Newbie 700c question ...good/better than 26"?

[Fiataccompli]

Hi folks. I am a long time cycling enthusiast and builder of my own road bikes. Recently a friend asked me to install an 80cc kit on a bike for him, so being a bike nut, having tons of spare bikes/parts/tools on hand I thought it would be fun (good father/son project also since my 15 year old is less enthused about building or restoring yet another road bike...). Anyway, I hit the expected learning curve and right now we are sorting out minor issues stemming from cheap mounting hardware, but ultimately the project turned out to be much fun. (Jamis Paragon 26" MTB with 700c fork/front wheel, set up the right lever to pull both brakes..all good..and fast it seems). Anyway, my question is whether there is some good documentation on motorizing 700c bikes. I have road bikes and hybrids that either would be a fine candidate to install a motor on. Seems like 28-40mm 700c tires would be plenty strong and I can make sure a rear wheel is stout enough....any reason not to go that route? I'd love to see other people's 700c projects.

Thanks in advance

 

[dodge dude94]

Folks have done 700c bikes, but the usual problem is with the frame size. A lot of 700c's have smallish frames that make for awkward mounting procedures. The other issue I can see with most 700c's is the lack of tire that the engine is turning. I think traction could be an issue, but I don't personally own one.

 

[MitchP]

I would agree with this guy ^^^ about the ride quality. Unless your streets are really smooth asphalt I can't see it being feasible to have 700c wheels. If you have really, really nice roads then **** yes, that would be a slick ride.

 

[Fiataccompli]

700c with 38mm+ wide tires? I know that's not fat tire bike width, but I guess I was thinking it would be pretty cushy...and the larger diameter would give a little more comfortable cruising speed (or more top end, depending on how you look at it). All that said, I ride 200+ miles a week most weeks on 23-25mm road bike tires (pedaling, that is) and I am rather used to posting and otherwise being comfortable despite rough roads and such. I was thinking an early 90s hybrid bike would be a good platform and may consider a cafe racer type bar setup....

 

[maniac57]

I recently built a fixie style bike with 700c rims. It rode like a dream...until the road got rough. Durability is the main issue in my opinion. Not enough rubber to cushion the rim.
I'd say if you are a careful rider, you can have good results.

 

[Fiataccompli]

Did you build the wheels?

 

[maniac57]

Nope. Used the stock wheels with no problems. I just went through and made sure the spokes were tight and the rims were true before mounting the kit sprocket. The buyer LOVES this bike so I assume it's holding up well. (He has not been back except to thank me for hooking him up)
The bike had yellow tires...yellow. *rolls eyes*

 

[Fiataccompli]

Those aren't the toughest of wheels at best but I guess that's good news. I was thinking of deep v type track wheels on maybe a hybrid frame or an old cheap road frame.

 

[maniac57]

One thing I did love was the flip flop hub. Remove the fixed gear and the kit sprocket bolted right up super easy. One of the easiest builds I've done.

 

[16v4nrbrgr]

Thruster Fixie, I'm sticking a HT on mine someday!

 

[MitchP]

Thruster Fixie, I'm sticking a HT on mine someday!

Just try keeping up with the pedals at 40mph!

 

[16v4nrbrgr]

You don't understand, it has a flip flop hub. That's the oldest joke on this site, lol.

 

[maniac57]

You don't understand, it has a flip flop hub. That's the oldest joke on this site, lol.

I thought I was the oldest joke on this forum?

 

[MitchP]

You don't understand, it has a flip flop hub. That's the oldest joke on this site, lol.

Yeah I know I had a fixie. I just thought it would be funny to ride a fixed gear motorized bicycle.

 

[Gaspumper]

I have a 66cc thatsdax engine on a 700c Schwinn Tourist, which is a flat-bar road bike. I recently swapped out the thin road tires for some Michelin City Tires (700x38) to give a little more cushion; they're wide, but not too wide, and slick. I've only gotten about 80 miles on my engine so far, so I don't have a ton of experience from which to draw, but I would say that the only downside to putting a HT on a road bike is the lack of suspension. Each bump you hit is a little more impacting than it would be with a front suspension fork. Other than that, I have had no issues with frame size, or anything else for that matter. I should also add that my rims are aero rims with a 28 spoke count. A little low for my tastes, but I've been keeping a close eye on them, and they've held up well so far. Nothing wiggled loose or out of true.

 

[Master-shake]

name the bike please?

I think I know which one your talking about. I have a neighbor with a black bike yellow tires and a fixed gear.

QUESTION: was it possible to hook up the motor straight to the fixed gear? would it have physically worked without the kit sprocket?

 

[maniac57]

name the bike please?

I think I know which one your talking about. I have a neighbor with a black bike yellow tires and a fixed gear.

QUESTION: was it possible to hook up the motor straight to the fixed gear? would it have physically worked without the kit sprocket?

No. You remove the fixed gear and slip the kit sprocket on the threaded hub. I used a couple wraps of thin sheet aluminum to center the kit sprocket on the hub and the kit ragjoint went on super easy. The kit sprocket is just a tiny bit too thick to use the threaded ring to install it.
It was one of the easiest builds I ever did. Engine mounts fit the frame perfectly.
I think the brand was kuwahara...black frame, yellow tires and yellow bar tape,ramhorn drop bars and decent centerpull brakes.

 

[Master-shake]

My question was,

Is is possible to use the sprocket that came with the bike?

I know it's only like a 20t or whatever but would it physically work with the kit chain?

 

[maniac57]

I think it physically fits the chain, but it would be geared so high with that small sprocket you would never be able to ride it with the engine engaged.
No way would a china girl pull that kind of gearing.

 

[Master-shake]

I've actually had my eye on that bike as a cheap speed bike. it would take some pedaling to get it started, but I'm sure the bike could go 40mph stock. could you check it out for me so I don't have to?

please?