Lightweight bike project

[Jimbo]

Hi guys,

Big thanks for all the experience shared so far! I've been weighing up the options, and whilst id like to keep it all super lightweight your experience has pretty much convinced me i cant get decent performance with a dinky motor. The bafang jewel is around the 2.1kg mark, whilst the mac500 is 4.3....okay its 2kg more but the difference in performance is worth the extra weight i think.

I've emailed cell man for 28 a123 cells and a mac500 high speed rear kit. Should be sweet, will see how i do on 5ah, can always add some more capacity if im not getting the range i need. Only question is does cell man make packs? I emailed him some time ago to place the order and asked if he could deliver the packs made up into a cylindrical arrangement, no reply yet though. If he cant how hard is to cook up a pack - im fairly handy with an iron and a glue gun, just not sure about balancing tags etc.

Again, massive thanks for the posts

 

[Jimbo]

Oh and whats the score with rear cassettes...my trek runs a nine speed rear, though apparently the mac can only take a 7 speed....will the gears still work, will the chain run off the end of the casette? Hmmmm, anyone make a nine speed, lightweight, 500w rear geared hub motor?

 

[jbond]

I don't believe anyone makes a rear motor with a cassette for the gears. They all take a freewheel. And freewheels are pretty much limited to 7 speed.

On "too much is never enough". This is from scanning the forums for a while rather than personal experience.

If you're serious about light weight and want assist with lots of pedal power rather than powered with optional pedalling.
- Cellman geared motor or Bafang QWSX. 20" motor laced into a 26" rim
- Lyen or Cellman controller with a 20-25A limit
- Baby Cellman A123 pack say 12S-2p for ultra light weight, short range. Or ECitypower/BMSBattery Shrinkwrap 36v15AHr LiNiCoMn for range.
This should top out at 22-24mph or so but will need some pedal assist to maintain it. It will still climb hills but slowly. It's really about pushing up the average speed and range while taking the sting out of the hills but it's still basically a bicycle that requires pedalling.

One step up from this that is still pretty light,
- BPM 20" 36v (code 9?) in a 26" rim
- Lyen or Cellman controller with a 30A limit
- Cellman 16s4p A123 pack. Or BMSBattery LiNiCoMn 48v-15AHr upwards
This should get you loads of acceleration and hill climbing, it will top out at 28mph or so and will hold it on the flat. It's heavy for a bicycle but not hugely so.

BSMBattery have started selling these ECityPower shrink wrap LiNiCoMn batteries. They're plug and play, safe, considerably lighter than an equivalent Ping LiFePo and cheaper. You lose out on lifetime with the predicted cycles being about half the quoted number for LiFePo. Unless you do lots of miles *every* day, that looks like a good compromise to me.