Friday 24 February 2012

Alu vs Carbon: Pinkbike's Santa Cruz Destruction testing video

Pinkbike's soon-to-be infamous video of carbon vs aluminium frames in the Santa Cruz labs:

http://www.pinkbike.com/news/santa-cruz-bicycles-test-lab.html

Carbon is a marvellous thing. It has the potential to be light, extremely stiff, and all that in fantastic shapes that simply can't be achieved with metal. Contrast that with aluminium, which is also light and extremely stiff, but can only make some shapes and those are slightly less fantastic (hydroformed alloy tubes look cool - I'm not 100% convinced that they're the best thing ever, as the distribution of metal can be unpredictable, your thin bits end up with thick walls, and the thick bits end up with thinner walls).

But I still have one reservation about using carbon parts on a bike designed for off road abuse - quality control. Just by looking at the outside of a frame you have no real idea about whether its been well designed, in terms of where the strength is, and whether it has been well made; the quality of the carbon cloth and resins that were used, have the pivot points for moving parts been bonded to the carbon properly, are the fibres all in the right direction to extract maximum strength from the material. In the competitively priced bike industry, especially at the cheaper end of the scale, that's a lot of unknowns. You could say similar things about aluminium but basically, its down to the tube's source and the weld quality: if your bike uses Easton tubes, that's one bit sorted, and the weld quality is practically a non-issue these days (who buys bikes based on weld quality, other than Orange customers, and people who aren't buying Commencals?).

Now its fairly clear that Santa Cruz take their QC seriously - the video is testament to that. It's pretty clear their frames will handle an enormous amount of abuse.

But I'm still waiting on the video that shows sharp rock impact tests on a carbon frame. Its far easier to bang a small hole in the side of a carbon tube, than it is to buckle the tube. And once you have that hole, the tube's integrity is compromised. Effectively ending the frames life. Aluminium, by contrast, well, you'll have a dent. Not the end of the world although a bit of a pisser if you like your bike to stay nice and shiny.

Personally, I am still a little scared by the possibility of carbon parts failing and leaving lethal sharp edges. I can't see the value for MTBs (with the exception of high priced flyweight XC bikes ridden by whippets). The cost/benefit just isn't there. You drop a bit of weight, sure, but for the average rider, is that really an issue? The land of MTB doesn't really care about aerodynamics; unlike road bikes, which are a whole different thing - carbon rims and frames are de facto for the aerodynamic benefits. But for a recreational MTB rider, to my mind aluminium for MTBs is just cheaper and as effective.

For sure, cheap aluminium can go wrong. Commencal's problems in 2009 are a well documented example.

But my hat still hangs on the aluminium hook. At least when I'm riding a MTB.

Saturday 18 February 2012

Spoke Notes

Tensionometers vs musical pitch

Serious wheelbuilders will use a spoke tensionometer to measure the spokes and to know when they have the spoke nipples at their optimum tightness.

What if your budget doesn't run to one of these tools? Or, you just want to check some pre-made wheels?

Well, fortunately, spokes make a predictable tone when they are plucked or twanged (just like a guitar). By comparing this tone with a predicted list, you can ensure your wheel has its spoke tensions correct.

A useful article here http://bikexprt.com/bicycle/tension.htm has a list of musical notes that match the optimum tension in both plain and db spokes.

The following four notes are the most common pitches for standard (3 cross) wheelbuilds:

700c plain spoke - approx 290mm - G - 392Hz
700c DB spoke - approx 290mm - A - 440Hz
26" plain spoke - approx 260mm - A - 440Hz
26" DB spoke - approx 260mm - B - 493Hz


Match them up to your own spokes using a tuning fork to make the musical tones http://www.seventhstring.com/tuningfork/tuningfork.html


Thursday 16 February 2012

Wheel Deal

Funn Bullet hubs, ACI DB spokes & Funn Xlrater rims... result:

F&R

Rear hub

Front hub

Rim detail
The rims are some strong beasties (28mm wide) and are made by Sun ("Funn Rims by Sun" it says on the labels) so quality isn't an issue. The front hub has the useful ability to swap between 9mm QR and 20mm with some press-in adaptors. Pretty standard fare now for hubs but quite neat when the hubs were first released (2008 or 2009 I think).

Friday 10 February 2012

Novatec MTB Hubs Review

Bling

Hope, Chris King, Royce, Hadley, White, the list of aftermarket hub manufacturers is almost endless. You can find fans of most of them if you look hard enough. And generally with good reason: a lot of the boutique hubs are very well made and have good backup service. For this you pay a decent sum: here in the UK a set of Hopes will run you near on £200, a pair of Royce, closer to £350, and for Kings, about £500. Not for the budget conscious!

Not Bling

But what happens before aftermarket? When you buy a bike in the first place? Especially for the sub £1000 bikes, which makes up the vast bulk of the bike market.

It'll come with some hubs. They might even be quite good hubs. They'll invariably have the word "Shimano" written on them - or the name of the bike manufacturer. Everyone knows Shimano. That leaves the in house branded items.

Badge Engineering

Chances are, if you've bought a Giant, or Specialized, or Trek, that the hubs have been made in Taiwan, like the rest of the bike. The companies Joytech, Formula, Chosen, and a few others, knock out these components in huge volumes, often to be rebranded and sold on. Not just by the big bike companies, but by the smaller guys as well, for instance in the UK take a look at Superstar Components who are quite open about only sourcing their gear from mass manufacturers and rebranding it (without adding an expensive advertising service). A lot of companies who simply want to complete their existing component range will source bits from these guys - compare DT Swiss (who make rims, spokes and hubs) with Specialized (who get rims from DT Swiss and hubs from Formula and spokes from who-knows-where).