105 shifters and disc brakes

markhewitt1978

I've been looking at getting a new bike which is a bit more general purpose than my road bike and I've been looking at some of the PlanetX offerings e.g. this one

http://www.planetx.co.uk/i/q/CBPXXLSTIA ... a-commuter

It says it has "Avid BB7 disc brakes" but standard Tiagra STi shifters, i.e. not disc specific ones.

I have a spare set of 5700 STIs would I just be able to swap out the Tiagra ones for my 5700 shifters and have the brakes still work ok?

ugo.santalucia

Yes, they are the same thing.

markhewitt1978

Thanks! I was under the impression previously you needed special shifters, learn something new

I'm considering the option of either buying a full bike or building up from a frame. Would using a set of RS10 wheels i.e. standard road rim braked wheels, be a daft thing to do on a bike using disc brakes?

ugo.santalucia

markhewitt1978 wrote:

Would using a set of RS10 wheels i.e. standard road rim braked wheels, be a daft thing to do on a bike using disc brakes?

Yes, if you can't fit the discs to the hubs, how are you going to brake?

markhewitt1978

haha, see that's saved a potential disaster

arlowood

markhewitt1978 wrote:

haha, see that's saved a potential disaster

Yes - I'm on the same learning curve as you but probably now a fair bit further along it.

Recently bought a Genesis Equilibrium Disc frameset and have been researching the kit needed to build it up.

Essentially you need a road disc specific wheelset which are built around hubs designed to take the disc rotors that act as your braking surface. 2 bacis types of hub design - the 6 bolt international where the rotors are bolted onto the hubs and the Shiimano centrelock where the rotors are clamped onto a splined boss on the hub.

As you'd expect with the Shimano system you're more or less stuck with Shimano hubs. With the 6 bolt system there are numerous hubs to choose from such as Novatech, Hope, Chris King etc depending on your budget. That really applies if you are considering going down the handbuilt route.

However there are factory disc specific road wheelsets available -Mavic Aksium One Disc and Kinesis Crosslight Disc to name just a couple

Another fact I've gleaned is that mechanical road disc brakes need specific compressionless cable outers in order to work most effectively. Currently not sure if the outers supplied with Shimano STI's qualify in that respect or whether you need to source some others. Still investigating but I'm one of our learned forum members will be along to put me right.

markhewitt1978

Thanks for that! As you say I'm learning!

The requirement for a new wheelset when building up from a frame may tip the balance to buying a full bike.

dgunthor

a road bike with mechanical (cable) disc brakes won't offer much better braking than rim brakes.

if you get hydraulic disc brakes and shifters you'd see an improvement, though in 22 years of road cycling i've not really felt the need for better brakes save occasionally for a torrential downpour day

Fabius

I agree with dgunthor.

I have just bought a road bike with rim brakes, I have a CX bike with mechanical disc and a hardtail with hydraulic discs. The mtb benefits hugely from the power of hydraulic discs, but there is no practical difference in power between mechanical discs and rim brakes on the road; the advantages are more to do with where you ride and the benefits of not dragging the braking surface through the mud and sludge.

Then there's the extra strength (weight) needed in disc wheels to cope with the higher forces at the hub. Before I experienced rim brakes I always said that if I bought a road bike it would have discs. I was wrong. They are plenty good enough

veronese68

I was running 105 levers with BB7 brakes and they worked a treat. Certainly far more consistent than rim brakes in all weathers, if a little noisy in the wet. More than powerful enough with good feel, I'd say better than rim brakes. But as always it depends on which rim brakes and which discs you've tried.
I've now fitted a Parabox hydraulic converter, and I'd say braking is probably no more powerful, but they feel better and I don't have to adjust them to compensate for wear. Full hydraulics would be better, but more than I can justify spending at the moment.