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Old 09-24-2013, 06:50 AM
Herdo Herdo is offline
Motorized Bicycle Member
Join Date: Sep 2013
Location: Glendale Arizona
Posts: 27
Default My first build. Need some advice and I have some questions.

Hello everyone! I am currently planning out the construction of my first motorized bicycle and I have some questions I am hoping you all can help me with.

First, I should start out with the parts list and go from there:

Schwinn straight bar frame: $150

Monark II Forks: $200

Crankset: $50

Handlebars/Grips: $60

Saddle/post: $50

26" 2.125" 12 gauge steel rims: $40

12 gauge spokes: $25

Sturmey Archer S30 3spd hub with drum brake: $90

Sturmey Archer XL-FD 90mm Front Hub OR X-FD 70mm Front Hub: $75

Quick Brick black tires: $60

Extra/Misc: $50

Total bicycle build (pre-motorbike addons): About $850

Motorized addons:

HuaSheng 49cc kit with 4G belt drive 5:1 ratio: $400

SBP Shift Kit: $200

Custom gas tank: $300

Total motorized addons: $900

Total cost: $1750 give or take $100 or so

Minimum cost (if I put the SBP shift kit and custom gas tank on hold for now): About $1250

Now, that is a lot of money, maybe too much. I plan on commuting on this bike 3 days a week 11 miles each way. So let's just say 75 miles a week or 3900 miles a year which we will round to 4000. I've read on several threads here that I should be able to get 4000 miles out of my motor with regular maintenance and upkeep fairly easily, and even if I had to replace the motor and shift kit annually, I would be happy considering I spend at least double that on gasoline annually as it is.

In Arizona, the law states that motor assisted bicycles must be driven below 19 miles per hour. I don't plan on going over that. I'm serious! One of the great things about living in the Phoenix metro area is that everything is on a grid, and my entire 11 mile ride to work can be made using entirely residential side streets. I honestly don't plan on riding over 15 - 20 mph hardly ever, so wear and tear on the bike should be kept down.

Overall, I am looking to build a bike that will last quite a while that will be very durable.

That being said, is there anything I am overlooking or forgetting? Also, is there anything that I am maybe over doing? I'd like to save some money wherever possible on this, but I'd also like to have a safe reliable bike with some style.

I have a question about the 90mm hub. I read in a thread here that someone mentioned having to get custom 12 gauge spokes for their 90mm Sturmey Archer front hub. I'd like to avoid this if possible, so would the 70mm work fine for my purposes? Like I mentioned previously, I don't plan on riding faster than 20mph at the most. Also, if anyone has built a bike using 26" x 2.125" rims with the 70mm hubs and 12 gauge spokes, could you tell me what rims and spokes you used? I'd like to be able to buy the correct parts to take to a bike shop to have them assemble and tune it. I've heard taking just the rims and hubs to a bike shop with them supplying the spokes costs an arm and a leg so I'd like to just buy all the parts on my own, but I have no idea what is fits together.

One final question; with the 4G T belt drive, should I look for the 100T (5:1) or the 80T (4:1)? I have read several comments where people recommend the 100T, but I am unsure what the actual difference is.

Thanks for taking the time to read this, I know it was lengthy.
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