I will attempt to continue my streak of evidently stupid questions by asking:

Has any thought been given to a double front chainwheel and shifter as an option as an alternative the 7-sprocket rear cluster and derailleur as used on the Querve? One commenter on the Violation model wrote that he wished for the Querve gearing to help accelerating from a traffic signal. Seems to me that this need could be adequately met with a single "low gear" while avoiding some of the mechanical complications of the rear shift. Rear coaster brake could be retained also (YMMV on whether that is an advantage

-R

Interesting question.
I don't have a MAB (motor assisted bike)yet,
but I'm working towards it.
I bought a 7-speed cruiser bike to put a motor
on. I wanted the multi-speed because I will mostly be riding in lots of city car traffic,and I also by law, have to use the 48cc
motor, which apparently has less low end torque than the 80cc,and because my bike has 14 gauge spokes, not like the 12 gauge that
ST bikes use.
I had to buy a bike because I needed an
"Astabula" one piece crank to clear the motor
width, and to keep the motor low in the frame.

Where can you buy Astabula cranks with double or even triple chain rings? I guess
their out there somewhere, I've never seen one though.
Your question will keep me wondering for awhile.

Cheers

Change Astabula to Ashtabula. A place in Ohio, somewhere by Bikeguy Joe.
I guess these types of old-fashioned
cranks were invented and manufactured
there in the past.
Anyway they are strong, easy to work on and last along time.

Ashtabula cranks were just one of several parts manufactured by that company. It named after the city it was in, Ashtabula, or Ashtraybula, or Ashtabeautiful, or.....

anyhow, they made parts for Schwinn I believe (forks, the blade type) and BMX "conversions" for 20" bikes in the late 70's. I haven't found the exact location of the old factory, but I do know it's been out of business since the 80's.

I'd look to ebay to find older Ashatbula bike parts.

the question Rolly posed got me thinking about the possibility of using front chainrings as a means of adding, 2 maybe 3 gears to a coaster
brake bike. The good:1) no derailer, and therefore easier maintainance, and better ground clearance.2)lighter weight because, no back brake calipers, no freewheel/cassette, no derailer.The bad: might not fit with a low motor mounting, can't use the bicycle drive train chain-guard, and from my experience, much slower gear shifting. Down is fast, up shifting is slow.

the late Sheldon Brown may he R.I.P,
has on his website, information about OPC(one piece cranks) aka ashtabula front chain rings, there is apparently, something known as a power disc, to be used on a OPC, so that you can add multiple front chain rings. do a search for "one piece cranks". These seem to be aluminum, seems like Spooky Tooth
could make these, aluminum or steel in their shop, and give their coaster brake customers
some different options!

Cheers, to my new Pals

I just did a search on ebay for "chain tensioner" then look under bicycle parts and there are some tensioers for turning a multi-speed bike into a single speed, but it would work for what you are talking about too.

So Joe,
You would then put that on the bike drive train side to take up the slack? Like the motor side. It could be spring loaded. Hope Rolly gives us a thumbs up, for all this thought!

No, the sprocket is wrong and I don't think it would hold up to an engine on it all the time. I was thinking more along the lines of using it for a tensioner for a front shift, or chainwheel shifter application.

The chain is different for coaster brake bikes. I'm not that "up" on all things bicycle, but I suppose you could change sprockets around to get a front deraileur/coaster brake bike.

yes i was getting mixed up, not realizing that you have to take up the slack in the chain, when you shift between front chain wheels. on a 10 speed the rear derailler
does that automatically, whether or not you change rear
gears or not. so the rear derailler is also a chain tensioner. just my lax brain at work!!

Anyway, I ordered a 48cc engine yesterday, finally.

Cheers to all

My bad as well - gave no thought to chain tension. However, "Astabula" and "power disc" were the magic words - I found them for sale ($20) here:
http://harriscyclery.net/itemdetails.cfm?ID=2548
Now, to sleuth around their site to see if they have a tensioner for a coaster brake bike. I suppose there may be a sufficient number of bikes with rear derailleurs and one piece cranks for there to be a market for this item without including coaster brake models, but it doesn't seem probable.

-Rolly

tiredcyclist wrote:
yes i was getting mixed up, not realizing that you have to take up the slack in the chain, when you shift between front chain wheels. on a 10 speed the rear derailler
does that automatically, whether or not you change rear
gears or not. so the rear derailler is also a chain tensioner. just my lax brain at work!!

Anyway, I ordered a 48cc engine yesterday, finally.

Cheers to all

Query and reply:

Q. Hello. I am interested in the Astabula chain ring adapter (your p/n CRA329). Can you tell me more about its intended application?

A. It is meant to allow the user to mount a single 110 or 130 bcd chain ring on an ashtabula crank.

---
Rolly, I've sort of given up with this whole thing,this topic. You had me thinkin too hard.
If you want to get a multispeed , you had better just get one. I get dulusional about these sorts of mechanical things, problems.
But I suppose you could make YOUR own Chain
tensioner, it would have to be from only North or South. Push up or Push down, or Pull up or Pull down.Same tension from top or bottom, not left or Right horozontal. I'm not a logic person, but I think you need to make a truth chart. Like tic tac toe. Think about the brake action. a/b- or a/b+
On the horozontal.
Cheers,
tiredcylist, my brake is a beer, by the wayside