Reverse Pull a Brake or Not!

[nsaints]

I read a lot of comments and suggestions on this forum as well as FB that reverse pulling a front brake is the default setup on a cable brake. End of..
And I was probably of that opinion until a few years ago

Here's why

A few years back I bought my GP, which has a standard all original front brake with standard factory cabling routing
The front brake operation is almost as good as hydraulic. Per the image below. That's me pulling the front brake lever as hard as I can

Further below is the same setup (original and genuine brake and actuator) on my SX and I can easily pull the lever to the bars !

The difference that I can easily see is that the SX has a 1.7mm brake cable dia. and the GP has a 2mm dia. brake cable
So rather than reverse pulling my SX (as I would have done), I'm going to fix why it's not as efficient as my SX - starting with a new 2mm dia brake cable

Anyone share the same or differing opinions?

GP with excellent cable front brake - lever pulled back hard (2mm dia cable)


SX with inefficient cable front brake - lever easily pulled to the bars (1.7mm dia cable)

[Rich Oswald]

Just my opinion, but that proves absolutely nothing as both brakes could be adjusted differently or the tightness of the cable could be much different.

[nsaints]

Both brakes are adjusted the same. By me !

But regardless what is the purpose of a reverse pull if a standard disc can operate slightly less than a hydraulic
Or is a reverse pull to compensate for other inefficiencies like too thin a brake cable?

[Covboy]

Hi Andy - are you suggesting that the thinner cable is stretching? I would have thought that neither would stretch, but the thicker one would be stronger, although the weakest link of both cables is probably the lead nipple

[nsaints]

I’m not sure what the answer is to one brake far better than the other. Although I can easily measure cable diameters against both machines
I did read recently, can’t remember where, the front brake cable should be no thinner than 2mm. Well clearly the SX has a thinner cable and has the worst brake. So I’ll definitely be buying a new cable. Cambridge Lambretta are advertising thicker dia. brake cables with reduced stretch made specifically for disc brakes.

I’m interested in any other possible inefficiencies. I appreciate one other inefficiency are pattern disc brake actuators
Is that the complete list

Thin brake cables and pattern actuators?

[dickie]

I'm definitely not an expert in cable manufacture, but I do have a lot of experience with steel ropes on winches.

The 'lay' of the cable can allow them to stretch if not optimised. I think this is when they are manufactured with all of the stands twisted the same direction. Larger ropes are made with groups of strands that are twisted one way, then the groups are twisted the opposite way.

This type seem to have less stretch in them.

What I'm saying is that some do stretch, but it's more to do with how they're made than their diameter.

[Storkfoot]

One of the best reverse pull disc brakes I ever did had a relatively short cable loop with the cable outer covered in petrol pipe- the thick rubber stuff for cars that you see in Halfords. I can only put this down to it keeping the cable from flexing too much. I’ve not done it since as it looks a bit naff, especially on a S3 where it is more visible.

There are many component parts to a disc brake- lever, cable, actuator, circlip holding the actuator ( some are thinner than others), pads themselves - clean braking surface and a smear of grease on the back, adjustment of the pads especially the static side, disc itself - despite me being no racer, in my experience, vented ones work best. They are all important. I am not sure that the cable is the most important factor. If you have a wonderfully operating cable and actuator but have poor pads that fade, you won’t have a good brake whether you reverse pull it, or not.

Have you seen this thread?

viewtopic.php?f=10&t=16298

[Fast n Furious]

It could be that the actuator rentention circlip is weaker on the SX and is flexing outward more under braking, giving you a spongy, full travel brake feel.
A simple visual inspection of the clip whilst pulling in the lever will confirm if this is a contributor. If the lever moves but the actuator doesn't, then the springing is in the cable
I would advise against using stainless circlips here as these do stretch. Just use regular carbon spring steel ones.
Make sure that the circlip groove is completely free of paint, so the circlip can sit in the groove as far down as possible. (I use a little wire brush attachment on my Dremmel)
The circlip groove does suffer over time on Disk brakes that have seen their fair share of service. The constant eccentric force applied to the groove wall by the circlip, causes the outer wall of the circlip groove to bevel. The more it bevels, the more the clip will "spring" laterally under braking.
There is a solution to redressing this issue but it involves a milling machine.
A modern quality front brake cable these days is 2.5mm and well worth fitting. The bigger the cable the less is the stretch.

Over the years I've heard many myths as to reverse pull or not. The only reason I can see to favour reverse pull is because the cable is slightly shorter and has less bends in it therefore making it more efficient.

[LambrettaMarky]

I fitted the reverse pull set up from Cam Lam as the front brake on my SIL GP200 was woeful.

The reverse pull kit definitely improves the lever feel and overall strength of pull to the front brake. However I have some new pads to fit now (Refren) as the originals were perhaps not great.

The new kit's cable was thicker so that needed accommodating in the handlebar assembly.

Clutch Cable Seat by KTM Marky, on Flickr

There was clearance in the lever too, so made a sleeve up to remove that:

Clutch Cable Spacer 2 by KTM Marky, on Flickr

Maybe it's due to mine not being Italian, but there was some fettling needed to get it all fitted:

Reverse Pull Brake Plate Mod by KTM Marky, on Flickr

[Warkton Tornado No.1]

F n F is correct about the inner cable diameter & mechanical losses, as is dickie about the inner construction.

However the outer cable construction & it’s routing inevitably make a difference. The outer is like a long coil spring, so when that has to be curved, effectively the gaps between the coil become greater on the outside of any radius. Inevitably, Bowden cables - to use the correct terminology - have far less mechanical losses in a straight run.

The construction of the outer should consist of the steel coil being made from rectangular section, not round (which is preferable for the speedo drive)

Some time ago, having had a brand new inner fail on first use with any gusto, I looked into the procurement of stout front brake cables & contacted a number of UK manufacturers - I am of an age that can recall the extremely well engineered Bowden cables that were produced for British motorcycles - but the responses I received were far from enthusiastic.

Personally, I think there is a need for a good quality, as stout as feasible, front brake cable assembly, particularly in today’s traffic…..

[Storkfoot]

F n F is correct about the inner cable diameter & mechanical losses, as is dickie about the inner construction.

However the outer cable construction & it’s routing inevitably make a difference. The outer is like a long coil spring, so when that has to be curved, effectively the gaps between the coil become greater on the outside of any radius. Inevitably, Bowden cables - to use the correct terminology - have far less mechanical losses in a straight run.

The construction of the outer should consist of the steel coil being made from rectangular section, not round (which is preferable for the speedo drive)

Some time ago, having had a brand new inner fail on first use with any gusto, I looked into the procurement of stout front brake cables & contacted a number of UK manufacturers - I am of an age that can recall the extremely well engineered Bowden cables that were produced for British motorcycles - but the responses I received were far from enthusiastic.

Personally, I think there is a need for a good quality, as stout as feasible, front brake cable assembly, particularly in today’s traffic…..

Last week, I bought a bgm Speedo cable. I have fitted it but not used it yet. I did notice that it was rectangular section and not the usual round. I wonder though whether this bgm cable for the disc brake is also rectangular section ?

https://www.scooter-center.com/en/brake ... -bgm6409fb

[Warkton Tornado No.1]

Last week, I bought a bgm Speedo cable. I have fitted it but not used it yet. I did notice that it was rectangular section and not the usual round. I wonder though whether this bgm cable for the disc brake is also rectangular section ?

I wouldn’t accept the rectangular section for the speedo as flexibility & low drag are the qualities that are necessary in such a scenario. When the tightness of the curvature inherent in the routing is considered, I wouldn’t imagine that the inner will have an easy life. After all, they do tend to break so easily

[Storkfoot]

Last week, I bought a bgm Speedo cable. I have fitted it but not used it yet. I did notice that it was rectangular section and not the usual round. I wonder though whether this bgm cable for the disc brake is also rectangular section ?

I wouldn’t accept the rectangular section for the speedo as flexibility & low drag are the qualities that are necessary in such a scenario. When the tightness of the curvature inherent in the routing is considered, I wouldn’t imagine that the inner will have an easy life. After all, they do tend to break so easily

We’ll see. Other than that, it appears better made than the Italian and Indian ones.

[nsaints]

Thanks for all contributions to this thread

Interesting comment Dickie about cable construction - I've suspected there's something different about the better performing GP front brake cable but never paid it more attention, other that measure it's diameter. I will inspect it closer

I'm fairly certain I've checked the actuator circlip in a previous 'this brake is crap, how can I improve it' mission. But I'll recheck.

I have ordered a CamLam Disc brake cable and await it's arrival

[hullygully]

referring back to the actuator arm, I found mine flexing the holding circlip too much, so I drilled & tapped two holes around the outside & above the circlip to retain & stop it flexing, plus drilling out the disc holes, removing circlip, using good disc pads & reverse pull.

[alex_hughes]

Apologies for a) posting something stolen from another forum many moons ago and b) the quality of the said item, I hope it is readable.



Using clutch lever is an interesting option.

One of the slight drawbacks of following Paul’s link to an earlier thread is a reminder how much time has gone by. And that we are still waiting on the WT1 solution to SIL cases substandard rear brakes

[Rich Oswald]

Both brakes are adjusted the same. By me !

But regardless what is the purpose of a reverse pull if a standard disc can operate slightly less than a hydraulic
Or is a reverse pull to compensate for other inefficiencies like too thin a brake cable?

You need a 2.5mm cable for reverse pull.

[dickie]

Apologies for a) posting something stolen from another forum many moons ago and b) the quality of the said item, I hope it is readable.



Using clutch lever is an interesting option.

One of the slight drawbacks of following Paul’s link to an earlier thread is a reminder how much time has gone by. And that we are still waiting on the WT1 solution to SIL cases substandard rear brakes

I'd forgotten about the clutch lever option. I did try this once and found you have to bend it a little to stop it from hitting the rim. With the longer lever, you can obviously apply more force but this is at the expense of lever travel.

My current front brake uses a Spanish lever which is longer than italian, but shorter than a clutch lever. Good luck finding one though!

[Storkfoot]

It could be that the actuator rentention circlip is weaker on the SX and is flexing outward more under braking, giving you a spongy, full travel brake feel.
A simple visual inspection of the clip whilst pulling in the lever will confirm if this is a contributor. If the lever moves but the actuator doesn't, then the springing is in the cable
I would advise against using stainless circlips here as these do stretch. Just use regular carbon spring steel ones.
Make sure that the circlip groove is completely free of paint, so the circlip can sit in the groove as far down as possible. (I use a little wire brush attachment on my Dremmel)
The circlip groove does suffer over time on Disk brakes that have seen their fair share of service. The constant eccentric force applied to the groove wall by the circlip, causes the outer wall of the circlip groove to bevel. The more it bevels, the more the clip will "spring" laterally under braking.
There is a solution to redressing this issue but it involves a milling machine.
A modern quality front brake cable these days is 2.5mm and well worth fitting. The bigger the cable the less is the stretch.

Over the years I've heard many myths as to reverse pull or not. The only reason I can see to favour reverse pull is because the cable is slightly shorter and has less bends in it therefore making it more efficient.

What’s the remedy with the milling machine please, F&F?

I’ve had a circlip pop off under braking. The circlip, I later discovered, was substantially thinner than the spare one I replaced it with but I can’t be sure that was the only reason it came off. The disc hub is an original Italian with virtually no paint left in the groove.

[alex_hughes]

I hope this isn’t going off topic, Nsaints was referring to a standard disc brake and obviously substituting brake lever for clutch lever is referring to standard drum brakes, which of course can also be reverse pulled.

For reference, a standard Italian lever, a Spanish lever, and a standard clutch lever.

That the clutch lever bends the wrong way is worrying me! And I’m not sure how you’d cable it up, because it’s narrower at the end. I guess there’s a way





Mr B sells shorter clutch levers, same length as Spanish, but also bending the wrong way.

The Spanish lever is going to get a trial on my S1 tomorrow. Didn’t even know I had it!