That would be lucky if that's the case. I did cut one of the fork ends. It was a serious pita with only a dremel and a hacksaw. I was going to cut both ends, but at the last minute decided not to. When attaching the wheel, I slide one end of the axle into the end I didn't cut, then slide/push/wiggle the other fork onto the other side of the axle. Same procedure in reverse to remove. Kinda a pita, but since I'm not constantly taking the wheel on and off anyway, not that big of a deal.
Anyone Using Moped Tires?
- Thread starter 5-7HEAVEN
- Start date
5-7,
Did you end up with DS80 forks or RM80? Or is there even a difference? I assume these small motorcycle forks have a 1" steerer? How did you determine these forks would mount up to your bike frame before you purchased?
Did you end up with DS80 forks or RM80? Or is there even a difference? I assume these small motorcycle forks have a 1" steerer? How did you determine these forks would mount up to your bike frame before you purchased?
I took a leap of faith and spent the $$ for research and development. That way, others can benefit from my experiment.
There's absolutely no information of what fits what, between different Suzuki models and their relationship towards bicycles. Nobody was interested in retrofitting Suzuki parts, until bicyclists and mopedders realized the K10 would fit. I was too late to buy new K10s and pickings are slim on ebay. However, thwere's a LOT! oflater-model Suzuki forks available. No one knows what fits what, so I'm the guy taking the chances.
Here's what I know:
DS80 forks fit the 1" tube. However, they're only available with drum brake. Theire fork legs are 26mm, I believe. The steerer tube is quite long, so need to be cut and rethreaded.
RM125 front ends are HUGE! and HEAVY! Believe it or not, they actually fit the 1" tube. However, the tube is tapered at the bottom with a large shoulder for the coned bearing. You'd have to machine off the shoulder to fit the bottom bearing, then cut and rethread. For a grotesquely monstrous and wide front end w/ dual-piston hydraulic brake and a bolt-on 21" (26.6" tire).....this is it.
RM80 has most potential. It's less than 1" longer than a bicycle steerer tube. It also slips right into the headset, using bicycle bearings and adjuster. 1986-up use hydraulic disc brakes. The triple tree has 7/8" STRONG handlebar clamps. Bicycle cruiser handlebar should fit, and RM80 brake lever w/master cylinder SHOULD bolt on.RM80's have 17" wheel (21.5" tire). Fork legs, axle,, RM80 & RM125 wheels arrive soon. Hopefully a mix/match of rotors and calipers will allow the 21" wheel replace the RM80's 17" one.
Need to do more researching.
There's absolutely no information of what fits what, between different Suzuki models and their relationship towards bicycles. Nobody was interested in retrofitting Suzuki parts, until bicyclists and mopedders realized the K10 would fit. I was too late to buy new K10s and pickings are slim on ebay. However, thwere's a LOT! oflater-model Suzuki forks available. No one knows what fits what, so I'm the guy taking the chances.
Here's what I know:
DS80 forks fit the 1" tube. However, they're only available with drum brake. Theire fork legs are 26mm, I believe. The steerer tube is quite long, so need to be cut and rethreaded.
RM125 front ends are HUGE! and HEAVY! Believe it or not, they actually fit the 1" tube. However, the tube is tapered at the bottom with a large shoulder for the coned bearing. You'd have to machine off the shoulder to fit the bottom bearing, then cut and rethread. For a grotesquely monstrous and wide front end w/ dual-piston hydraulic brake and a bolt-on 21" (26.6" tire).....this is it.
RM80 has most potential. It's less than 1" longer than a bicycle steerer tube. It also slips right into the headset, using bicycle bearings and adjuster. 1986-up use hydraulic disc brakes. The triple tree has 7/8" STRONG handlebar clamps. Bicycle cruiser handlebar should fit, and RM80 brake lever w/master cylinder SHOULD bolt on.RM80's have 17" wheel (21.5" tire). Fork legs, axle,, RM80 & RM125 wheels arrive soon. Hopefully a mix/match of rotors and calipers will allow the 21" wheel replace the RM80's 17" one.
Need to do more researching.
I have more information:
The RM125 suspension is monstrous and heavy. However, its 1" steerer tube can be made to fit. It is 7.25" from base to bottom of threaded area. But the tube's bottom tapers widely to 1.5" at the base. You'd have to machine the base to 1" to fit a bicycle. 1985-up use dual-piston hydraulic brake. Its forks are a whopping 43mm diameter.
Suzuki DS80 is similar size to K10. Its 1" tube is 6.625" long. bicycle bearings and cups should fit. All DS80 forks use drum brakes; forks are 26mm diameter.
K10 might use 25mm diameter forks.
The RM80's distance from lower bearing base (of the triple tree) to end of the threads is 6.1875" (6" & 3/16"). Bicycle bearings and cups fit. Forks for 1986-88 forks are 33mm size.1989-up suspension uses 35mm diameter forks.
The upper bearing cone is NOT threaded. It is followed in place by an adjustable spanner nut.
Yes, there is a bolt that threads into the top of the steerer tube.
I have the wrong bearing cups on my bike. I'm using 3/32" loose bearings top and bottom. The triple tree feels great, but I can see the bearings. The correct cups should fix this.
Right now, I have the slightly oversized RM80 upper bearing cone on. I'm temporarily using the RM125 and DS80 cones as spacers. Everything tightens up well as a mockup. I'm not keen about using the RM80 cone, because the motorcycle headset MUST have been larger than a bicycle's. There isn't enough thread for the bicycle cone to drop onto the bearings. One option is to rethread the tube. HOWEVER, it seems like the Suzuki has quality fine thread, while the bicycle bearing cone has pipe thread. The bike's cone doesn't "feel right", wobbling down the Suzuki's threaded shaft. I wouldn't want the bike shop to re-thread and ruin it for the Suzuki's threaded spanner nuts.
Second choice is to simply dremel off the bike's cone's threads, so the cone slides, not threads down onto the steerer tube.
Third option is to braze the cone's inside diameter and machine for it to slip onto the shaft.
Fourth option is to have a machine shop machine a new bearing cone.
I'm cheap, I'll leave the RM80's bearing cone or dremel the bike's cone. They make threadless aluminum spacers for 1" steerer tubes, so I'll replace my temporary spacers with these:
http://www.ebay.com/itm/BIKE-BICYCL...Cycling_Parts_Accessories&hash=item43bd355523
Quarters in the pictures show how much bigger the RM80 and RM125's forks are. DS80 fork's diameter is quarter-size. Note that the RM125's triple tree swallows the entire fork leg! Notice how much taller, wider and thicker the 125 is, compared to the others.
The RM125 suspension is monstrous and heavy. However, its 1" steerer tube can be made to fit. It is 7.25" from base to bottom of threaded area. But the tube's bottom tapers widely to 1.5" at the base. You'd have to machine the base to 1" to fit a bicycle. 1985-up use dual-piston hydraulic brake. Its forks are a whopping 43mm diameter.
Suzuki DS80 is similar size to K10. Its 1" tube is 6.625" long. bicycle bearings and cups should fit. All DS80 forks use drum brakes; forks are 26mm diameter.
K10 might use 25mm diameter forks.
The RM80's distance from lower bearing base (of the triple tree) to end of the threads is 6.1875" (6" & 3/16"). Bicycle bearings and cups fit. Forks for 1986-88 forks are 33mm size.1989-up suspension uses 35mm diameter forks.
The upper bearing cone is NOT threaded. It is followed in place by an adjustable spanner nut.
Yes, there is a bolt that threads into the top of the steerer tube.
I have the wrong bearing cups on my bike. I'm using 3/32" loose bearings top and bottom. The triple tree feels great, but I can see the bearings. The correct cups should fix this.
Right now, I have the slightly oversized RM80 upper bearing cone on. I'm temporarily using the RM125 and DS80 cones as spacers. Everything tightens up well as a mockup. I'm not keen about using the RM80 cone, because the motorcycle headset MUST have been larger than a bicycle's. There isn't enough thread for the bicycle cone to drop onto the bearings. One option is to rethread the tube. HOWEVER, it seems like the Suzuki has quality fine thread, while the bicycle bearing cone has pipe thread. The bike's cone doesn't "feel right", wobbling down the Suzuki's threaded shaft. I wouldn't want the bike shop to re-thread and ruin it for the Suzuki's threaded spanner nuts.
Second choice is to simply dremel off the bike's cone's threads, so the cone slides, not threads down onto the steerer tube.
Third option is to braze the cone's inside diameter and machine for it to slip onto the shaft.
Fourth option is to have a machine shop machine a new bearing cone.
I'm cheap, I'll leave the RM80's bearing cone or dremel the bike's cone. They make threadless aluminum spacers for 1" steerer tubes, so I'll replace my temporary spacers with these:
http://www.ebay.com/itm/BIKE-BICYCL...Cycling_Parts_Accessories&hash=item43bd355523
Quarters in the pictures show how much bigger the RM80 and RM125's forks are. DS80 fork's diameter is quarter-size. Note that the RM125's triple tree swallows the entire fork leg! Notice how much taller, wider and thicker the 125 is, compared to the others.
Attachments
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K10's are hard to find now. I grabbed me a pair from the ebay seller right before they sold out. However, for anyone who might find a pair, here is some info. The steerer tube is 6" long. There is a threaded hole on top of the steerer tube to bolt the top clamp on. The steerer tube threads will accept a bike's threaded bearing cone. I had to play around with what to use on the top part of the headset, and ended up with a bearing cone, the washer that slides into the groove (dont know what its called) and a modified cap nut (the one that usually goes on top of your headset and has a crown that stops it once it gets so far down on the threads, dont know the proper term for it either). What I did was cut off the crown part with a dremel. I was then able to tighten the nut down on the steerer tube as far as needed. I put some blue threadlocker on it, then bolted my top clamp on like normal.
5-7HEAVEN,
Excellent information that is very useful for those whom are considering doing a light motorcycle fork swap. Suggest moving this data to it's own thread and cross-linking to this thread for reference.
Excellent information that is very useful for those whom are considering doing a light motorcycle fork swap. Suggest moving this data to it's own thread and cross-linking to this thread for reference.
Thanks, man. It just morphed into front suspension choices, after I opted for motorcycle tires.
I'm gonna keep the RM125 triple tree. Parts are plentiful, and it has dual-piston hydraulic disc brake and huge motorcycle tire (26.7" diameter).
It'd make a hellacious Frankenstein bike.
I'm gonna keep the RM125 triple tree. Parts are plentiful, and it has dual-piston hydraulic disc brake and huge motorcycle tire (26.7" diameter).
It'd make a hellacious Frankenstein bike.
My RM80 fork legs arrived, so I slipped them and an inverted handlebar into the triple tree.
The distance from the axle to the bottom of the tree is 22".
The fork's width @ 13" from the axle is 4". My Dunlop tire is 3" wide, leaving 1/2" clearance both sides.
These legs are heavy!
One nice feature is that they are air-filled, not oil-filled. They'll be MUCH easier AND less messy to experiment for ride height.
The triple tree top plate has upper leg clamps, also making for easy adjustments.
Waiting for the 17" and 21" wheels to arrive.
The distance from the axle to the bottom of the tree is 22".
The fork's width @ 13" from the axle is 4". My Dunlop tire is 3" wide, leaving 1/2" clearance both sides.
These legs are heavy!
One nice feature is that they are air-filled, not oil-filled. They'll be MUCH easier AND less messy to experiment for ride height.
The triple tree top plate has upper leg clamps, also making for easy adjustments.
Waiting for the 17" and 21" wheels to arrive.
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I decided to trial-fit the hydraulic calipers onto the RM80 fork.
Of course, the RM80 single-piston caliper bolted directly to the fork's bracket.
As expected, the larger RM125 dual-piston caliper did NOT bolt onto the fork.
However, it DID bolt into one bracket hole. A simple flat "E-shaped" bracket could be fabbed to reach the large caliper's second bracket hole.
Another option would be to disassemble the calipers, compare the bolt patterns of both mounting plates, then modify the larger one as needed.
The RM80 & RM125 rotors and wheels should be here soon for further fitment.
Of course, the RM80 single-piston caliper bolted directly to the fork's bracket.
As expected, the larger RM125 dual-piston caliper did NOT bolt onto the fork.
However, it DID bolt into one bracket hole. A simple flat "E-shaped" bracket could be fabbed to reach the large caliper's second bracket hole.
Another option would be to disassemble the calipers, compare the bolt patterns of both mounting plates, then modify the larger one as needed.
The RM80 & RM125 rotors and wheels should be here soon for further fitment.
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The good news is that the RM80 and the RM125 wheels arrived today.
No shipping damage and both in good condition.
Bad news is that both wheels and calipers won't bolt onto the 1987 fork.
I think the RM80 wheel is a late-model one with a 13mm axle, which was included. My fork uses a 12mm axle or smaller in diameter.
The RM125 wheel's front axle is even larger. However, the sealed bearings seem to be interchangeable between the three axles' sizes. The RM80's 12mm axle, wheel spacers and bearings SHOULD slip into the larger RM125 wheel hub.
Now comes the challenging part.
All caliper measurements taken previously don't apply. The RM80's rotor is 200mm diameter; the Rm125's rotor is 240mm size. None of the caliper/wheel/rotor options are even close, except of course the RM80's caliper, rotor and its 17" wheel. MAYBE the simplest way is to mount the smaller hub to the larger wheel. Finding correct length and size spokes might be problematic. The 17" wheel uses 11g spokes; the larger wheel has 10g ones, I believe. It would've been sweet if the rotors would interchange, but the bolt circles/patterns are different. If the larger rotor could be machined 20mm shorter to fit the smaller caliper in its original mounting position, there'd only be 10mm contact area for the caliper to grab.
While waiting for the correct axle, bearings and spacers to arrive, I used a length of 7/16" all-thread to mock up the wheels to the RM80's fork. It looks as if the larger wheel will fit perfectly onto the smaller fork, but not its rotor. No matter which caliper is to be used, a rectangular-shaped adaptor needs to be butt-welded onto the caliper bracket to bolt onto the fork.
And of course, both calipers' pistons are frozen, and the master cylinder's cover screw is frozen too.
But that's the easy part of the job.
No shipping damage and both in good condition.
Bad news is that both wheels and calipers won't bolt onto the 1987 fork.
I think the RM80 wheel is a late-model one with a 13mm axle, which was included. My fork uses a 12mm axle or smaller in diameter.
The RM125 wheel's front axle is even larger. However, the sealed bearings seem to be interchangeable between the three axles' sizes. The RM80's 12mm axle, wheel spacers and bearings SHOULD slip into the larger RM125 wheel hub.
Now comes the challenging part.
All caliper measurements taken previously don't apply. The RM80's rotor is 200mm diameter; the Rm125's rotor is 240mm size. None of the caliper/wheel/rotor options are even close, except of course the RM80's caliper, rotor and its 17" wheel. MAYBE the simplest way is to mount the smaller hub to the larger wheel. Finding correct length and size spokes might be problematic. The 17" wheel uses 11g spokes; the larger wheel has 10g ones, I believe. It would've been sweet if the rotors would interchange, but the bolt circles/patterns are different. If the larger rotor could be machined 20mm shorter to fit the smaller caliper in its original mounting position, there'd only be 10mm contact area for the caliper to grab.
While waiting for the correct axle, bearings and spacers to arrive, I used a length of 7/16" all-thread to mock up the wheels to the RM80's fork. It looks as if the larger wheel will fit perfectly onto the smaller fork, but not its rotor. No matter which caliper is to be used, a rectangular-shaped adaptor needs to be butt-welded onto the caliper bracket to bolt onto the fork.
And of course, both calipers' pistons are frozen, and the master cylinder's cover screw is frozen too.
But that's the easy part of the job.
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More experimenting.
The 1987 RM80 fork leg uses an axle 10mm thick.
Later model RM80s use 13mm diameter axles.
The axle of a 1986 RM125, of which I'm using its wheel, is almost 16mm diameter. The axle steps up to 20mm at one end, and is clamped in place by the RM125 fork leg. There is a threaded nut on the other end.
Altho there is a HUGE size and strength difference between the 10mm and 16mm axle, I won't be pounding the hills with my motorized bicycle. A Suzuki 10mm axle SHOULD handle the task of riding the streets
I received the smaller 1987 RM80 axle and its bearings. These new bearings SHOULD press into the RM125 hub. All I need to find is a bearing puller.
Once that's done, I can move on towards adapting either the RM80 or the RM125 caliper onto the RM125 wheel and rotor. I had noticed that the RM80 wheel and rotor uses equal-length axle spacers. While mocking up the larger wheel onto the smaller fork, equal-length spacers push the larger rotor into the fork's right leg. Rm125 axle spacers are uneven. One is 29mm; the other is 17mm long. Both RM80 spacers are 22mm long, so the wheel's rotor-side will need extra spacing. The other side will need to be shortened.
On another note, I found the correct bicycle headset bearings. The fork sits well in the headset. However, the top bearings are slightly exposed to weather. I need to find a bicycle bearing cover to protect them.
The RM80 fork also sits VERY high on the triple tree bracket. I emptied all the nitrogen gas from the forks, but it still sits high. After the wheel and tire are mounted, I'll disassemble the fork legs and cut the internal springs for fitment.
Now where's that bearing puller?
The 1987 RM80 fork leg uses an axle 10mm thick.
Later model RM80s use 13mm diameter axles.
The axle of a 1986 RM125, of which I'm using its wheel, is almost 16mm diameter. The axle steps up to 20mm at one end, and is clamped in place by the RM125 fork leg. There is a threaded nut on the other end.
Altho there is a HUGE size and strength difference between the 10mm and 16mm axle, I won't be pounding the hills with my motorized bicycle. A Suzuki 10mm axle SHOULD handle the task of riding the streets
I received the smaller 1987 RM80 axle and its bearings. These new bearings SHOULD press into the RM125 hub. All I need to find is a bearing puller.
Once that's done, I can move on towards adapting either the RM80 or the RM125 caliper onto the RM125 wheel and rotor. I had noticed that the RM80 wheel and rotor uses equal-length axle spacers. While mocking up the larger wheel onto the smaller fork, equal-length spacers push the larger rotor into the fork's right leg. Rm125 axle spacers are uneven. One is 29mm; the other is 17mm long. Both RM80 spacers are 22mm long, so the wheel's rotor-side will need extra spacing. The other side will need to be shortened.
On another note, I found the correct bicycle headset bearings. The fork sits well in the headset. However, the top bearings are slightly exposed to weather. I need to find a bicycle bearing cover to protect them.
The RM80 fork also sits VERY high on the triple tree bracket. I emptied all the nitrogen gas from the forks, but it still sits high. After the wheel and tire are mounted, I'll disassemble the fork legs and cut the internal springs for fitment.
Now where's that bearing puller?
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Slide a section of cut innertube over the headset. It should stretch over the headset to keep it somewhat weatherproof.
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Still mocking up.....
While waiting for bearing removal tool to arrive, I mounted the large wheel onto the fork, bicycle upside down.
Using a 10mm RM80 axle in a 16mm RM125 hub for fitment. With the 26" motorcycle wheel and its 17mm/29mm axle spacers,
both the RM80 and the RM125 calipers line up with the 240mm rotor.
They just don't bolt onto the left fork's caliper bracket.
Besides, the large wheel sits 19mm off towards the left fork. Shaving down the smaller spacer and adding washers to
the larger spacer will center the motorcycle wheel.
Caliper bracket adaptor needed to be made anyway. Now it'll be extended 10mm inward. Either RM80 or RM125 caliper will work,
but I might as well use the larger dual-piston one.
So far, the caliper adaptor is the only item needing to be fabbed, to install a 26" motorcycle tire, its hydraulic 240mm-320mm (9.45"-12.6"!!) disc brake
and motorcycle suspension onto a bicycle.
While waiting for bearing removal tool to arrive, I mounted the large wheel onto the fork, bicycle upside down.
Using a 10mm RM80 axle in a 16mm RM125 hub for fitment. With the 26" motorcycle wheel and its 17mm/29mm axle spacers,
both the RM80 and the RM125 calipers line up with the 240mm rotor.
They just don't bolt onto the left fork's caliper bracket.
Besides, the large wheel sits 19mm off towards the left fork. Shaving down the smaller spacer and adding washers to
the larger spacer will center the motorcycle wheel.
Caliper bracket adaptor needed to be made anyway. Now it'll be extended 10mm inward. Either RM80 or RM125 caliper will work,
but I might as well use the larger dual-piston one.
So far, the caliper adaptor is the only item needing to be fabbed, to install a 26" motorcycle tire, its hydraulic 240mm-320mm (9.45"-12.6"!!) disc brake
and motorcycle suspension onto a bicycle.
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I am a little curious. Now don't get me wrong, my bike is no lightweight considering the front end alone weighs 30 lbs, and the engine itself weighs a good bit. But I've just noticed that you aren't using many bicycle parts besides the pedals and the frame. Motorcycle and moped parts tend to be a bit heavier than bicycle parts. Personally, the only reason I myself am not that concerned with weight that much is because I'm using a 98cc minibike engine, and with the pullstart, there is no pedaling dead weight for me. But I'm just wondering, what engine are you putting in this bike, and are you at all concerned with the amount of weight you will be adding with all these heavy parts? I can tell you one thing, pedaling a single speed bike that weighs over 100 lbs without motor assistance is no cakewalk my friend. Just saying.
Thanks for asking questions, bigbutterbean.
Weight is DEFINITELY the greatest detractor of this motorcycle front end and rear tire project.
My present commuter, a Diamondback/Tanaka motorized bicycle, tips the scale @ 60lbs. I'm hoping this project will weigh 90lbs or less.
Power will be from either a ported 2.8hp Tanaka 47R engine or a 4.5hp CY460 engine.
Acceleration will suffer, but I'm shooting for only 35mph or better.
Pedalling this bike should be no problem with 8 speeds. I know from past experience that resistance from drive train sprockets,
8mm chain and transmission is very light. A child could pedal the crank with one hand.
Weight is DEFINITELY the greatest detractor of this motorcycle front end and rear tire project.
My present commuter, a Diamondback/Tanaka motorized bicycle, tips the scale @ 60lbs. I'm hoping this project will weigh 90lbs or less.
Power will be from either a ported 2.8hp Tanaka 47R engine or a 4.5hp CY460 engine.
Acceleration will suffer, but I'm shooting for only 35mph or better.
Pedalling this bike should be no problem with 8 speeds. I know from past experience that resistance from drive train sprockets,
8mm chain and transmission is very light. A child could pedal the crank with one hand.
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I pretty much planned my build around top speed as well. I chose what I hoped would be optimal gearing, shooting for a 32mph redline. I knew the bike would be too heavy to pedal. I just figured if I didn't achieve my top speed goal, I'd figure out what needed to be changed and change it then, but seriously hoped I wouldn't need to. Luckily I didn't. The added weight of the engine and front end didn't add enough weight to make the top speed suffer. I chose the exact right gearing for the speed I wanted, and the engine has enough torque to overcome the weight of the bike and myself. I don't know what kind of torque the tanaka 47r makes, but I would probably go with the larger hp engine, having a choice between the two. Just my $0.02.
Strangely, the Tanaka has more torque. From a standstill, if you give too much gas, hang on!
The motor wants to slip your butt right off the back of the seat!
The only problem with the 460 is that it breaks clutch springs, and you're stuck 20 miles from home.
The Tanaka has NEVER given me any problems.
Gearing was trial and error from the start. On the flats and medium hills, low gears won't matter much.
HOWEVER, for very steep ramps and killer hills, EXTREMELY low gearing is what pushes you uphill like a motorcycle.
When my motorized bicycle was first built, 1st gear was 27.89:1 and final drive was 12.27:1. Good for flats and medium hills, but not for steeper inclines.
With 11t/32t, low gear dropped to 35.7:1, which was much better. When my flimsy 22t chainring sprocket cracked, I could only find a 24t replacement.
First and high gear dropped to 32.73:1 and 11.25:1. Finally, I went for big gears. The 54t chainring was swapped for 72t, and cassette changed to 11t/34t.
Low gear is now 46.36:1, and final drive of 15:1. Low is only used for very steep hills and ramps.
Second and Seventh gears of 38.18:1 and 17.73:1 get the job done excellently.
With complete motorcycle front end, hydraulic brake and tire, bike weighs 46lbs. That's without rear wheel, chain, sprockets and engine.
I'll keep the same gear ratios for future builds.
The motor wants to slip your butt right off the back of the seat!
The only problem with the 460 is that it breaks clutch springs, and you're stuck 20 miles from home.
The Tanaka has NEVER given me any problems.
Gearing was trial and error from the start. On the flats and medium hills, low gears won't matter much.
HOWEVER, for very steep ramps and killer hills, EXTREMELY low gearing is what pushes you uphill like a motorcycle.
When my motorized bicycle was first built, 1st gear was 27.89:1 and final drive was 12.27:1. Good for flats and medium hills, but not for steeper inclines.
With 11t/32t, low gear dropped to 35.7:1, which was much better. When my flimsy 22t chainring sprocket cracked, I could only find a 24t replacement.
First and high gear dropped to 32.73:1 and 11.25:1. Finally, I went for big gears. The 54t chainring was swapped for 72t, and cassette changed to 11t/34t.
Low gear is now 46.36:1, and final drive of 15:1. Low is only used for very steep hills and ramps.
Second and Seventh gears of 38.18:1 and 17.73:1 get the job done excellently.
With complete motorcycle front end, hydraulic brake and tire, bike weighs 46lbs. That's without rear wheel, chain, sprockets and engine.
I'll keep the same gear ratios for future builds.
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Ok what about Moped tires on bicycle rims. I was thinking about wrapping my 20" (16" actual size) bicycle wheel in a better tire.