Disc brakes, hydraulic versus cable

[reohn2]

Don't you run the risk of getting air into the system with hydraulic brakes if you have to up end the bike to remove a wheel? Thinking about if you have to fix a puncture when touring. Cable brakes would therefore be better in this situation.

I've never had the need to turn a bike upside down when removing a wheel,so can't se that as a problem even if it's true that it would let air into a hydro system,which I'm not convinced it is.

It might just have been coincidence but after having removed and refitted the wheels on my Longitude (by committing the cardinal sin of turning it upside down to do so ) I found that my brakes had become non-existent, requiring a thorough bleed to get them working again. I'd never had hydraulics on a push bike before so I was a bit surprised.

So it is true then

I've never removed a rear wheel without turning a bike upside down and have no idea how hard it is to do it any other way !

I find the Longitude a bit of a pain to get the rear wheel out with the rear facing d/outs,and have resigned myself to removing the chain should I puncture on the trail.
Rear wheel removal vertical d/outs are easy enough with the bike upright IME.

[Brucey]

FWIW if there is a small amount of air in the reservoir and this migrates into the brake circuit when the bike is inverted, it ought to migrate out again fairly easily too. Trailside, this is most easily accomplished by orienting the MC so that the drilling to the reservoir is uppermost (which may require that flat bar levers are temporarily rotated on the bar if you normally have the levers pointed downwards) and exercising the brake.

If you can do, pump the caliper pistons out further than normal (by removing the pads and/or disc) and then push the pistons back again; this should force any air into the MC reservoir.

Note that this behaviour is only ever caused by the brakes being short of fluid or badly bled to begin with; there shouldn't be any air in the system, not even in the reservoir. The best procedure for bleeding the brakes to avoid this occurrence varies slightly with the model of brake and its installation, but in any event it is easy to do it wrong, so easy in fact that many folk think it is 'normal' for their brakes not to work properly if they ever turn their bikes upside down, i.e. they have never had the brakes in the correct condition. If the brakes are correctly installed and correctly bled this behaviour is not 'normal' at all.

cheers

[nomm]

vote for TRP spyre and spykes from me - a lot better performance than my bb7s and a lot less faff than hydros on my MTB

[reohn2]

vote for TRP spyre and spykes from me - a lot better performance than my bb7s and a lot less faff than hydros on my MTB

That I find surprising as the Spyres that came on my Longitude were no better than BB7's which I have on other bikes and which I Swapped for BB7's as despite a few remedies including trying different pads,I couldn't stop the Spyres from squealing when hot.

[Mike_Ayling]

Another option is to use rims with a hard coating. Ryde still offer some rims with CSS coating and Mavic offer some with 'exalith' treatment. Realistically such rims ought to do at least 20000 miles.



cheers

Ryde are/have discontinued the CSS coated rims.
These were only available in 559 (26inch)

We bought our tandem from Thorn with these rims fore and aft.
When new the rims felt like fine sand paper which smoothed out after about 5,000 km and the braking was not quite as good as at the start but still adequate and in the wet the usual one wheel rotation wipes the rims and then braking is as normal. The rims require special hard pads which last a long time.

Due to perceived wet weather braking issues Thorn then recommended CSS on the rear only where re lacing the Rohloff hub to a new rim too frequently might be some sort of issue and an ordinary rim at the front which could be replaced more easily.

There is a bloke here in Melbourne who has achieved 40,000 km on his CSS rims and they are still going!

Mike

[Brucey]

Another option is to use rims with a hard coating. Ryde still offer some rims with CSS coating and Mavic offer some with 'exalith' treatment. Realistically such rims ought to do at least 20000 miles.



cheers

Ryde are/have discontinued the CSS coated rims.
These were only available in 559 (26inch)

We bought our tandem from Thorn with these rims fore and aft.
When new the rims felt like fine sand paper which smoothed out after about 5,000 km and the braking was not quite as good as at the start but still adequate and in the wet the usual one wheel rotation wipes the rims and then braking is as normal. The rims require special hard pads which last a long time.

Due to perceived wet weather braking issues Thorn then recommended CSS on the rear only where re lacing the Rohloff hub to a new rim too frequently might be some sort of issue and an ordinary rim at the front which could be replaced more easily.

There is a bloke here in Melbourne who has achieved 40,000 km on his CSS rims and they are still going!

Mike

not sure what Ryde are planning in the future but at present both SJS and Spa still list 700C CSS rims
https://www.sjscycles.co.uk/rims-700c-29er-622/?type=css

https://www.spacycles.co.uk/m2b0s116p2364/RIGIDA-Grizzly-CSS

cheers

[Mike_Ayling]

I stand corrected about the CSS rims being made in 622 and still being available but they are definitely no longer being made by Ryde.

http://thorncyclesforum.co.uk/index.php?topic=13246.0

Mike

[Cyril Haearn]

Please show me 15 miles of down hill in the Uk that needs both brakes. What a wonderful ride. On or off road?

May I volunteer to ride the machine back up?
Should upending a cycle be discouraged or banned? I did it recently to oil my front brake cable with the help of gravity

[rmurphy195]

No need for these with cable https://www.planetx.co.uk/i/q/BSPLPSP/plastic-pad-spacer

[flat tyre]

Thanks for all the interesting comments. My current thoughts are to stick with rim brakes!
Three main reasons for this;
1) Reliability. I do about 8000 miles a year and ride in all sorts of weather and nothing I've read here gives me comfort that either of the disc brake systems will not let me down when out on the road, or may require lengthy maintenance operations.
2) Ease of build. I've built several bikes with rim brakes and I'm not sure if I want to go up the learning curve with disc brakes.
3) Weight.. My estimate is that hydraulic disc brakes will add something like 700g to the weight of the bike, probably less that this for cable disc brakes.
There is also a cost consideration, hydraulic disc brakes would add something like £350 to the cost of the bike.

[reohn2]

Flat tyre
1)you couldn't be more wrong about maintenance and reliability
2)cable discs are as easy to build and maintain as any rim brakes,learning curve is about 1hour after that they're a doddle.
3)discs do weigh slightly more than rim brakes,though not appreciably.