Apprehensive First MB Build - Cranbrook

[agentjosh77]

Well, first of all thank you everyone for your time.

I just found a nice used Huffy Cranbrook Men's Cruiser bike and bought it.

I have been planning on getting a Grubee 48cc to install on it:

http://www.gasbike.net/grubee-skyhawk-gt2b-48cc-black-finish-bicycle-engine-kit.html

The reason for this post is to ask a few questions before I purchase a engine kit.

I have searched quite extensively to find information about others using the Cranbrook along with a Grubee, but haven't seemed to run across any threads dedicated to the specific setup and was curious to know if anyone out there has any advice for the build.

I have definitely come to learn that with the Cranbrook you either take off or thoroughly enforce your front fender.

Also I have read about some trouble with the rear hub when trying to fit on the sprocket. What thoughts about this do some of you have? Keep the pedal break or abandon it and go with and hand break?

Besides that I was curious if anyone had any thoughts about a Grubee setup, would it be a good choice for the Cranbrook. (like others on the forum I am under a nice tight budget and the Grubee seems to be the most financially reasonable option at the moment)

The biggest concern I have right now is about mounting the engine correctly to the bike, because it sounds like I will have to either fabricate or purchase a mounting kit for my frame. Is this correct?

Thank you everyone for taking the time to read this. Hopefully this will answer some of my questions and shake some of this darn apprehension!

 

[bluegoatwoods]

Don't be too apprehensive. The issues you mentioned can be dealt with.

I won't bother trying to explain to you what you'll want to do. There'll be others with Cranbrooks who can give you more detailed advice. They'll come along, too, because you titled this thread really well; it's perfectly clear what the subject will be. Good job! A good title is worth it's weight in gold.

I'll check back in a day or two to make sure of this. If no one notices it, then I'll try to help.

 

[rockvoice]

hey agentjosh, that bike will work fine.
first off, the grubee motor is a great choice, ive used from most of the diff company's and to me there the best.
I woudn't eliminate the coaster brake. just add front brakes for shure and/or rear also but keep the coaster for additional or back-up breaking.

you will have to take the coaster arm off the rear wheel to attach the sprocket, while you have it off (and before you install sprocket) you will have to remove the bearing dust cover and grind the crown that goes over the hub. if your carefull you can use tin snips to take the crown off, you want the cover to just fit inside the hub and not around the outside (some just throw out the dust cover but not recomended)

also the motor mounts to the rear mount fine , you will have to make a mount for the front like the photos i put below here.

hope i havent confused you more .

 

[agentjosh77]

Bluegoatwoods and Rockvoice thanks for the reply.

I agree with you on the coaster break. I have an older mountain bike that I will more than likely pilfer the back and front brakes off of.

The rear sprocket attachment I have looked over enough now that I believe I have a better grip on what to expect. I don't have access to a grinder, would a metal file be able to tackle the task?

I think that the whole process will be more solidified in my head when I have the sprocket in my hands and I can see what I am up against.

If anyone has any pictures of exactly what grinding and finishing work they performed on the back section of their Cranbrook that would be more than helpful!

O also, Rockvoice do you happen to know what hardware you bought to fabricate your front mounting bracket? To me it looked like a few simple brackets, plates, and nut and bolt sets.

Stepping into a the new realms of small engines and bicycles is becoming quite enjoyable.

Thank you for your replies. They have definitely eased some of the apprehension.

 

[rockvoice]

hey, that front mount is just a piece flat metal stock about 2 or 3 inches wide and comes in 4 foot lengths at home depot or lowes or places likes that.
find a u-bolt that fits around your tube in front .

drill two holes to bolt the plate to the motor and two holes for the u-bolt
the previous photo should show the rest. you remove the two studs for the front mount and bolt the plate into those (the kit comes with those bolts)
then u-bolt to the wider hole aroud your frame.

also the grubee kit comes with another front mount that ive used and it works well too. but you would have to drill into the frame.

and you can file the dust cover it will just take longer. check around the forum ive seen photos somewhere that show how much to remove.

 

[agentjosh77]

That all sound great! It's good to hear that the Grubee kit comes with a front bracket that works. I don't really have a problem with drilling into the bike frame. Are there any known issues when doing this?

Thank you again for the reply.

 

[GearNut]

Extra holes in your frame, anywhere, can weaken it.
Try to avoid creating weak points and you will avoid creating stress failures.

 

[agentjosh77]

Well I suppose then that taking a small bit of time and setting up a mount would be a worthy precaution.

 

[bluegoatwoods]

Yes, drilling through the frame should be avoided. Especially since the alternative is pretty easy.

Here's what I did with my drive sprocket. I took the dust cap from the hub and laid it down on the sprocket, centered as well as I could. I drew a line around it with a marker.
Clamped the sprocket down and started making radial cuts with my jig saw from the existing hole out to the line I had drawn. You can picture it, I'm sure; at this point the hole in the sprocket looked like it had teeth. The I started cutting across these teeth. From the inner corner of one to it's opposite outer corner. Repeat as much as possible until you have an inner surface that's a little bit rough. I think I smoothed that surface out with a dremel tool, but I imagine that it could be done with a hand file.

I hope I described that clearly. My sprocket is probably not perfectly centered, but it's close enough that I can't see any wobble and my bike runs fine. Chain derailment is not a problem.

 

[agentjosh77]

That sounds like it is a pretty reasonable solution. I will have to consider that when I start in on the modding.

Thanks again!