Improving 'long drop' caliper brakes

[Samuel D]

cables I don't think make much difference unless there is a lot of friction with gammy outers/inners and they're gnarly, personally I've never had problems with any brand or unbranded that were in good condition.

Cables do make a big difference. A slight change of friction felt when pumping the lever through the pad-clearance zone is multiplied enormously when the pads hit the rim. Of course you won’t feel it as friction then – you’ll just have to pull the lever harder than you would with less cable friction.

New stainless cables, new Shimano housings, and Shimano Cable Grease (part number Y04180000) will transform the braking on most averagely maintained bicycles.

High-quality pads (e.g. Kool-Stop or Swissstop) may also make a significant improvement.

Changing the callipers is the last thing I’d try, though that too may make a difference if you go to a model with ball bearings at the pivot (e.g. BR-R650) instead of one without (e.g. BR-R451). Cable pull ratio should match, but with 8-speed STIs you’re probably safe there.

[CREPELLO]

Changing the callipers is the last thing I’d try, though that too may make a difference if you go to a model with ball bearings at the pivot (e.g. BR-R650) instead of one without (e.g. BR-R451). Cable pull ratio should match, but with 8-speed STIs you’re probably safe there.

Hi, Samual D. You alluded to a difference between the Shimano R650 and R450/1 in some previous threads, namely a difference in bushing quality. Your mention of ball bearings in the pivot of R650 callipers is interesting and news to me. Also the inferred inferiority of the R450's. Can you demonstrate or describe the difference of the two callipers in some greater detail?

I always suspected the 2 models were essentially the same, except finish quality - mainly painted v anodised.

[Samuel D]

Item number 6 of the BR-R650 exploded view diagram (PDF), which Shimano calls a Ball Retainer Unit, is a thrust bearing with ball bearings to reduce pivot friction.

It is Shimano part number Y84B98050, seen here in a photo.

The otherwise similar BR-R450 and BR-R451 lack this part (PDF).

Pivot friction may seem irrelevant when you play with the brake lever with the bicycle stopped, but when braking hard the rim tries to pull the brake pads around with it, creating a large reaction load in the pivot that greatly increases the friction compared to that felt in the pad-clearance zone.

That friction here is detrimental is shown by Shimano’s major friction-reducing efforts in their latest calliper designs and user reports of strong braking with those models.

Still, the lower cost brakes should still work well if set up with low-friction cables and good pads. Most bicycles that have been ridden in the rain for a year or two have high cable friction, which is why new cables often make a big difference.

[The utility cyclist]

cables I don't think make much difference unless there is a lot of friction with gammy outers/inners and they're gnarly, personally I've never had problems with any brand or unbranded that were in good condition.

Cables do make a big difference. A slight change of friction felt when pumping the lever through the pad-clearance zone is multiplied enormously when the pads hit the rim. Of course you won’t feel it as friction then – you’ll just have to pull the lever harder than you would with less cable friction.

New stainless cables, new Shimano housings, and Shimano Cable Grease (part number Y04180000) will transform the braking on most averagely maintained bicycles.

High-quality pads (e.g. Kool-Stop or Swissstop) may also make a significant improvement.

Changing the callipers is the last thing I’d try, though that too may make a difference if you go to a model with ball bearings at the pivot (e.g. BR-R650) instead of one without (e.g. BR-R451). Cable pull ratio should match, but with 8-speed STIs you’re probably safe there.

You mention fitting new, well that's not the comparison I made, clearly if fitting new that will improve matters

I use the latest Dura Ace brake cables and whilst excellent do not impart a huge swathe more braking differential over a set of bog standard cables with similar/same levers/calipers. it's the pads, how they are set up, how much attention to the braking surface you pay and of course some brake calipers are better than others, oh yeah and understanding how to brake correctly.
In fact I have recently fitted a set of cables that were manufactured well over 30 year ago and are not stainless, didn't have any special grease in them, no polymers and lo and behold still managed to lock the rear wheel up from speed on a 1950s bike fitted with a set of std drop dual pivots (A550s) and with a pair of non aero levers. Funny how I managed to do that without resorting to your solution and that is hardly abnormal/unusual.

Clearly if any cable is a bit gunked up, has a bad run due to a sharp corner or two or has corrosion that will affect things but no-one has to replace with high end expensive cables to get a brake to work sufficiently or even very efficiently well.

High quality well set up pads will make more difference (there is no "may" about it) than equal condition cables whether they cost £30 or £3

[CREPELLO]

Item number 6 of the BR-R650 exploded view diagram (PDF), which Shimano calls a Ball Retainer Unit, is a thrust bearing with ball bearings to reduce pivot friction.

It is Shimano part number Y84B98050, seen here in a photo.

The otherwise similar BR-R450 and BR-R451 lack this part (PDF).

Pivot friction may seem irrelevant when you play with the brake lever with the bicycle stopped, but when braking hard the rim tries to pull the brake pads around with it, creating a large reaction load in the pivot that greatly increases the friction compared to that felt in the pad-clearance zone.

That friction here is detrimental is shown by Shimano’s major friction-reducing efforts in their latest calliper designs and user reports of strong braking with those models.

Still, the lower cost brakes should still work well if set up with low-friction cables and good pads. Most bicycles that have been ridden in the rain for a year or two have high cable friction, which is why new cables often make a big difference.

Many thanks for clarifying that. I'd considered this point previously, partly as you had alluded to this in past posts, but I had never seen the evidence before and nobody here has ever mentioned it. I thought long and hard before upgrading the callipers on my Spa Audax from RX100 DP long drops. They are superficially similar to R650's. I ended up buying 650's again because I'd had better performance with them on my Mercian.

[Brucey]

FWIW even back in the days of SP calipers, Shimano's top models used ball bearings in the pivots for similar reasons. Such bearings can make a difference to how the brake works for sure, but most folk who complain about their brakes have all kinds of other, much more basic problems than this, concerned with badly prepared, unlubricated cables, rubbishy brake blocks, worn rims, bad setup, mismatched levers/calipers etc

To the above list one might add the OP's lack of familiarity with dropped bar bikes; many flat bar users who try dropped bars complain that braking from the hoods is difficult; I suspect that this uses muscles that don't get much of a workout on flat bars.

cheers

[keyboardmonkey]

Item number 6 of the BR-R650 exploded view diagram (PDF), which Shimano calls a Ball Retainer Unit, is a thrust bearing with ball bearings to reduce pivot friction.

It is Shimano part number Y84B98050, seen here in a photo.

The otherwise similar BR-R450 and BR-R451 lack this part (PDF)....

Many thanks for clarifying that...

+1

[BrownBear]

+1 impressed with R650s

[Samuel D]

I also like my BR-R650s. Good brakes and easy to work on. They felt expensive when I bought them, but I’m glad I did.

Looking closely at the exploded views again, it seems the R650 also has a more elaborate second pivot arrangement than the R451. Is that small cylindrical insert a bushing in a different material? The R451 does not have it.

In any case, the reaction load at the second pivot is smaller than the load at the main pivot, because of the shorter pivot-to-pad distance.

There is a good explanation of the bending loads at the pivot bolt here, from which you can see why ball bearings can be a good idea at that location.

By the way, I try to very slightly angle down the noses of the pads on the front brake, relative to the rim, so that when the calliper arms bend forward under hard braking, the forward tips of the pads don’t wander into the tyre. My Exal XR2 rims have a very narrow (short vertically) braking surface.

[Bmblbzzz]

FWIW even back in the days of SP calipers, Shimano's top models used ball bearings in the pivots for similar reasons. Such bearings can make a difference to how the brake works for sure, but most folk who complain about their brakes have all kinds of other, much more basic problems than this, concerned with badly prepared, unlubricated cables, rubbishy brake blocks, worn rims, bad setup, mismatched levers/calipers etc

To the above list one might add the OP's lack of familiarity with dropped bar bikes; many flat bar users who try dropped bars complain that braking from the hoods is difficult; I suspect that this uses muscles that don't get much of a workout on flat bars.

cheers

I don't think this is anything to do with muscle strength. Familiarity plays a part but is not the whole story; I no longer have a flat-barred bike but when I did (until very recently), I found the V-brakes on that MTB were much stronger than the dual-pivots on the road bike from the hoods, even though I rode the drop bars more. I think the problem is innate to the hoods position; in this position, your fingers are pushing the brake lever towards your body but in an almost parallel direction with your forearms. In contrast, when braking from the drops or from flat bars, your hand is pulling the lever towards you. This is both more powerful and more controllable. Familiarity will improve braking from the drops but it will never be as powerful or controllable (for the same brakes) as braking from the drops.

[Brucey]

To the above list one might add the OP's lack of familiarity with dropped bar bikes; many flat bar users who try dropped bars complain that braking from the hoods is difficult; I suspect that this uses muscles that don't get much of a workout on flat bars.

I don't think this is anything to do with muscle strength.

well, if you had no muscles, the brakes wouldn't come on at all.... I agree the brakes are unlikely to ever work quite as well from the hoods as the drops but the muscle groups used when braking from the hoods are odd ones that articulate the wrist, which otherwise only get a workout when doing things like playing racquet sports or when wielding a hammer all day long.... I have encountered dropped bar neophytes who were at first literally as weak as a kitten when it came to braking from the hoods, probably because they hadn't ever had any cause to use those muscles to do any real work before.

Familiarity plays a part but is not the whole story....

of course. I don't think anyone would say it was?

cheers

[PH]

What about those cross top levers? I had them on my first drop bar bike and found the braking to be somewhere between the hoods and drop positions. As time went on I both got used to braking from the hoods and adjusted my bars so as to be comfortable in the drops, found I was using them less and took them off, but I think they were a useful for the transition.

[CREPELLO]

Item number 6 of the BR-R650 exploded view diagram (PDF), which Shimano calls a Ball Retainer Unit, is a thrust bearing with ball bearings to reduce pivot friction.

It is Shimano part number Y84B98050, seen here in a photo.

The otherwise similar BR-R450 and BR-R451 lack this part (PDF).

Pivot friction may seem irrelevant when you play with the brake lever with the bicycle stopped, but when braking hard the rim tries to pull the brake pads around with it, creating a large reaction load in the pivot that greatly increases the friction compared to that felt in the pad-clearance zone.

That friction here is detrimental is shown by Shimano’s major friction-reducing efforts in their latest calliper designs and user reports of strong braking with those models.

Still, the lower cost brakes should still work well if set up with low-friction cables and good pads. Most bicycles that have been ridden in the rain for a year or two have high cable friction, which is why new cables often make a big difference.

Many thanks for clarifying that. I'd considered this point previously, partly as you had alluded to this in past posts, but I had never seen the evidence before and nobody here has ever mentioned it. I thought long and hard before upgrading the callipers on my Spa Audax from RX100 DP long drops. They are superficially similar to R650's. I ended up buying 650's again because I'd had better performance with them on my Mercian.

Just today I have stripped cleaned and lubed my old RX100 DP's for a new build run-around. I was interested to know what bushes were used on the pivot bolts, as the PDF diag above for the R450 doesn't suggest any at all, or are there integrated brass bushes?

The RX100 uses what look to be PTFE plastic bushes, which look identical in shape to the two deployed on the R650 pivots. There weren't marked or deformed in any way, which surprised me a little. The brake parts all went back together pretty easily (I used a dab of spray grease on the pivots), the hardest thing being getting the pivot bolts tight enough without binding up.

They'll now go on the new build, which is going to have straight bars. A direct comparison with the pre-reconditioned callipers will not really be possible, as I expect the straight bar brake levers to give a stronger braking response, than drop bar levers.