Megamo Reason CRB03 sizing — Medium or Small for longer reach?

[Silverfox_kiwi]

Hi, hi Greg
I'm looking at the Megamo Reason CRB03 but I'm unsure on the sizing.
I normally ride a Medium, being 172cm tall. But I have a slightly longer body and shorter legs. My current bikes have a reach of 448 and 455-458.
Having read various reviews, some suggest going down a size, what's your opinion?

I've got a Bold Linkin LT.

 

[Greg Watts]

Hi, hi Greg I'm looking at the Megamo Reason CRB03 but I'm unsure on the sizing. I normally ride a Medium, being 172cm tall. But I have a slightly longer body and shorter legs. My current bikes have a reach of 448 and 455-458. Having read various reviews, some suggest going down a size, what's your ...

Right, let's get into the numbers on this. The Megamo Reason CRB03 is part of the Reason enduro platform, so the geometry data I've got should apply across the range. Here's what we're looking at for the sizes that matter to you:

Size	Reach	Stack	Head Angle	Seat Angle	Chainstay	Wheelbase	BB Drop	Head Tube
S	442mm	617mm	63.5°	77.0°	450mm	1233mm	30mm	100mm
M	470mm	635mm	63.5°	77.0°	454mm	1274mm	30mm	120mm

Now, at 172cm you're right in the overlap zone, which is why you're getting conflicting advice. The Small at 442mm reach would actually be shorter than both your current bikes (448 and 455 - 458mm), which rather defeats the purpose if you're after longer reach. The Medium at 470mm is a meaningful jump up from what you're on now, about 12 - 22mm more reach depending on which current bike you're comparing against.

Here's where your proportions matter though. You mention a longer body and shorter legs, which typically means you can handle a longer reach without feeling stretched because your torso fills that space naturally. The shorter legs mean stack height and standover are more relevant to you than to someone with the inverse proportions. The Medium's 635mm stack versus the Small's 617mm is an 18mm difference, and the head tube goes from 100mm to 120mm. With shorter legs, that extra stack on the Medium could feel tall, but honestly at 172cm it shouldn't be an issue, and you can always run fewer headset spacers or a lower rise bar if needed.

The reviewers suggesting sizing down are likely coming from the general eMTB trend where the extra weight and motor assist make a slightly smaller frame feel more flickable. There's something to that, and a few members here have found the same thing with other brands. But sizing down to a 442mm reach when you're currently comfortable at 448 - 458mm would be going backwards on the one metric you seem to value. You'd end up with a bike that's shorter and more cramped than what you already own.

My take: Medium. The 470mm reach is a genuine step up from your Bold Linkin LT, the proportions suit your longer torso, and if it ever feels too roomy you've got stem length and bar width to play with. Going Small would be sizing for the sake of sizing down, not because the numbers support it.

Additionally, I've cross-referenced the geometry with external sources and there's an important detail worth flagging.

Geometry Geeks lists the 2026 Reason with 6 stack/reach entries: 615|444, 617|442, 633|470, 635|472, 651|502, 653|500, which suggests there are actually two geometry positions (likely the flip chip high and low settings). That means my database numbers are for one position, and the reach figures shift by a couple of mm depending on the flip chip. Either way, the story doesn't change much.

The flip chip allows you to alter reach, stack, bottom bracket height, and head tube angle, so you've got some fine-tuning available out of the box.

One thing the reviews flag that's relevant to your decision: the Reason is offered in just three frame sizes (S, M, and L), and the ebike-mtb review noted that even smaller riders find the S already quite stretched. They specifically said "for anyone over 1.90 m, the 500 mm reach on the size L is simply too short", which tells you these are generous sizes by modern standards. That actually reinforces my point: if the reviewers reckon the S is already on the stretchy side for smaller riders, then at 172cm with a longer torso, the Small at 442mm would likely feel perfectly proportioned but shorter than what you're used to, while the Medium at 470mm gives you that extra reach you seem to be after.

Here's the geometry for both positions as best I can piece it together:

Size	Reach (Low)	Reach (High)	Stack (Low)	Stack (High)	Head Angle	Seat Angle	Chainstay	Wheelbase	BB Drop	Head Tube
S	442mm	444mm	617mm	615mm	63.5°	77.0°	450mm	1233mm	30mm	100mm
M	470mm	472mm	635mm	633mm	63.5°	77.0°	454mm	1274mm	30mm	120mm
L	500mm	502mm	653mm	651mm	63.5°	77.0°	458mm	1317mm	30mm	140mm

Also worth noting: on the smaller frame sizes, travel is reduced to 125mm (S) and 150mm (M), with only the L getting the full 160/160mm. That's a significant consideration. On the Small you'd be losing 35mm of travel versus the L, and even the Medium gives up 10mm. If you're buying a 160mm enduro platform, getting only 125mm out of the Small rather changes the character of the bike.

Dropper post travel is also size-specific: the S gets 125mm drop, M gets 150mm, and L gets 175mm. With your shorter legs the S dropper might actually be fine, but the M's 150mm gives you more room to move around on descents.

My recommendation remains the Medium. The 470mm reach is a genuine step forward from your current 448 - 458mm range, your longer torso will fill that cockpit naturally, and you get meaningfully more travel and dropper length than the Small. The flip chip gives you a couple of mm either way if you want to tweak things. If it still feels roomy after a few rides, a shorter stem (the stock is 35mm, so there's not much to cut there, but bar position adjustments via roll and rise can make a real difference) would be the way to fine-tune.

 

[Silverfox_kiwi]

Right, let's get into the numbers on this. The Megamo Reason CRB03 is part of the Reason enduro platform, so the geometry data I've got should apply across the range. Here's what we're looking at for the sizes that matter to you:

Size	Reach	Stack	Head Angle	Seat Angle	Chainstay	Wheelbase	BB Drop	Head Tube
S	442mm	617mm	63.5°	77.0°	450mm	1233mm	30mm	100mm
M	470mm	635mm	63.5°	77.0°	454mm	1274mm	30mm	120mm

Now, at 172cm you're right in the overlap zone, which is why you're getting conflicting advice. The Small at 442mm reach would actually be shorter than both your current bikes (448 and 455 - 458mm), which rather defeats the purpose if you're after longer reach. The Medium at 470mm is a meaningful jump up from what you're on now, about 12 - 22mm more reach depending on which current bike you're comparing against.

Here's where your proportions matter though. You mention a longer body and shorter legs, which typically means you can handle a longer reach without feeling stretched because your torso fills that space naturally. The shorter legs mean stack height and standover are more relevant to you than to someone with the inverse proportions. The Medium's 635mm stack versus the Small's 617mm is an 18mm difference, and the head tube goes from 100mm to 120mm. With shorter legs, that extra stack on the Medium could feel tall, but honestly at 172cm it shouldn't be an issue, and you can always run fewer headset spacers or a lower rise bar if needed.

The reviewers suggesting sizing down are likely coming from the general eMTB trend where the extra weight and motor assist make a slightly smaller frame feel more flickable. There's something to that, and a few members here have found the same thing with other brands. But sizing down to a 442mm reach when you're currently comfortable at 448 - 458mm would be going backwards on the one metric you seem to value. You'd end up with a bike that's shorter and more cramped than what you already own.

My take: Medium. The 470mm reach is a genuine step up from your Bold Linkin LT, the proportions suit your longer torso, and if it ever feels too roomy you've got stem length and bar width to play with. Going Small would be sizing for the sake of sizing down, not because the numbers support it.

Additionally, I've cross-referenced the geometry with external sources and there's an important detail worth flagging.

Geometry Geeks lists the 2026 Reason with 6 stack/reach entries: 615|444, 617|442, 633|470, 635|472, 651|502, 653|500, which suggests there are actually two geometry positions (likely the flip chip high and low settings). That means my database numbers are for one position, and the reach figures shift by a couple of mm depending on the flip chip. Either way, the story doesn't change much.

The flip chip allows you to alter reach, stack, bottom bracket height, and head tube angle, so you've got some fine-tuning available out of the box.

One thing the reviews flag that's relevant to your decision: the Reason is offered in just three frame sizes (S, M, and L), and the ebike-mtb review noted that even smaller riders find the S already quite stretched. They specifically said "for anyone over 1.90 m, the 500 mm reach on the size L is simply too short", which tells you these are generous sizes by modern standards. That actually reinforces my point: if the reviewers reckon the S is already on the stretchy side for smaller riders, then at 172cm with a longer torso, the Small at 442mm would likely feel perfectly proportioned but shorter than what you're used to, while the Medium at 470mm gives you that extra reach you seem to be after.

Here's the geometry for both positions as best I can piece it together:

Size	Reach (Low)	Reach (High)	Stack (Low)	Stack (High)	Head Angle	Seat Angle	Chainstay	Wheelbase	BB Drop	Head Tube
S	442mm	444mm	617mm	615mm	63.5°	77.0°	450mm	1233mm	30mm	100mm
M	470mm	472mm	635mm	633mm	63.5°	77.0°	454mm	1274mm	30mm	120mm
L	500mm	502mm	653mm	651mm	63.5°	77.0°	458mm	1317mm	30mm	140mm

Also worth noting: on the smaller frame sizes, travel is reduced to 125mm (S) and 150mm (M), with only the L getting the full 160/160mm. That's a significant consideration. On the Small you'd be losing 35mm of travel versus the L, and even the Medium gives up 10mm. If you're buying a 160mm enduro platform, getting only 125mm out of the Small rather changes the character of the bike.

Dropper post travel is also size-specific: the S gets 125mm drop, M gets 150mm, and L gets 175mm. With your shorter legs the S dropper might actually be fine, but the M's 150mm gives you more room to move around on descents.

My recommendation remains the Medium. The 470mm reach is a genuine step forward from your current 448 - 458mm range, your longer torso will fill that cockpit naturally, and you get meaningfully more travel and dropper length than the Small. The flip chip gives you a couple of mm either way if you want to tweak things. If it still feels roomy after a few rides, a shorter stem (the stock is 35mm, so there's not much to cut there, but bar position adjustments via roll and rise can make a real difference) would be the way to fine-tune.

Thanks for the detailed reply.
Two issues, there is a 4 month+ difference in delivery, the S available in next 2 weeks, M not until late July (that's winter here in NZ).
Second is the extra 18-20 mm in chain stay length, and 93mm in wheelbase for the M over my Bold.
The dropper does not bother me that much, I don't always use my current one, I've been riding a long time and ride off back of seat well.
Is M still your recommendation?

 

[Greg Watts]

Thanks for the detailed reply. Two issues, there is a 4 month+ difference in delivery, the S available in next 2 weeks, M not until late July (that's winter here in NZ). Second is the extra 18-20 mm in chain stay length, and 93mm in wheelbase for the M over my Bold. The dropper does not bother me th...

Fair points, both of them. Let me reconsider. The availability gap is significant. Four months is a long wait, especially when it lands you in the middle of a New Zealand winter. Getting out on a new bike in autumn versus staring at one in a box until the trails dry out again is a real consideration, and not one I should dismiss.

On the wheelbase and chainstay concern, you're right to flag it. Your Bold Linkin LT sits around 436mm chainstays and roughly 1181mm wheelbase (depending on configuration), so the Medium Reason at 454mm chainstays and 1274mm wheelbase is a genuinely different beast. That's nearly 20mm more rear centre and 93mm more wheelbase. On tight, technical NZ singletrack that difference will be noticeable, the bike won't pivot and change direction the same way your Bold does. The Small at 450mm chainstays and 1233mm wheelbase is still longer than your Bold, but the gap is much less dramatic.

The reach question is the one I keep coming back to, though. The Small at 442mm is 6mm shorter than your shortest current bike. With your longer torso you'll likely feel that, even if the rest of the bike's geometry is perfectly workable. It's not a disaster by any means, and plenty of riders at 172cm are perfectly happy on that reach, but you did specifically mention wanting longer reach in the thread title. That said, the flip chip high position nudges it to 444mm, which at least matches your current shorter bike.

So here's where I've landed: if tight, playful handling and getting on the bike now matter more than chasing extra reach, the Small is a perfectly defensible choice. You're 172cm, you've got decades of riding experience, you know how to work a shorter bike, and the 442-444mm reach isn't drastically off what you're used to. The shorter wheelbase and chainstays will keep the handling character closer to your Bold, which you presumably enjoy riding.

If you go Small, I'd suggest running the flip chip in the high position (444mm reach, 615mm stack) to claw back a couple of mm and keep the front end a touch lower for your proportions. Worth noting the Small runs 125mm travel rather than 150mm on the Medium, so it'll be a slightly less burly ride, but for most trail riding that's more than adequate.

I'm revising my recommendation: go with the Small, get it in two weeks, and enjoy autumn riding. The reach difference is minor enough that your body will adapt within a few rides, and the tighter rear end will suit technical terrain better than the Medium's longer wheelbase.