Advice on buying a CX bike

GGBiker

I am thinking if getting a CX bike with the intention of racing it in the Autumn season, don't know a lot about them so would really appreciate some advice. Probably don't want to spend more than £1k.

Main questions are:

- What is a good weight for a CX bike for racing (so that it won't be a bar to competing, for example I would consider a road bike of 7-8kg to be reasonable for road racing, what is the CX equivalent, perhaps 8-9kg or more?)

- Disc vs traditional caliper brakes: Disc seems great in theory, is it being widely adopted or is it seen as being a bit unnecessary? I would be concerned about wheels being more difficult to get as it is relatively new technology.
Another negative for discs is that I might want to stick a pair of road wheels on the bike for winter road training which would be easy with traditional brakes.

- Clinchers vs tubs. Like most people I ride clinchers on the road and don't see that tubs make a significant difference for this use, also a clincher is generally easier to fix a puncture on, with road cycling nobody wants to ends up stranded 50 miles from home. With cyclocross racing though it's a bit different, racing on a short course I'll never be more than half a mile from my car. A few people have mentioned to me that tubs give a huge performance advantage over clinchers due to being able to run at low pressures for grip (with less risk of pinch flats or rolling the tyre off than a clincher if I understand correctly). Any opinions on this?

- Any specific bikes in this price bracket that people would recommend? I am tempted by the Planet X XLS with disc brakes, don't see much else that seems to offer value at this price. I would also consider buying an alu frame cheap and building the bike myself, maybe a kinesis Crosslight or something similar? A frame with mudguard eyelets and clearance would be handy for winter road training.

duckson

Looking at a Rose Pro DX Cross as a winter / wet bike (road use only), these have mudguard eyelets and the spec is pretty configurable so not just off the peg 'you get this spec, end of' like most bikes.
SRAM Force 22 build is 8.7kg so very respectable!

tgotb

Weight - I've seen a handful of bikes (generally with single chainring) as low as 7kg, my XLS is about 7.5kg (double chainring, not standard build), but that's very much the lighter end of the spectrum. Anything in the 8-9kg range should be fine. You're going to end up flicking it over barriers and lifting it onto your shoulder a lot, aswell as lots of accelerating out of corners, so light is good.
Brakes - disc definitely better, but cantis are fine; the better you get at 'cross, the less you need the brakes. That said, if you get hooked on the sport you may end up with a load of wheels, which means you'll be stuck with whatever you decide now (I suspect this is one reason more people haven't switched to discs). Discs are only going to get lighter/better. But at the end of the day either are going to be fine.
Tyres - You can get most of the benefit of tubs with a fraction of the cost/hassle, with tubeless. If you're serious enough for tubs to be worthwhile, you're probably going to want at least two sets (with different treads), plus a set of clincher wheels for training. Why not start off on clinchers or tubeless, and if you get keen and move onto tubs you've got the clincher wheels for training. I doubt any amateurs train on tubs. Most of the field will be racing on tubeless or clinchers at local league level, it's only really at National level that the majority of riders are on tubs. Tubs are undoubtedly better (I'm switching this year) but probably not worth it until you've done a bit of racing; to begin with, technique is going to be more important than tyre choice.
Bikes - I really rate the XLS as a race bike; I bought the frameset and built it up myself. Watch out for cheap deals on eBay, I just bought another XLS frameset for £400, because the paintwork had a couple of chips. Kinesis Pro6 is also popular, almost identical geometry, and takes mudguards etc (I have one built up as a commuter, though I'm sure it'll see a race course at some stage).

Kimble

the xls looks excellent. 105 will be a good level of spec. think the discs are the one to go for myself and you can get good value on a spare set of wheels like novatec cxd's for just £350 which can be your race wheel. if this is the winter trainer I'd use the stock ones with some 25mm gatorskins for your winter road work and something like those CXD's (in tubular) for cx racing. at 1420g they should get you a very light race rig with the carbon PX CLX.

I use a Boardman CX team with BB7 brakes and really happy with the discs (VS Canti's) but think the new trp's are supposed to be better. PX might be able to change them for you pre purchase if you wanted a change.

tgotb

A bit of perspective on some of the disc brakes I've used:

Started with BB7s, so these are my benchmark. Seem to work pretty well, easy enough to set up. Require periodic servicing (total strip down and rebuild); if you don't do this, the pad adjusters sieze and stop working. Need to adjust both pads separately as they wear.

Switched to TRP Spyre, with a new bike build. Quite a bit lighter, pads don't tend to rub as much. Once set up, can adjust for pad wear using the cable adjuster. Hard to imagine a better cable disc brake.

In both cases, cable contamination was an issue, even with supposedly sealed cables. In muddy conditions the cables were getting noticeably sticky after a month or so (because of the cable routing, I suspect this is more likely to be a much bigger issue with discs than cantis). Like most cross bikes, mine get pressure-washed pretty frequently, and I'm sure this was a contributory factor.

Switched again to Parabox (full hydraulic), mostly because I found some cheap ex-demo sets. Setup process is pretty time consuming and fiddly, but once installed they are virtually fit and forget. No need to adjust for pad wear, but the real eye-opener is the fact that there's been no degradation in performance because they hydraulic system is completely sealed; despite zero maintenance they're as smooth as the day I fitted them. For this reason, I even fitted them to my commuter!

I'm not suggesting you fit hydraulics, but for CX disc brakes they're definitely the future.

Note that most brakes (definitely the Spyre and Parabox) come with organic pads, which get really badly eaten in some conditions. On one occasion mine went from brand new to completely ineffective in about 30 minutes; on the positive side, I learned a lot about how to get round a course without using the brakes. Sintered pads last way better, and any difference in performance is irrelevant for cross.

devhads

Wow, 7kg or 7.5kg is really good going for a cross bike. I've got a single chainring set up and have managed to get it to about 8.8kg (roughly weighed with me holding it on bathroom scales). My frameset is not bad at 2.1 kg and I've got Ultegra 6800 (apart from cranks which are CX50) so all my extra weight must be in my wheels (Racing 5 CX) and finishing kit?

I was thinking of getting another set of wheels and was always wondering what the other benefits of tubs are apart from running at low pressure. I can run my Challenge clinchers (or open tubulars as they call them), with latex tubes at low 20s front and mid 20s rear. What extra benefit would tubs give me? Even lower pressures? What else that is worth the hassle of gluing etc?

As for finishing kit, do people generally use carbon stems, bars and seatpost for cross?

tgotb

I did make a real effort to keep the weight of mine down; most components are carbon, and I've just accepted that I may have to repair/replace them a bit more often; I do know how to repair carbon components, which is a bit of an advantage, and I kept the costs sensible by buying stuff 2nd-hand and looking out for special offers. Couple of bits I doubled up on when there were special offers, in anticipation of 2nd bike.
Wheels: Hand built (by me), Novatec 711/712 hubs, Stans Iron Cross rims, DT Comp spokes on high tension side, DT Revo spokes on low tension side. ~1400g total
Rotors: KCNC Razor
Tyres: Mostly Clement tubeless
Seatpost: Lightweight carbon
Stem: Cheap alloy, 130g
Bars: FSA carbon (special offer)
Shifters/mechs: SRAM Rival
Chainset: FSA SLK Lite
Brakes: TRP Parabox
Frameset: Planet X 1.9kg
Pedals: Time ATAC XS

The weight is obviously less of a benefit when there's another 8kg of mud stuck to the bike, but for the drier races it has to be a benefit.

Tyre pressure: I've raced tubeless at 19psi (on purpose) and 17psi (by accident), and the extra few psi really make a difference. The only real issue I've had with tubless is burps, and that (and the prospect of even more supple sidewalls) is what's luring me to tubs next year. Having TT'd on tubs in the past and sworn never to touch another one again, I'm not looking forward to all the faffing. I still TT on clinchers...

GGBiker

I'm leaning towards canti brakes for interchanging wheels with my road bikes and availability of wheels, main issue is I have campag 10 speed on those.

So I'll either buy a frame, cheap kinesis or dolan, ideally something with mudguard eyelets for winter road duties and build it up. Others that look good are the Ridley x-bow 105 for £850 and the Cannondale caadx 105 for £870.

Any thoughts on other frames? I have a spare set of fulcrum racing 7 wheels that I could use for the self build so could be economical, can get a campag veloce groupset for about £300 buying piecemeal, would probably prefer an fsa 46/36 chainset as the campag power torque is a maintenance nightmare (removing it requires special tools and is a bugger even with the tools ).