Advice for BBSHD on Surly Big Dummy?

[Sphragis]

Hi Everybody,

Long time lurker, first time poster!

As the title says, I’m seeking advice on converting my current Surly Big Dummy using a BBSHD.

I’d like to run an IGH, and am thinking of going with the Sturmey Archer RS-RK3.

https://www.nashbar.com/sturmey-archer-rsrk3-3sp-disc-hub-36h-black-hkc3k.btss.s00.bx/p606484?gclid=EAIaIQobChMIsvfH9KnO4gIVAa_ICh1r0A6aEAQYASABEgJkFfD_BwE

I think lacing that to a Sun Rhyno Lite or a Cliffhanger would do the trick as far as carrying capacity.

Are there any downsides to also using the Terracycle chain-tensioner with the Bafang?

https://t-cycle.com/products/surly-big-dummy-idler-kit

I’d like to upgrade the brakes to a set of hydraulic. I see that Surly is using Tektro Orion HD-M745 on their new Big Easy:

https://www.tektro.com/products.php?p=236

But the reviews on these are mixed. Any strong opinions out there? Any suggestions as to particularly good hydraulics? Would 180 rotors do the trick, or should I go bigger? And, would it make sense to get hydraulics made for E-Bikes in particular?

Finally, any suggestions on chainring and rear sprocket pairings? I am not interested in speed, but rather in torque. I need to get up hills while loaded. I’m comfortable chilling out at slow speeds and enjoying the scenery more than anything. My legs are just getting older, and I want to be able to use this to haul our camping supplies (or, occasionally, my wife) over distance and and over rolling hills.

Many thanks in advance for any thoughts, suggestions, criticisms, etc.!
Sphragis

 

[amberwolf]

I’d like to run an IGH, and am thinking of going with the Sturmey Archer RS-RK3.

Make sure you don't exceed the torque input limit of the hub, with your pedalling plus the BBSHD's output. Also, make sure you ramp power on, and don't slam it on, or it will shear the teeth of the internal gears of the hub, eventually (probably not immediately). There's pics around here somewhere of the insides of at least one IGH used with a middrive setup, after this happened--I forget which drive (custom built I think) and which IGH.

I don't know the limits of that hub, but you should find it in the datasheet for it from SA.

Any suggestions as to particularly good hydraulics? Would 180 rotors do the trick, or should I go bigger? And, would it make sense to get hydraulics made for E-Bikes in particular?

Couldn't tell you about hydraulics, but I'm using a single plain old Avid BB7 cable-operated with 200mm rotor ($70 from Amazon), with an Avid adjustable lever I already had. It can easily skid the front wheel (max possible braking) on my ~300lb SB Cruiser cargo trike, with me on it (another ~200lbs), and with Kirin (one of my St. Bernards) in the back, or a big load of groceries or dog food. Or I can modulate it for just the featheriest of slowing down.

Havent' tested it yet with the trailer and really heavy cargo.

Previously I used a dual-rim-brake setup (two sets of rim brakes) because the crappy suspension fork legs twisted so much the pads didn't seat on the rim flat during braking. A single set would've worked fine if I'd had the stiff fork I do now (no suspension). I'm using the disc now because I broke the susp fork in a crash and the fork I had to use as a replacement only had disc mounts, and the rim of the wheel I wanted to use wasn't rim brake compatible, along with setup issues in adding the rim brakes to the fork, etc.... But the disc works fine, so I'll just keep using it.

 

[Chalo]

You are likely to break the internal gear hub by feeding it more than human torque and power. I've broken some gearhubs with only muscle power, and modest primary gearing (2:1).

Have a strategy to deal with that. Or use a hub with more structural margin.

 

[dogman dan]

No IGH.