Full Suspension Leaf Bike 1500W Build

[Apartunis]

Hydraulic brakes only get one chance to show me how they fail. When they inevitably fail then I replace them with advanced versions using stainless steel wires instead of baby oil or paint remover.

 

[DanGT86]

I agree about the hydraulic brakes. I want to like them. They feel amazing. But my first hydro brakes were Sram. They would lock up when the sun heated up the lever. I bled them a couple of times and they ruined several planned rides. I have 2 friends who have had similar problems with their SRAM brakes. Apparently they have released entire generations of garbage hydraulic brakes that require constant bleeding yet they will still ruin your day.

My whole fleet runs BB7 cable brakes with odyssey linear cable. They are the best cable brakes I know of.

Looks like the bike is coming together nicely.

 

[GoFastGus]

My whole fleet runs BB7 cable brakes with odyssey linear cable. They are the best cable brakes I know of.

How do they do for heat management and brake fade on e-bikes? My understanding was that hydraulic brakes did better with heat management. Plus the higher-end hydraulic calipers (ex. Sram code) have larger pads than BB7 calipers. What have been your use cases for BB7 calipers?

Looks like the bike is coming together nicely.

Thanks! Over time, over budget, and overstressed, but it’s been quite the learning experience.

 

[GoFastGus]

Hydraulic brakes only get one chance to show me how they fail. When they inevitably fail then I replace them with advanced versions using stainless steel wires instead of baby oil or paint remover.

Can you give me a little more insight into your chassis/powertrain/brake setup? I’d love to learn more about what’s worked well for you and what hasn’t.

 

[Apartunis]

Can you give me a little more insight into your chassis/powertrain/brake setup? I’d love to learn more about what’s worked well for you and what hasn’t.

Life is hard for my ebikes. I replace them more often than I would prefer due to cars hitting them, booby traps in the bike lane or frame breakage from heavy batteries and luggage on bad roads. When I build one I use whatever parts are available to me and cheap. There is not a repeated formula. I have gotten away from mid drives and controllers that use displays. I use steel frames for repairability and more reasonable tubing shapes, but when I break one I usually replace it rather than repair.

I use e-car or server rack battery modules that are always rectangular so they go on the rear rack.

I use no nonsense V brakes or long reach caliper brakes when the bike supports them. I use cable discs when that is the only simple way. My "newest" e-bike is a Surly Preamble with electric parts transferred from two earlier broken frames. Because the bike does not support rim brakes I have Avid BBDB brakes on it. Those were the predecessor of BB7. They are about 25 years old but work great.

I would not recommend the Surly Preamble for e-bike conversion because it not only does not support rim brakes, it does not support any kind of kickstand. It disappoints me that way every time I use it.

One of my other operational bikes started out as a cruiser so I adapted it with a rear BB7 disc because that was easiest. V brake on the front of that bike.

The only other two wheel e-bike I have running uses a V brake in front and a U brake in rear. I have two e-trikes with coaster brakes in the back. One has a Tektro Aries front cable disc and the other has a big caliper brake in front. Both use front hub motors.

 

[99t4]

My understanding was that hydraulic brakes did better with heat management.

What made that understanding? The heat is generated and concentrated at the point where the rotor and pads abrade against each other. Called friction brakes. The friction generates the heat. All other things being equal (pad material and size, rotor size, etc.), hydraulic vs. cable operated shouldn't have any difference in heat management.

 

[99t4]

I also redesigned my right torque arm so it attaches to the frame via a bolt hole instead of snugly fitting into the corner. I still need to cut it out of metal.

Can you make that hole smaller? So the bolt just barely fits thru the hole? That would make it even better, if you can achieve the precision.

 

[DanGT86]

How do they do for heat management and brake fade on e-bikes? My understanding was that hydraulic brakes did better with heat management. Plus the higher-end hydraulic calipers (ex. Sram code) have larger pads than BB7 calipers. What have been your use cases for BB7 calipers?

I run a DH bike with a heavy MXUS hub and 72v 10ah battery. Its probably 80lbs and I'm 185lbs. Ive done some paved track racing with hard braking from 50mph to 10mph. Basically as hard as I could brake without going over the bars. I have not noticed any issues with excessive fade.

The DH non Ebike is 203mm rotors and BB7s. Never had any instance where the power was inadequate.

I think heat management has more to do with the rotor size and design as well as the pads. I actually take a bit of comfort knowing I cant boil my cables the way one could boil fluid.

Im my opinion any disk brake I have ever ridden can lock up the wheel. The improvements in brakes are for modulation and lever feel. Cable brakes are old tech and do require more pull force. There are reasons the industry has gone all hydraulic. The majority of riders do fine with them.

I just couldn't stand the idea that I could pack up the bikes for a dream mtb trip and have a bleed I did perfectly still fail for no reason. I'm willing to sacrifice the fancy tech for reliability and easy quick repair.

 

[GoFastGus]

What made that understanding? The heat is generated and concentrated at the point where the rotor and pads abrade against each other. Called friction brakes. The friction generates the heat. All other things being equal (pad material and size, rotor size, etc.), hydraulic vs. cable operated shouldn't have any difference in heat management.

There are significant differences in the mechanical and hydraulic disc brakes on the market that impact heat management. 4 piston hydraulic brake pads are generally larger than 1 piston mechanical brake pads (source: having replaced pads on my Tektro Orion, Sram Code, and Avid BB5 brakes). To be fair, 2 piston hydraulic and 1 piston mechanical brakes probably have similar pad sizes. Theoretically, the fluid behind the pistons helps conduct heat away from the brake pads, but I don't have any data as to heat shed through fluid. Caliper design also plays a role shedding heat to the air, but again, I have no data on differences. I found this paper on thermal models of bike hydraulic disc brakes, but I don't know enough about the subject to fully interpret the paper. Here's a thread on specific heat absorption capacity which touches on some of the differences between brake systems.

To be clear, I concede that 1 piston mechanical and 2 piston hydraulic systems with similar pad material, pad size, rotor size, etc. probably have negligible differences in heat management. The market offers 4 piston hydraulic calipers, but not 2 piston mechanical calipers, so if I want better heat management than either the 1 piston mechanical or the 2 piston hydraulic, the 4 piston hydraulic caliper with ≥8" rotors seems like the way to go.

 

[GoFastGus]

Can you make that hole smaller? So the bolt just barely fits thru the hole? That would make it even better, if you can achieve the precision.

What are you envisioning as a fastener for the top derailleur hole? I don't have a good idea of what kind of fastener to use. It's not threaded on the inside, it just has a hex key hole. The bottom derailleur hole isn't bolted to the frame, but it notches in and will be pressed against the frame by the axle nut. Unless/until I figure something out with the top derailleur hole, using the axle nut, the TA fitting snugly into the frame, and the bottom derailleur hole will (hopefully) hold me for the freewheel side.

 

[GoFastGus]

I run a DH bike with a heavy MXUS hub and 72v 10ah battery. Its probably 80lbs and I'm 185lbs. Ive done some paved track racing with hard braking from 50mph to 10mph. Basically as hard as I could brake without going over the bars. I have not noticed any issues with excessive fade.
The DH non Ebike is 203mm rotors and BB7s. Never had any instance where the power was inadequate.

That's good to hear!

I think heat management has more to do with the rotor size and design as well as the pads. I actually take a bit of comfort knowing I cant boil my cables the way one could boil fluid.

I agree. OEMs and successful race teams study brake thermal load and carefully match rotor size and pad material among other factors to their constraints.

Im my opinion any disk brake I have ever ridden can lock up the wheel. The improvements in brakes are for modulation and lever feel. Cable brakes are old tech and do require more pull force. There are reasons the industry has gone all hydraulic. The majority of riders do fine with them.

If this hydraulic system shits the bed I'll cobble together a cable system. If that's anywhere near as good as a hydraulic system at its best I'll probably be a mechanical brake convert.

I just couldn't stand the idea that I could pack up the bikes for a dream mtb trip and have a bleed I did perfectly still fail for no reason. I'm willing to sacrifice the fancy tech for reliability and easy quick repair.

The only thing that puts a bigger frown on my face than re-bleeding my brakes is rebuilding my shock. The worst part about mechanical brakes is running cables through a frame, but that can be mitigated with a length of string.

 

[99t4]

What are you envisioning as a fastener for the top derailleur hole? I don't have a good idea of what kind of fastener to use. It's not threaded on the inside, it just has a hex key hole.

Okay, I had to really zoom in to see that it was not a threaded hole there in the dropout like I thought at first. So can you drill and tap a hole in the flat part of the dropout where I marked in red, with a hole in the same location on your TA, just large enough so the bolt can barely pass thru with no slop?

 

[GoFastGus]

Okay, I had to really zoom in to see that it was not a threaded hole there in the dropout like I thought at first. So can you drill and tap a hole in the flat part of the dropout where I marked in red, with a hole in the same location on your TA, just large enough so the bolt can barely pass thru with no slop?

I could probably do that. I need to get a few hours of seat time on this bike before I think about swapping brake systems, changing TA designs, etc.

 

[bananu7]

If this hydraulic system shits the bed I'll cobble together a cable system. If that's anywhere near as good as a hydraulic system at its best

The best cable-actuated systems don't come close to even mediocre hydraulic systems in terms of control and reliability.

The stories about hydraulic brake failures are repeated without the context of cable brakes in the generation prior failing way more often and way more spectacularly, while also being a pain to set up and maintain. Every single high-performance vehicle application uses either hydraulic or pneumatic brakes instead of mechanical linkages nowadays. They are good to stop an F1 car, a MOTOGP bike running 300+km/h, an enduro motorcycle after 6 hours of a hard race in extreme conditions - but somehow:

I could pack up the bikes for a dream mtb trip and have a bleed I did perfectly still fail for no reason

I'm sorry, but I can't roll my eyes hard enough (and yeah, i've read the rest of that post I pulled the quote from so treat it as a response to a general attitude, not you personally Dan).

Of course you do you, but I'd do a bit more research than just listening a few heavily biased forum users (myself included).

P.S. As far as heat management goes, the community of Surrons I ride with run hopelessly inadequate (in theory) brakes (like Hope V4 etc.) for their machines weighing over 60kg and pulling over 20kW. By far the most common failure that can be traced to heat management are... bent rotors, because the thicker ones won't fit in the calipers. Last time I checked, rotors are the same between cable and hydraulic disk brakes.

I think heat management has more to do with the rotor size and design as well as the pads. I actually take a bit of comfort knowing I cant boil my cables the way one could boil fluid.

Hence that's spot on.

 

[GoFastGus]

Of course you do you, but I'd do a bit more research than just listening a few heavily biased forum users (myself included).

To me, the heart of the issue is the quality of data available about things like brake systems. Everyone has anecdotal evidence, but it's full of bias and rarely includes hard data that can be verified independently. Many of the groups who run experiments on bike brake systems using the scientific method (i.e. OE brake manufacturers, high-budget race teams, etc.) have very little incentive to share those results and conclusions. I'd guess some of the student papers from FSAE/Baja electric could have good data and conclusions that could be extrapolated to our use cases. Some folks on here are really starting to push into their territory.

P.S. As far as heat management goes, the community of Surrons I ride with run hopelessly inadequate (in theory) brakes (like Hope V4 etc.) for their machines weighing over 60kg and pulling over 20kW. By far the most common failure that can be traced to heat management are... bent rotors, because the thicker ones won't fit in the calipers. Last time I checked, rotors are the same between cable and hydraulic disk brakes.

I'm running a 203x2.3mm rotor in the front; IME I've never seen a big name bike caliper advertise that it can take thicker than 2mm rotors, but the Sram Code Bronze can fit 2.3mm rotors on brand new pads. 15% more thermal mass/capacity than a 203x2mm rotor, and ~95% the thermal capacity of a 223x2mm rotor without the risk of damaging my fork. Funny enough, the issue was actually that the caliper bracket interfered with the rotor, nothing a little love from the mill couldn't fix. Can you tell me more about the brake systems these Surrons are running?

 

[GoFastGus]

Shock update:
The reason why it puked out fluid while the IFP chamber was being pressurized is because somebody took out the o ring in the rebound adjuster shaft and forgot to replace it! In fairness, the tutorial I watched said if you don't replace it, that's most likely where the shock will fail. I just forgot the replacement step, that's all.

After replacing the o ring, rebuilding the shock, and re-pressurizing the IFP chamber and the air can, the shock is now installed on my bike!!

Just to be clear, I'm mounting the shock upside down for more clearance from the battery box.

Just in case anyone rebuilding an old Fox Float shock stumbles upon this post, here's every resource I used rebuilding this shock:
RP23 Rebuild
https://www.mtbr.com/attachments/rp23-rebuild-pdf.1971494/
Piston shim stack photos:
happyride.se: artikel bakdampare i allmanhet och fox float rp23 i synnerhet, page 4 (swedish thread)
Avalanche Downhill Racing (not the clearest photo)
Youtube: Full Rebuild Rebuild P1 P2 P3 DIY IFP Chamber Fill Video 1 Video 2
I'll double check this is my comprehensive resource list, and I'll throw my part list in too bc I ended up buying 3 different rebuild kits just to get all the parts I needed, not to mention all the little metal balls and springs I lost. Nothing like spares!

 

[bananu7]

Can you tell me more about the brake systems these Surrons are running?

This deals just with the LightBee-sized machines, as the Ultra and larger already come with proper motorcycle-style floating calipers and master cylinders - the standard thickness for the front disc there is 3.0mm, with some heavy-duty models upping this to 3.2mm

With a lighter bike, most people will run high-end downhill brakes instead, and two main brands are the ones I see most common - aforementioned Hope in the largest possible configuration, or similarly-sized equivalent from Magura (a bit cheaper). In a few cases, I've heard about people grinding the pads slightly to allow the thicker rotor to fit. Basically everyone goes with the thickest they can find.

They offer surprisingly good feel and seem to have enough capacity for a couple heavy brakings even on larger descents, but I would be very wary to use them e.g. in the mountains. Another downside is expensive and more frequent maintenance (parts, pads etc.).

For a lightweight (<50kg) 1500W bike, any of those will be much more than enough to stop reliably from any speed you'll conceivably reach. On my personal ebike (~30kg, 2.2kW) I just run regular MTB brakes with a 203mm front rotor and have 0 issues with the speed i normally travel at.

 

[GoFastGus]

This deals just with the LightBee-sized machines, as the Ultra and larger already come with proper motorcycle-style floating calipers and master cylinders - the standard thickness for the front disc there is 3.0mm, with some heavy-duty models upping this to 3.2mm
With a lighter bike, most people will run high-end downhill brakes instead, and two main brands are the ones I see most common - aforementioned Hope in the largest possible configuration, or similarly-sized equivalent from Magura (a bit cheaper). In a few cases, I've heard about people grinding the pads slightly to allow the thicker rotor to fit. Basically everyone goes with the thickest they can find.

Good recommendation! It looks like I could get a Hope Tech 4 V4 caliper for roughly double the price I paid for my Sram caliper. A 3mm thick rotor has 30% more mass than a 2.3mm thick rotor, and a 3.3mm thick rotor has ~43% more mass than a 2.3mm thick rotor. This seems like a good route to explore if my current system overheats too easily since if I don't increase the rotor diameter I can keep my current fork.

They offer surprisingly good feel and seem to have enough capacity for a couple heavy brakings even on larger descents, but I would be very wary to use them e.g. in the mountains. Another downside is expensive and more frequent maintenance (parts, pads etc.).

The region I live in was covered by glaciers during the last ice age, so the topography is pretty flat around here. Between the landscape, regen braking, and good friction braking technique, I'm not super worried about brake fade from long descents.

For a lightweight (<50kg) 1500W bike, any of those will be much more than enough to stop reliably from any speed you'll conceivably reach. On my personal ebike (~30kg, 2.2kW) I just run regular MTB brakes with a 203mm front rotor and have 0 issues with the speed i normally travel at.

Good to hear! I'll report back on how adequate my system is for my use case once I get some seat time.