The FMB Super Mud is Alex Forrester's go to full mud tubular, with countless corners on them, who better to ride and review the new open tubular version?
FMB OPEN TUBULAR REVIEW - Alex Forrester - October 2019
Out of the box, the tyres have that supple, handmade cotton tubular feel.
I have been left close to despondent trying to get a new Challenge open tubular on to a rim, resorting to inflating with the tyre not quite on and leaving overnight before finally finishing the job! The FMBs weren’t what you’d call loose but, with a bit of effort, could be persuaded on to the rim without recourse to swearing or tyre levers. I fitted them with latex tubes.
Inflating up to around 40psi popped them on the seat of my tubeless rims, before letting them down to riding pressures. On a 20 mm internal width rim, the FMBs came up at just over 35 mm. So, not suitable for a UCI race but a useful bit of volume for home racing!
For a sighting lap on a grassy/muddy course, we went for a conservative 23 psi in the rear and 20 in the front to begin with. At these pressures the feel was not quite as ‘floaty’ as a low-pressure tubular but the grip was good. It felt like the extra volume compared with a 33 mm tubular should allow lower pressures.
The sidewalls look worryingly pale and delicate but a good jet washing brought them up nice and clean, with no apparent signs of damage.
My race following day was a seriously muddy affair at the Droxford round of the Wessex League. The mud was really clogging and sticking to the bikes. I decided not to use the wide open tubulars and opted for the narrower 33 mm FMB Super Mud tubulars to maximise frame clearance and minimise mud build-up on the tyres (recall how Wout used narrower tubulars in Valkenburg). However, on the more grassy, but still slippy U12 course, our eldest used the new FMB open tubulars to great effect! Maybe the first of many wins on this tyre? I’m not sure what pressures he used — I just give them to the kids really soft and let them tell me whether they need their tyres ‘up or down a bit’!
For a 65 kg rider, my 20 psi front pressure equates to ~24 cm^2 contact (using The Cyclocross Bible pressure look-up contour map). This is equivalent to, e.g., ~23 psi for an 80 kg rider. The ‘Wyman Rule’ would recommend a pressure of more like 26 psi for clinchers (for a 65 kg rider) but, as mentioned above, I thought the FMB open tubulars could go lower. In fact we’re already below the 21 psi ‘Wyman Rule’ figure for tubulars.
The next test outing was a muddy training session where I started with pressures at 21/19 psi rear/front but quickly reduced to 19/17.5 psi rear front. This is in the mud/sand region of The Cyclocross Bible plot, at 28 cm^2 contact area (50% more area than the ‘Wyman Rule’ pressure). At these pressures the FMB open tubular started to feel much more like the Super Mud tubular itself, with excellent grip and ‘feel’ on some really slippy corners.
As a comparison, we ran the Challenge Limus open tubular at the same pressures in the same training session. Riding on FMB Super Muds is a great way to improve your cornering confidence and speed. Switching from the FMB open tubular to the Challenge Limus open tubular was equally effective at removing this confidence.
The FMB has a 33 mm tubular tread on a 35 mm open tubular casing. This gives a large area of sidewall in comparison to the Challenge. I measured about 15 mm of sidewall on the Challenge and 24 mm on the FMB. This significantly improves the suppleness of the tyre and helps give a tubular ‘floaty feel’. The flip side of this is that the tread isn’t there to provide grip (although the Challenge has a bit more ‘empty’ rubber on the sidewall than the FMB). However, in the muddy conditions these tyres are designed for, just how far over are you going to be leaning? Are you really going to use those side nobbles?
There was some discussion at the training session over whether it was a fair comparison, as the Challenge is much narrower. However, both tyres are available and within the rules for all but UCI races.
So, it is a fair comparison — and the FMB wins hands-down.