Large Crankset and Chainrings

[marty]

On Electric Bike Project # 1, Bionx PL350. I garbage picked a bike with larger front gears, 30T, 40T, and 50T. Installed bigger crankset on electric bike. Leave on largest 50T front gear and 16T rear gear and all is good. Never shift gears.

Now I am building Electric Bike Project # 2. Can not find a garbage bike with large front chainring. Look at new ones. Prices are almost the same as a Kmart bike.

As of now, large chainring is 4 bolt, 104 BCD. Crank is 170mm. Bottom Bracket is FSA MEGA EXO. Could change the whole crankset and bottom bracket if necessary?

Is there any online used bike part sellers? Think steel chainrings are better then aluminum? Stronger. For junk yard car parts go to car-part.com Search auto junk yards all over the country. Give me a used frame with a large steel chainrings and aluminum cranks for $50 or so and I will be happy.

BCD = Bolt Center Distance
T = Tooth

 

[fechter]

Try Craigslist. You can get whole bikes cheap and part them out. If you're patient, you will find one close by.

 

[marty]

Look at Ebay, 1103 items found in: Cranksets & Bottom Brackets. Send some questions asking:

"Of what material are chainrings made from. If not sure? Get a magnet. Magnet will stick to steel but not to aluminum."

So far they all are aluminum. Went to one local bike junk yard. Found a few old rusted 48T chainrings. Looked at Craigslist, waiting for replies.

Am I crazy to want steel chainrings? Aluminum seems like a stupid material for a gear. Suspect that new $150 Kmart bikes might have steel chainrings? Seems wasteful to buy a complete bike for one part? Might be able to harass cheap bike manufactures till they send me a part? Anyone have any other ideas?

 

[fechter]

On a large chainring, you have lots of teeth to spread the wear over. I've never seen a large chainring wear out. On smaller sprockets, you definitely need steel.

 

[marty]

I want steel This is like hunting. Some people hunt for ducks, deer, or rabbits. I hunt for Cranksets.

Found this: Crankset Truvativ Iso-Flow Triple 52-42-30 Cr-Mo chainrings
Cr-Mo = Chromium Molybdenum. CrMo is steel.

See it at http://www.schwinnbike.com/products/bikes_detail.php?id=797
Found it. Now where to buy it????????????

 

[Timbo]

These guys are by no means local to you, but it couldn't hurt to send an email...

http://www.bicyclerecycle.com.au/

 

[marty]

These guys are by no means local to you, but it couldn't hurt to send an email...
http://www.bicyclerecycle.com.au/

Australia? That's pretty far. Called local bike shops. Bought - Used, Shimano Sora FC-3303, Gearing:52-42-30T, Steel Chainrings, Crank Arm Length is 175mm. Original Crank Arm Length is 170mm. Don't think 5mm will make much difference? Had to buy different bottom bracket. Bike shop guy tell me about many, many, many, different bottom bracket sizes. Have not done surgery to see if it will fit?

Front derailleur will not fit any more. Will have single 16T gear in rear. Plan on 52T on front and 16T rear. No gears to shift is one less thing to think about. No shifters on handlebars is less clutter. If battery dies? I could use my manual hand shifter to shift to smaller gear in front. [manual hand shifter is attached to the end of my arm] Also called a greasy finger shifter.

 

[marty]

Electric Bike Project # 1 - Bionx.ca PL350 has pedal assist and thumb throttle. Copy from Bionx.ca
BionX is an energy management system that provides power-assist that is proportional to the rider's effort. Therefore you remain in control and can request power-assist from the motor only when you need it, according to the energy level you want to spend and distance you wish to cover. With BionX, your bike remains a bike and riding remains a sport.
Works well with 50T front gear and 16T rear wheel. Never shift gears.

Electric Bike Project # 2 will be Crystalyte 406 rear motor, 36V 35A Start Immediate Controller, 48V 20Ah Li-ion Battery
Unlike Bionx, twist throttle looks like it will be variable speed? Will there be any pedal assist if throttle is not turned? Am I thinking clearly about my idea of 52T front gear and 16T rear gear? Got 26" wheel mountain bike. There are no hills here in Buffalo NY.

 

[fechter]

You might try digging around at http://store.airbomb.com/Index.asp
A great place for bike parts. I did find some steel ones, but only in the smaller sizes (32t).

 

[marty]

Already bought - Used, 52-42-30T, Steel Chainrings. See picture in last post.

Questions are:
Electric Bike Project # 2 will be Crystalyte 406 rear motor, 36V 35A Start Immediate Controller, 48V 20Ah Li-ion Battery
Unlike Bionx, twist throttle looks like it will be variable speed? Will there be any pedal assist if throttle is not turned? Am I thinking clearly about my idea of 52T front gear and 16T rear gear? Got 26" wheel mountain bike. There are no hills here in Buffalo NY.

 

[Mathurin]

no throttle = nuthin from the motor. They do make PAS that work with Clyte though, but it works on rpm & maxes out around 75ish.

Your choice of gearing would sound nice if you were running on 36v


http://www.sheldonbrown.com/gears/
+
http://www.kreuzotter.de/english/espeed.htm

 

[marty]

After riding Electric Bike project #1 [Bionx PL350] on some dirt trails, I have come to the conclusion that I WANT gears. Front derailleur don't fit due to larger gears. Hits the rear suspension pivot part. I make it fit Grind and file top of derailleur so it can move up as far as possible. Grind and file derailleur cage so it don't hit gears. Grind and file more. Grind and file more. It works. I have 3 speeds

Front derailleur now weighs about 1/2 as much as it used to.