So I picked up this Hercules from either the late 60s or early 70s and the rims have to much rust to salvage. My question is what is the max size rim that can fit? The current wheel size is 26X1 3/8. It has no fenders and I am planning on keeping it that way, so that will make fitting bigger rims easier.
Rim Size
- Thread starter 155mm
- Start date
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I've had a few of those Hercules over the years. I rode in all the liberty ports when I served on Carriers back in the 80's. This photo is from 1982 and a hundred pounds ago. 
The frame is such that you can't go any bigger or wider, even if you don't use hand brakes. There are pretty good quality 26 x 1 3/8 tires nowadays though.
The frame is such that you can't go any bigger or wider, even if you don't use hand brakes. There are pretty good quality 26 x 1 3/8 tires nowadays though.
You probably don't have a lot of room between the stays, but if you have a ruler, you can take some measurements at various points along to stays to determine what will fit. A measurement is worth a thousand mock-ups, and a million guesses by online commentators.
Without seeing it, its hard to say. The 26x1-3/8 rim is likely a 590 mm ISO diameter (650A), already larger than a lot of sizes. You might possibly squeeze a 700C wheel in if you use a very narrow tire (like 21 mm). But short of that, I think that you're already probably at the limit. Replacement 650A/26x1-3/8 rims aren't that hard to find. Even aluminum ones are available, due to the popularity of that size on old British bikes.
155mm, it's been 35 hours since you posted this; have you grabbed the tape measure yet? Quickest route to a definite response.
Rick da Jawa: Gotta disagree with you. A 590x38 is theoretically the same diameter as a 700x23c. Unless 155mm's bike is from the very early 60s, it is Raleigh buuilt and will easily take a 700x28c, maaaaaaaaaybe squeeze a 700x32c in there; in either case, no fenders--or thin new-style fenders.. This is why the OP should have taken some measurements at about 311mm up the fork blades and stays, to measure how much room there is going up and side-to-side at that point. Raleighs are odd in that they tend to clear more out back then they do up front. Oh, btw, that fork probably takes a scrawny 5/16" axle and is spaced very narrowly, at like 81mm. So, you'll need to modify the fork if you want it to take a modern/common hub. Back is spaced about 115mm, so there's that, too. If you want to swap the fork, you'll need to replace the headset. Even if you find a Raleigh-built fork for 28" wheels, the steerer tube will almost certainly be too short for your frame.
My advice: If the Herc ain't a step thru, flip it as-is for a quick $100 and buy the bike you want. If it's really clean, you might get more. If it's a step-thru, you might get $75...
Rick da Jawa: Gotta disagree with you. A 590x38 is theoretically the same diameter as a 700x23c. Unless 155mm's bike is from the very early 60s, it is Raleigh buuilt and will easily take a 700x28c, maaaaaaaaaybe squeeze a 700x32c in there; in either case, no fenders--or thin new-style fenders.. This is why the OP should have taken some measurements at about 311mm up the fork blades and stays, to measure how much room there is going up and side-to-side at that point. Raleighs are odd in that they tend to clear more out back then they do up front. Oh, btw, that fork probably takes a scrawny 5/16" axle and is spaced very narrowly, at like 81mm. So, you'll need to modify the fork if you want it to take a modern/common hub. Back is spaced about 115mm, so there's that, too. If you want to swap the fork, you'll need to replace the headset. Even if you find a Raleigh-built fork for 28" wheels, the steerer tube will almost certainly be too short for your frame.
My advice: If the Herc ain't a step thru, flip it as-is for a quick $100 and buy the bike you want. If it's really clean, you might get more. If it's a step-thru, you might get $75...
Pulled out the tape and took some measurements, came up with seat stay to right below the brake mount 355.6mm, chain stay to about a half inch before the kickstand is 349.3mm, width at that measurement is 44.4mm, and a dropout width of 114.3mm. Front has plenty of room and the dropout spacing is 98.4mm. Head tube without cups is 115mm. My plan is to rebuild the rear wheel using the Sturmey Archer 3 speed that came with it, front wheel is going to be built with an old Miche hub from an 80s C-Dale. Considering I am stationed in Okinawa and the vintage bike is non-existent here and the fact she only cost me $20 my plan is to rebuild her and see where my vision takes this old piece of iron. Build thread will begin within the next week or so.
I did a search for a Hercules with 700c and came up with this. I can't be sure the wheels are 700c, but they look like it.
