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  • Steve--
    replied
    Originally posted by AZguy View Post

    I understood you were talking in generalities and that's why I was trying not to come across combative (I guess I didn't do a good job), however the OP was asking a very specific question:



    I'm trying to address that concern and was explaining that he should be able to go faster than that on his build and what the likely things he needs to do

    More the engineering response vs. the theoretical I suppose
    No, not at all, you didn't come across as combative. Any fault/error/misunderstanding was on me.

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  • Retrorockit
    commented on 's reply
    You can "get away' with a lot of things.I want the best performance from my brakes every time. I bed in my pads.
    When going from organic to metallic pads residue form the old pads can lead to huge noise and grabbing issues. Clean rotors (abrasives are good for this) are a must. Bedding in will "just happen" over time. But if the first stop is a hard one they won't work as well as they should.
    I worked as a mechanic in the truck rental industry. The thought of a customer, with perhaps no experience driving trucks,renting and loading up a vehicle with green brake pads seems like an accident waiting to happen. For me bedding in is part of the job. When bedding in you intentionally use the new brakes hard. The braking sucks. After the bedded brakes cooled the stopping is much better, and stays that way.
    If you do the test I suggested with green organic pads they will almost always fail. If you bed them in they may be just fine.Organic pads vary greatly in composition. Some aren't much more than cardboard. There could be some organic pads that are very good. I just don't know which ones they are.

  • AZguy
    commented on 's reply
    Organics bed *much* faster than metallic and frankly you can get away without bedding at all without much if any issues

    Metallic should be bedded and if you don't deliberately do it, they'll typically bed on their own after a considerably longer time and usually make a lot of noise (especially squealing) until bedded and will sometimes still be noisy after

    A lot of shops avoid metallic because customers will complain about them being noisy although they sometimes get accused of going organic for cost (organic on steel are usually the cheapest option) and because they last much less time... I suppose their might be shops that do this but the owners I've talked to just don't like the customers complaining about the noise and they too often would end up replacing the metallics they installed with organic because the customer keeps bringing the bike back...

  • 73Eldo
    commented on 's reply
    Do metallic pads have a different bedding process? I don't recall any of the videos I watched about bedding mention different pads using a different or not needing the process. Same thing with videos talking about the differences, they never mentioned bedding in their reviews.

  • Retrorockit
    commented on 's reply
    I have no experience with Hydros on a bicycle. I'm sure some of them are up to Ebike service, and some of them aren't. I was an early adopter of disc brakes and went with BB7 at the time. I converted that 2004 bike to BBSHD and needed bigger rear rotor (185mm/185mm) and metallic pads to make it work for me.
    I'm sure the modulation is better with hydros. BB7 is considered much better than other mechanical discs in that regard, so generic mechanical discs may not be as good.
    Aside from boiling fluid, there is the possibility of popping out a piston when working on/transporting the bike with a wheel removed. Also the need to adjust mine every few days means I'm down there checking the thickness of the pads every now and then.
    The test I gave above will work to evaluate the heat rejection capacity of any brake, hydro or mech. I'm not saying one is better than the other, I'm just saying make sure your brakes can do what you need them to do. Newer bikes come with hydros, that's just the way it is.

  • AZguy
    commented on 's reply
    Just for fun - getting plenty off-topic but best brakes I've ever owned and ridden on were these Brembos (after ditching the ABS)... amazing stopping power on pretty much any surface...



    On this moto:


  • AZguy
    replied
    After decades and a million miles on motos (the first few had cable pull drum brakes - yuck), and four bicycles with hydraulics, I'm in love with the feel and control of good hydraulics. I have cable pull discs on one bike but it's a beater/loaner so don't really care. On the e-bike beast I posted a photo of I did a beautiful stoppie for about fifty feet with the most gentle grease job landing a week or so ago and wouldn't even think of that on the cable pull brakes LOL - sure impressed a couple of my moto friends

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  • Retrorockit
    replied
    The fluid on my bike will never boil. There isn't any. For my fast street riding where traction is good Avid BB7 mechanical discs are reliable and effective.
    Here's how I decide when to switch to metallic brakes. Test your brakes as hard as you can. On flat ground that means full acceleration and repeated hard stops. Even heat up the brakes by dragging them under power ( this simulates a long downhill run without the danger). On a full speed stop the brakes should require high hand pressure at high speed, and you should need to modulate the pressure lower as the bike slows. If you find yourself adding pressure as the bike slows you have a lining issue. The resin in the pads is boiling onto the rotors and lubricating the brakes.
    A fluid problem will show up as the brake levers sinking without an increase in pressure.
    The metallic pad BB7 combo also eliminates the constant brake adjusting that happens with organics when run hard. Yes you can hear them.
    With new organic pads you should heat them up when new, and let them cool. This produces a "heat treated" dry layer. As the pads wear this layer will work it's way down through the lining material.
    Racers call this bedding in the pads, and they will prepare several sets this way so they never have "green" brake pads on the vehicle. ( Don't do this on drum brakes, it will glaze the linings.)
    Any discussion of adding top speed to a heavy bike should begin with the brakes.
    Last edited by Retrorockit; 01-19-2021, 08:26 AM.

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  • AZguy
    commented on 's reply
    I run metallic too - they say you want organic on aluminum for downhill but there will always come a point where the fluid will boil and bye-bye braking... had this happen in my truck going down a serious set of switchbacks (White Mtns in NV) - was going slow but they'll heat up anyway if you are dissipating potential energy faster than they can shed it (there's my physics for the day =] )... had organic on the bike but the metallic last 5x as long and I don't do downhill often - metallic are supposedly better for short hard braking anyway which is more my style...

    I've always said as long as the juevos aren't bigger than the brain you're likely ok... I've certainly come across plenty of moto guys where the opposite is true...

  • Retrorockit
    commented on 's reply
    We're already pushing pedal bike parts beyond their design limits with a BBSHD conversion. I run a "vintage" Downhilll wheelset and metallic disc brake pad setup on the street. It seems to be good enough for fast and flat use. But I'm not sure that there's much reserve capacity for heavier, faster, or more intensive use. The metallic brake pads I use fit the Avid BB7 cable brakes, and also the Avid Juicy hydraulics.They say don't use them for DH racing on the hydraulics. So some sort of thermal design limits are being approached on some disc brakes. This will only show up at the worst possible time!
    The Schwalbe Big Ben Plus tires I'm running are 50kph rated and say "moped" on them in the bead area. But there's only so much you can do. Sometimes "juevos" are not the solution, they're the problem!

  • AZguy
    commented on 's reply
    I'm with you - it's not practical to ride much more than 40kph (~25mph) on a BBSHD hardtail... range goes into the crapper and and for me at least it's just plain scary. It isn't unstable or anything like that and I've got plenty of time doing 150-200kph (~90-125mph) on motos so not really lack of juevos, but motos have so much more mass (5-10x!) and I'm wearing much better gear (all armored and moto helmet, leather gloves, etc.) on them and that was when I was a lot younger... even if the bicycle is loaded down with gear it's going to be significantly less than half my weight and it just doesn't feel "secure" at those speeds, the places I ride (never on street) are narrow with nearby obstacles, etc. and I really don't want to take spill even at 40kph... I'm already suffering enough from all the fights with gravity and speed where they won =]

  • AZguy
    commented on 's reply
    Haha - you never know these days... I'm sort of middle of the road by today's standards, 80-85kg 180cm but the bike is very tall and I sit only somewhat leaned forward generally (my eyeballs are higher than most all the bikes I see on the multi-use paths) and I carry a lot of heavy stuff around

    I agree and as I mentioned grades and winds have huge effect - From OP's post it sounds like he's never seeing much above 40-41kph and so I'm still thinking parameters and/or gearing

  • Retrorockit
    replied
    My guess is it would take a 2500W controller and a large custom 60V battery to keep the Amps down and have some useful range. I have no personal experience with this.
    Then the question of controlling a hardtail bike with large bouncy low pressure tires would become an issue. At some point one of the purpose built electric motorcycles would be more appropriate.

    Leave a comment:


  • 73Eldo
    replied
    Did we ever know more about the OP? 100 pound difference in the rider is huge especially at higher speeds or a positive grade. You put a big person on what is likely a fairly heavy bike with not the best components to start with you got a lot not going against you and the wind could be an issue. Open prairie, desert, or tundra along with being near large bodies of water can often mean there is always wind vs being in a more urban area were there are lots of things to block the wind.

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  • AZguy
    commented on 's reply
    As mentioned I have no problem going into the mid-30mph range (>50kph) on my pig with a stock (non-ludicrous) BBSHD consuming ~1500W from a 52V shark pack so I see no reason the OP can't exceed 40-41kph with proper gearing and parameter settings and expect that's where he needs to look
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