MB-1-E ... what a difference!

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MB-1-E's picture
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I worked on the MB-1-E today.
Replaced the 60 tooth hub sprocket with a 72 tooth.
Added a short chain section to make up the difference.
I also reset the controller to default settings.
The new ratio is now 12:1 (was 10:1).

Before the sprocket change I could get up to 20 mph but it took maybe 3/4 block to get up to speed and the bike was sluggish on any noticable hill.

It was getting close to getting dark when I finished up, so I thought I'd check it out on the back street where there was no traffic.

I flipped the switch to 24 volt and clipped the alligator clip (my temporary igniton key) on to the positive to fire up the controller.
I took off slowly to make sure everything was in order then goosed the throttle ...
... I almost did a wheelie (wheel never left the ground) but it really has some torque. I was up to 19 mph in 3 seconds.

I headed around the block and on a straight stretch (level roadway) I slowly went from 19 to 20 mph.
My batteries weren't fully charged, I rode about 6 miles earlier in the day. On a fresh charge I might be able to top 20.

Man, What a Difference!!
I think this bike will really take the hills now.
I didn't have a chance to try any yet but with the way it shot off the line I have little doubt.

What's amazing is that I didn't seem to loose any top end speed. This is definately what it needed.
I knew the change in ratio would make a difference but had no idea how much.

WOW!

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Dave B

MB-1-E
Electric - Bridgestone MB-1 Mountain Bike

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chas_stevenson's picture
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Re: MB-1-E ... what a difference!

Dave,

I thought you were over geared that is one reason I suggested you make one change at a time. With this lower ratio you will also get more range and you still have a good top speed. Can't wait to hear how it takes the hills. I am so happy your hard work has paid off. Now is the time to start reprogramming that fancy controller you have to get the most out of the bike. I have one more suggestion, I would set the controller settings all to a low setting the test the bike and get some times, speeds, amp and voltage readings. Then change one parameter and see how it effects the base-line readings, set that parameter back and change another. I would make large changes so I could tell what each change does. When this process is complete you should be able to tell how you want to set the controller to get the best power and speed while using the least amount of power, amps.

Keep the front wheel low,
Chas S.
My Bicycle Pages

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Re: MB-1-E ... what a difference!

Dave,

I'm waiting on you to make the changes. Well, I guess it is time I catch up to you. I am off work Monday and Tuesday, will have to order that 48 tooth rear sprocket to get above a 10 to 1 ratio. Then I'll decide on whether to order another gates sprocket, my 64 tooth may also have to be changed to, to, to,,,, waiting on you Dave,

Chuck

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Re: MB-1-E ... what a difference!

Hi Chas,

I really should not have reset the controller to default at the same time I changed out sprockets.
I said I wasn't going to do that but wanted to start from a known point (i.e. Alltrax default).

The sprocket change was quite an ordeal. I made an AutoCAD drawing of the spoke configuration, hub and new sprocket so I could get the bolt circle just right.
The first sprocket I didn't do this, I just traced the spoke pattern on to some paper and it wasn't really very accurate, my previous sprocket bolt spacing varied slightly.

I also cut a ring from some firm, spongy padding (from a set of knee pads) and placed it on each side of the spokes this time and sandwiched this and the spokes between the sprocket and the retaining ring. (I only had it on one side before)
I like the way it created a very solid mounting for the sprocket.

Now, I can work with the controller settings (One at a time as you suggest) to get a feel for how each effects a change.
I can always return to where it is now just by using the default.
I agree that starting with low settings is a good place to start. Maybe I'll just carry a small notepad so I can log my readings.

I need to get set up for taking some voltage and amp readings. I have a "Doc Wattson" but it's only rated to 100 Amps ... I'm not sure how I can get around that. Is there any way that I can use a shunt of some sort in conjunction with the Doc Wattson meter? I'd love to be able to use it since it gives Ah readings, Wh readings, voltage, Amps and peak readings for the above.

I can hook up my digital multi-meter for voltages, perhaps I should look into getting an ammeter that will handle 200 Amps.
Any suggestions for something fairly accurate but not terribly expensive?

Thanks for the encouragement, it's been a long road but it's really starting to pay off. Feels pretty good to get such drastic results today. :)

Dave

MB-1-E
Electric - Bridgestone MB-1 Mountain Bike
Icon Photo of lighning striking Eiffel Tower Jun 3, 1902, taken by MG Loppe'

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Re: MB-1-E ... what a difference!

Quote:

Then I'll decide on whether to order another gates sprocket, my 64 tooth may also have to be changed to, to, to,,,, waiting on you Dave,

... to what ever gives you an 11:1 to 12:1 total.
I think both of us are in the same weight class but you have an extra quarter horse motor so ...

... I think the 12:1 will be about right for my 3/4hp, you might want closer to 11.5:1 or even 11:1 with the more powerful motor.

You have been getting good speeds, even on hills but your motor is getting pretty hot so getting away from the 10:1 is probably a good idea.

This darn trial and error stuff starts to get a bit expensive after a while, doesn't it?
I'll let you all know how the bike takes the hills.

I do eventually want to change to the synchronous belt. If I can find a 72 tooth 5mm pitch belt pulley and longer belt it would likely make for the best all around setup.

20T drive pulley with 72T driven = 3.6 ratio
22T drive sprocket with 72T driven = 3.27 ratio
11.78 Total Ratio

The V-belt is working fine but I think the synchronous would be a lot less fricton and never slip.

Dave

MB-1-E
Electric - Bridgestone MB-1 Mountain Bike
Icon Photo of lighning striking Eiffel Tower Jun 3, 1902, taken by MG Loppe'

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Re: MB-1-E ... what a difference!

Dave,
I took the day off, posted a build under the collaborative handbooks, not a neat presentation, will probably add another comment or two.

My drive is 10.4 to 1. I got down on my hands and knees to get some part #s for the build post,, my gates pulley is a 68 tooth. Gates had the 64 tooth on backorder, I remember now, I asked if they had anything close and they sent me the 68 tooth. So, I think closer to 12 to 1 would be good for me, I probably won't loose speed.

Outside ambient temperature has a very dramatic effect on my motor temp. In the mornings when I ride to work in 60 to 70 degree F temps, motor is warm, could hold your hand on there for an hour and never say it was uncomfortable. Coming home when the temps are in the eighty to ninety range F, motor is to hot to touch, maybe about 5 seconds before I have to remove my hand.

What is your chain noise on your present setup. I think most would say mine is'nt bothersome, but, with my 15 tooth sprocket it was basically silent. My current drive is primary belt, 21 and a 68 tooth. Secondary is a 14 and a 45 tooth. To eliminate chain noise I was thinking to buy that 48 tooth final chain sprocket combined with a 16 tooth chain sprocket already in my arsenal. Then get a belt sprocket in the 84 tooth range. Yes, these gear ratio changes get expensive, I always buy 2 belts, that is $20, the 48 tooth sprocket will be $30 with shipping, That Gates pulley will be in the $30 to $40 range I'm sure. These changes should drastically increase the life of the chain and sprockets, reduce chain noise to zero, decrease my motor temp,, whats a hundred bucks?

chuck

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Re: MB-1-E ... what a difference!

Hi Chuck,

Haven't had a chance to check out your build post yet but I certainly will. (I've been out riding every chance I could get the last two days .. hehe)

I don't get much chain noise with my 22T/ 72T setup but the freewheel makes some noise (22T is on the freewheel ... on the jackshaft).

I bent an adjustment bolt this afternoon. It's a grade 8 bolt too. I went up a steep little hill comming off a trail and over torqued it I guess. That little 3/4hp motor has got some torque in it!
I think the problem is that the bolt softened up a bit when brazed. This is on one of the adjustable struts (1/2" EMT conduit).

Sounds like you're getting it worked out on the ratio thing. The higher ratio makes it easier on everything (except adjustment bolts, I guess).
At 12:1 I top out right at 20.6 mph.
I assume your will be around the same since we are both working from a 3000 rpm motor. It might drop you speed a little but you'll shoot off the line and be able to climb steep inclines without slowing down or start very easily from a stop on a hill.

I'll drop by and check out your build this evening.
Glad you got it documented. It's good reference for others and yourself at a later date.
Thanks for your work in doing that!

I was climbing lots of hills today. Went on some back woods trails, rode along the power lines and just some slow cruising down the streets too.

Happy Trails ...

Dave

MB-1-E
Electric - Bridgestone MB-1 Mountain Bike
Icon Photo of lighning striking Eiffel Tower Jun 3, 1902, taken by MG Loppe'

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Re: MB-1-E ... what a difference!

Dave,

Take some more pictures of the chain adjustment areas and where they terminate at what looks like the motor on the right side and where the struts attach on the jack shaft plate, both sides. Looks to me like this will need to be upgraded, at least on the chain adjustment. From the pics, from your blog post chapter 12, looks like the theaded rod is 3/16" or less. If that is what bent I think it is being caused by a left and right movement of the whole motor assembly. A gusset between the two struts made from 14 gauge steel welded to the struts below the motor would strengthen the assembly. A good time to learn how to gas weld. EMT does'nt have much strength, I would upgrade to plumbing pipe on the struts, steel schedule pipe has very good welding characteristics, is thick walled. EMT would lose strength when heated, it becomes brittle, generally you don't want to braze or weld emt because of the gasses are toxic from the galvanization. Plumbing pipe will gain strength from welding. I don't recommend brazing steel of any type unless it was made at the mill for brazing. Hot rolled steel has a surface crust that brazing does'nt penetrate and contains impurities that weaken the bond. Brazing is a surface bond, if done on steel that is very clean it can approach the strength of a weld. In theory only, brazing is stronger than welding. Gas welding steel is much more forgiving and fairly easy to learn. I mig weld just about everything, but, can't cut steel with a mig setup. Gas gives you a lot of flexibility, cuts, is portable, solders, brazes, bronze welds and steel welds.

chuck

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Re: MB-1-E ... what a difference!

Thanks Chuck,

The bolt is a 1/4-28.
So not much meat left once threaded.
Weight applied strictly in compression would probably be ok.
Actually the stress was from the bracket rotating toward the back of the bike.
I'll go to a larger diameter bolt and
a new bracket with a stop to prevent it from
rotating back like it did.
I liked the fact that the 28 tpi made it
easy to fine tune the chain adjustment but
a larger bolt is definately needed.
I'm glad to report that the new 72T sprocket
stayed right in place. The mounting of that
sprocket is what I thought might be the weak
link.
I'm glad it held up, it was quite a lot of work to get mounted correctly.
I don't think there is much of any movement from side to side on this setup, but a cross brace couldn't hurt and might make it all just a bit more rigid.

Slightly Off Topic:

I ordered a rack for the back of my pickup that
mounts in my trailer hitch receiver. Now I'll
be able to take the bike and my dogs out for
a run. I can also run a ramp into the cargo
carrier to make it easy to load up the bike
and go hit the backroads.

Dave

MB-1-E
Electric - Bridgestone MB-1 Mountain Bike
Icon Photo of lighning striking Eiffel Tower Jun 3, 1902, taken by MG Loppe'

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Re: MB-1-E ... what a difference!

Dave,

I understand why, no, how that adjustment bolt bent now. It is hard to believe the torque from the motor bent a 3/16 grade 8 bolt! I would still like some closups of the adjustment. My Peltzer style jackshaft is being made on the side by a friend of mine who works at a machine shop. I think I will make another bike like yours that is more on the assist side, smaller motor with a small nimh pack. I have an aluminum frame mongoose rigid tail that is very light just begging for a little motor.

One of the main reasons I abandoned the Raliegh, there are three reasons, was the difficulty of chain adjustment. Second reason was lack of a good front suspension. Third was the bike was very tall and I just felt a little uncomfortable at speed. The mongoose is a shorter frame similar to yours and came with a front suspension.

Chuck

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Re: MB-1-E ... what a difference!

Hi Chuck,

Sounds interesting. You might think about a BB mount motor that incorporates your gearing for that build. You could go with a 500-650w brushless and still be able to climb those hills.
Some of those brushless motors are up to 97% efficient.

Something like this 1050W BB kit:
I think this is a Cyclone Kit, can't remember.

1050W-bike.jpg

Looks like fun!

Dave

MB-1-E
Electric - Bridgestone MB-1 Mountain Bike
Icon Photo of lighning striking Eiffel Tower Jun 3, 1902, taken by MG Loppe'

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Re: MB-1-E ... what a difference!

I've thought about bottom bracket drive, currently, not to apealling to me, motor would have to be very small, driving the front chainring and freewheeling have to be worked out. If i had a metal lathe I would just fabricate my own bottom bracket, use a couple of sprag clutches, throw the bottom bracket bearings on the bike away, put in sealed roller bearings, put that gates pulley on the left side attached to a sprag and the bikes chainring attached to a sprag on the right side, really very easy to do, "just hav'nt bought that lathe yet". Should buy a lathe, but I just would'nt use it enough to justify the space it would use up, shops pretty crowded.

Chuck

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Re: MB-1-E ... what a difference!

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Should buy a lathe, but I just would'nt use it enough to justify the space

... ya but you could turn all my stuff too Chuck, would that help ya justify making just a little bit of room for it? :D

Dang, now I'll have to go look up what a sprag clutch is ... :?

Dave

MB-1-E
Electric - Bridgestone MB-1 Mountain Bike
Icon Photo of lighning striking Eiffel Tower Jun 3, 1902, taken by MG Loppe'

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Re: MB-1-E ... what a difference!

Sprag clutch is basically a one way bearing or freewheel if you will.

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