SH50 cleats may have disappeared at about the same time as PD-M515 was introduced; this was (I think) the first of a new generation of SPD pedals which (confusingly) used some of the same cleat part numbers (eg SM-SH51) but the parts themselves were different.  Thus you can get cleats with the same part numbers which are actually different; thanks shimano!..    FWIW using old SM- SH51 cleats in newer pedals gives more float than in older ones. Using 'new' (made after ~1997) SM-SH51 cleats in older SPD pedals gives almost no float at all.

There are also differences (even in 'new' cleats) as to how many teeth there are which bite into the sole of the shoe; this can mean that some replacement cleats will just bolt onto the shoes with the exact same alignment, and others won't, being prone to end up slightly cocked.

All good stuff.....

cheers

[LittleWheelsandBig]

The double-hinged SPDs allowed you to clip in heel first, as well as toe first. The single-hinged SPDs are slightly tetchier about how you clip in. The change of SPD cleat was designed to both ease entry with single-hinge pedals and allow more float.

HK loved the fixed position SPD cleats and we still have a couple of unused sets that don’t work worth a damn in modern SPDs.

[rogerzilla]

More weirdness.  I've just stripped a set of M525 pedals for the first time in almost three decades (these are NOS but I had some back in the 90s; they cost me £72 new, after shopping around).

1. The lock collars are threaded the same way around as the pedal-to-crank threads.  These days, it's the other way around.  I doubt mechanical precession has changed, so did Shimano get it wrong?

2. The bearings in these old chunky monsters are 1/8", not 3/32".

3. There are no lip seals.  You really did have to pack these with grease in the hope that water couldn't penetrate between the lock collar and the axle.

4. You need 11mm and 8mm spanners for the bearing adjustment.  Who has a thin 11mm spanner lying around, or the real tool, PD-73?  Luckily Shimano do a nice little flat hex spanner in 11mm...as a fishing reel accessory!

5. The axle has no bearing surfaces.  Assuming spares were available, all the bits subject to wear or pitting are small and replaceable; the barrel, the adjustable cone and the small race sandwiched between the barrel and the lock collar.  This may explain the lack of lip seals: if water ingress only costs you a couple of quid in parts, it's not as serious.

[Brucey]

https://si.shimano.com/api/publish/storage/pdf/en/ev/PD-M525/EV-PD-M525-1169A.pdf

most of the features you describe can be seen in the EV techdoc above.   Lockbolt threading is weird though....?

cheers

[rogerzilla]

I'm getting confused - I've used a TL-PD40 for M520 pedals, so it must be the same.  What's thrown me is that the tool is marked on the wrong side, unless you hold it in a vice and turn the pedal...I find it easier to hold the pedal in a Workmate and turn the tool!

So the tool says to turn the right pedal lock collar anticlockwise to loosen, but it's really clockwise viewed from the back (left hand thread), which is the way I do it (and the way you do modern ones with a hex bolt rather than a splined collar).

 

[Brucey]

ah, so lockbolt threading is 'normal' after all....   I was surprised when you said it mightn't be; I've greased and adjusted PD-M525 and whilst it might be wishful thinking,  I'd probably have noticed if it was different to normal.

cheers

[rogerzilla]

Am I missing something, or is the little rubber collar that goes over the axle and stops the last set of balls falling into the barrel missing from the exploded diagram?  The M525 definitely has it.

[Brucey]

not sure if it is plastic or rubber, but normally there is such a collar (in all such axles that use the 'cartridge' bearing format). It is not always shown on the EV techdoc, but it usually is.

One change that has occurred in SPD pedal threading in recent years is in the cones and locknuts.  Prior to about eight years ago all SPD pedals used the same (RH) threading for cone and locknut in the left and right pedals. However starting with the XTR pedals (I think PD-M980) revised parts were issued in which the LH spindle assy remained unchanged, but the RH spindle assembly started to use LH threading on the cone and locknut. 

  This change was then implemented in most new SPD pedal models, and retrospectively in some extant models.

So for example PD-M530 has always had a 'new type' RH spindle assembly, but PD-M520 (being older) didn't.  So

https://si.shimano.com/api/publish/storage/pdf/en/ev/PD-M520/EV-PD-M520-2235.pdf

shows the same pn for the LH spindle  as PD-M530

https://si.shimano.com/api/publish/storage/pdf/en/ev/PD-M530/EV-PD-M530-3203B.pdf

but the RH spindle assy has a different pn between the two pedals.  The difference is the threading on the RH pedal spindle for the cone and locknut.

In point of fact I do not believe that EV techdoc for PD-M520 is accurate any more, unless they have started issuing different parts against the same pn (which shimano have form for);  IIRC the most recent PD-M520 pedals I have seen have a LH thread on the cone and locknut in the RH pedal.

To date, regardless of model, all those spindles with LH threading on the cone/locknut in the right side pedal have had a splodge of paint on the end of the spindle; without this you would in many cases be guessing.

cheers

[hatler]

Can I just say that this thread is the absolute epitome of yacf.

[Brucey]

FWIW in the face of rising prices from most sources, I recently bought a (spare) set of PD-M520s in decathlon, and because the shelf was marked £19.99 this is what I expected to pay.  Also this had been the price indicated on the web just a few days earlier when I'd looked. 

However when the things were scanned, the till indicated ~£25.  When I pointed out that the shelf was marked differently, the price was adjusted, but I reckon I might have bought the last pair at the 'old' price.   

It doesn't seem that long ago that you could find multiple listings for new PD-M520 (with cleats etc)  on ebay for £18-£20.  Now....?  No chance. PD-M520 prices are almost double what they were just a few years ago.

I've always serviced my SPDs as necessary and looked after the bearings.  However plenty of other folk have treated them almost as if they are 'disposable'.

I think that more people will be servicing their SPD bearings from now on; it also remains to be seen whether (good as they are) shimano can charge more for PD-M520s in the face of cheaper knock-offs, inferior though those might be.

cheers

[rogerzilla]

The M520 (and M540) seem to be slightly budget versions of M747, the first "racing" SPD, where Shimano really started minimalising the size of the body.  Not everyone liked this, as lumps like the M737 and M525 had more foot support.

[Brucey]

surely that mantle belongs to PD-M515, and PD-M505?  These are dead ringers for PD-M747, and use the same type of 'platform' bindings.

By contrast PD-M520 and PD-M540 use the later 'open' style bindings, which have considerably improved mud shedding ability.


PD-M747


PD-M515, with 'cartridge' pedal bearing assembly


PD-M505, using non-cartridge bearings, requiring expensive tool to adjust (like PD-M535, PD-M323, PD-M324 etc)

cheers

[rogerzilla]

Can I just say that this thread is the absolute epitome of yacf.

Yes, Asperger's Cycling Forum

[Crumbling Nick]

I'll add that PDM-520 gained its mud-shedding ability at the price of very rapid wear with SM-SH55 cleats (it's long enough ago that I can't remember whether pedal or cleat was trashed, though cleat seems more likely). The replacement SM-SH56 resolved the issue at the price of releasing under upward tension, which is pretty life-threatening for fixed/single speed riders accelerating in traffic. Shimano duly updated the documantation, which seems to imply the new feature has always existed.

Multi-release is quite useful without a freewheel, since the foot to be released is not always in the best position to twist out laterally, even if you can fluently use either foot.

[Brucey]

I'll add that PDM-520 gained its mud-shedding ability at the price of very rapid wear with SM-SH55 cleats (it's long enough ago that I can't remember whether pedal or cleat was trashed, though cleat seems more likely).

The cleats which are/were compatible with each pedal (e.g. at the time of launch) are  indicated on the EV techdoc for each pedal.  So for PD-M515 for example, both cleats SM-SH51 and SM-SH55 are indicated.  However for the 'open' style binding pedals such as PD-M520 and PD-M540 only SM-SH51 is indicated.

This makes perfect sense when you look at the cleat and pedal design; SM-SH51 cleats have 'shoulders'  (or 'ears', alongside the cleat model markings) and the rest of the cleat is otherwise mostly flat-bottomed



whereas earlier cleat designs such as SM-SH50 and SM-SH55 have no 'shoulders' on them. Worse than that, the edge of the 'racetrack' opening has a chamfer on it at the sides.



In nearly all SPD pedals prior to those with 'open' bindings, the support platform between the jaws ensures that vertical loads transfer between the cleat and platform, whether the cleat has shoulders or not.  Only when the cleat is severely worn does the situation arise where the tops of the jaws bear against the shoe directly.

However in many pedals especially those  with 'open' bindings, significant vertical load transfer occurs between the 'shoulders', racetrack sides  and the corresponding parts of the pedal, especially on the inboard side of the cleat.  If you offer up an earlier 'shoulderless' cleat to an 'open' SPD pedal, it is almost a clean miss between the base of the cleat and the relevant part of the pedal. At best there is limited support offered, by a small part of the cleat that will soon wear.

So it is no wonder it wasn't a happy marriage between SM-SH55 and PD-M520; AFAICT they were never meant to work together.   I don't think I have any documentation from early PD-M520 pedals; I was too busy trying to wear out various PD-M515 pedals to buy any PD-M520 to start with.  Perhaps someone could comment as to whether they ever recommended SM-SH55 cleats with these pedals?  I rather suspect they didn't; they clearly are not well designed to work together.

cheers

[Brucey]

remember that I mentioned there are two different SPD cleats with the same number?

Here you can see PD-M747 which uses SM-SH51 (and SM-SH55) cleats

https://si.shimano.com/api/publish/storage/pdf/en/ev/PD-M747/EV-PD-M747-1521B.pdf

and here you can see the (later)  PD-M515 which also uses SM-SH51 (and SM-SH55) cleats

https://si.shimano.com/api/publish/storage/pdf/en/ev/PD-M515/EV-PD-M515-1830B.pdf

you can see that the illustration of the SM-SH51 cleat is different between the two; at the heel of the cleat the radius is different. This means there is less float with the revised SM-SH51 cleat in any pedal. In fact in older pedals -especially those which used SM-SH50 cleats originally- there is about half as much float when the first version of SM-SH51 is used, and virtually none when the second version of SM-SH51 is used.

Correspondingly older cleats such as SM-SH50 or SM-SH55 give large amounts of float with newer pedals.  However as noted above I do not think that these older cleats should be used with 'open' binding pedals, only 'platform binding' types. So for example PD-M515 would probably work (albeit with much increased float) with SM-SH50 cleats, but with PD-M520, I wouldn't use either SM-SH50 or SM-SH55; not only would the float be increased, but the cleat wouldn't be supported properly either.

cheers

[rogerzilla]

I found the EV for the original M737 pedals, and they used 3/32" bearings (like most SPDs).  Was M525 the only one with 1/8" balls?

I also see - unless it's missing from the EV - the M737 had no lip seals either, relying on the close fit of parts, the length of the lock collar and (ideally) full grease packing to keep water out.

[Brucey]

I thought PD-M737 had seals (they may be part of the lockbolt?). I am also surprised that PD-M525 had 1/8" balls, but since I've only ever adjusted PD-M525 then I may just not have noticed.

Since I have examples of both pedal types in a box somewhere, if curiosity overcomes me (and I can find them.....), I ought to be able to demonstrate both points yea or nay.

cheers

[Crumbling Nick]

Brucey, many thanks for an excellent explanation. I have gained much understanding.

I've dug out the instructions for the PD-M520s (plus M959 & M540), dated Jan-2003. I installed them in May-2004. The instructions state "User only Shimano single release mode cleats (SM-SH51). Other types of cleats such as SM-SH52/SM-SH55 cannot be used as they do not provide stable enough step-out performance or sufficient holding force.". I must have taken this as a piece of corporate backside-protecting & duly discovered that it was not true with relatively unworn cleats, but they didn't last long. Eventually I resorted to SH51s. A rather interesting moment on the Birmingham Mainline canal, when I only just failed to fall over the parapet of a bridge persuaded me that they were not a wise choice.

I don't seem to have PD-M515 instructions, but do have M505 (dated Nov-2000) & M324 (dated Jun-2000) which use the same design of bindings. Both instruct use of SH51,SH52 & SH55 cleats, implicitly approving their use. The M324s, my first SPDs, came with SH55 cleats, which is how I discovered them.  The M505s NoS came in 2 Shimano plastic bags, but without cleats (one bag may have been already opened). Curiously they had SM-PD22 reflectors pre-fitted, which I think superseded PD21. Instructions for PD22s are dated Dec-2006, which looks distinctly late for new M505s, & say they are for use with M970/M959/M770/M540/M520/M515/M505pedals only(!) - looks rather catholic to me.

Incidentally I have, I hope, solved my problem by sourcing a collection of used & NoS PD-M515s, PD-M505s & SM-SH55s that is probably enough to last as long as my fixed-wheel cycling. At 74, that looks pretty finite .

[Brucey]

We're all learning here; the niceties of the different release between SM-SH55 and SM-SH56 cleats are lost on me, for I have never used the same pedals with both cleat types and with a fixed gear.  [Most of my fixed gear SPD riding has been done with SM-SH51 cleats in M515 pedals.]  That there is a difference of some kind isn't a massive surprise, since the cleat is chamfered differently; it is mostly the nose that is chamfered in SM-SH56, rather than both ends (but less) on SM-SH55.

FWIW I have discovered that it is possible to both

1) reshape cleats by grinding them selectively and/or
2) build up worn cleats using MIG welding.

This means that such things as

- converting cleats from single release to multi-release 
- converting cleats to some halfway house between single and multi-release
- converting cleats to have a 'handed' release
- recovering worn cleats

are all possible.  FWIW I have discovered that under certain circumstances SPD release can be inhibited with cleat/pedal combinations that seem to work OK at first.  To get a clean release you need a combination of three things

a) that the cleat can rotate freely, with only the spring loading of the jaws for resistance
b) that the heel of the cleat doesn't have a wear groove in it from the rear jaw of any appreciable depth
c) that the pedal has a 'kicker ramp' in the direction of release.

I suspect that (even slightly worn) cleats in certain bindings fail on point a), and that is if the cleat is retained properly to start with. Genuine SPD pedals with 'platform' type bindings have 'kicker ramps' built in to both sides of the rear part of the platform; these force the cleat upwards and out of the rear jaw when twisted.  These become 'essential' should the rear part of the cleat be even slightly worn with a groove in it, otherwise the rear jaw can hang on for grim death.

A lot of knock-ff SPD pedals have no kicker ramps on either side, and this can seriously impede release, once the cleats are even slightly worn. However PD-M520 pedals (and all other shimano with 'open' type bindings) only have a kicker ramp on one side; this means that normal release (twisting heel outwards) with SM-SH51 cleats is unimpeded, but in an emergency (eg prang) the cleat won't always release cleanly if a foot twists inwards .  You can check that this is or isn't the case by twisting the heel inwards and seeing if the release is still good or not.

Like many things, SPDs look simple but there are a few twists that can catch you out!

cheers

[rogerzilla]

M525 has a "V" shaped cutout in the rear retention plate which gives zero float with SH50 cleats.  All other SPDs I have (or have seen photos of) have a larger half-moon cutout.

[Brucey]

PD-M525 may be an oddball for all I know but all 'early' SPDs have a much narrower opening in the rear jaw.  PD-A525, PD-M323 (amongst others) are somewhat  like this too.

cheers

[rogerzilla]

I looked at an M737 photo from eBay and the cutout is a lot more like later pedals.  I think M525 may have been a technological blind alley.