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Whoa!

Community Veteran
Posts: 7,149
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Registered: 30-08-2007

Whoa!

This morning approaching a downhill T junction a cyclist was riding along the centre between the traffic:
To set the scene, imagine if you will a man of mid 30's appearance, looking as if had just left a YvesSaintLauren boutique having said "no expense spared, dress me for cycling" And they did! sparing no expense! sitting on what to me seemed to be the cycling equivalent of an off-road Land Rover. However, I know nothing about modern bikes. But I digress, as this has little bearing on what followed.
From my vantage point high up in my coach seat I could see this vision in Lycra was having considerable trouble stopping his bike, judging from the way he was gripping the brake levers with a vice like grip, and maniacal expression on his face, eventually, having decided that he wasn't going to stop before careering onto the junction, he put his feet down and imitated a respectable speedway like slide into an undignified heap, fortunately unhurt except a severely dented ego.
This got me thinking about cycle brakes. Its a long time since I was a regular cyclist and track racer (with no brakes) The bike in question here was fitted with the current trend for disk brakes. And, I wonder what advantage this type of brake has over the traditional wheel rim type. The disk type seem to be only fitted to mountain type bikes, it is quite noticeable that they are not fitted generally to sports or road racing bikes, by a group that usually embraces advances in bike technology very quickly.
I could well imagine that the small surface area of bike disks against the much larger area of a wheel rim would leave them at something of a disadvantage. Not only that some of the disks look distinctly fragile.
Experience; is something you gain, just after you needed it most.

When faced with two choices, simply toss a coin. It works not because it settles the question for you. But because in that brief moment while the coin is in the air. You suddenly know what you are hoping for.
21 REPLIES
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Re: Whoa!

I love my disc brakes.. however as with all things you get what you pay for.
Highly useful when ploughing through mud as they don't get clogged up and are also much better in the wet and decent pads are much harder wearing.
There are also hydraulic types - good - and those operating with a steel wire - poop.
I would be interested to know what said bike was you saw - probably full suspension too.
Why people insist on buying full sus to ride on the streets I'll never know.
EDIT: they do require a bit more maintenance
Will Moderate For Thanks
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Re: Whoa!

You'd hope there is a good reason for disc brakes on bikes vs traditional, the traditional type applies the friction on the rim, far away from the axle, think about how much torque (turning force) you get at the axle generated by the moment you have between the brake pads applied near the axle and the turning force of the wheel, I'd much prefer to apply the friction on the wheel rim where there is a smaller moment than on the brake disc. Sad
Somebody will tell me why I am wrong I guess .... Smiley
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Community Veteran
Posts: 7,149
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Registered: 30-08-2007

Re: Whoa!

Sorry adiewoo, don't know. It certainly seemed fully suspended, and it was er! black. If I see it again will see if I can identify it.
You could ask the same thing about large 4x4's only ever used for school runs and shopping trips.
Experience; is something you gain, just after you needed it most.

When faced with two choices, simply toss a coin. It works not because it settles the question for you. But because in that brief moment while the coin is in the air. You suddenly know what you are hoping for.
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Re: Whoa!

From long and bitter experience of cycling in the wet with rim brakes they are basically useless as they aquaplane.
Disc brakes have a couple of advantages - they are further from the road so tend to stay a bit drier and the disks are often/always (I am not sure which) perforated so there is much less chance of building up a water film under the pads.
In the dry I would agree that rim brakes should be better but only if the rims are clean - any mud on them will be picked up by the pads and drastically reduce the coefficient of friction.
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Re: Whoa!

And if you get a stone in the pads your rims are shot to bits!!!
Amuses me watching all these people on 'cheap' full sus bikes bobbing up and down wasting all their energy..
Will Moderate For Thanks
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Re: Whoa!

I wonder then if, you obviously much more experienced riders might hazard a guess what was going wrong this morning with the bike in question?
Experience; is something you gain, just after you needed it most.

When faced with two choices, simply toss a coin. It works not because it settles the question for you. But because in that brief moment while the coin is in the air. You suddenly know what you are hoping for.
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Re: Whoa!

what were the weather conditions
Community Veteran
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Re: Whoa!

Quote from: adiewoo
Amuses me watching all these people on 'cheap' full sus bikes bobbing up and down wasting all their energy..

Yes, from my racing days I remember that bobbin' was useless, correct set-up was much more important, ball of the feet on the pedals not the lazy instep etc. Let the legs do the work.
Experience; is something you gain, just after you needed it most.

When faced with two choices, simply toss a coin. It works not because it settles the question for you. But because in that brief moment while the coin is in the air. You suddenly know what you are hoping for.
Community Veteran
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Registered: 30-08-2007

Re: Whoa!

@Oldjim. Fine, sunny, cold after much overnight rain, road surfaces damp in patches.
Experience; is something you gain, just after you needed it most.

When faced with two choices, simply toss a coin. It works not because it settles the question for you. But because in that brief moment while the coin is in the air. You suddenly know what you are hoping for.
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Re: Whoa!

Thoughts...
Cheap or loose discs
Inexperienced rider
warn pads
Will Moderate For Thanks
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Re: Whoa!

Quote from: adiewoo
loose discs

Resulting in loose rider.
I'm not a biker myself but my colleague next door is a fanatic. He has spend hundreds of pounds an a pair of wheels Shocked  No frame, tyres etc just wheels Lips are sealed
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Re: Whoa!

new bike and he didn't take it back for a first service after a few weeks (Halfords offer that and I am sure more specialist shops do as well) and the brakes needed adjusting
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Re: Whoa!

I'd agree with oldjim as new brake cables stretch. I remember many a time years ago fitting new cables and then having to retighten them every week for the first month.
Strangely brake cables on cars don't seem to need this..
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David_W
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Re: Whoa!

I read somewhere once, a long time ago, that rear suspension on a bike was a bit of a no-no.  They theory being then the suspension on the rear absorbs some of the pedal power so having it is pretty inefficient, at least I think that's what the theory is.
Disc brake though are what I had on my mountain bike and are also on my motorbike (front wheel only, rear is drum - motorbike) pulling my front brake on a motorbike will stop you pretty darn quickly, I'm not really sure what material is pressed against the disc but modern ones on a mountain bike use hydraulics so are a lot more reliable than they used to be.
As for why the guy fell off, could be he'd been over-using the brakes so the disc was hot which effects the brakes - yep, re-read it, downhill so he'd been liberal on the brakes, heating up the disc which reduced the braking efficiency.