Cheap Sachs XR1 upgrade

[neptronix]

Motorcycle/scooter tires provide a great suspension of their own, but yeah, a 20 incher is best paired with a suspension anyway..

The adapter i mentioned can be used to push the sprocket inwards significantly, which makes chain driving a bike with tapered chainstays a non-problem. Same with the recumpence adapter.. i think it has 1/4 inch or more of inward offset..

Defeat? no way. You can also run dual 2 stage geared hubs. You can go to a 24" rear wheel to free up more space for mounting a motor.. the only frustrating thing is finding the optimal choice you will be happy with long term.. in the meantime, we have analysis paralysis.. i have been there myself for most of this journey

 

[Chalo]

The problem with a mid drive is still the strength of the bicycle chain. I've tried to get several manufacturers to make modified rear derailleurs that can accept a BMX chain. but there is no interest. Over 1kw, drivetrain problems start to become a thing because of this.

If you are okay with losing lots of speed on hills and being limited to 1000w-ish, a BBSHD would work.
Beware that it does have it's reliability issues.

Both of these are problems with gearing. If the smallest sprocket you use in the system is 16t, and chainline is acceptable, the chain will hold up just fine. People have reliability problems with BBSHD for one of two reasons: either they use too high a ratio and don't let the motor spin up appropriately (which is hard on the controller and heats up the motor), or they use sprockets that are too small and have terrible chainline. Both these things are avoidable. First, don't use one of those dumb aftermarket chainrings that moves the chainline outwards and reduces its size. Second, shuffle your most useful cassette sprockets into the positions that have good chainline, and lock out the others with the derailleur's limit screws. Under no circumstances should you ever use 11t, 12t, or 13t sprockets with motor power-- if the gearing isn't high enough, use a bigger chainring.

For a cargo bike or a tow bike, using a 42t stock front sprocket in front and 16-34 or 16-40 gears in back should do the trick nicely.

 

[qwerkus]

Lightning Rods big block, Cyclone 4.8kw, QS1000 are all options that could be run on an independent driveline. The big cyclone has the advantage of a 6:1 planetary gearbox but it may not like to handle heavy regen.
I'm currently investigating the QS.

The LR won't fit because the oversized downtube with the cable exit hole where the mid drive motor sits (this is also a problem for the BBSH btw). Also very large and very pricey. Running a BB-Style mid drive on the left also hits the controller box welded behind the bb on this frame. I could sure grind it away, but the controller box is actually one of the few nice things on this frame I'd like to keep. Cyclone is too wide and way to noisy.

The adapter i mentioned can be used to push the sprocket inwards significantly, which makes chain driving a bike with tapered chainstays a non-problem. Same with the recumpence adapter.. i think it has 1/4 inch or more of inward offset..

Defeat? no way. You can also run dual 2 stage geared hubs. You can go to a 24" rear wheel to free up more space for mounting a motor.. the only frustrating thing is finding the optimal choice you will be happy with long term.. in the meantime, we have analysis paralysis.. i have been there myself for most of this journey

The problem with "top hat" style 6bolts adapter is not the sprocket, but the brake disc rotor. Since the Adapter is at least 5-8mm thick, it pushes the rotor towards the dropout, which makes it rub against the chainstay. You need large dropout to use a top hat adapter, as avner pointed it.

The 24" wheel with a larger motor would be nice though, but it would lower the rear wheel by 2" or more, depending on the tire. The BB is already low on that bike, because it was originally a 28", so I would hit the road with the pedals or my foot. I'd have to build some sturdy dropout extension, to lower the rear wheel by at least 1.5". Wasn't considering that much frame modding, but if it solve everything else (larger dropout for the 6bolt adapter, large enough motor for single stage reduction),I might consider it. Is there a thread here compiling all dropout mods ?

First, don't use one of those dumb aftermarket chainrings that moves the chainline outwards and reduces its size.

Not sure I get what you mean: aren't Lekkie & co supposed to move the chainline inwards (towards the BB). Anyway, if bbshd it is, I'd go 3sp shimano inter3. Not many gears, but should be enough for a motor this powerful and solve all chainline issues.

 

[neptronix]

Oh if it's originally a 28" wheeled bike, then forget it.

You missed a critical piece of what i said. Tophat adapters typically have more inward offset than they consume in terms of height; otherwise the size of sprocket that can be used is limited. Maybe you've seen a retardedly designed one with no offset, but that is the exception to the rule.

Here is a retarded, poorly designed one ( bad machining ). You'll notice it has a pretty decent inset nonetheless..



This is the godly recumpence adapter.. in this picture, i have the sprocket in the wrong position, but you get the idea..

 

[Chalo]

First, don't use one of those dumb aftermarket chainrings that moves the chainline outwards and reduces its size.

Not sure I get what you mean: aren't Lekkie & co supposed to move the chainline inwards (towards the BB).

I think a Lekkie ring can do this down to 40T or so. There are rings smaller than that which must accordingly sit outboard of the gear casing. Don't use one of those.

 

[qwerkus]

Oh if it's originally a 28" wheeled bike, then forget it.

Exactly. But following our discussion about efficiency, I'm already planing a 24" DD hub on an old 26" specialized fully. Probably a 9c or leaf, if they finally make aluminium stators. In the meantime, I'm probably going to upgrade the sachs with the bbshd.

I think a Lekkie ring can do this down to 40T or so. There are rings smaller than that which must accordingly sit outboard of the gear casing. Don't use one of those.

ok got it. But how can you mount a smaller chainring without having it sit outwards ? You can't overlap the motor with 38t, which was what I would be aiming for

 

[qwerkus]

Oh if it's originally a 28" wheeled bike, then forget it.

Exactly. But following our discussion about efficiency, I'm already planing a 24" DD hub on an old 26" specialized fully. Probably a 9c or leaf, if they finally make aluminium stators. In the meantime, I'm probably going to upgrade the sachs with the bbshd.

I think a Lekkie ring can do this down to 40T or so. There are rings smaller than that which must accordingly sit outboard of the gear casing. Don't use one of those.

ok got it. But how can you mount a smaller chainring without having it sit outwards ? You can't overlap the motor with 38t, which was what I would be aiming for I was hoping of of those cheap chinese spiders would do the trick:

 

[qwerkus]

Update: I may have finally found a motor. It turns out our favorite company for hot rod hub motors also makes a high power gear motor: the mxus GDR-19

5kg and 5.8 reduction. I hope for a stronger motor than the mac, although the mac comes with 16poles and this one only has 10. Works with standart KT controller. The main issue is a super wide width of 140mm and only space for a 6sp freewheel. Looks like an overbuild machine which promises a lot of grinding / bending / fitting fun. Also cable exit from the axle = a pain.

 

[qwerkus]

Well, that's one strange chart I got from MXUS for the GDR-19



It looks like a super slow wound mac, which has been loaded to death.

 

[cheapcookie]

Hey qwerkus, have a look at this thead https://endless-sphere.com/forums/viewtopic.php?f=28&t=100485&p=1470723#p1470723.
I understand you intend to haul cargo, but for commuting...

 

[qwerkus]

Hey qwerkus, have a look at this thead https://endless-sphere.com/forums/viewtopic.php?f=28&t=100485&p=1470723#p1470723.
I understand you intend to haul cargo, but for commuting...

Saw it - interesting discussion, but it's pretty clear to me that with cargo, ditching the rear brake is a no-go. With 203mm disc front and 180mm rear, and can barely stop a bike + me + 80Kg trailer past 30kmph going downhill.

 

[cheapcookie]

Hey qwerkus, have a look at this thead https://endless-sphere.com/forums/viewtopic.php?f=28&t=100485&p=1470723#p1470723.
I understand you intend to haul cargo, but for commuting...

Saw it - interesting discussion, but it's pretty clear to me that with cargo, ditching the rear brake is a no-go. With 203mm disc front and 180mm rear, and can barely stop a bike + me + 80Kg trailer past 30kmph going downhill.

Scary...

 

[qwerkus]

Edit: Got a GDR 19! Strange beast - will post some pics asap.

 

[E-HP]

Edit: Got a GDR 19! Strange beast - will post some pics asap.

Updates??