Yet Another Cycling Forum

General Category => The Knowledge => Topic started by: Whitedown Man on January 13, 2019, 01:11:46 pm

Title: Brake Pad Screw - Use Or Ornament?
Post by: Whitedown Man on January 13, 2019, 01:11:46 pm
The standard Shimano rim brake shoe / pad setup includes a small screw that - at least in theory - fixes the pad to the shoe. Does this screw actually serve any purpose, or is it just ornamental? Campagnolo brake shoes don’t have this screw and seem none the worse for its absence.
Title: Re: Brake Pad Screw - Use Or Ornament?
Post by: Kim on January 13, 2019, 01:14:29 pm
Stops you jettisoning the pads when you use the brake to stop the bike rolling backwards as you push it up a steep slope, surely?
Title: Re: Brake Pad Screw - Use Or Ornament?
Post by: Cudzoziemiec on January 13, 2019, 02:05:04 pm
As Kim says, but in practice the pads are so tight in the holders that I really don't think they'd come out. Although my pads and holders are mismatched brands (neither Shimano) so maybe if you're full Shim, they're a looser fit.
Title: Re: Brake Pad Screw - Use Or Ornament?
Post by: fuaran on January 13, 2019, 02:12:51 pm
Often the screws just end up rusting, so you can't remove the pads. So you have to replace the whole holder/pad anyway.
Title: Re: Brake Pad Screw - Use Or Ornament?
Post by: drossall on January 13, 2019, 04:00:48 pm
Weinmann-type pads were slide-in at one point, forty years ago. A friend of mine fitted his shoes the wrong way around, and had the experience of watching the pads fly forwards when he put the brakes on. He survived :thumbsup:

I changed some pads recently and wondered whether the screws were important. I don't think that the pads are likely to move. However, the screws could be a safety device in case of incorrect fitting, as above.
Title: Re: Brake Pad Screw - Use Or Ornament?
Post by: Kim on January 13, 2019, 05:41:08 pm
The V-brakes on my hybrid have the inserts secured by split pins, which - while much less inclined to rust in place than grub screws - are a pingfuckit of the highest order.

After losing a pad twice on the same ride (I'm not sure why that particular pin kept escaping[1], but standing astride the bike waiting for others to catch up on group rides seems to be a good way to set up a pad-loosening rocking movement), I replaced the missing pin with a bit of wire, twisted to hold it in place.  This has held the pad securely for over a year now, and will be trivial to remove when it needs to be replaced.


[1] I replaced it with the spare from my toolkit, but that too disappeared.
Title: Re: Brake Pad Screw - Use Or Ornament?
Post by: sojournermike on January 13, 2019, 06:40:12 pm
I know a man who has lost pads from holders when stopping hisbtrike rolling backwards down Greenhow Hill. I use the little screws.
Title: Re: Brake Pad Screw - Use Or Ornament?
Post by: Jurek on January 13, 2019, 07:05:04 pm
FYI
The lil' screws have M3 threads.
Title: Re: Brake Pad Screw - Use Or Ornament?
Post by: Pickled Onion on January 13, 2019, 07:21:53 pm
As Kim says, but in practice the pads are so tight in the holders that I really don't think they'd come out.

You would think so, but I managed to lose a brake pad in the middle of nowhere in the middle of the night while on tour. These were the kind with the split pin that Kim described - the screw seems a better option. I put a drop of oil on when fitting the screw kind, it doesn't interfere with the threadlock paste they come with and they don't corrode, even after a couple of winters.
Title: Re: Brake Pad Screw - Use Or Ornament?
Post by: Cudzoziemiec on January 13, 2019, 07:51:36 pm
I've only ever seen split pins on pads for V-brakes and screws on pads for sidepulls. I don't remember the V-brakes being so tight in the holders. Not sure if there's any engineering reason why split pins couldn't be used on sidepulls – perhaps lack of clearance?
Title: Re: Brake Pad Screw - Use Or Ornament?
Post by: andrew_s on January 13, 2019, 09:03:23 pm
Screws go in from the outside of the bike, the pins from the side of the holder.
I'd guess that road pads & holders are short enough that the brake would get in the way of your fingers if a pin was used.
Title: Re: Brake Pad Screw - Use Or Ornament?
Post by: Ian H on January 13, 2019, 09:34:25 pm
I use the split-pins, but never the screws.  V-brake blocks seem to be a looser fit than caliper ones.

Title: Re: Brake Pad Screw - Use Or Ornament?
Post by: Brucey on January 14, 2019, 01:25:03 am
the screws are M4 threaded.  If you are worried about them getting seized, loosen them when they are new and apply a little copper-ease or something.

They are important.   Campag don't use screws but I am told that comparatively recently they have revised their brake block holders to include a spring clip which does the same job, i.e. it prevents the brake block from falling out should it become loose for whatever reason.

One reason the screws are important is that the fit of the brake block inserts can easily deceive you.   One reason for this is that rubber and plastic mouldings can continue to change size and shape after they are out of the mould; often this process carries on for months or years.

For example  I have struggled to fit new  inserts into new holders, (to the extent that I couldn't have easily removed them) only to find that they would practically fall out by themselves six months later.  I wondered if being on the bike had caused this somehow; forunately I had assembled a spare set, and those had sat in a drawer unused. They were just the same.

Even if they are tight to start with, there is basically no way to be 100% sure that brake block inserts that you buy won't shrink in this way, so if you are tempted not to use the screws, think again.

cheers
Title: Re: Brake Pad Screw - Use Or Ornament?
Post by: Oxford_Guy on January 14, 2019, 07:55:31 am
Current Campagnolo brake shoes have the little screws and now take standard "road" brake pads.
Title: Re: Brake Pad Screw - Use Or Ornament?
Post by: Ian H on January 14, 2019, 10:06:09 am
the screws are M4 threaded.  If you are worried about them getting seized, loosen them when they are new and apply a little copper-ease or something.

They are important.   Campag don't use screws but I am told that comparatively recently they have revised their brake block holders to include a spring clip which does the same job, i.e. it prevents the brake block from falling out should it become loose for whatever reason.

One reason the screws are important is that the fit of the brake block inserts can easily deceive you.   One reason for this is that rubber and plastic mouldings can continue to change size and shape after they are out of the mould; often this process carries on for months or years.

For example  I have struggled to fit new  inserts into new holders, (to the extent that I couldn't have easily removed them) only to find that they would practically fall out by themselves six months later.  I wondered if being on the bike had caused this somehow; forunately I had assembled a spare set, and those had sat in a drawer unused. They were just the same.

Even if they are tight to start with, there is basically no way to be 100% sure that brake block inserts that you buy won't shrink in this way, so if you are tempted not to use the screws, think again.

cheers

Interesting, but none of that has happened to me in more than 25 years of not using the screws.
Title: Re: Brake Pad Screw - Use Or Ornament?
Post by: Brucey on January 14, 2019, 03:23:52 pm
Current Campagnolo brake shoes have the little screws and now take standard "road" brake pads.

they do brake block models which are made to the shimano pattern, accept shimano pattern inserts and use screws. They also do brake block  models which use the campag pattern inserts and (apparently, I've not dismantled any myself) use spring clips to retain the inserts.


Interesting, but none of that has happened to me in more than 25 years of not using the screws.

you have been lucky; they don't go to the expense/bother of fitting them just for fun.

cheers
Title: Re: Brake Pad Screw - Use Or Ornament?
Post by: Ian H on January 14, 2019, 05:21:22 pm

you have been lucky; they don't go to the expense/bother of fitting them just for fun.

cheers

I expect US liability laws have something to do with it.  But given my mileage, I reckon it's a little more than luck.  I have never removed one that's been less than very securely in place.
Title: Re: Brake Pad Screw - Use Or Ornament?
Post by: Brucey on January 14, 2019, 05:51:15 pm
sometimes you make your own luck; holders and brake blocks vary.

Possibly the change in campag's policy has been brought about by possible litigation, possibly it reflects a real difference in the way their brake blocks are made, so that they are easier to fit and/or are more likely to come loose.

Having had inserts come loose in their holders, I shall continue to use the screws/pins/clips where possible!

cheers
Title: Re: Brake Pad Screw - Use Or Ornament?
Post by: fuaran on January 14, 2019, 05:57:24 pm
Or just use one-piece brake blocks. They are almost as cheap as cartridge systems anyway (at least for V-brakes).
Title: Re: Brake Pad Screw - Use Or Ornament?
Post by: Oxford_Guy on January 14, 2019, 06:00:05 pm
Current Campagnolo brake shoes have the little screws and now take standard "road" brake pads.

they do brake block models which are made to the shimano pattern, accept shimano pattern inserts and use screws. They also do brake block  models which use the campag pattern inserts and (apparently, I've not dismantled any myself) use spring clips to retain the inserts.


There are quite a number of different pattern Campagnolo brake inserts, quite apart from the Shimano pattern ones e.g. post-2000, pre-2000, earlier etc.
Title: Re: Brake Pad Screw - Use Or Ornament?
Post by: Brucey on January 14, 2019, 06:19:42 pm
Current Campagnolo brake shoes have the little screws and now take standard "road" brake pads.

they do brake block models which are made to the shimano pattern, accept shimano pattern inserts and use screws. They also do brake block  models which use the campag pattern inserts and (apparently, I've not dismantled any myself) use spring clips to retain the inserts.


There are quite a number of different pattern Campagnolo brake inserts, quite apart from the Shimano pattern ones e.g. post-2000, pre-2000, earlier etc.

indeed. However I am told that the most recent change in campag fit holders is to have spring retainers built into the holders, as from ~2013 I think. I assumed that this didn't coincide with a change in the insert fitment per se, but I don't know that for sure.

I think if you have campag holders with screws in, they accept shimano inserts.

cheers
Title: Re: Brake Pad Screw - Use Or Ornament?
Post by: andrew_s on January 14, 2019, 06:50:07 pm
I expect the main reason for the screws/pins is so that numpties who fit the pad holders with the open end forward don't kill themselves so easily.

Whilst the pads on correctly fitted holders can come out (in my case when doing a 3-point turn wheeling a loaded touring bike, using the rear brake to stop the reversing leg), it's less likely to be an immediate problem, as the bike will be near stationary.
Title: Re: Brake Pad Screw - Use Or Ornament?
Post by: rogerzilla on January 14, 2019, 08:25:32 pm
I remove old pads by lightly applying the brake and pushing the bike backwards.  After removing the screws, obv.
Title: Re: Brake Pad Screw - Use Or Ornament?
Post by: Oxford_Guy on January 15, 2019, 06:49:49 am
I remove old pads by lightly applying the brake and pushing the bike backwards.  After removing the screws, obv.

Good tip (should also work for some Campag pads)
Title: Re: Brake Pad Screw - Use Or Ornament?
Post by: Oxford_Guy on January 15, 2019, 07:08:25 am

I think if you have campag holders with screws in, they accept shimano inserts.


Correct, and they don't accept the previous generation of Campag blocks that went in their shoes that don't have screws.
Title: Re: Brake Pad Screw - Use Or Ornament?
Post by: trekker12 on January 15, 2019, 01:07:13 pm
I expect the main reason for the screws/pins is so that numpties who fit the pad holders with the open end forward don't kill themselves so easily.


This,

There is a risk the pads can be installed backwards by the untrained or inexperienced. Yes I know it clearly says FORWARD on the cartridge but that doesn't stop some people who wonder why bike shops charge them so much for servicing something a simple as a bicycle.

I always fit them (and many other bolts on a bike) with copper slip, I always check the direction but sometimes if I'm trying to get a bike working in a hurry late one evening and mistakes can happen. I've built numerous bikes in the past 20 years without major mishap but I'm not immune to silly little errors.
Title: Re: Brake Pad Screw - Use Or Ornament?
Post by: Paul on January 15, 2019, 01:15:38 pm
...
For example  I have struggled to fit new  inserts into new holders, (to the extent that I couldn't have easily removed them) only to find that they would practically fall out by themselves six months later. 
...
This, almost every time. It's never occurred to me until now that the blocks had shrunk, but it makes sense to me.
Title: Re: Brake Pad Screw - Use Or Ornament?
Post by: Brucey on January 17, 2019, 01:01:39 pm
I visited an LBS (on the other side of town) yesterday and the younger of the two mechanics was showing me his latest project, a 1980's frame from out of the lightweight unit in Nottingham, with nominally 50mm brake drop. Currently in use as a commuting machine/project, obviously the rear brake (a modern Campag one with 49mm drop) didn't quite reach.  In fact he only had one brake.

 " I hope you don't maintain your customer's bikes like that..." I said. 

He muttered that he planned to hook up the rear brake soon.

"Its not that which really worries me" I said, directing his attention to the front brake.  He looked puzzled.  More pointing, more puzzlement. Eventually I had to explain to him that he'd fitted the brake shoes the wrong way round, i.e. with the open end facing forwards.  The other mechanic hadn't noticed either. 

He'd been riding for about a week with the brake (his only brake) like that. I was amazed the blocks hadn't just spat out; "they were a tight fit going in" I was told....  FWIW they were the recent campag holders without any secondary retention mechanism. No idea what inserts they were.

Reminds me why I don't let other people work on my brakes..... :o :o

cheers
Title: Re: Brake Pad Screw - Use Or Ornament?
Post by: Cudzoziemiec on January 17, 2019, 01:05:18 pm
Ulp!