gearing question

[andyinchville1]

HI,

I don't weight much more than you and my 36T pulls me fine here in relatively hilly VA....I have used a 32 before and it is capable of much higher speeds....If you goal is 40 MPH....probably have to gear up to keep revs reasonable...(I run a Dax 70)

Andrew

 

[Dean]

Feelinalright,

I don't know if you did that on purpose, but I think its cool that the bike's brand name (model?) is Iron Horse.
Kinda fitting, with the engine and all.




Dean

 

[feelinright]

Yeah the Iron Horse thing was'nt intentional but yeah I do think the name fits. When I was looking for a bike for this motored bike project there are tons of bikes out there but this bike seemed the best for this engine kit. Alot of the more expensive bikes use double butted tubes which would not be good mounting an engine to it especially in aluminum. Also I needed to have a 7 speed gear setup for the stanton hub and a decent suspension fork. But it was the 36 spoked rims and the sale price of 200 bucks that sold me.Would have preferred a chromoly frame but those are getting harder to find these days and did not feel like making my own frame since it would cost me more to build a frame than to get a whole bike.

This bike is holding up well, I've even jumped a few curbs and speed bumps and hit 38mph yesterday and get 35mph consistantly. Having lots of fun and can't wait for summer.

 

[Dean]

Feelinalright,

Sounds like you found a winner of a bike.
I'm not too "up" on frame construction.
Could you please explain what a "double butted frame" is and what is the cost of building your own frame (ballpark is fine) ?
Building something from scratch is an avenue I've been thinking about with my own proposed project.

(PM or email me, if you prefer)



Dean

 

[feelinright]

certainly dean. Double butted tubes are machined inside typically so that near the ends the tube is of normal thickness for a few inches and then most of the tube is made thinner to save weight. The idea is that a bicycle tube needs to be stronger near the welding areas and thinner for the rest of the tube. Good for a regular bicycle but not so good if you are going to attach a 15 pound engine to the middle of the downtube and seattube.

As for how much a frame cost to builds depend on the tools you have already. You should have a tig welder if you are going to do aluminum or titanium or chromoly steel. Another option is fillet brazing which is what I do which is the cheapest way to build a frame yourelf. I have been able to braze frames with mapp gas and a brazing torch and found nickel silver rods to work great. An oxy/actelane torch is preferred. Brazing can only really be done with chromoly steel or any other steel but chromoly is by far the way to go for most custom frames. Then you will have to build a jig. I built one around a frame I had sitting around although you can buy one they start about $1500 which is way too much for hobbyist like me. I would say tools aside the tubing,brake mounting etc probably cost about $200 to $400 a frame more or less in most cases.Most frame builders will charge $1500 and up for a fillet brazed chromoly frame and that's because alot of time and work goes into a frame. I have built about 5 frames mostly because I had a few ideas for some frames and wanted to see how it was done.I also like the idea of having a bike that no one else in the world has(a true original). As far as saving money though Asian aluminum frames are cheap and as good of quality as can be made as far as aluminum goes. A good cromoly frame should last a lifetime but are getting hard to find because Asian bicycle factories are focusing all their efforts on carbon fiber and aluminum. Hope that helps. There are plenty of websites for/by amatuer frame builders out here on the net. I have been thinking of building a frame in the future specifically for a bicycle engine although it may be a while.Making a frame is very hard work and for me always involved getting burnt, chocking on fumes and usually a new scar somewhere but being able to ride a bike I totally designed for my needs is priceless.

 

[Dean]

Thanks for the explanation.
I wonder how long they've been doing that.
I'll have to check with my own bikes, both of 1970's vintage, and see if I can hear any difference when I tap on the tubes in different areas.

I wonder if you could build a decent bike frame from the metal tubes used for automobile exahust pipes.
That metal isn't all that heavy and it can be shaped and welded fairly easily (I used to work in a muffler shop, so that's how I know).
I would think you could build a one piece paralellagram-shaped frame and weld the ends to the hub for the pedals, then run the single brace piece across the middle of the frame, as you see in most bikes.

The tubing would be of much larger diameter than pretty much anything else out on the road (think "Cannondale-frame-on-acid" ).

I think the pipes are fairly inexpensive and you can rent a hydraulic pipe bender with mandrels big enough to work it, from any rent-a-center.

...might be an interesting experiment, anyway.




Dean