Three parts of a comfort bike are sold as the thing that smooths a rough surface, and they are not equally good at it. A fat tyre at a sensible pressure, a sprung or elastomer seatpost, and a suspension fork sit at the front of nearly every showroom pitch, usually in that reverse order, because the fork is the one a buyer can push down with a thumb in the store. Pushing on it tells you almost nothing. What matters is which of the three is working at the frequencies a paved path actually produces, and which is just adding weight and a service interval.
Tyre volume is the suspension you already paid for
A 40mm tyre run at a pressure appropriate to your weight is doing more than most riders assume, and it does it everywhere: under the saddle, under the hands, under the pedals, at both ends of the bike at once. The reason is bandwidth. Air in a tyre responds to the small, fast, continuous inputs that make up chipseal, brushed concrete, root heave and expansion joints, and those inputs are the ones that fatigue you over an hour. A budget coil fork with a heavy spring and no meaningful damping simply does not move for those. It waits for a curb. A careful reader checks the sidewall for the pressure range, then checks whether the rims and frame clearance actually allow the width the tyre promises.
Pressure is where most of the available comfort is lost. Plenty of comfort bikes leave the shop pumped to the number molded into the sidewall as a maximum, which is a ceiling, not a recommendation, and at that pressure a 40mm tyre behaves like a narrow one. Drop it in five pound steps across a few rides, riding the same stretch of bad pavement each time, and stop when the steering starts feeling vague in corners or you can feel the rim through a sharp edge. Heavier riders need more, lighter riders considerably less, and the front can usually run a few pounds below the rear. The Consumer Product Safety Commission oversees bicycle safety requirements for bikes sold in the United States, and tyre and rim compatibility markings are part of what you should confirm before you go wide.
A seatpost that moves is honest about what it does
A suspension seatpost only cushions one contact point, and that limitation is also its strength, because the seat bones are where a large share of road buzz reaches you on an upright bike with a swept bar. Elastomer posts are simple, quiet and light, typically adding a pound or less, and they give maybe an inch of travel that takes the top off square-edged hits. Parallelogram designs move the saddle rearward as they compress, which keeps your leg extension roughly constant instead of shortening it. The tradeoff is bob: a soft post sinks and rebounds with each pedal stroke if the spring rate is wrong for your weight, which is why the good ones are sold in weight-rated elastomers you can swap.
Maintenance is modest and non-negotiable. Elastomers stiffen in cold weather and eventually take a set, so plan on replacing them every few seasons. Sprung and telescoping posts need the shaft wiped and greased occasionally or they develop a click and then play. Both need the frame's seat tube checked for insertion depth, since a suspension post's usable length is shorter than it looks.
What a fork earns, and what it costs
A suspension fork on a paved-path bike earns its keep in a narrow set of conditions: dropped curbs, gravel connectors, rough shoulders, potholes taken at speed. For those, an inch or two of travel with a real damper is genuinely useful. The problem is that the forks fitted to inexpensive comfort bikes are usually undamped coil units weighing three to five pounds more than a rigid fork, sprung too firmly to move under normal riding and too slow to recover when they do. They add weight where it hurts steering, they dive under braking, and after a couple of wet winters the stanchions pit and the bushings knock.
If a fork is on the bike you want, check it for a lockout, a preload adjuster and a replaceable seal, and check whether the shop will service it or just replace it. A fork worth having is one that was specified deliberately rather than fitted to fill a price point, and you can usually tell within one ride over a familiar rough block.
Spending the comfort budget in order
Sequence the money. Get the widest tyre the frame clears, set the pressure to your weight rather than the sidewall maximum, ride it for two weeks, and only then decide whether the remaining harshness is under your seat or under your hands. If it is the seat, a weight-matched suspension post is a cheap and reversible fix. If it is your hands, a grip change, a bar with more sweep or padded tape usually beats a fork, and costs a tenth as much.
The one test worth running before you buy anything: ride the same quarter mile of bad pavement, at the same speed, after each change. Comparisons across different routes tell you nothing.