off road rear hub as mid drive build blog
- Thread starter John Bozi
- Start date
Chalo
100 TW
Miles said:
Seems like it would also have the effect of adding resistance to suspension movement when the brake is applied.
speedmd
10 MW
Just the opposite. It allows to rear to float over stuff while holding more constant torque on the wheel and not torquing the swing into compression. Greatly reduced the chatter / hopping you get on washboard stuff when applying the rear break. Motor cycles have been doing this for 30 plus years. Not sure I like it on top of the swing and compressing the rod. Keeps it out of harms way a bit more.
John Bozi
100 kW
Have just renamed this thread as I have changed the direction I want to head in.
Yesterday I did a big ride on the single track terrain with my current on road bike, which has given me better perspective of what works.
I had over heating issues a lot, was getting to 100 degrees quite a few times on a hot day. There were trails where the motor just came to a stand still but I don't mind as I really didn't enjoy climbing up such steep firetrails any way. There was a lot of other stuff that I enjoyed. Yes I was thinking how the 12t mac would go, but considering how rough the terrain was I know people don't recommend them for that, so the slowest mac is not on the cards anymore.
I am planning to get a cromotor, unless there is a tougher more torque and fast motor out there you can tell me about...
This is my plan. I want the rear to be a pitbike rim and tread with the biggest knobs as possible. The front I am not sure which size but it should be able to use the knobiest tyre that would fit inside a double crown fork. The front wheel size would be nice to be somewhere between the pitbike tyre and a normal 26" tyre the forks are made for.
Then for the batteries I will go lipo and use 6s to stay the same as the guys I ride with as it would be easy to charge at whoevers place without taking my own stuff.
My top speed I want (with those big knobs and smaller rear) on road to get there should be 60kmh constant.
Help me design how much battery I will need, what controller spec and what voltage to aim for.
As for the type of bike there is a good chance this will have to become a custom built bike. since I'll have a smaller rear tyre I will probably go for the smallest chainring, and I want to stick to the concentric single arm at rear like the pit bikes.
Yesterday I did a big ride on the single track terrain with my current on road bike, which has given me better perspective of what works.
I had over heating issues a lot, was getting to 100 degrees quite a few times on a hot day. There were trails where the motor just came to a stand still but I don't mind as I really didn't enjoy climbing up such steep firetrails any way. There was a lot of other stuff that I enjoyed. Yes I was thinking how the 12t mac would go, but considering how rough the terrain was I know people don't recommend them for that, so the slowest mac is not on the cards anymore.
I am planning to get a cromotor, unless there is a tougher more torque and fast motor out there you can tell me about...
This is my plan. I want the rear to be a pitbike rim and tread with the biggest knobs as possible. The front I am not sure which size but it should be able to use the knobiest tyre that would fit inside a double crown fork. The front wheel size would be nice to be somewhere between the pitbike tyre and a normal 26" tyre the forks are made for.
Then for the batteries I will go lipo and use 6s to stay the same as the guys I ride with as it would be easy to charge at whoevers place without taking my own stuff.
My top speed I want (with those big knobs and smaller rear) on road to get there should be 60kmh constant.
Help me design how much battery I will need, what controller spec and what voltage to aim for.
As for the type of bike there is a good chance this will have to become a custom built bike. since I'll have a smaller rear tyre I will probably go for the smallest chainring, and I want to stick to the concentric single arm at rear like the pit bikes.
Chalo
100 TW
If you want a direct drive hub motor, you can either have 40mph or you can have good steep hill climbing performance. Run a 40mph hub at less than 10mph under load and you'll cook it. My best guess is that a hub would have to be capable of better than 40mph to climb rough steep grades efficiently, and in that case you would not be able to do so slowly or you'd overheat.
torker
100 kW
+1 If you want to go fast u go for a fast wind. Best thing to do is get the 12t slow wind and bump the volts till u get the speed u want.
John Bozi
100 kW
I had no idea that greyborg had a concentric suspension. The bottom section is exactly what I am looking for. Although the top is too big and I find the canopy quite ugly. Maybe since they hand build them could do a custom just changing the top?
Anyway if I go the big heavy motor approach and if the suspension doesn't crunch the chainring into the ground I would love something like 22" rear and 24" front on this.
Anyway if I go the big heavy motor approach and if the suspension doesn't crunch the chainring into the ground I would love something like 22" rear and 24" front on this.
John Bozi
100 kW
It's been over a year of riding since I first started this second build blog, and most of what I learnt steered in some way my main bike.
My main bike you can see in my signature is now running 19" rim = 20" rear bicycle wheel and recently added bafang 750w mid drive. It is still not 100% complete with battery mounting and protection covers yet, however, I still know after just one ride it still is not powerfull of enough for my ultimate mountain climber.
so I have retitled this again as I am not a fan of hundreds of unfinished threads when this is the place for reaching the same goals....
I am not interested in gng or lightningrods or cyclone style mid drives. I hate the tons of chains and sprockets all over the bike.
I am interested in keeping the same power of about 5kw I run now on my off road bike but be able to run that a similar hub motor mounted out of the wheel.
I would like to study up and collect info here for all parts needed before buying anything for it, so I don't keep making errors for non compatible elements or parts which that are not going to achieve my desire for the no question best climber ever.
I'd like to stick to what I know which is hub motors and controllers and not venture into a thousand different motors and controllers etc.
I hope I don't sound like a broken record, but I do eventually build something based on my thinking out aloud...
so here are the new points:
bare big hub motor (like my current 4065 or maybe cromotor) for sheer copper mass
motor out of the wheel so that I can reduce the rpms with chain and large sprocket.
I am not sure how to run two freewheel sprockets on the rear axle on the normal right, and I don't think bicycle cassettes or freewheel chainrings can handle 5kw, so for now
left side chain drive to disc brake mount holes
issues to overcome for now that I forsee are:
rear brake, constantly running chain since no freewheel on the brake, chain tension and mounting of the hub motor position.
One solution to a lack of rear disc brake, but not sure how great it is to run a coaster brake hub on the rear. Of course I would still have front disc brakes... however the one below is too narrow for mtb dropouts... and coasters would probably cook.
will need to find an adapter:
http://www.bicycledesigner.com/rotor-and-sprocket-adapter.html
have no idea if these would see the chain hitting the tyre
http://custommotoredbicycles.com/sprockets_for_disc_brake_hubs_unviversal_disc_sprocket_adapter
My main bike you can see in my signature is now running 19" rim = 20" rear bicycle wheel and recently added bafang 750w mid drive. It is still not 100% complete with battery mounting and protection covers yet, however, I still know after just one ride it still is not powerfull of enough for my ultimate mountain climber.
so I have retitled this again as I am not a fan of hundreds of unfinished threads when this is the place for reaching the same goals....
I am not interested in gng or lightningrods or cyclone style mid drives. I hate the tons of chains and sprockets all over the bike.
I am interested in keeping the same power of about 5kw I run now on my off road bike but be able to run that a similar hub motor mounted out of the wheel.
I would like to study up and collect info here for all parts needed before buying anything for it, so I don't keep making errors for non compatible elements or parts which that are not going to achieve my desire for the no question best climber ever.
I'd like to stick to what I know which is hub motors and controllers and not venture into a thousand different motors and controllers etc.
I hope I don't sound like a broken record, but I do eventually build something based on my thinking out aloud...
so here are the new points:
bare big hub motor (like my current 4065 or maybe cromotor) for sheer copper mass
motor out of the wheel so that I can reduce the rpms with chain and large sprocket.
I am not sure how to run two freewheel sprockets on the rear axle on the normal right, and I don't think bicycle cassettes or freewheel chainrings can handle 5kw, so for now
left side chain drive to disc brake mount holes
issues to overcome for now that I forsee are:
rear brake, constantly running chain since no freewheel on the brake, chain tension and mounting of the hub motor position.
One solution to a lack of rear disc brake, but not sure how great it is to run a coaster brake hub on the rear. Of course I would still have front disc brakes... however the one below is too narrow for mtb dropouts... and coasters would probably cook.
will need to find an adapter:
http://www.bicycledesigner.com/rotor-and-sprocket-adapter.html
have no idea if these would see the chain hitting the tyre
http://custommotoredbicycles.com/sprockets_for_disc_brake_hubs_unviversal_disc_sprocket_adapter
Chalo
100 TW
John Bozi said:One solution to a lack of rear disc brake, but not sure how great it is to run a coaster brake hub on the rear. Of course I would still have front disc brakes... however the one below is too narrow for mtb dropouts... and coasters would probably cook.
I use a Velosteel coaster hub on one of my bikes, and it's a very nice functional part. It's a copy of the Fichtel & Sachs Torpedo coaster brake hub first brought to market in 1903 and produced by Sachs until the early 1990s. Tooling to produce it was exported to Czechoslovakia in the 1950s, and it's still made there by Velosteel. It has a much softer, more controllable engagement than the typical Taiwanese coaster hub, but still skids the wheel on demand. The original Sachs Torpedo was reputed to last 250,000 km without unusual care.
The one from Big Boy Cycles that's in your picture is much, much bigger than the Torpedo copy, and it has an aluminum shell. Both those difference would suggest that the Big Boy hub can dissipate a whole lot more heat than a normal coaster hub. I bet it would be a fine choice for a rear brake, if you're okay with having only a single gear and not being able to pedal backwards freely.
Keep in mind that rear braking is self-limiting-- that is, the more rear brake you use, the more weight shifts to the front wheel, leaving less traction available for further braking at the rear. Thus sensitivity is more important than gross power for a rear brake.
I like to combine a big front disc, boosted linear-pull, or self-servo cantilever brake in front, with a normal unboosted rim brake in back. (My only two-disc bike accomplishes a similar trick by having some gearhub oil wept onto the rear disc most of the time.) That way I have plenty of power for nose wheelies in front, with more latitude to deal with compromised traction conditions in the rear.
This is one of my bikes, it goes up the hills like a steam train and comes down equally as fast, iv also got another bike with a bbs2 mid drive kit in it, and although it looks more stealthy it isnt as quiet as the cro, its virtually silent.
John Bozi
100 kW
Chalo thanks for your experienced info, I'd give this coaster brake set up a try if it weren't for the narrow axle. I don't think there are too many other products to choose from.
If that's a stock cro it will not do on the mountains I ride. My main riding buddy has one and sure it does fly up steep mountains with it's huge leeway of copper mass but will overheat eventually. Usually it will do one slow long steep mountain climb but then be at its limit for the next.
The only hub I have seen do it over and over again is a custom rewound 4065 vented in a 24". The rewinding looks much too complex for me and I am not sure it would handle what I ride now either because when I rode with that guy he had to stop and wait for me in the past, which would have been cooling his motor too.
Now I run two motors and if he rode at my speed there is no way I would overheat first.
My typical ride now is 90 minutes non stop often with about 5 base to top mountains in a row with lots of shorter very steep climbs.
https://www.youtube.com/watch?v=QpkSdSWF7Jg&feature=youtu.be&list=PLzqojlpNeKR3t_VglNJXlBRmy_6rz9GuX
In the above video you see the dual motor approach. What I don't like is the weight of the bike. the 4065 vented 20" would pull up mountains with no overheating if kept at about 50kmh until the battery runs out, unfortunately the reality of off road riding is that you need to go about 20kmh and that is where the overheating occurrs.
I am tired of trying to totally new things and trusting people's advice because 99% of them don't do the same terrain. That's why ideally I would run my vented 4065 and the same 20" wheel and then give it a reduction to drop it down to my average ride speed of 20kmh.
I don't care that I would give up my top speed of 60kmh, I rarely do it and fear for my life doing it, fear for my families future too.
You've got a nice bike there though mate.
crea2k said:
If that's a stock cro it will not do on the mountains I ride. My main riding buddy has one and sure it does fly up steep mountains with it's huge leeway of copper mass but will overheat eventually. Usually it will do one slow long steep mountain climb but then be at its limit for the next.
The only hub I have seen do it over and over again is a custom rewound 4065 vented in a 24". The rewinding looks much too complex for me and I am not sure it would handle what I ride now either because when I rode with that guy he had to stop and wait for me in the past, which would have been cooling his motor too.
Now I run two motors and if he rode at my speed there is no way I would overheat first.
My typical ride now is 90 minutes non stop often with about 5 base to top mountains in a row with lots of shorter very steep climbs.
https://www.youtube.com/watch?v=QpkSdSWF7Jg&feature=youtu.be&list=PLzqojlpNeKR3t_VglNJXlBRmy_6rz9GuX
In the above video you see the dual motor approach. What I don't like is the weight of the bike. the 4065 vented 20" would pull up mountains with no overheating if kept at about 50kmh until the battery runs out, unfortunately the reality of off road riding is that you need to go about 20kmh and that is where the overheating occurrs.
I am tired of trying to totally new things and trusting people's advice because 99% of them don't do the same terrain. That's why ideally I would run my vented 4065 and the same 20" wheel and then give it a reduction to drop it down to my average ride speed of 20kmh.
I don't care that I would give up my top speed of 60kmh, I rarely do it and fear for my life doing it, fear for my families future too.
You've got a nice bike there though mate.
John Bozi
100 kW
one guy has the cro in 26" but I think changing to 24" now. The other who is the true climber uses what looks like my 4065 but totally rewound. Sheesh if I could pay someone $200 and guarantee me that my 4065 would be in the right speed at 20-30kmh slower I'd pay the money today.drew12345 said:
It just all about brute force. It's heavier than my hub... he was running 24s so umm 6kw? ah
he supposedly put fans on his controller too so lets see how that goes. thats just important as the motor....
Recently I dream if I can have a custom swing arm that is longer to fit the motor right in front of the rear wheel. Then I can change my sprocket sizes easily for different stuff.
I dream of 5kw in granny gear but with a 3 way switch or otherwise I'd be staring up at the stars with the daisies...
John Bozi said:
Thanks !
, iv not tried it on any mountains yet, so will have to see how I get on. 4motus.com where I bought the frame do make a liquid cooled cro though, im pretty sure it would crawl up a mountain again and again with a big enough radiator on the front.
Chalo
100 TW
John Bozi said:
Whether it can easily be spaced wider is dependent on factors unknown to us. Most coaster brake hubs use a 3/8"-24 threaded axle that can be replaced by a 3/8" UNF threaded stud of whatever length is desired, with cylindrical spacers between the locknuts and bearing cones to widen the over-locknut dimension-- I have done this to fit 110mm coaster hubs to 130mm and 135mm frames. The Velosteel Torpedo copy hub uses a special axle with a swaged-on right side cone and a square end; it can't easily be replaced with a wider axle.
If the Big Boy hub uses a plain axle with a commercially available thread diameter and pitch, then the axle can be spaced wider for whatever frame width is appropriate. If the axle uses a nonstandard thread or has an integrated bearing cone, things get much more complicated. The wider the spacing, the larger in diameter the spacers and locknuts must be to keep the axle stabilized and the dropouts well supported. If more than a few mm of extra spacing is necessary, then threaded spacers like extra-thick locknuts would be a good idea.
John Bozi
100 kW
All sounds a bit too complex Chalo... if I get serious about it I'd email the vendor.
Came across this Hanebrink x3, which really made my imagination run. However they must still be running low amounts of power through the bicycle chain drive parts.
Came across this Hanebrink x3, which really made my imagination run. However they must still be running low amounts of power through the bicycle chain drive parts.
This thread might interest you, using hubs as a non-hub mid drive:
http://endless-sphere.com/forums/viewtopic.php?f=6&t=38553
http://endless-sphere.com/forums/viewtopic.php?f=6&t=38553
John Bozi
100 kW
spinningmagnets said:
Thanks spinning magnets without a doubt I have seen that thread and followed quite a few others.
A lot of them are going through either the chain ring freewheel or using smaller powered motors both of which seem redundant compared to just going a lightning Rod's or AFT kit.
bzhwindtalker looks to have given up that project and even his LMX has moved onto the big block or bht motors too.
I was keen to see what John at CR is doing but don't seem to find much detail there... His mounting style is probably closest to what I am thinking for my build. I want a short chain clean build where I just can't see that happening with the motor mounted in front of the bb
REcumpence doesn't answer PMs and I can't hijack his thread either. Was interested in his brake sprocket but no info on his site...
John Bozi
100 kW
Matt got back to me about his
This with my love of the narrow wide for holding chains
sorts the sprocket brake situation. Not saying much about what it would be like to have the chain rolling all the time or how the motor would connect to the chain. Or what kind of chain since this would suit only a bicycle chain. According to most people 2kw is the limit, not sure if it is the limit if keeping a perfect straight line without shifting though....
This with my love of the narrow wide for holding chains
sorts the sprocket brake situation. Not saying much about what it would be like to have the chain rolling all the time or how the motor would connect to the chain. Or what kind of chain since this would suit only a bicycle chain. According to most people 2kw is the limit, not sure if it is the limit if keeping a perfect straight line without shifting though....
