Hello there, this project (not quite finished yet) is my second such retro-mod build onto a vintage mountain bike. I find the quality of old chromo double butted frames is something you have to pay good money for nowadays but you can get them for next to nothing if you don't mind doing a bit of general restoration work on an old mountain bike. They make quite nimble commuters and the usually oversize tubing gives them a reasonable stiffness for city roads and kerbs.
So yeah I know the componentry isn't the highest grade and the wattage is on the lower end of the scale being approx 250watts but it does just fine as a pedal assist as I've already tried it out on a previous build. I was on a low budget too so tried to make it without spending more than $300 more than what I already owned.
Had the following components already:
Old mountain Bike Tange double butted frame, xt octalink cranks, new vee brakes. Approximate value $150,
icharger hobby style charger, $120.
black canvas pencil case for controller $0
Riser handle bars $0 (leftover from a previous build but sanded and painted grey).
New threadless stem, $40 value but again I had this in my parts bin.
Spend:
Cheap Conhis motor (e-groupset) 24v 200w. $150
Overvolted to 29.6v 8 cell lipo. Should be approx 250w when overvolted.
2x5000mah 4cell turnigy Hardcase lipo. $80
2 x Lipo alarms $10
1 x fire proof charging bag $5
1 x Drok battery capacity meter $8
1 x Anodized water bottle bar clamp $11
1 set foam lock-on bar grips $7
1 x used real wheel (original one had a bad freehub) $20
1 x compact canvass battery bag $15
1 x complete set of brake and gear cables $15
1 x set thumb shifters $29 (still waiting for these to show up and the cables.)
1 x quill stem to threadless adapter. $30
As you can see I didn't spend much and a lot of the sundry items were due to wanting to make the old bike look and feel a bit newer.
Originally the bike was not in a condition to ride because I hadn't ridden it in 12 years or more although it was always stored under shelter so it wasn't too far gone.
Decent quality tubing.
Forks were a problem though. Dropouts were too short for a front motor solid install. Required lengthening of the dropout slots by welding on some thick washers and grinding out the slots. Easier said than done.
This is them all finished.
Also made some mini torque arm/safety device using the washers that came with the wheel motor.
Finished torque arms both sides
Whilst I had the welder out I decided the rear rack was about 4 inches too long visually so I cut and shut the front extension off it and left just the rectangular rack portion. I think it looks quit proportional now although I forgot to get a before pic. Trust me, it looked very wrong.
Wire routing is always an issue with these setups, they tend to have so much length to them so I routed via downtube to utilize the full cable length and minimize the amount of work cutting and soldering.
The pencil case controller bag required some velcro tabs (6 in total) I hot glued them in position and asked a favour from my wonderful mother to sew them securely.
I didn't like the feel of the full length twist throttle so I cut'n'shut it to a half twist and added some plushy foam grips I got on ebay for $7.
Batteries will go in the back. I am still waiting on a bag I bought on eBay. It will look very similar to this one in the pic but a bit lower in height. My goal was to build it slim and tidy. I'm not a big fan of big battery packs and I tend to do a lot of pedaling so range is quite good still. If I need more battery capacity I will swap to this bag in the pic and add two more 4 cell batteries to bring it up to 10aH.
The original battery meter LED's on the throttle won't be accurate any more since I'm overvolting and also the low voltage cutoff in the controller will be too low. I opted for a Drok Battery meter which I have yet to wire up. Installed in a little project box and mounted on the bars using a bottle cage clamp adapter for the bars. On the Drok circuit there is a spot for a piezo alarm which I will add inside the box to give me an Audible warning of low voltage. I will also set the circuit to be permanently on (No sleep mode) whilst the battery is connected so I have no excuses. On the batteries themselves I will monitor individual cell voltages using balance lead lipo alarms they cost about $5 each and will be good insurance until I feel comfortable that the Drok circuit alarm is accurate enough.
So yeah I know the componentry isn't the highest grade and the wattage is on the lower end of the scale being approx 250watts but it does just fine as a pedal assist as I've already tried it out on a previous build. I was on a low budget too so tried to make it without spending more than $300 more than what I already owned.
Had the following components already:
Old mountain Bike Tange double butted frame, xt octalink cranks, new vee brakes. Approximate value $150,
icharger hobby style charger, $120.
black canvas pencil case for controller $0
Riser handle bars $0 (leftover from a previous build but sanded and painted grey).
New threadless stem, $40 value but again I had this in my parts bin.
Spend:
Cheap Conhis motor (e-groupset) 24v 200w. $150
Overvolted to 29.6v 8 cell lipo. Should be approx 250w when overvolted.
2x5000mah 4cell turnigy Hardcase lipo. $80
2 x Lipo alarms $10
1 x fire proof charging bag $5
1 x Drok battery capacity meter $8
1 x Anodized water bottle bar clamp $11
1 set foam lock-on bar grips $7
1 x used real wheel (original one had a bad freehub) $20
1 x compact canvass battery bag $15
1 x complete set of brake and gear cables $15
1 x set thumb shifters $29 (still waiting for these to show up and the cables.)
1 x quill stem to threadless adapter. $30
As you can see I didn't spend much and a lot of the sundry items were due to wanting to make the old bike look and feel a bit newer.
Originally the bike was not in a condition to ride because I hadn't ridden it in 12 years or more although it was always stored under shelter so it wasn't too far gone.
Decent quality tubing.
Forks were a problem though. Dropouts were too short for a front motor solid install. Required lengthening of the dropout slots by welding on some thick washers and grinding out the slots. Easier said than done.
This is them all finished.
Also made some mini torque arm/safety device using the washers that came with the wheel motor.
Finished torque arms both sides
Whilst I had the welder out I decided the rear rack was about 4 inches too long visually so I cut and shut the front extension off it and left just the rectangular rack portion. I think it looks quit proportional now although I forgot to get a before pic. Trust me, it looked very wrong.
Wire routing is always an issue with these setups, they tend to have so much length to them so I routed via downtube to utilize the full cable length and minimize the amount of work cutting and soldering.
The pencil case controller bag required some velcro tabs (6 in total) I hot glued them in position and asked a favour from my wonderful mother to sew them securely.
I didn't like the feel of the full length twist throttle so I cut'n'shut it to a half twist and added some plushy foam grips I got on ebay for $7.
Batteries will go in the back. I am still waiting on a bag I bought on eBay. It will look very similar to this one in the pic but a bit lower in height. My goal was to build it slim and tidy. I'm not a big fan of big battery packs and I tend to do a lot of pedaling so range is quite good still. If I need more battery capacity I will swap to this bag in the pic and add two more 4 cell batteries to bring it up to 10aH.
The original battery meter LED's on the throttle won't be accurate any more since I'm overvolting and also the low voltage cutoff in the controller will be too low. I opted for a Drok Battery meter which I have yet to wire up. Installed in a little project box and mounted on the bars using a bottle cage clamp adapter for the bars. On the Drok circuit there is a spot for a piezo alarm which I will add inside the box to give me an Audible warning of low voltage. I will also set the circuit to be permanently on (No sleep mode) whilst the battery is connected so I have no excuses. On the batteries themselves I will monitor individual cell voltages using balance lead lipo alarms they cost about $5 each and will be good insurance until I feel comfortable that the Drok circuit alarm is accurate enough.
