I’ve been diligently hauling my Commencal Normal Disc 2008 mountain bike the 8ish miles back and forth to work for the past six months or so now. Though it’s not my much missed Diamondback Ascent ’92, the Normal is a fine and capable steed, more so since I acquired it at a bargain half price (from Real Cycles, Carryduff). But, given that it’s home is the tarmac of the Antrim and Shore roads I’d felt for some time that the large 2.1″ off road tyres and suspension forks were surplus to requirements and extra weight and drag that I didn’t need on my regular 500ft grind up the side of Cave Hill.
And so a project was born: fit rigid forks and slicks to the Normal to convert it to a more suitable “urban commute” configuration.
Hmm. Upgrades.
After much research (thank you, as ever, t’internet), I chose the following as replacements for the heavy Suntour XCR-100 LO suspension forks and chunky Kenda Karma tyres that came fitted as standard to the Commencal.
Forks: F8 Rigid Forks, by Orange Mountain Bikes
 Orange F8 Rigid Forks |
A number of factors pointed me towards these Orange Mountain Bikes F8 Rigid Forks.
|
Tyres: Ultra Gatorskin, by Continental
 Continental Ultra Gatorskin |
Continental Ultra Gatorskin tyres are described as “the ultimate wire bead training & racing tyre where puncture protection is priority”. I think there”s not much more frustrating than trying to make your way to work only to be stopped by an errant fragment of someone’s discarded beer bottle lying in the road, so armored, puncture resistant tyres are my ideal choice for cycle commuting. There are tyres that are lighter than the Ultra Gatorskins, but with less protection. There are also heavier tyres that are all but impregnable. I chose the Ultra Gatorskins as I felt they struck the right balance between speed and strength. |
Surgery
After printing out some likely looking fork fitting instructions, I took myself off to the garage “workshop” for an evening and set about my Commencal’s front end with spanners, hammers and other entirely unsuitable tools. I’ve performed quite a bit of DIY bike butchery in the past but I was still a little bit daunted by this project as, according to the instructions, there were a couple of tricky parts and stages where it could all go horribly wrong and leave me with no bike, a set of ruined forks and a lot of explaining to do.
Before, with suspension forks and off-road tyres
With new Orange F8 rigid forks partially fitted
New forks fully fitted, headset and bars reassembled
The finished article!
I’ve made more photos available in the excitingly entitled Picasa web album “Fitting Orange F8 rigid forks and Continental Ultra Gatorskin slick tyres“.
As you can see from the pictures, however, changing forks would appear to be within my capabilities after all. I managed to save myself a (proper) bike mechanic charge, not wreck my work bike and have a bit of manly fun with tools, bearings and grease in the process.
After that, changing tyres to the Ultra Gatorskin slicks was child’s play!
The results are in
I’ve now been on a number of commute runs with the new machine. There’s not much difference in the handling of the bike, if anything it’s a touch more nimble and responsive at cornering and filtering through traffic. The ride position and geometry have also hardly changed.
The ride itself, however, is very different. The combination of rigid forks, slim tyres running at high pressure (95psi) and a stiff aluminium mountain bike frame gives a fairly hard ride with every vibration and bump being transmitted from the road surface. I never realised before this just how bad and uneven the roads are along my commute route; come on Northern Ireland Roads Service, sort it out, these are supposed to be A-roads, darnit! I find myself taking a more careful line around gratings and uneven parts of the surface and I’ve had a couple of bone jarring impacts with hidden potholes that I didn’t see. It’s not unbearable though and I’m quickly getting used to the new dynamics, though I expect they’d be tiring on longer rides.
As you’d expect, the slick tyres offer much less rolling resistance than the chunky off-road models that were fitted before. Combined with a guess-timated weight reduction of 1.1Kg (from 14.5Kg), I feel the bike is easily 2-3mph faster with the same rider power input. Given my previous “cruising” speed of 15-16mph this would seem to be a significant efficiency improvement of over 12%. I’ve heard it said that the gain in going to a full on road bike is 25-30%, so for an investment of £80 and a few hours hammering I’ve got myself half a roadie’s worth of extra performance. I’m very pleased with this result! The tyres also grip well in the wet and give confidence while travelling at speed or going into corners, and this confidence is increasing all the time as I get used to the new handling characteristics. No punctures yet either, touch wood.
And the looks? Well, let’s just say I now refer to it as the “Mutant Freak Bike”.
But it’s quick!
You, kind Sir, have been bookmarked. Good show. I now bid you good day.
Hey, nice read!
Been thinking of a front end overhaul of my Rockhopper. Considering a pair a Kona P2′s or Charge Nozzles.
As I can lock out the Rockshox on the front though, worried this may be a false economy, so it’s a change of tyres first I think, and a switch from EA30 risers to a flat bar with bar ends for a better riding position.
Also thinking about getting rid of front derailleur as I never shift from the large front ring … which would ultimately convert the bike to a 9 speed … not sure whether to take that plunge though.
15st is the recommended maximum for carbon fibre forks?
Dammit, another good reason to lose weight, if one more stone is enough to break my bike!
(I will say, the carbon fibre is pretty good for cushioning shocks as well as the weight reduction.)
Changing the tyres will make the biggest difference I think, and I wouldn’t be without bar-ends as I find that riding position very comfortable. Changing to rigid forks is a “nice to have”, as they do save quite a lot of weight and are fully rigid unlike even locked-out suspension forks, but it’s far from essential.
Change your tyres and bars and ride for a while, then see what you feel like.
It depends on the forks but I looked at a couple of makes and they did have the same ballpark upper limit. I’d say the limit would be higher though if you’re not planning on doing any off-roading!
Hey – great post. Just wondering how far can you push this bike off-road now? What kind of surface do you think would be its limit, i.e. gravel path, farm track, etc. ?
I think, given the width and pressure of the tyres now, the bike would start to bog down anywhere the surface was soft or easily disturbed, such as a muddy track or large gravel path. I did a quick run over some wet grass and the grip was OK, but it cut a ditch into the soft earth. It’s fine on harder surfaces like hardcore paths, and would probably give enough grip on dry or packed mud too. The Continental Ultra Gator tyres are quite grippy.
Is there something in particular you might be riding over?
For real comfort go for a steel frame with carbon forks I ride an On One 456 with slicks and it’s a beautie on the road.
hi i was just wondering when changing to slims did u have to change the whole wheel or just the tyres in order for the disk brake to fit on to the hub?
Just the tyres. They fit nicely on to the existing wheels, which were built around disk hubs so I had no worries about the brakes.
Great article, how are you getting on with the gearing ?
I’ve got a very similar looking bike – GT Zum 2.0 with disc brakes, small frame (too small really, but I have adapted with a long seat post). I’ve got the Gatorskins too and they’re great. Been using them for over a year and no punctures yet (used to about one per week with the supplied Tioga City Slickers – mainly flint and glass from the daily 7 mile commute to work both off and on-road).
Your article has inspired me to replace the heavy suspension forks with some lighter cro-mos, so thanks for the info!
Gearing? In any case, I’ve switched to a full-on road bike for the commute now, a Carrera Virtuoso, complete with panniers. I’m getting on fine with the gearing on that!
You’re welcome Lee, and good luck!
You’re truly a good webmaster. The website loading speed is amazing. It kind of feels that you are doing any unique trick. Also, The contents are masterwork. you have performed a excellent activity in this matter!
Hi,
Have just completed my own conversion, to move to a more XC style machine. I have a GT Avalanche 3.0 which came with stock SR Suntour XCM forks, 2.1 Kenda Nevagal off-road tyres and GT specific riser bars.
First phase was to fit Orange F8 forks and Continental 1.9 Double Fighter semi-slicks. Found bike to be much faster and lighter. Today I’ve replaced the riser bars with flat to see what difference it makes – I’ve gone cheap on the bars (Halfords Bike Hut 6061 T6 @ £14.99) in case I decide to go back to risers. The bike’s looking nice and retro – will see how the flat’s work out tomorrow.
Great Blog
Jonathan