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A question of brake reach ~

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A question of brake reach ~

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Old 02-19-14 | 02:08 PM
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You're saying that the difference in mechanical advantage between long and short reach brakes
would be negated if the calipers are made of stiff material?
what are we referring to ? difference between 2020/2019 standard reach

and 2019/1 & 2020/1 (or 2020/2 for the rear, w/o the downtube bumper button) shorter reach .

I suppose you can do the math for the leverage ratio change, but what if feels like will be subjective
and primarily an opinion.
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Old 02-19-14 | 02:17 PM
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For a given pad, it's all about mechanical advantage (lever length). You have two fundamental givens, the brake bridge location and the wheel diameter. This combination determines the distance between the pivot point and the braking surface. No mater which caliper/lever configuration you use, this remains fixed for a given wheel (27" or 700C). the distance can be altered by using an offset brake bolt, but now you have included an additional moment arm in the system equation as you have two "anchor" points for the caliper. The question is which is going to flex, impacting performance, the caliper moment arm or the offset bolt. Likely not the latter. Is this why people like to use them as they can use a caliper with a shorter reach?

What are the remaining variables to consider?

Spring rate (does not need to include how long or short the engagement point is), the distance from the cable to the pivot, as discussed, and the lever moment arm. So given the lever arm distance is fixed you have two variables left to compare between the calipers, the distance from the cable to the pivot and the spring rate. The spring rate should not really be a factor as you can overcome the spring regardless of the rate. I doubt the difference would impact your perception of braking capability vs. actuation performance. Some brakes systems are hard to use but work very well, just difficult to modulate!

So between the two calipers, is there a difference in the distance between the cable and the pivot point? If yes, the longer distance should give you better braking capability.
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Old 02-19-14 | 02:42 PM
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[QUOTE][The question is which is going to flex, impacting performance, the caliper moment arm or the offset bolt. Likely not the latter. Is this why people like to use them as they can use a caliper with a shorter reach?/QUOTE]
The reason Campy drop bolts exist is that some brake bridges were too high to use Campagnolo brakes.
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Old 02-19-14 | 04:00 PM
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Originally Posted by fietsbob
what are we referring to ? difference between 2020/2019 standard reach

and 2019/1 & 2020/1 (or 2020/2 for the rear, w/o the downtube bumper button) shorter reach .

I suppose you can do the math for the leverage ratio change, but what if feels like will be subjective
and primarily an opinion.
I was asking noglider for clarification of his statement. I guess I should have quoted him.
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Old 02-19-14 | 04:05 PM
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Did look up the correct part numbers in my Catalog 17 a least ..
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Old 02-19-14 | 05:59 PM
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[QUOTE=aixaix;16509884]
[The question is which is going to flex, impacting performance, the caliper moment arm or the offset bolt. .
This was sort of my main question...amount of flex, which could affect performance. But it's likely sixes in my example. Still, there are slight differences in the design and shape of the two calipers, with the shorts having less material in spots compared with the longer arms. Mainly the neck area just north of the shoe mounting flat. But the difference in amount of deformation under loading, if any, could be negligable.

I may try the shorts with the curent 27's and the long reach on 700c wheels this summer sometime. But then my controlled experiment might go out the proverbial window what with more introduced variables., etc.
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Old 02-19-14 | 06:29 PM
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I started this thread, with dread.
I'm no engineer, and easily misled.

I learned not a thing,
but what argument can bring.

I just know that no brakes and you're dead.
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Old 02-19-14 | 06:40 PM
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......Jed.
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Old 02-19-14 | 09:12 PM
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...what he said.
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