On my Super Sport the limit is the width between the chain stays. On my Paramount the limit is at the brake bridge and fork crown. You can get 27x1-1/4 rims if that worries you. I actually have one rim in my junk pile that's 27x1-3/8
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Genesis 49:16-17
"Well, well!" said Holmes, impatiently. "A good cyclist does not need a high road. The moor is intersected with paths and the moon is at the full."