Reply to: Mountain Bike

[threaded]

Well yes, you could given the right materials.

With ordinary rim and pads, can you apply enough braking force to skid the front tyre at speed on dry tarmac?

I can. You have to get your weight right behind the seat or you'll go over the bars.

[threaded]

Yeah, my brakes aren't particularly well adjusted - there's a largish gap between the rims and pads when they're slack. I've tried adjusting them to be closer, so that less use is needed of the lever, but this never seems to quite work without rubbing or binding occurring on one or both sides of the rim. Probably you need wheels and everything else connected to the braking to be in good order to get them really close like when new.

Sounds like your wheels need truing, and bearings servicing.

[threaded]

I quite fancy better brakes, especially for the wet. The rim ones you get on bikes are shockingly poor in my experience, not stopping you anywhere near as fast as you are used to in a car, though no doubt better materials exist than what I've got on mine. They are nice and simple though.

Better pads help an awful lot, leather is best, next up is the cable run itself, I use a sealed system - Gore Ride-On

But for in the wet you really can't beat drum brakes. I have them on my commuter bike. Originally MTBs used drum brakes too, it's why they used to call them 'packer racing' as after each long down-hill you'd have to pull the wheels off, take the drum brake off and 'pack' it with some fresh grease.

Halfords were selling a very old fashioned MTB as a commuter bike some time ago, drum brakes, alfine gearing, was quite a sweet bike.

[threaded]

How can it b dangerous? When I were a lad, (here we go) I used to do everything on a cheapo £90 mountain bike, I even entered the odd race, did some really rough riding around the the world championship course in Malvern where I grew up, no suspension, not even caliper brakes. For 95% of the riding you would do in the UK any mountain bike would be fine, it won't fail. THe only catastrophic failure of a bike I have seen was somebody using £1000 pace forks, which snapped on a really rough downhill race I was doing a few years ago. However the nice to have's cost more, such as hydro disk brakes and nice forks.

It's generally the suspension rebound that makes them dangerous. I've seen people unweigh as they crest and the bike then catapults them quite some distance.

On a cheap MTB you're best going for no suspension, and if you go that path a Cyclo-cross bike would probably be better for a beginner, as the bigger wheels make if more forgiving and less likely to tram line.

My 29er has no suspension, caliper brakes and armoured tires. Only problem this year with that was snapping the rear axle.

[threaded]

I tend to agree. Except where a small percentage difference in performance is a big deal, such as in competitive racing. The biggest factors are:

• Aerodynamics. Losses here are more to do with the rider than the bike, e.g. position, frontal area and and clothes worn
• Other frictional losses. Occur mostly at the tyres rather than in an expensive or cheap transmission
• Weight. Rolling resistance is proportional to weight, as is going up hill, but rider weight dominates

Positioning on the bike is important and hence a size of the frame to suit, but that shouldn't add to the cost.

Expensive bikes may also have low tolerances for failure, being just man enough to do the job for a given weight.

Quite correct, as an example: swapping from steel ball bearings to ceramic is worth 5 watts, which if you're up the top of the sport is a lot smaller percentage than someone lower down the ranks. Also ceramic bearings tend to last a lot longer, don't need so much maintenance, and require a lot less grease, so the improvement lasts a lot longer too. So are one of the few things that are 'worth it'.

Frame sizing is a good one to mention, latest fashion is for 'compact' frames, which don't fit anyone really, so to get a good fit, you have to get a frame made, which isn't as expensive as you'd think.

Weight really is a biggy. I've seen people drop significant amounts of money of lightweight kit, whereas if they'd cut out a few beers a week they'd save even more.

And component weight limits: often hard to find unless you can get right to the manufacturer (i.e. can speak Chinese) minimum is to check the limits on the wheels and suspension, also instantaneous loads, so you know what kind of riding it can take.

'Race' bikes tend to be good for one race and then need a serious looking at. Example: brake pads on my MTB will last 90 minutes, which is enough for most races, but on marathons, 12 & 24 hours, I need to make sure I've got enough spares or I'll be having to buy new disks before the next race. You can buy 'endurance' pads which will last quite a while, but aren't anywhere near as good at stopping you, especially in the wet.

Similar thoughts goes for tires, I sometimes use a Dutch Perfect which is a very heavy armoured tire, as I know with that I will not get a puncture, so don't need to carry spare tubes, tools, etc.. Yet other races I know I need the extra grip and traction a Racing Ralph/Nobby Nck set up will give me.

[realityhack]

Or do what a mate's brother did once, while we were all out cycling, went down a very steep incline, and at the bottom of the hill there was a BT van parked up with the back doors wide open, engineer preparing to fix a telephone wire/pole.

We blazed past his van, but this chap slammed into the back, flying over the handlebars and straight into the back of the van, with such force he bounced out and landed, flat on his back, on the road.

Barely containing our laughter, we approached him, as the engineer asked 'you ok mate?'. Still on his back, in shock, he replied "It's ok! I'm a qualified psychiatric nurse!".

Ribbed him for weeks afterwards.

[DaveB]

Cycling into the back of a car is my plan B, if I ever need to stop when going downhill

I've been over two cars in my reckless youth, on motorbikes though 1) Moped with poor brakes in the wet and probably some inattention on my part 2) Riding in the dark without my specs on - I decided best course of action there was to plough straight into the back of it it rather than swerve. Went clean over both times. Well, except I always used to bash my knee (forget which one now) on the way over.

Only done that the once on a motorbike but I made it count.

Went into the wing of an ummarked police car and bounced of the bonnet on the way over

[TimberWolf]

The other way of doing it is to do what my brother did and cycle into the back of a parked car, while going up hill...

Cycling into the back of a car is my plan B, if I ever need to stop when going downhill

I've been over two cars in my reckless youth, on motorbikes though 1) Moped with poor brakes in the wet and probably some inattention on my part 2) Riding in the dark without my specs on - I decided best course of action there was to plough straight into the back of it it rather than swerve. Went clean over both times. Well, except I always used to bash my knee (forget which one now) on the way over.

[DaveB]

My front brakes work don't operate anywhere near that level. Seems like they do need adjusting, or more likely replacing.

The other way of doing it is to do what my brother did and cycle into the back of a parked car, while going up hill...

[TimberWolf]

It needs a few things to happen at once, good brakes, bad posture on the bike, but yes, it's eminently possible. In fact it's easier to do at lower speeds as the wheel locks up more readily and is less likely to slide.

My front brakes work don't operate anywhere near that level. Seems like they do need adjusting, or more likely replacing.

[Spacecadet]

Having enough braking force in the front wheel to risk go over the handle bars isn't something I need to worry about with my current brakes. Are you saying that you can manage this with your rim brakes?

Well it's been 10 years since I did any serious mountain biking.

But yes, the bike I had did have sufficient stopping power to send me over the handle bars.
This was a bike that didn't leave much change out of £1000 though!

[DaveB]

Having enough braking force in the front wheel to risk go over the handle bars isn't something I need to worry about with my current brakes. Are you saying that you can manage this with your rim brakes?

It needs a few things to happen at once, good brakes, bad posture on the bike, but yes, it's eminently possible. In fact it's easier to do at lower speeds as the wheel locks up more readily and is less likely to slide.

[TimberWolf]

On dry tarmac you'll end up over the handlebars before the front wheel skids.

Shifting your weight backwards gives more grip to the rear wheel aiding braking there and makes it more difficult for your momentum to tip you over the handle bars.

Having enough braking force in the front wheel to risk go over the handle bars isn't something I need to worry about with my current brakes. Are you saying that you can manage this with your rim brakes?

[Spacecadet]

Well yes, you could given the right materials.

With ordinary rim and pads, can you apply enough braking force to skid the front tyre at speed on dry tarmac?

On dry tarmac you'll end up over the handlebars before the front wheel skids.

Shifting your weight backwards gives more grip to the rear wheel aiding braking there and makes it more difficult for your momentum to tip you over the handle bars.

[TimberWolf]

It can

Well yes, you could given the right materials.

With ordinary rim and pads, can you apply enough braking force to skid the front tyre at speed on dry tarmac?