Another thread on frames: 700c

[SimonMTL]

I've been reading threads about proper donor bikes, and everyone goes to full-suspension cheapo bikes.

I'll be using a rear-wheel Golden Motor 500W and a PingPing LiFePO4 36V15Ah battery (10lbs). I thought about getting a hard frame, 700c wheels like Giant's urban bikes:

http://www.giant-bicycles.com/en-CA/bikes/lifestyle/1780/30785/

22" steel frame, no suspension except on the seatpost, cushy seat, big thin wheels. This bike would go pretty fast!

I intend to have the Golden Motor put on the 700c wheel by the LBS. Supposedly, an electric motor will go about 15% faster on a 700c compared to a 26" wheel.

My commute? 25km on flat ground. I want to go as fast as possible, with pedaling to help the motor.

I don't want any overweight, older, non-athletic e-bikers to give me the reasons why I should go with a full suspension bike instead. I'm tall, fit, and want to have a very fast bike. People that seem to favour the FS bikes seem to have some big powerful engine and a bunch of batteries. I've strived to keep the weight low so far, so I don't feel like getting something heavy. I might even go for the aluminium version of that bike (Cypress R).

Any thoughts? Or is it really, really a bad idea to go for non-suspension?

 

[drewjet]

I say go for it. I am an overweight Lycra-crowd wanna be. I love my touring bike. Put a decent seat/post on it and you will be fine.

 

[albie]

it wouldn't go that fast. You should be fine with your setup (most it will do will probably be around 30 - 36km/h).

 

[TylerDurden]

I don't want any overweight, older, non-athletic e-bikers to give me the reasons why I should go with a full suspension bike instead.

OK. I will tell everyone but you... getting the aluminum version will make a fairly fast bike that lasts briefly. But it would be a great way to experiment with physics: compressile strength, unsprung weight, alloy brittleness, etc. You can also learn the craft of re-lacing spokes into a rear hubmotor and wheel.

700c v. 26" might not make much difference >30mph.

A tall, fit cyclist that wants to go as fast as possible should get a fully-faired recumbent with a large chainring and an X5@96V.

 

[recumbent]

Steel frames flex more, are safer and have more comfort than aluminum.

Make sure your wheels are strong, use fatter than usual tires, this will give you extra smoothness and flat protection.

You will be fine under 25MPH, which is plenty speed 98% of the time.

 

[D-Man]

Steel frames flex more, are safer and have more comfort than aluminum.

Make sure your wheels are strong, use fatter than usual tires, this will give you extra smoothness and flat protection.

You will be fine under 25MPH, which is plenty speed 98% of the time.

There seems to be a lot of different steel and aluminium frames in different thicknesses. There must be some good aluminum road bikes or they wouldn't make them. If they were so stiff, no one would ride them. They wouldn't sell. I read that any material can be made in the right thickness so that they all flex the same. The "reynolds" types all have numbers. The higher the number the thinner the frame. That makes it easier. But the aluminum ones don't seem to have numbers so each manufacture calls it there own special name. (I'm guessing) Now how would you know if an aluminum frame flexes more then another aluminum frame?

 

[recumbent]

Aluminum frames are lighter than steel (in general), the drop-outs look chunkier, the pipes are larger, the welds are huge, and just looks strong.
Aluminum is popular, no doubt about it, I have one aluminum frame and two steel frames, like them both, but for electric conversion, steel is more predictable, forgiving, and above all, comfortable.

Whenever you see bikes with broken frames, chances are it's aluminum or carbon fiber breaking at the steering tube area. Now-a-days bikes are built very well, just pick what you want :|

 

[SimonMTL]

700c v. 26" might not make much difference >30mph.

If the engine spins at a maximum speed, a larger wheel will cover more ground in a single revolution, hence the 15% or so better speed.

I must say, though, that looking at electrified FS MTBs, and then clicking on the link I gave for that Giant road bike, which looks so plain, the FS MTBs look really nice. I guess I was hoping someone here actually had tried their motor-hub on different wheel sizes and would be able to give an informed answer. I think we're all guestimating the difference here. But in real life, how does that translate?

One of the bikes on this board has wicked Maxxis Hookworms 26x2.5. Yet I had the feeling a narrower tire, say 1.5, would be much quicker and have a lot less friction? I guess when your bike is 96V you don't really care about these minute details, eh?

 

[albie]

700c v. 26" might not make much difference >30mph.

If the engine spins at a maximum speed, a larger wheel will cover more ground in a single revolution, hence the 15% or so better speed.

I must say, though, that looking at electrified FS MTBs, and then clicking on the link I gave for that Giant road bike, which looks so plain, the FS MTBs look really nice. I guess I was hoping someone here actually had tried their motor-hub on different wheel sizes and would be able to give an informed answer. I think we're all guestimating the difference here. But in real life, how does that translate?

One of the bikes on this board has wicked Maxxis Hookworms 26x2.5. Yet I had the feeling a narrower tire, say 1.5, would be much quicker and have a lot less friction? I guess when your bike is 96V you don't really care about these minute details, eh?

I've got a hookworm on my rear... have to say massive improvement over 2.0. Cushions bumps and everything...especially on a hard tail.

you can go 1.5... but be prepared on feeling everything on the road. I dunno about you but i would rather have traction at high speed rather than less friction besides the hookworm is as close to a semislick as you can get (they are great in wet weather too)

 

[D-Man]

The whole skinny tire vs fat tire thing, is for people that pedal. High pressure vs lower pressure. Pedallers feel the difference. Motors don't. Like Simonmtl says "its minute details" with 96 volts.

 

[SimonMTL]

OK. I will tell everyone but you... getting the aluminum version will make a fairly fast bike that lasts briefly. But it would be a great way to experiment with physics: compressile strength, unsprung weight, alloy brittleness, etc.

OK, so you were right. Just as I tried fitting my hub motor in the rear dropouts, I had to spread them apart for things to fit. The aluminium bent..... I'm not taking any more chances, I'll go for a full suspension steel frame!

Found 2 on eBay with 26" wheels: PACIFIC Highlander (100$ shipped), and MICARGI Polo (210$ shipped), one with horizontal dropouts, one with vertical dropouts. Any necessary preference for either? Do I still need torque arms on a steel frame?

 

[cerewa]

the ratio of speeds you will get on 700c compared to 26 inch is about 27 to 26 (700c tires are about 27 inches in diameter, less for skinny tires).

In my opinion, suspension is NOT the way to go but fat (non knobby) tires at somewhat low pressure are good - you do want a little bit of cushioning for the bumps (with electric power, you can go faster if you don't hurt yourself or slow down with every bump).

Don't worry about weight too much - to a 500w motor, adding 5 pounds of weight hardly matters at all.