Funky sized cottered cranks on an old straightbar.

[mofoco1]

Redoing a Columbia-ish looking 26 boys straightbar. It came with cottered cranks, which I just thought someone threw on there in a pinch. Well looks like I was wrong. I thought I was just going to throw on a set of NOS hollow OPC I had been saving. Well as you can see in the picture it is a small size. What the heck. I can't see how these cranks will fit. So anyone have a clue and what my options are?

 

[Jpromo]

This.. this is a head-scratcher. Most of the frame looks like a Columbia, yes. But the style of the seat stays and binder bolt don't fit with the time period of the rest of the frame. Any chance the seat stays were damaged and then pinched by hand and bent up to the original collar? If it is Columbia, then the BB cups have been switched out at some point.. unless they're threaded.. which opens the option that..

it's European. There was a period where american-inspired balloon type frames were being manufactured across the pond. They looked similar but didn't quite have the same fluidity of the american designs.

At any rate, the fork is not original. I'm pretty sure it's from a 20s Davis-built bicycle and could be worth a few bucks.

 

[mofoco1]

I know the Raleigh's and such used a pinched rear upper stay/seatpost clamping. The rear fender bracket in between the stays is strap not tube. No there was no repair all was done when new. BB is has not been changed although I am thinking I may have to swap it out( Pain in the ... though). BB is not threaded, I have to mic the BB axle to see how big it is. I thought I had this build in the bag too! Yes someone a while ago had mentioned that they thought the forks were early Davis. How the heck this this mismatch of parts come to be? Rear stays are identical to my 64 Columbia tandems rear stays also.

 

[The Black Monark]

Possibly Stelber?

 

[mofoco1]

Checked on the Stebler, but I did not see a pinch bolt upper seat post set up on any of them. The rear dropouts look more like Murray with that swept back look. I saw what looked like the Columbia design but it was shorter. Appreciate the shout out though.

 

[Bendix]

Looks like a Thompson bottom bracket.

Maybe something like this would fly:

http://store.velo-orange.com/index.php/ ... ckets.html


There are a few brands, this was just the first to show up when I googled them... :wink:

 

[mofoco1]

Have kind of decided to just keep this klunker as there was not much interest in the whole bike just the Davis forks. So here is a question maybe someone here will answer.
Can any decipher what the serial number 1476636 on the bottom bracket of this mystery bike. no other markings but I measured the rear dropouts on the Columbia Tandem cruiser(pic 2) and it is identical in size and dimensions including all the fender holes. The freaking BB is the killer though. Here's my dilema, I have figured a way to make this thing work but it comes at a cost of a BB conversion, new custom billet cups and 3 pc. cranks Last pic shows the BB conversion(actually a repair BB for stripped threaded BB shells).
BB kit = $30
custom billet cups = $50
vintage 3pc cranks = $50-$100
shipping both ways for BB to machinist and back. = $15
---------------------------------------------------------------
Total = $145-$195

OR
Do I cut and grind the BB off the frame and replace it with one off a free donor?
Cost do modify in parts = $0
Have Certified Welder reweld BB and all other welds and maybe gusset it a bit = $50-$75
Vintage OPC sealed BB = $50-75
---------------------------------------------------------------------------------------------------
Total =$100-$150
There's really only about a $50 difference either way, what's everyone take on this. I can whack it off in a few hours and have it tacked so it's not like I have not done this before, but do I leave it somewhat original, as I do not know what it really, is there is no great sentimental attachment to originality. What's the consensus?

 

[LukeTheJoker]

You could always keep the original cranks... New locking pins are readily available if they were damaged coming out...

Luke.

 

[The Black Monark]

Maybe sell the fork, buy another project frame, and mothball this one?

 

[mofoco1]

Told myself that I would finish whatever I started and have to see it through now. I have a 6 other frames that are going to get klunked as well, so it's not a matter of ditching it for another frame. I am not going to mothball or shitcan or scrap it. I am also going to really use it, like a klunker was supposed to, so cottered cranks probably not the best choice. Anyone know dimensionwise how a Thomson BB cottered spindle compares to a square taper spindle, can it fit and work with the smaller cups, cause that would fix everythying right off the bat.

 

[blown240]

If your going to use it like a klunker should be used, tearing down the mountain in the dirt, then I would have the new BB shell welded in. That way you have a nice, new, sealed BB in there and can use whatever cranks you want.

 

[sqrly]

There are "old bike shops" that actually have a selection of square tapered bb spindles. They make many different ones that have various offsets to position the chainline. In the past (when I worked at a bike shop that was well outfitted with repair parts) I have used square spindles with cups that were originally for cottered spindles. You have to take alot of accurate measurments and check the bearing wear line. The biggest problem I see is the possibillity of the spindle being slightly smaller in diameter and finding a shop with stuff on hand. The shop I worked at had about 15-20 different spindles maybe more. We carried a huge selection of small parts to keep almost any bike on the road. I think we were the only shop that well stocked in a hundred mile range, maybe more. If you decide to go that route, you will need the bb, frame, intended crank and rear hub, to get the chainline correct.

That being said, I have a girls bike with that smaller bb and have had a few boys bikes over the years. I dont think they are worth the hassel. Also, a cottered crank is just as strong as a square drive crank. And more often than not, the square taper spindle will break before the cottered spindle. Proper cotter insertion is the key. The nut on the cotters is NOT to be used for installation, but for holding purposes only.. Must use a cotter press or a hammer and (steel) tube to insert and bind the cotters.

This was all typed on my phone so excuse any gramatical or punctuation errors and especially goofy words after numbers.