rknj

So I'm converting up a 1970s Ross Gran Eurosport into a fixie (the bombproof, bad-weather-riding, "I ain't stealin that thing!" kind), and am debating which cranks to use. I pretty much have two options, either keep the Shimano one-piece crank that came with the bike (which is in good shape, will be very very easy to maintain, and doesn't make the bike look worth stealing), or use the '05 Truvativ Elita cranks off my road bike (damaged the big chainring and decided to just upgrade the whole setup instead of replacing the ring) with the ISIS BB and converters. Opinions? Anyone ride a fixie with a one-piece crank on it that can say whether it's worth doing?

sivat

The biggest problem with a one piece crank is that you can't adjust the placement of the chainring to correct the chainline. Unfortunately, thats also the problem with isis cranks, since most isis bbs are the same length. It appears, from the info on sheldon's site, that all of the truvative cranks have a 48.5mm chainline to the center ring. What type of hub are you using on the rear wheel?

genericbikedude

and what is the current chainline with the OPC?

humancongereel

bulletproof bmx cranks, 165mm. or profile, or rpm, or...

for a beater, just use something like that.

The LT

old shimano 600 road doubles with a cheap shimano 107mm BB shouldn't run more than 50$ or so

Landgolier

Wait, does the bike currently have a true 1-piece, or like one of the chainrings is permanently on the R crank? Most actual 1 piece cranks have the oversize BB shell, so without a converter you really don't have much choice.

DiegoFrogs

Also beware that some of the Rosses that I'm familiar with that had ashtabula cranks also had Shimano's daft "Front Freewheel System." If this is the case, you may need to replace your cranks as a part of every possible solution.

Personally, I'd just stick with the one piece cranks.

genericbikedude

If you have a front freewheel rear wheel, you have a potentially multi-geared fixed bike, though I'd not use it without a bashguard for safety.

DiegoFrogs

And when he backpedals with his derailer, who will put humpty-dumpty back together again?

And if he just aligns the chain with an appropriate sprocket, what will keep the "fixed cluster" from spinning off when he applies reverse torque?

Slavic

That's true for Road cranks, I guess. There are a plethora of bmx cranks (flatlanders often use 165 or 170mm cranks for ground clearance) that may work for you.

Allow me to link you.

One piece cranks use a "USA" bb, so you can pick up some cranks that you probably won't ever break and should fit the bill for a nice price, unless you're really concerned about weight for some reason. Plus, the dude that owns Flatlandfuel is a super nice dude, and would probably work out a deal for you on anything.

rknj

sivat: I don't yet have a hub for the rear wheel.

generic: No chainline with the OPC yet since I don't have the rear wheel or hub.

Landgolier: It's a true one piece crank, I've taken off all the chainrings, nuts, bearings, etc. It has the oversized BB cup, but I have a converter a friend ended up not needing on his bike, so I can go either way.

Diego: Supposedly this model has the front freewheel system, but I can't find any mechanism that looks like it. I can't seem to find much info on it either, beyond that it exists and was a bad idea.

Slavic: Thanks for the link, I'll check it out.

I'll be happy with one gear on this bike, maybe a flipflop hub if I get zealous. The less parts to break, the more I'll like this bike.

trons

you can measure the crank's chainline without a rear anything. see chainline measurement-front https://www.sheldonbrown.com/chainline.html