Seeking suggestions for brake upgrade for Dolomite/BBSHD build

bluestrings

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What works for a Mongoose/BBSHD without paying more than what the bike cost? Two piston adequate? Cable w/ hydraulic calipers or full hydro?
Something compatible with brake sensor.
 
OK it looks like a choice between the Shimano BL-MT501/MT520 and Madura MT500 mid level hydraulics would be the most sensible for the Dolomite. With a 28.5 Ah battery pack and BBSHD the Dolomite is going to take on some weight. These sound like they'll have adequate stopping power. Probably ought to put on 180mm/203mm rotors.
 
Avid review looks good too. Just saw a full set for sale used $179 exclnt cond. Includes 185/203 rotors. No need to bleed but I'd probably have to swap longer lines due to ape hanger handle bars. That would be really convenient to pull the trigger and grab it. But I'm new to this and inclined ask if that would be reasonably safe way to go. Things are really adding up and an opportunity to save a few bucks here is tempting. Thoughts?
 
Magura MT5's are pretty much the best ebike brakes around. You can go crazy with say Hope brakes or something, so its possible to spend a lot more and get a little better stopping power.

Best option is the MT5 brakes and then buy the cheaper, and better, Tektro Type 17 2.3mm thick rotors. They were originally a niche product for downhill bikes but then Tektro realized they could call them ebike rotors and sell them by the shipload. MT5's normally use proprietary, thicker 2,0mm rotors and the 2.3's work, albeit just barely when the pads and rotors are both fresh/new.


The site says $39 each rotor but you can find them online for $25.

The MT5e is an ebike-capable brake with much improved brake levers, which are meant to satisfy certain moped ebike regulations in the EU but which end up just being a lot better. They use red HIGO cutoff plugs, which you can either buy adapters for, or just buy a compatible wiring harness that has red plugs instead of yellow ones. California Ebike sells those.


Here are the red-to-yellow adapters. Its cheaper just to buy a replacement wiring harness, and cleaner too.
 
Magura MT5's are pretty much the best ebike brakes around. You can go crazy with say Hope brakes or something, so its possible to spend a lot more and get a little better stopping power.

Best option is the MT5 brakes and then buy the cheaper, and better, Tektro Type 17 2.3mm thick rotors. They were originally a niche product for downhill bikes but then Tektro realized they could call them ebike rotors and sell them by the shipload. MT5's normally use proprietary, thicker 2,0mm rotors and the 2.3's work, albeit just barely when the pads and rotors are both fresh/new.


The site says $32 each rotor but you can find them online for $25.

The MT5e is an ebike-capable brake with much improved brake levers, which are meant to satisfy certain moped ebike regulations in the EU but which end up just being a lot better. They use red HIGO cutoff plugs, which you can either buy adapters for, or just buy a compatible wiring harness that has red plugs instead of yellow ones. California Ebike sells those.


Here are the red-to-yellow adapters. Its cheaper just to buy a replacement wiring harness, and cleaner too.
I know this thread is a couple of months old, but I feel it applies directly to my question and may complete the picture for other with similar questions.


I purchased a Fat Bike from a family member that has a Bafang M620. It needs some work. The rear brake does not work (lever pulls but it goes to the bar). I have a bleed kit on the way that will hopefully arrive Monday along with some other parts that I need including 2 inner tubes as it has 2 tires that will not hold air for long.

After reading the thread I can imagine that an E-Fat Bike with a very powerful motor could benefit from larger, better brakes. I found some MT5e's for a very good price and have a question about rotors. If the bike currently has 180 rotors (front and rear) would a very heavy bike like a E-Fat Bike benefit for going with larger rotors. From reading, I gather that the MT5e's work with 180, 203 & 220 rotor sizes (I understand that I need to choose 2.3mm thick rotors). I know I will need a caliper adapter if I go with a bigger than stock diameter rotor (if you can please help me find the correct adapter and the bolts). Is there any disadvantage (other than the little bit of weight and the extra adapter) that would make this not a good idea. I have not weighed the bike, but I imagine that it weighs around 80 pounds in the Fat Bike configuration. This is the same bike frame but mine has a different (fat bike) front fork and a wider rear dropout rear suspension.


I may in the future (if I like e-biking) build a set of mountain bike wheels on fat bike hubs so that I can enjoy more of a mountain e-bike.

Thank you in advance for any information you can share with me.
 
... have a question about rotors. If the bike currently has 180 rotors (front and rear) would a very heavy bike like a E-Fat Bike benefit for going with larger rotors.
Generally speaking, yes. Even bikes that say the max rotor size is 180mm, I have never had an issue going with 203's front or rear.

From reading, I gather that the MT5e's work with 180, 203 & 220 rotor sizes (I understand that I need to choose 2.3mm thick rotors).
They go with any rotor diameter provided you use the right rotor adapter. And you do NOT need to use 2.3mm rotors. Its just a smart move as they are inexpensive and an upgrade over other options that are typically more expensive. Magura calipers are meant to take Magura rotors, which are 2.0mm thick. Thats versus typical rotors which are often 1.8mm thick, and can be as thin as 1.4mm. So the great majority of off-brand brake rotors will not work. For a factory fit you can use any size of Magura Storm HC rotor, or the newer Magura MDR-C rotor. Both have lots of meat on them and are 2.0mm thick.
I know I will need a caliper adapter if I go with a bigger than stock diameter rotor (if you can please help me find the correct adapter and the bolts).
The bolts are a simple M6 socket cap you can get in a hardware store. You can re-use whatever is on the bike already as the bolt engagement doesn't change. However I have found it makes some sense to buy longer bolts so I get complete engagement of all the available threads instead of a bolt that only goes in 3/4 of the way. Buy stainless steel and get some M6 washers to put under the socket cap but over the caliper.

The adapters should be Magura brand. I won't get into specifics of why but you can guarantee perfect caliper-to-rotor fitment on the first try with no resorting to washer stacks to match things up when you use matching Magura adapters. With a 203mm rotors front and rear, assuming you have typical mounting (I cannot guarantee this) you want an IS mount 203 Rear adapter, and a post mount 203 for the front, assuming your fork has more or less standard 160mm post mounts. Without knowing the mount type for the rear and the front fork, its only educated guesswork.

Is there any disadvantage (other than the little bit of weight and the extra adapter) that would make this not a good idea.
In real world use? No. You could crack open some schoolbooks, theorize its possible to have too much braking force and posit some potential consequences from that, but in practical reality that never happens. Even so, if your front fork is rated for a 203mm rotor then you're within spec. Same goes for the frame. I've done 203 rotors with frames whose spec says 180 max and never had an issue. And that includes cargo bikes that get up to a total system weight of 500 lbs loaded. If you are doing extreme downhilling or something like that and you are slamming on the front brakes mercilessly then maybe you want to live with a smaller diameter rotor within spec.

I can tell you from experience that rotor diameter is secondary to a good strong 4-piston caliper that has good modulation (two finger braking on the levers) which lets you ... fine tune your panic stops. One of my emtb's has a 160 on the front and a 180 on the rear, and I did that because it was a vintage build from the early days of disc brake usage. Brake mounts in 1999 were nowhere near as robust as they are in 2023. That bike also has MT5e's and it stops just fine.
 
I received my Magura mt5e brakes in the mail. Now to figure out what the bike has and what I need to buy. I plan to buy Tektro Type 17 2.3mm thick rotors in 203mm. What about the mounts? The front appears to have a and adapter bringing the size of the rotor up to a 203m and the rear is adapted to 180mm. The front adapter is marked A_m203. I see no marking on the rear adapter. Is the front adapter supposed to be offset and tilt the front caliper like that or is that the wrong adapter for a front 203mm rotor? Maybe the bosses on the shock are originally intended for a 160 disk? The previous owner's install job was a hack job. The front caliper adapter was not tightened down all the way and there was a gap between the shock bosses and the adapter because the washers on the mounting bolts were digging into the shoulder on the adapter (lower bolts that mount the adapter to the shock bosses). I turned down the captive washers on the bolts and the adapter now fights tight on the shock bosses. What adapters should I get to do this correctly? Thank you.
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Best results with these brakes - as in perfect fit with no shims every time on the first try - is to use Magura adapters. Don't re-use what you have. Adapters are not universal across brands. For example Avid adapters assume an Avid fit kit which has semi-hemispherical washers under the caliper that take up additional space, so the adapters are shorter to compensate.

From your pics, you need post mount adapters (not IS type) both front and rear. Usually post mount is only used on front suspension forks but there is no official standard, and your bike proves the rule.

For an overview, go here and click on the pdf link in the first section of this page


Scroll down the page of this pdf, which has a table/matrix where you can cross ref your rotors and your mounts to find the model of adapter you need.
 
I have seen that chart before but the version I saw was not a PDF and it was so small that I could not make out the model numbers and the sizes. So, if I had a front fork that was set up for a 160MM rotor I would need a QM 42 adapter but if I had a front fork set up for a 180mm rotor I would need a QM 44. That is assuming I have 160mm bosses or 180mm bosses on my front fork. The fork is an RST Renegade Fat Bike fork, and I cannot find much information on it or I would just use that for reference. Are there any measurements of the fork or the adapter that I can take to find exactly what adapter I need? I have a 203 rotor already (although it is too thin (ideally) for the Magura calipers) so that should help some. What about how to find the correct rear adapter without knowing what rotor size the rear frame is made for? I finally found a source for the Tektro Type 17 203mm rotors @ 29.99 each with free shipping.

What are my best options to make the Magura electrical connectors play nicely with the Bafang M620 wire harness. Can I just trim the little raised plastic boss off the inside of the Magura connector and rotate the connector to line up correctly with the Bafang harness? I have some extremely fine chisels made for wood carving that would slice it off without any problem if that would solve the problem. I know they make new harnesses for the Bafang but then I have to take the bike apart and run the connectors through the frame. This was a purpose built Ebike with a M620 and not a BBSHD kit that someone put together.

Thanks.
 
I would just try a 160 and see if it fits. Most suspension forks have 160 post mounts. And if it doesn't, you get to buy another one. Or... look for markings on your existing adapters and see what they say on them. Ordinarily you would check your frame specs and see what they say about the brake mounts. Same with the fork.

Whatever you do don't do surgery on anything in the electrical connections. I know some people show how to do it but as far as I'm concerned its a totally half-assed way to do the job.

California Ebike sells wiring harnesses with Magura red higo plugs and they have an M620 version - but only for UART protocol motors with the round higo plugs. E-bike-technologies.de sells short red-to-yellow adapters. I have bought those and also had him make me custom cables when I was doing brake splitters to connect to two separate motors for awd bikes.. There are also short red-to-yellow adapter cables out there but you'll have to hunt for them. Luna had some in stock years ago, cheap and I bought ten of them :).

EDIT: I googled "red higo to yellow higo adapter" and up popped a seller right away in the UK I think selling an adapter cable.
 
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