goldfinch

I got a BCAmerica Rover mixte frame and some parts that a person was trying to build up into a bike but got it messed up. The bike likely originally was a single speed or three speed because there are no cable stops. The guy I got it from wanted to convert to a triple on the front and seven on the rear. He had the rear triangle "expanded" to fit his 26 inch seven speed cassette wheel. He put a triple crank on it and a top pull front derailler. It had a square taper bottom bracket. Then he stopped the project and put it in his shed and gave it to me several years later.

The wheels and frame look like new. I have a claw rear derailleur I put on the rear but I discovered a number of problems with the front. The front derailleur he put on will not go low enough, the cage hits the frame. Also, the bottom bracket spindle seems way too long (it measures at 125mm) and the derailleur will not go out far enough to shift to the biggest ring. Plus I have to get some kind of cable stop for the front derailleur. So, I am thinking about options and am having trouble with figuring out what would work best at a reasonable cost. I need help deciding what to do and what parts to use.

Possibilities and issues:

1. Convert to seven speed, and have only a single on the front, eliminating front derailleur. It seems for this option I would need a new crank (the one that is on there is a square taper but the rings don't come off). Would I also need a new bottom bracket or spindle? This is not a cartridge style. I notice that not all cranks give the recommended size on the specs when you order the crank, but I assume I would get a spindle consistent with the crank. Also, wouldn't I have an issue with the chain dropping off so I would need chain a chain guard of some type? If I would need not only a single speed crank, but one with chain guards, and a new bottom bracket, it seems like the cost is going to get up past what the bike is worth. I cannot seem to find cheap single speed cranks that don't have a huge ring and thus don't seem the best solution for a bike like this one.

2. Try to get it to be a 21 speed. This seems to require a new bottom bracket spindle and a new front derailleur, but how would I figure out what would work? I have no idea what the proper spindle length should have been. Is it possible to have a bottom pull front derailleur (that may be more likely to clear the frame) when there are no cable guides on the bottom of the bike?

3. Make it a single speed. Ditch trying to have seven on the rear. In this case I would need spacers on the rear and a new single speed crank. I am wondering if my too long bottom bracket spindle would work because I could have all the spacers on the inside of the rear wheel. This might be the cheapest option.

I did drag the bike down to the local bike coop. The person who helped me didn't have much more experience than I do and all we managed to do was diagnose the current problems, the mechanic was no real help with solutions.

nfmisso

Pictures required.

Recommendations/comments

* get a Shimano UN26 or UN55 BB to suit the crankset you have. Can you ID the mfg of the crankset?
* get a low end bottom pull FD; like a Shimano FD-TZ30/31.
* low end bikes from the '80's and earlier rarely had cable stops. Most ran cable housings the full length. Origin8 offers a variety of cable stop clamps that can be used for brakes and derailleurs: Amazon.com : Origin8 Alloy Cable Stop : Sports & Outdoors
* get a bag of these, and donate the excess to the co-op: Amazon.com : Nylon Screw-on Under Bottom Bracket 2 Cable Guide, Bag of 10 : Bike Cables And Cable Housings : Sports & Outdoors you can drill and tap a hole in the BB housing for the screw, or just remove the screw and stick it in place with 3M foam tape - clean both parts thoroughly with alcohol and let dry, then apply tape.

Bill Kapaun

IF it's a loose cup type BB, see if swapping the spindle will help.
Many are offset. Downside is it'll move the L pedal out more.

goldfinch

Helpful, thanks. I'll see if I can ID the crank. It says Shimano but I didn't see a model stamped on it but I'll look closer. Where do you put a clamp on cable stop for a bottom pull derailleur? I'll try to get some pictures tomorrow.

I did try turning the spindle around but still too long.

Bill Kapaun

Can you read the "CODE" on the spindle?
I've found spindles here, but have no idea about quality. Service was good-
Husky Bicycles: Bottom Bracket Parts

And Sheldon has a chart here-
Sheldon Brown's Bottom Bracket Size Database

Retro Grouch 

I love doing these kinds of projects. The core issue is you're trying to fit parts onto a bike frame that wasn't designed for them. The real trick isn't getting it to work, the trick is finding the right components, which is a trial and error process, without spending a fortune. I'd think a bike coop, assuming you don't have a big box of spare parts, would be a huge benefit.

I'm a little surprised that you don't seem to have a vision for the bike. I think that, since all of the parts on a bike work together, it's important to have a picture in your mind of the finished project before starting. What kind of brakes and handlebar controls are you planning to use?

likebike23

I would start by looking at the chain line first, see if the chain is straight when in the middle ring and cog. You'll have better luck if the chain line is good. I've had good luck using 80's mountain bike components on projects like this. I'm referring to cranks that have 28-38-48 or 26-36-46 rings. I also like the Shimano FD-AL11 for projects like this. It has a stop for cable housing when using a down tube clamp-on cable guide, it works with a wide range of ring sizes, has enough travel for triples, and is cheap. Here is a picture of my wife's mixte, it has 7 cogs and a triple which were not original and it works great.

goldfinch

I have tackled the brakes, and have some old side pull brakes that should work, to be cabled much like likebike's mixte in the picture in the previous post. I have a set of swept back handlebars I plan to use. I did have a pair of grip shifters but they will not work on these bars because the handlebar grip area is not going to be long enough, so I was thinking I would go with some thumb shifters, probably friction since there is such a long cable length.

That is the extent of my vision. I see a pretty bike with silvery parts. I probably complete the bike and give it away.

goldfinch

Chain line does not look right, part of the reason I think the bottom bracket spindle is too long.

Does that clamp on cable stop for your front derailleur stay put?

goldfinch

I found the model number on the crank, a Shimano FC-MC16. According to Sheldon's chart the bottom bracket spindle should be a 110 or 113. So, how do I decide which? Should I go to the coop and search through spindles and stick them in my bottom bracket? Are all spindles created equal beyond length and bottom bracket shell size?

StephenH

Well, my thought was go heave it in a dumpster and work on something else...

Bill Kapaun

The different lengths are for different rear DO spacings. (126, 130, 135...)
A wider rear requires a bit wider chain line.
You should be "safe" with the 113 if you were to buy a cartridge type BB.

IF you look at Sheldon's chart, you'll see the bottom one is for a 70mm shell and has 3mm wider center to center spacing than those for 68mm. (B dimension)

So, if you want a spindle, get something with a 32mm drive side end.
Your selection may be limited enough that you'll have to put the "long" end on the NDS.

likebike23

Yes it stays put just fine. It's a typical Suntour clamp on guide that goes on the down tube just in front of the bottom bracket. These kind of guides require that you run a small piece of housing from the guide to the front derailleur. If you use a clamp like this, make sure the front derailleur has a stop on it for the small piece of housing. The cable stop higher up on the downtube is a newer Origin8 (I think), 2 stop, hinged clamp. Lastly, you would need a cable stop for the chainstay that would hold the housing for the rear derailleur.

goldfinch

I figured I would need one stop for the front derailleur, on the downtube, then run the cable on through a double taped on cable guide under the bottom bracket up up to the front derailleur. I would use no stops for the rear, just run a solid length of housing. I would use zip ties to batten down the cable. Is there a reason this wouldn't work beyond aesthetics?

goldfinch

Thanks. Very helpful.

goldfinch

I am adverse to waste.

likebike23

One reason not to run a continuous run of housing to the rear derailleur is friction, that's a long run. If you are running a clamp-on stop and an under BB guide for the front, why not just get a double clamp-on stop and use the under BB guide for both front and rear? The only additional cable stop you would need is for the chain stay near the drive side dropout. This would give you 1 run of housing from the shifter to the down tube guide and 1 short piece of housing from the chain stay stop to the rear derailleur.

goldfinch

Thanks.

likebike23

^^No problem.

fietsbob

Alternate .. seek out a Sachs Hybrid Rear Hub .. 7 speed Cassette driver on a 3 speed IGH.. and lac a rear wheel around It,

then You can have Both a 21 speed drive train and a single chainring.. Crank.

goldfinch

If I was keeping the bike I might mess with something like this, but the bike is too big for me so it is going down the road when I am done.

Retro Grouch 

Believe it or not, by measuring the rear dropout spacing.

If your dropout spacing is 130mm, use the 110 spindle. If it's 135mm, use the 113 spindle. That should yield the straightest chainline to the middle of the cassette or frreewheel.

Bill Kapaun

What size rings on the crank?
IF the FDER won't go low enough, you may need bigger rings?
IF it has something like 22-32-44, you may need something like 28-38-48.

Retro Grouch 

Probably the cost effective solution but then you'd miss the fun of doing it. Hey, it's January. It's cold and nasty outside. That makes it a good time to screw around with my bikes inside.

goldfinch

It is finally warming up here in Tucson. I like afternoon bike projects and all my neighbors know that.