Why do cx racers run such narrow gearing?

I posted an earlier thread about what gearing i am going for on my new bike, but the question that has been bugging me for ages is, why do cx bikes have such incredibly tough gearing? I watch the replays of top guys like nys and van aert etc grinding their way up slopes, killing themselves, and having to get off half way up and wonder why it is this way. Is there a historic reason? Is spinning up in a low gear not more sensible?
Just wondered really.
Just wondered really.
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http://app.strava.com/athletes/1920048
BUT
screw that I am unfit and come from a MTB background, I want an easy gear that spins up and wheel spins a lot as I go up hill, I cant be doing with grinding my censored off.
Traction, not gearing, is generally the limiting factor on steep climbs in cyclocross races.
Although they probably have a better idea than someone who hasn't actually taken part in a cyclocross race.
the point about it being faster to get off and run, and it helpfully blocks the racing line too, i think only applies to the sharp end; at the middling amateur level I have done a fair few races wherein I have rode uphill (spinning like crazy admittedly on either an MTB or my MTB geared cx bike...) and passed people. But thats hardly the sharp end.
Lots of people have realised it and run a single chainring at the front. If you need a double, I guess a 34/44 would be more adequate or even a 34/42.
The lack of sensible rear cassettes is down to derailleur capacity more than anything, if you pair your drivetrain with a MTBike derailleur like an XT Shadow you can run up to 36 or even 40 Teeth and it doesn't jam with mud as easily as the road (cyclocross) do... it doesn't even snap as easily as the road derailleurs do, but obviously you don't look the part... as you need to use inadequate components in cyclocross... it's part of the unwritten rules...
Some are written though, for instance the fact that you have to run < 33 mm tyres, when it's obvious that a 40 or 50 mm one would be much better in real mud... but that keeps the old tradition of gluing a tyre to a hoop of metal alive and the UCI is all about making sure you don't ride anything Eddy Merckx and De Vlaeminck would find exceedingly modern.
MTB components are actually getting pretty mainstream, depending on your groupset manufacturer. One big advantage of SRAM is that you can pair road shifters with an MTB mech, and quite a few riders have shifted (sorry!) to SRAM for this reason. A short cage MTB rear mech will happily handle a 36T sprocket, but other than for niche races like 3 Peaks, there's no real need.
As for tyre widths - allow wider tyres and you change the nature of the sport. If you want to race 50mm tyres and twiddly gears, you can. It's called mountain biking.
Restrictions have never helped the sport... for years the UCI have resisted disc brakes to nobody's gain... for years they asked hour record attempts to be done on a Merckx alike bike... to the point that nobody cared anymore, they still impose a frankly pointless 6.8 Kg weight restriction on road bicycles, which limits innovation in materials and technology (let's be clear, carbon is not a new material).
Personally I think being open to innovation of any sort can only be a good thing
Funnily enough the most open minded about innovation seem to be the folks at CTT UK, whose only restrictions are a result of safety concerns
As to the pros being stupid and narrow minded...
Ugo I know trolling is the new black, hell play it right and it can get you elected US President, but have you spent any time at all in a competitive environment? Met many competitive types who turn their back on genuine technical advantage?
I guess the sweet spot is probably not far off 33 mm and running 50s would most likely lose you a race in all but the deepest mud conditions...
On balance the rule is probably unnecessary... the nature of the course decides which tyres or else are the most appropriate.
PS, good to know about SRAM... especially now that Shimano 11 is no longer compatible with MTB... is the quality a bit better than it was a few years ago when SRAM shifters were basically disposable?
That's all you seem to be able to say... every time someone disagrees, he must be a troll.
Your narrow mind can't see beyond your little bubble of races, glue and tubular tyres. PROs are conservative because they are only interested in winning races and whatever works for them has to be good enough for Joe average too.
The point is: CX bikes began to sell when the UCI relaxed the regulations and allowed disc brakes... manufacturers began to flog bikes that people actually wanted to buy... as opposed to pieces good for a museum... not just folks living in a bubble, but normal folks... in fact mostly normal folks, some of them even get interested in your bubble and benefit your own little garden!
Relaxing the regulations on tyre size means manufacturers would begin to churn out frames that can take bigger tyres, so one could for instance tap into the market of 27.5 inch MTBike wheels... of which there are plenty, as opposed to some road wheels with some dodgy CX credentials and bearings that need replacing every other week.
None of my two CX frames can take tyres designed to go on a 27.5 inch wheel, simply the rear triangle is not wide enough. So one has to look at gravel bikes, which have marginally more clearance, although often not enough, but they are in essence hard tail MTBikes with drop bars and with no suspensions (yet).
The CX market has to somewhat benefit from MTBike development, as road components are getting more and more fiddly, expensive and delicate and unsuitable to be used in mud
haha so wrong
Even the people who ride mtbs in our league know this isn't true & so they mostly run narrow cx tyres or narrow mtb ones, on there mtb bikes. The fast ones do anyway, the ones that don't soon end up with 5kg of mud clogging there wide mtb "mud tyres" making them pretty useless.
Wider tyres aren't necessarily better in mud. Narrow tyres can cut through the mud and get grip on the firm surface below the top layer.
There is also the issue of the mud / leaves / stones sticking to the tyre and getting jammed in the chainstays. Obviously frame design impacts this to a degree, but there is only so wide you can splay the stays when there are standard bottom bracket and hub widths and you need clearance for the cranks and ideally also want a Q factor that isn't crazy wide.
There are also cons to using a MTB rear derailleur, rather than a short cage road one - presumably because they run lower to the ground they tend to attract more leaves and the like, and a close cassette will have a tighter chain across it's gears than one where the chain has been set for a monster bail out gear. Shorter chains seem to help limit the chances of rear mechs ripping (obviously, there are also pros to a wide ranger cassette on a single ring - e.g. no front shifting, weight, simplicity etc.).
Pros etc just have a second bike & a pit crew so clearance is less of an issue...
No.
I think SRAM shifters may have become more reliable, or maybe the more expensive ones are more robust. I blew up a couple of Rival shifters on my commuting bike, probably 4-5 years ago. The replacement Rival shifter has lasted 4 years with no issues, and is still going strong. My CX/Road bikes were all built with second-hand SRAM Red shifters (second-hand Red being a lot cheaper than brand new Rival), and have had no issues at all. For me, at least, the mean time between failures is large enough for reliability not to be a concern.
As others have said, wider tyres are unlikely to be an advantage in mud. Where they would be more of an advantage is in early season races on relatively rough, dry terrain (rocks, roots etc) where the extra volume provides some suspension, and also allows you to run lower pressures without destroying your rims. This terrain is not common on CX courses, but does occur occasionally; an extreme example is the 3 Peaks race, where the descents could be ridden a lot faster and more easily on MTB tyres (and even more so with suspension).
Apart from the fact that allowing MTB tyres would change the nature of CX racing, riders would also need to own a much wider selection of tyres to allow them to choose the best width for the conditions aswell as the best tread. Therefore the rule has an important function in controlling costs. Using the 3 Peaks race as an extreme example, if the equipment rules were opened up and you wanted to compete at the sharp end, you'd probably need a road bike, a TT bike, two CX bikes, two MTBs and an army of helpers to get them to the right changeover points. As it is, the top riders can compete on two CX bikes with one helper, and have only the smallest advantage over those competing on one bike.
Bigger tyres can be ran at lower pressure without the need for expensive and frankly antiquated "sew-ups". 20 PSI or less are not uncommon in MTBikes with tubeless... So yes, you do get more grip.
I don't think Q factor should be of great concern for a bicycle designed to be ridden for an hour or two... I don't even think the difference would be so majestic... we are talking 5 mm each side, you'd probably hardly notice
I have used an XT shadow rear mech for the past 3 years now... I still have to find a drawback... other than I need an inline barrel adjuster. Before I got fed up of riding in the mud, I used to go out quie a lot in the Surrey and Chiltern hills, where the chances of clogging a derailleur with leaves are greater than in a muddy field, but nothing... after all they are designed to do just that, so it's not surprising they do it better than a derailleur designed to be ridden on tarmac
This is a funny one, as the UCI promoted the "athlete hour record" as a way to keep costs down, which were spiralling, due to high tech bikes. The record anyone can have a go at, as all you need is Eddy MErckx's bike...
The funny thing is that nobody could actually buy a bike that was compliant with the UCI rules, so it had to be made bespoke and was actually more expensive than buying a top of the range pursuit bike.
The argument is pointless, anyone will compete within his/her means and your collection of bikes and wheels goes to show that if the rule is meant to limit costs, then the rule doesn't work...
By that logic then a fat bike would make a great cyclocross bike. You only need enough grip, which can be achieved by cyclocross tyres. I race on clinchers at the high 20s psi and don't have any grip problems.
Even so, all the grip in the world doesn't help you if your wheels won't go round because the mud stuck to them has jammed in the chainstays.
There are some courses where MTBs are faster than cyclocross bikes, but they are pretty few and far between and are usually at the lower end races where the course designer doesn't follow the guidance and basically just designs an XC MTB route.
I also use my cross bike for blasting around in the woods and it is great fun. I've never had any problems with my rear mech there, and I use a short cage road one. I've also used my cross bike at various trail centres and off road routes in the Lakes and Yorkshire Dales without any problems.
Cyclocross racing is very different in that by the time you come to race then potentially several hundred riders have destroyed the course by riding multiple race or warm up laps on your line. This is very different to you picking your own line through a wood, and it forces you through a LOT of mud. If the mud is followed by leaves, twigs or stones these instantly stick to the mud and get jammed everywhere - especially the jockey wheels, which will rapidly stop being able to rotate and will rip your hanger off.
At a recent race that I attended 1 in every 7 riders snapped their hangers - and a good chunk of the field had a pit bike and crew who could wash their bike every half lap to try to prevent the breakages.
I've done a fair amount of mountain bike routes on my cross bike and the bike needs hosing off afterwards. After only 40 minutes of cyclocross (I'm a vet now
Yes, me too. I'm happy with my tyres but my next frame will have more rear clearance (my front forks are okay).
I guess my point is not coming across the way I mean it... I am basically against over-regulation... defining a tyre size means that manufacturers have to conform and the scope for new designed is somewhat limited. Discs opened up things dramatically and allowing different tyre sizes would give even more scope.
Whether that will result in a change of equipment by PROs or not is irrelevant... as a consumer I am interested in more choice and I would really like a drop bars bike that can take 2.5 inch tyres on 650b rims... I think it would be popular, some folks would use it for CX, others for a ride on the Ridgeway, others to go shopping or whatever...
Whether anyone would win the Worlds or not on it I am frankly not bothered
Build it, I've basically done that but with 26" wheels as that's what I had. The great thing is if you have a bike like that it'll easily take 29er wheels with CX tyres too.
I'd really like 27.5, which basically keeps gearing unchanged. I'd probably have to fit MTB cranks to make it work on a wider rear triangle... can you buy a MTB double chaniset?
Yep, a good few still about from Shimano and others and still being produced with the new, top of the range kit:
http://www.chainreactioncycles.com/shim ... prod119769
I'm running a 46T at the front with an 11-36 at the back (although I'm using bar end shifters so can currently only just get the 32). It's massively over-geared for MTB but the idea was to have a do anything bike, MTB trails to road riding with my club. So far it's worked well but when I have the money I'll be updating the bar ends to get the full gear range and fitting a double crankset. If you want drop bar shifters with an MTB rear mech you'll need to run a wolftooth Tanpan or something similar:
http://www.wolftoothcomponents.com/coll ... cts/tanpan
But if the CX set-up gives you the gear range you want it'll be fine without.