No. The M3 has no Bluetooth radio, no ANT+ radio and no app of any kind, which is how the model was built and not a feature that fell off it. Nothing on the bike broadcasts, so a third-party cycling app and a group cycling projection system both have nothing to connect to. Where a room needs that, the Keiser M3i Indoor Bike puts the M Connect Display on the same family of frame and broadcasts over Bluetooth 4.0 on the CSCS, FTMS, CPS and Keiser Proprietary profiles.

Connectivity and size. The M3 carries a computer display that reads out RPM, watts, kilocalories, trip distance, elapsed time and gear, and sends none of it anywhere. The M3i carries the M Connect Display with Bluetooth 4.0, pairing to fitness apps, heart rate monitors and group cycling projection systems. The M3 is also the smaller machine at 44 in. and 87 lb against the M3i's 49 in. and 92 lb, and the M3i fits a rider from 4 ft 10 in. to 7 ft on a four-way Studio Curve handlebar.

Twenty-four working gears, numbered 1 to 24, on magnetic resistance. Above them sits Gear 88, which serves as the emergency brake and is not a riding gear. The gear number stays on the computer screen while you ride, so a coached instruction like Gear 16 for three minutes means the same thing on every M3 in a room.

Rider height on the M3 runs 58 in. to 84 in., which is 4 ft 10 in. through 7 ft. That span is set by the frame, so it is the one fit figure the adjustments do not change.

Up to 350 lb, and the rating covers a rider seated, standing out of the saddle and climbing on or off. The 87 lb the M3 weighs itself is a separate figure and it only matters on the day the bike moves: 87 lb round a stair turn is a two-person lift whatever the rider on it weighs.

The M3 measures 44 in. / 1118 mm tall, 26 in. / 661 mm wide and 51 in. / 1296 mm deep. At 44 in. it is the shortest bike on this frame, level with the M3i Studio, so a basement joist or a sloped loft wall is rarely the thing that stops it; the 26 in. across the handlebar and the 51 in. front to back are. Allow clear floor behind the saddle for getting on and off, and clear air above the bar for a rider riding out of the saddle.

No. The M3 has no heart rate function and nothing to pair a chest strap to, so heart rate is the one number the computer will not show you. Riders who want it on the screen should look at the M3i, whose M Connect Display reads heart rate alongside watts, cadence and gear.

No. The computer runs on two AA alkaline batteries and the rest of the bike is entirely mechanical, so an M3 can go into a garage or a basement with no outlet anywhere near it. Keep a spare pair of cells with the bike and the changeover takes a minute.

No. The M3 runs a fixed gear system with no freewheel, so the cranks turn for as long as the wheel turns and a rider slows the bike through the legs. Gear 88 is the emergency brake for anything faster than that. Riders arriving from a road bike usually take half a session to lose the habit of stopping their feet.

Dimensionally, yes. Both stand 44 in. tall and weigh 87 lb on the same 26 in. by 51 in. footprint, so a room that takes one takes the other. Everything above the frame diverges: the M3 carries a computer display that broadcasts nothing and runs on two AA cells, while the M3i Studio carries the Studio Display with 72 gears, a generator in the flywheel hub and both radios live. The M3 also fits a taller rider, 58 in. through 84 in. against the Studio's 5 ft to 6 ft 2 in.

Keiser covers M Series Cardio for three years all inclusive, excluding labor and wearable parts, and the wearable parts, handles, pedal cage, straps and saddle, carry ninety days. Cover does not extend to accident, abuse, improper use, neglect, improper maintenance, improper assembly or failure to follow the assembly instructions, and equipment exported out of the US is outside the terms unless it was bought through a Keiser distributor in the country of installation.

All four of them. The Keiser Bike Dumbbell Holder is the one to read carefully, because it fits the M3 and the M3i and a frame built before May 2016 has no tapped hole for it and needs a retrofit first. The M Series Assembly and Maintenance Kit covers every M Series Indoor Bike, the Keiser Gel Seat Cover stretches over a "narrow" saddle of the kind the M3 carries, and the Keiser Floor Mat answers to a wider scope again, M Series Cardio machines. Each one is ordered on its own.