99cc rack mount 3 speed spoke drive MTB
- Thread starter silverbear
- Start date
SB, if you are running an auto clutch then a lock down type of affair will work fine, something like Curt is talking about or a spring. You really wouldn't need a lift clutch unless that's what you want. I would favor a positive down lock of some kind. The hub will free wheel when rolling or pedaling the bike. That way the tension is easily adjusted. The whole thing can be raised raised if pedaling a long distance like in a break down. I had one build where I had a threaded rod that could be turned to adjust tension, worked very well. Another build had slotted braces that the engine unit could be raised or lowered using cam locks like on a seat post. I think positive locks are better than a spring. However with the scissors lift the spring tension is somewhat multiplied and coupled with the weight of a heavier engine would work too. Its your preference.
Funny you should mention that. I retrieved the other two shift deals I mentioned and then remembered the rest of the side mount rig you just mentioned, brought it in for the snow to melt off of it and read your email. Mine isn't all there, but I think the important stuff is. I would need to make up the rod which must go to the dropout area on the bike frame. Between the three something can be adapted to work.
I was also thinking more about the tires and it seems to me that with the gearing figured out the Innova would be best so long as there is enough downward pressure of the spokes into the grooves. Spacing of nubs and grooves between is just right.
SB
I was also thinking more about the tires and it seems to me that with the gearing figured out the Innova would be best so long as there is enough downward pressure of the spokes into the grooves. Spacing of nubs and grooves between is just right.
SB
A threaded positive lock down would be pretty easy to do. I'll study the one Curt is talking about and see if it can be adjusted for downward pressure. What do you think, Curt?
No, the scissors jack would be redundant. (Still a great idea, though.)
What about a spring loaded idler pulley for the drive belt? Should I have one? Or is it enough to adjust tension on the belt at the hub "dropout" slots at the end of the engine mount rails?
SB
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Okay, it sounds like we can make this pretty simple and straightforward. The two angle iron rails are locked down with something like all thread rods at the hub end, but can be adjusted for how much pressure there is on the crosswise drive spokes pressing against the tire. The Innova tires will be fine since we can assure adequate pressure.
No need for an engine lift since there is an automatic clutch and if the bike needs to be pedaled it can be since the drive hub freewheels. Breakdown is not a concern since this is going to be a very reliable setup (!), but the rods being adjustable could remove pressure against the tire. Perhaps the rods could use turnbuckles for adjustment.
There is also no need for an idler pulley since belt tension can be maintained by adjusting the spoked hub's position in the slotted ends of the angle iron rails. One belt, two pulleys, automatic clutch, 3 speed drive roller transmission.
This is a very simple setup which looks bulletproof to me. Can't wait to see how this rides! I'm ordering tires tonight... Woohoo!
SB
No need for an engine lift since there is an automatic clutch and if the bike needs to be pedaled it can be since the drive hub freewheels. Breakdown is not a concern since this is going to be a very reliable setup (!), but the rods being adjustable could remove pressure against the tire. Perhaps the rods could use turnbuckles for adjustment.
There is also no need for an idler pulley since belt tension can be maintained by adjusting the spoked hub's position in the slotted ends of the angle iron rails. One belt, two pulleys, automatic clutch, 3 speed drive roller transmission.
This is a very simple setup which looks bulletproof to me. Can't wait to see how this rides! I'm ordering tires tonight... Woohoo!
SB
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That sounds like a good plan to me too Silverbear. Simple and straightforward is a good design method to follow in my book 
Thanks, Anne.
So far, so good. Fair weather melted the snow accumulated over that past few days and I made some progress on the spoke drive MTB. I changed the handlebars to ones more comfortable for me, as I like to sit upright. I wanted to change the seat, but discover the seat post is of a greater diameter so switching seats will be more complicated. Later.
I removed the Predator engine from the Panther, checking to see that the Jacobsen 147cc 2 stroke will indeed fit into the Panther frame and it will. The 99cc Predator needs a lot of cleaning up. Oil needs to be changed and I have to figure something out for a gas tank. The one that came with the engine would be just right, but I think I gave it away. Perhaps someone on the forum has one that needs a home.
I cut a pair of rails and drilled out holes near the end so they could bolt onto the mount. In the photo I have them held up with a piece of metal at an upward angle. They will sit lower when the engine is bolted into place and the 3 speed drive hub is mounted. I cut the rails extra long so they can be shortened up once I determine how far back the drive hub needs to be. Then cut them to length and cut slots for the hub axle to slide into. The hub drive sprocket has been removed and one like it from a Shimano hub is ready to mail off to Curtis Fox who is picking up a weld on 7" hub from his local tractor supply and will tack it to the sprocket before sending it back to me.
I precariously set the engine in place and am pleased that is is close to being centered and still has the drive pulley in what will be a good alignment with the driven pulley at the hub. Very pleased!
Tires, tubes and liners have already shipped and will be here Tuesday. By then I expect to have the engine mounted and the rail ends slotted and ready for the hub. The last thing to do will be to determine how long the pulley needs to be and make the purchase.
And the other last thing (ha) among several will be running the shifter cable and adjusting it so that the gears hit as they are supposed to.
I had made up an exhaust manifold for the engine when it was in the Panther and find that reversing it will make for an easy short pipe going straight back and will probably get a muffler. I had also changed the carburetor to an NT speed carb and made an air cleaner from an old Altoid can filled with stainless steel wool.
Hopefully in a couple of weeks this will be a rider...
SB
So far, so good. Fair weather melted the snow accumulated over that past few days and I made some progress on the spoke drive MTB. I changed the handlebars to ones more comfortable for me, as I like to sit upright. I wanted to change the seat, but discover the seat post is of a greater diameter so switching seats will be more complicated. Later.
I removed the Predator engine from the Panther, checking to see that the Jacobsen 147cc 2 stroke will indeed fit into the Panther frame and it will. The 99cc Predator needs a lot of cleaning up. Oil needs to be changed and I have to figure something out for a gas tank. The one that came with the engine would be just right, but I think I gave it away. Perhaps someone on the forum has one that needs a home.
I cut a pair of rails and drilled out holes near the end so they could bolt onto the mount. In the photo I have them held up with a piece of metal at an upward angle. They will sit lower when the engine is bolted into place and the 3 speed drive hub is mounted. I cut the rails extra long so they can be shortened up once I determine how far back the drive hub needs to be. Then cut them to length and cut slots for the hub axle to slide into. The hub drive sprocket has been removed and one like it from a Shimano hub is ready to mail off to Curtis Fox who is picking up a weld on 7" hub from his local tractor supply and will tack it to the sprocket before sending it back to me.
I precariously set the engine in place and am pleased that is is close to being centered and still has the drive pulley in what will be a good alignment with the driven pulley at the hub. Very pleased!
Tires, tubes and liners have already shipped and will be here Tuesday. By then I expect to have the engine mounted and the rail ends slotted and ready for the hub. The last thing to do will be to determine how long the pulley needs to be and make the purchase.
And the other last thing (ha) among several will be running the shifter cable and adjusting it so that the gears hit as they are supposed to.
I had made up an exhaust manifold for the engine when it was in the Panther and find that reversing it will make for an easy short pipe going straight back and will probably get a muffler. I had also changed the carburetor to an NT speed carb and made an air cleaner from an old Altoid can filled with stainless steel wool.
Hopefully in a couple of weeks this will be a rider...
SB
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SB, unless I am missing something Im not sure how you are going to drive the hub. If the hub is mounted to the same rails as the engine then the pulley will be inside the rails and off line with the engine, correct? The pulley is inside of the axle which is the mounting point to the rails.
Oh my gosh, you're right. I was somehow picturing the driven pulley to the outside of the rail. Oh man... now what? Can the engine move off center so that both pulleys are inside the rail? It would be a couple of inches for the engine. Back to the drawing board...
Or, maybe the 3 speed roller needs to be mounted off the seat post, below the level of the engine.
SB
Or, maybe the 3 speed roller needs to be mounted off the seat post, below the level of the engine.
SB
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You can jackshaft to a pulley that is inside the rails to the hub, keeping the engine centered which would be best for good balance. However my Lifan FD has a similar weight engine completely off set to one side and its not very noticeable in operation. So a shift of a few inches probably wouldn't be that bad.
You will need to trim the top of the rails away a bit in the hub area to allow the belt clearance. If you jack shafted you could run the larger pulley on the jack shaft and two smaller(3") pulleys from the shaft to the hub eliminating clearance issues in the rail area. Building a jack shaft is not a big thing to overcome. Don't be discouraged, just regroup.
You will need to trim the top of the rails away a bit in the hub area to allow the belt clearance. If you jack shafted you could run the larger pulley on the jack shaft and two smaller(3") pulleys from the shaft to the hub eliminating clearance issues in the rail area. Building a jack shaft is not a big thing to overcome. Don't be discouraged, just regroup.
With a jackshaft it seems to me I would be running very short belts. Is that a problem? Would I be better off mounting the driven pulley and 3 speed hub off of the seat post?
SB
SB
I think the primary belt will not be that short with a 6/7" driven pulley. The belt to the hub may be. However there are short belts easily found. Im running a 21" on the Maytag. You can also maybe run the jack shaft slightly forward to increase the secondary belt length. I would determine where the hub is going to be placed as the next step. That will determine the options/placement for a jack shaft.
Doesn't the motor have to be turned around and drive on other side for friction drive? I am thinking put the jackshaft up front the run the belt back to hube .that way you could do a double reduction, like 3" to 4" then down to 21/2" then to like 4" or 5" and the jack shaft pulleys could be the aluminum ones cheeper as I might have some............Curt
I don't believe so. CB2's Maytag is set up this way with the drive roller pulley on the left side of the bike. It is easy for me to get confused with this stuff and then figure in gearing and it's a good way to get a headache.
I sent off the driven hub sprocket this morning and it is supposed to arrive at your place on Monday. Since we're back to having a jackshaft we need to rethink the pulley size at the hub, whether 6 or 7.
I have two smaller pulleys. One is aluminum at 2 1/2" and the other is cast iron at 3" (actual diameter at outer edge is 2 3/4). I guess it would be best if they were the same size, eh?
SB
I sent off the driven hub sprocket this morning and it is supposed to arrive at your place on Monday. Since we're back to having a jackshaft we need to rethink the pulley size at the hub, whether 6 or 7.
I have two smaller pulleys. One is aluminum at 2 1/2" and the other is cast iron at 3" (actual diameter at outer edge is 2 3/4). I guess it would be best if they were the same size, eh?
SB
Curt is right SB. Remember the primary drive belt on my bike is twisted to reverse the motion. I hadn't even noticed the orientation of the engine. Another hurtle to overcome. Turning the engine around is simple but it positions the cylinder forward which moves the engine back on the mount. This is like the original Point Beach build I did. It worked fine. Perhaps a seat post mount for the hub and the jackshaft at the front of the mount like the Point Beach crossing over to drive the hub? Refresher link of the PB. http://motorbicycling.com/showpost.php?p=288811&postcount=9
Oh boy... I told you guys this stuff gives me a headache. Okay, nothing is far enough along to require redoing. So the engine gets turned around so the drive pulley is on the right side of the engine and the engine is mounted further back on the rails and the jackshaft carrying a pair of 3" pulleys is mounted toward the hinged end of the rails. And the SA shifter hub is mounted on the seat post. Is that right? Now I'm going to need to study the seat post mount you made.
SB
SB
Thanks for posting the link to your Point Beach build CB, - very useful for our edumication
Silverbear I know what you mean. Sometimes when I'm sitting beside a bike visualising which way everything needs to rotate and be connected to what my brain protests too.
Silverbear I know what you mean. Sometimes when I'm sitting beside a bike visualising which way everything needs to rotate and be connected to what my brain protests too.
A few more changes. My good friend Fasteddy has been in communication and suggested that I put the 99 Predator back into the Panther with the canoe sidecar once I've done some maintenance work on it, repainting here and there. As he sensibly points out, it is a done build and everything is set up for that engine. True. He further suggests that the 147cc Jacobsen engine would fit nicely into a 1950's Monarch which had been given to me and which I gave to Steve (fasteddy) a couple summers ago and which he proposes to give back to me when he comes to bike camp this summer. And before he comes he will weld in the Jacobsen mounts. As he sees it the bike should get an inframe tank ( I can make one out of tin thanks to the cool flange tool Tinsmith gave me) and which would be very cool with the leaf spring fork Curtis Fox has been working on for some time now and further suggests it be belt drive (and it so happens that I made up an old Monarch wheel with a red band Bendix hub and vintage 10 gauge Whizzer spokes this winter). The wheel is done and has a home made sheave on it.
Whew... another project getting in line. Do I need another bike? Not really. Would this Monarch be cool? Oh, yes!
So, the short of it is that I have just now placed an order for a 79cc 3hsp Predator engine to go on this rack mount MTB $99.00 for the engine on sale,$6.99 to ship it and with tax a little under $115.00 total. It will be here in a few days. Now I don't need to find a gas tank, either.
SB
Whew... another project getting in line. Do I need another bike? Not really. Would this Monarch be cool? Oh, yes!
So, the short of it is that I have just now placed an order for a 79cc 3hsp Predator engine to go on this rack mount MTB $99.00 for the engine on sale,$6.99 to ship it and with tax a little under $115.00 total. It will be here in a few days. Now I don't need to find a gas tank, either.
SB
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That is a really good deal on that engine Silverbear, clone engines cost a whole lot more than that here unfortunately.
The eternal question, 'Do I need another bike?' Possibly not, but the question really should be, 'Do I need the pleasure building another bike will give me?' The answer to that question is easy, - 'Yes!'
The eternal question, 'Do I need another bike?' Possibly not, but the question really should be, 'Do I need the pleasure building another bike will give me?' The answer to that question is easy, - 'Yes!'