Middleburn has arrived from the UK.
Well, we’ve got RS7, RS8, RO1, RO2…and RS8…?
We got confused since they’re called just numbers
So, this time, I’m trying to introduce them to you one by one.
There’re so many “chain line” and “R” in this review.
Today, I’m not going into their history and background.
Check it out if you’re interested in these cranks, but not sure which is the one for you.
Then, let’s move on to the first one.
The first one is RO series for road bikes.
I’m not sure if this “RO” means “ROAD”, but it’s easy to remember.
“RO1” for the square taper bottom bracket.
“RO2” the 24mm outboard bottom bracket.
Even though the BB specifications are different, their iconic slender silhouette doesn’t change so much.
They’re magical cranks match any kind of bikes from BIKE FRIDAY to RIVENDELL.
Does it fit a bike like this? So, I brought SURLY Midnight Special.
The reason why I was wondering is the wide chain stays.
It often happens with old square taper cranks, but sometimes chainstays get in the way of crank arms and a chainring.
I just thought that the cranks from small brands tend to have these kinds of issues.
I don’t want you guys have that sort of matters, so I’m trying to check it.
Slender and smooth line of a curve, yet still looks beefy and glossy.
Don’t you think so?
The Q-factor (the distance between the pedals) is about 135mm which is relatively wide.
As you can see, there’s quite a space between the crank arm and the chainstay.
Of course it matches road bikes,
gravel bikes such as BLACK MOUNTAIN CYCLES Mod Zero and Monstercross,
and Rivendell Roadini and Charlie H. Gallop.
The chainline with dedicated spider would be 43.2mm (as double chainrings), so I think it’s not so hard to use it for 1x setups.
For RO1 (square taper), the chainline and Q-factor would be different depending on a shaft length of the bottom bracket.
It’s gonna be almost the same 154mm Q-factor when it’s installed with a 113mm bottom bracket.
The chainline would be about 44mm with the dedicated spider, so it’s also a great choice for 2x setups.
If you wanna install it as 1x, it seems to be good to use 108mm bottom bracket, but it’s depending on a frame.
When it comes to 1x, MIDDLEBURN releases this chainring.
*MIDDLEBURN* RS8/RS7 X^type uno chainring (as known as “UNO chainring”).
It’s originally designed for RS series for MTBs, but I tried to put it on the RO crank.
With RO2 crank, I could install it with no problems.
The chainline is about 43mm which is a bit narrower, but I think it doesn’t matter so much.
(For 142mm rear spacing with 11-speed, the chainline should be about 47mm.)
So, what about RO1 crank?
With 113mm bottom bracket, the chainline is gonna be about 37mm, so it doesn’t work.
I didn’t tighten the crank bolts all the way up, but there was no clearance in between.
Although we have a long shaft bottom bracket like 123mm, the chainline would be less than 40mm and I’m not sure it actually works.
Then, here it is. *MIDDLEBURN* X-type uno boost chainring.
They look almost alike,
but there’s a 5mm difference in their thickness.
UNO BOOST is a bit thinner than UNO, so it can make the chainline close to the crank arm.
I tighten a crank bolt all the way up and it looks like this.
BOOST 1x chainring. It’s got a less offset than the original UNO chainring and the chainline is gonna be about 40mm.
I think it works with a longer shaft bottom bracket.
Oh, it was only for those who really wants to install the chainring onto RO cranks,
but it’s so easy to use it with the crank I’m going to introduce to you below.
RS series for MTBs.
It’s named “RS7” and there’re “square taper” and “X-type” for 24mm outboard BB.
Umm, their names are hard to understand. I got confused.
I hope they’ll change the names someday…
They seem to be almost alike at the first glance, but there’s an obvious difference.
(The front is RS7.)
It’s actually got a bit sharper shape.
Its linear design reminds me of macho like “Virtua Fighter”.
Does RS7 square taper crank fit recent MTB frames?
So, I tried it with this frame.
How is it gonna be?
I made it! MIDDLEBURN gives it a super wide Q-factor and it’s 170mm.
I put it on with 113mm bottom bracket. I can see how much it is offset.
The distance between the chainstay of Karate Monky is about 130mm, so there’s quite a space.
So, it also fits Bridge Club, Evasion and La Cabra.
I really wanted this crank when I was struggling to install a square taper crank on a bike which is compatible with 3″ tires.
Unfortunately, we currently run out of UNO chainrings for this RS7 square taper crank.
But, don’t be so sad. You can still use it with this.
*MIDDLEBURN* RO1 SQ Double Road Spider
This one is originally for RO1 square taper crank that I’ve already introduced above, and it’s 94PCD.
The chainline is about 50mm.
I think it works with a 118mm bottom bracket, and a 123mm for boost hubs.
94PCD STRIDSLAND chainring looks nice on it.
This combination makes you look like an accomplished MTB rider.
It’s really great that you’ve read this long review so far. I believe you must be bored of tons of numbers and alphabets.
So, here’s a cute picture. This is a stray cat around my home.
“RS7 X-type”, a MTB crank for 24mm outboard bottom bracket.
If you wanna put MTB crank with PHILWOOD Outboard Bottom Bracket, this is the one.
(Sometimes it gets hard to install the crank into the bottom bracket since they’re both highly precise.)
The Q-factor is about 190mm. It’s a bit too wide, but it’s probably good for a off-road.
UNO chainring for 135mm or 142mm spacing, and BOOST UNO chainring for 148mm spacing.
If you wanna use this crank with RO2 Spider, I’d like to recommend you to use it as 2x.
It might not be so much trouble for BOOST hubs, but the combination of the spider and single chainring provides 3mm offset to the outside, so I wanna make it clear just in case.
The last one is “RS8”.
Actually, this is the model we build up this Evasion with. 
For 73mm BB shells, but when you don’t need a wider Q-factor.
Ming-Ming from Hatagaya store has already installed this crank into his own Evasion.
He’s gonna introduce this bike to you guys soon.
It’s basically the same as RS7, but the Q-factor is about 182mm. Umm, isn’t it pretty much the same, is it?
Still in the same design as RO series, so I think you can choose it for how it looks.
FYI, you can use the same chainrings as RS series for NON-BOOST or BOOST hubs.
We’ve used this crank a lot before since we got many of them for the first batch.
Through this review, I found that I really like the shape of RS7.
If the crank on my SURLY 1×1 gets broken, I’ll buy a RS7 square taper crank.
Bye.
