Praxis are known for their for forged chain rings, and range of bottom bracket converters. I’ve used both in the past with great success. So it was with some interest when it was announced that they were producing cranks under the Turn brand. But there are a few things that make the Girder M30 MTB cranks stand out from the crowd.
The M30 spindle
The bike industry
seems to use the word ‘standard’ as some sort of joke, especially when it comes
to bottom bracket standards. Turn make just one crank and axle, and the M30
aluminium spindle is 30mm thick, and hollow. It steps down to 28mm on the left
side. The short, thick and light axle is very stiff without a weight penalty. The
only downside is the use of a different tool interface to most BB cups.
Change your bottom bracket, not your crank
Praxis have shown
their expertise in bottom brackets, and you choose the correct BB to suit your
frame. All the Praxis M30 bottom brackets are compatible with Turn cranks:
English threaded BSA, Shimano press fit, BB30 or PF30.
So while a Shimano
press fit or regular threaded BB might offer a pretty wide stance, the narrow shells
of a BB30 or PF30 frame don’t, which can decrease bearing life. The M30 bottom
brackets place the bearings outside the frame, allowing a really wide stance
for stiffness and large bearings for long life.
Forged arms
A great axle and
bearing interface is all well and good, but Turn finish the product off with
hollow forged crank arms. This is probably the best construction method for
alloy cranks. Turn have used a process that aligns the grain of the metal through
a very high amount of pressure when forging, resulting in a stronger and
stiffer product than other forged cranks. Independent testing has shown the
Zayante crank (the road cousin of the Girder) to be the stiffest on the market.
The Girder M30 is
currently only available in 175mm and in a 104BCD 1x option in Australia. Praxis
rings come as standard (see inset review).
Get set and go
I fitted the Girders
on my hardtail, taking the opportunity to set it up as a 1x10 rig at the same time.
The M30 BB was the PF30 model, which uses a sleeve that the BB threads into to
expand and lock into place. It works well and stayed creak free for the entire
test.
What really struck me
was the wide stance. But beyond having outboard bearings, the crank’s arms are
wide, and so is the ‘Q-factor’, the distance between your pedals. The cranks
and bottom bracket felt absolutely amazing when pedalling out of the saddle –
there are always lots of variables but they did feel astonishingly stiff. But
sitting and spinning up a climb, they also felt really wide.
It was similar when
looking at the drivetrain too. The chain line wasn’t great in the lower half of
the cassette. It was really loud in the four lowest gears, and didn’t feel
smooth when backpedalling.
Fitting these to an XC
styled bike where I’ve optimised the Q-factor and chain line did make for a big
change. I didn’t notice the feel after a few more rides, but the chain line
never really felt good, or ran any smoother. on bikes with a 73mm BB shell this
is unlikely to be a problem.
The Girder M30 is a
trail crankset, not one aimed at light Italian carbon cross-country bikes. And
with that in mind, it’s brilliant. one of the best BB interfaces has been
married with a versatile range of bottom brackets, and brilliant manufacturing
to create a strong, stiff and good value crankset.
SO GOOD
- one crank to suit
them all
- Perfect combination
of strength, weight and price
NO GOOD
- May compromise
chainline
- Not for weight
weenies
PRICE 300$
incl. chain ring. M30 BB: 110$
Praxis 1X Wide/Narrow chain ring
I tested the Girder
M30 cranks with a 32t Narrow/Wide chain ring from Praxis. Unlike their other
rings these are machined, not forged. They don’t need to shift, just hold on. I
used a new Shimano XT 10 speed chain when setting it up, with a clutch rear
mech – as recommended. My chain never budged for the whole test period.
The narrow-wide option
has been accepted as almost completely secure, and Praxis still recommend an upper
guide for rough terrain or just added security. Even in rockier riding on a
hardtail in Sydney the chain stayed put though. The ring is available from 30-38t
sizes, and has a hard anodized black finish which looked great and adds to the
product life.
SO GOOD
- Good value and size
range
- Easy to fit and
change
NO GOOD
- Limited to 30t
minimum on 104BCD
