Descending question

Ruprecht

Just wondering can anyone offer any advice to me. I think that this is without doubt one of the most knowledgable forums on boards.ie and has been a great source of info to me in the past, so I am hopeful.

I have been on my new road bike a good bit over last few weeks getting used to it and enjoying it. Took me awhile to get used to the high speed descents and the drop bars but getting on mostly fine now and going longer distances, improving times etc.

One issue that I still have, is that there is a descent locally of about a straight 2km. When descending, it feels like my rear wheel is rotating on ice and that at any second the rear wheel will slip sideways. This occurs about 40kmh with the result that I end up getting nervous and slowing/braking. I reckon if this was not an issue, a speed of at least 60kmh would be possible by most riders on that section of road.

I dont think its anything to do with the rear wheel as I go faster than 40km on other descents with no problems. The bike is only 8 weeks old and the tyre is fine. Could a crosswind cause this? The bike is lighter than I have ever had at about 9kg. What is the best way to counteract the issue whilst maximising speed?

Thanking you in anticipation.

bcmf

what position are you adopting when descending. If you are putting most of your weight on the front even small bumps will have an effect of 'kicking' 'slipping' your back wheel. Your back wheel can take a huge amount before you come off.Its keeping your front wheel under control which is the key.

Ruprecht

bcmf wrote: »

what position are you adopting when descending. If you are putting most of your weight on the front even small bumps will have an effect of 'kicking' 'slipping' your back wheel. Your back wheel can take a huge amount before you come off.Its keeping your front wheel under control which is the key.

I have tried both crouching low in the drops and a more upright position on that stretch but in both instances I guess I would have alot of weight on the front of the bike.

bcmf

next time try and even out the weight. descending is all about practice,confidence and knowing the limitations of your bike/tyres. Try different positions as you go. Braking; I use this rule; Back brakes for slowing and controling and front for stopping. Practice and confidence.

doozerie

Yes a crosswind can cause this, or at least contribute to it, and in combination with a bike being lighter than you are used to the feeling can be amplified as you can have the feeling that the tyres are barely touching the road. Deep- or semi-deep section rims can add to the effect too as crosswinds tend to catch them more.

There are other factors too though so checking your position on the bike is worth doing. Beware that if you are feeling slightly cagey at all on a descent then it can have the effect of making you stiffen up a little which makes bike handling more difficult and compounds matters. Also, just to rule out any fundamental mechanical problems, check that neither of your wheel axles is loose (with the wheels in the frame hold the rim and check whether it rocks loosely from side to side), that you don't have noticeable buckles in either wheel, that both wheel are centred (check by eye the distance from the rim to the frame tubes either side of it), that both wheels are in the same plane/in-line, and that none of the spokes feel noticeably looser than any others in each wheel. Even though the same problem doesn't show up on other descents it is no harm carrying out these simple and quick checks anyway, and on a regular basis in fact.

And sometimes, you just have off days - during a ride on Sunday last I ended up practically diving for my brakes (often a bad choice in those circumstances!) while coming down Old Long Hill, a road that I have descended many times in the past without problems. My speed was higher than usual coming down it, peaking at 70kph, and that combined with a slight crosswind on one short relatively open stretch made it feel like the back wheel was lifting by a lot. It was probably no worse an effect than usual but on the day it just felt much more pronounced.

Mr Velo

doozerie wrote: »

Yes a crosswind can cause this, or at least contribute to it, and in combination with a bike being lighter than you are used to the feeling can be amplified as you can have the feeling that the tyres are barely touching the road. Deep- or semi-deep section rims can add to the effect too as crosswinds tend to catch them more.

There are other factors too though so checking your position on the bike is worth doing. Beware that if you are feeling slightly cagey at all on a descent then it can have the effect of making you stiffen up a little which makes bike handling more difficult and compounds matters. Also, just to rule out any fundamental mechanical problems, check that neither of your wheel axles is loose (with the wheels in the frame hold the rim and check whether it rocks loosely from side to side), that you don't have noticeable buckles in either wheel, that both wheel are centred (check by eye the distance from the rim to the frame tubes either side of it), that both wheels are in the same plane/in-line, and that none of the spokes feel noticeably looser than any others in each wheel. Even though the same problem doesn't show up on other descents it is no harm carrying out these simple and quick checks anyway, and on a regular basis in fact.

And sometimes, you just have off days - during a ride on Sunday last I ended up practically diving for my brakes (often a bad choice in those circumstances!) while coming down Old Long Hill, a road that I have descended many times in the past without problems. My speed was higher than usual coming down it, peaking at 70kph, and that combined with a slight crosswind on one short relatively open stretch made it feel like the back wheel was lifting by a lot. It was probably no worse an effect than usual but on the day it just felt much more pronounced.

70kph??? Sweet Mother.... i have seen 56Kph on my computer at times, and that felt fast. Being honest, i'm just not a brave enough descender.

doozerie

I'm not a particularly brave descender either, but that stretch of road is steep and quite straight so you have good visibility and can let the bike go (there is a car park entrance/exit as it levels off a bit after the steep section so you do need to be prepared to slow by the time you get to there). Even if you just freewheel it you can pick up quite a bit of speed.

Greyspoke

The fact that you say you can go faster than 40kph on other descents would seem to suggest that the problem might lie more with that specific stretch of road than you yourself. Is the road surface very smooth and worn like that glassy tar surface you sometimes encounter? Other than that maybe it is more exposed to crosswinds which certainly contribute to a feeling of instability. You will always go faster on some descents anyway for a variety of reasons - just relax and don't worry about it too much.

Ruprecht

Thanks for all the answers folks. I will do all those checks this evening Doozerie as something could be off kilter.

Greyspoke, its that straight downhill stretch from The Glen of the Downs to the turnoff for Delgany. Its really a gradual downhill in the hardshoulder rather than steep descent but you sure build up some speed there. However as I come down steeper decents into Kilmac with no similar problems, it could be that surface is very smooth or there are crosswinds there. Not sure if anyone has had similar problems on that stretch.

doozerie

Someone posted a link to this page on descending some time back and it is worth a read. It focuses on cornering but there is a lot of other good advice in there too on descending generally.

Oh, and on the topic of speed generally, what constitutes a fast speed is all relative. For me, 70kph on a descent is pretty fast, for others it's not that fast. At the extreme end of the scale, as posted in this thread, you have the likes of Tyler Farrar sprinting on what appears to be a flat stretch of road and hitting 78kph!

Ruprecht

I saw that article a few weeks ago on here Doozerie and I have put many of its recommendations into practice as best I can on the local descents to fairly good effect. Still have my hands near the brake though!

tulachmhor

It's amazing how much confidence bears in relation to descending.
I used to be absolutely fearless when motoring downhill at 60kph and over.
I often adopted a crouched position,with my hands on the drops and generally trying to keep myself as light as possible on the bike.Tension deinitely affects how one handles the bike.
However,in the not too distant past,I was flying downhill at about 50-60kph and I hit a pothole which resulted in a puncture to my front tyre.It took me maybe 100metres or more to come to a halt and when I eventually did I was truly shaken.
Ever since then my confidence whilst descending has been well and truly shattered,so I now find myself holding back and breaking incessantly in order to contain my speed.
Moreover,my riding style has changed,in that I am much more rigid and tense when descending,which obviously affects how the bike rolls down any steep incline.
I'm hoping that my nerve will return sometime soon,but having been out of the saddle for nearly 2 months now,that isn't likely to change anytime soon.
I suppose it's about regaining confidence through continual practice,both physically and mentally.

crosbie

Try and get ur hands on a book called 'Teist of the Wrist' - can't remember the author. It is about motorbike riding but essentially the principles are the same for all 2 wheeled machines at speed. It will give you a great understanding about the forces going on and what braking etc will do the the bike dynamics.

This article is good for starters:

http://russellcarter.net/downhill.html

Hope this helps.

route66

doozerie wrote: »

<SNIP>
while coming down Old Long Hill, a road that I have descended many times in the past without problems. My speed was higher than usual coming down it, peaking at 70kph
<SNIP>

According to my Catseye Computer, I hit 74.5 kmp/h (46MPH) on Old Long Hill last Sunday 27th on my Trek FX 7.3. I can confirm it feels ridiculously fast - maybe about 20 more than I should have been doing - and also very dangerous :eek: Now that I've done it, I'll be pressing the brakes - rather than the pedals - harder the next time.

I wonder will I ever be able to reach that speed when heading in the Roundwood direction :P

xz

route66 wrote: »

According to my Catseye Computer, I hit 74.5 kmp/h (46MPH) on Old Long Hill last Sunday 27th on my Trek FX 7.3. I can confirm it feels ridiculously fast - maybe about 20 more than I should have been doing - and also very dangerous :eek: Now that I've done it, I'll be pressing the brakes - rather than the pedals - harder the next time.

I wonder will I ever be able to reach that speed when heading in the Roundwood direction :P

Hit 80 km/h there at last years WW200, wouldnt do it now though,I was a lot heavier then, but did hit 74km/h coming down the old Rathnew/Wexford road last weekend, but had a tailwind.

Greyspoke

Ruprecht wrote: »

Greyspoke, its that straight downhill stretch from The Glen of the Downs to the turnoff for Delgany. Its really a gradual downhill in the hardshoulder rather than steep descent but you sure build up some speed there. .

That's interesting - The only thing I can think of now is that you are going pretty fast along the hard shoulder of what is often a very busy road so it's quite possible that you are getting buffeted by the passing of faster traffic on your outside - probably a far more likely cause of what you are experiencing than a deficient road surface.

Greyspoke

route66 wrote: »

According to my Catseye Computer, I hit 74.5 kmp/h (46MPH) on Old Long Hill last Sunday 27th on my Trek FX 7.3. I can confirm it feels ridiculously fast - maybe about 20 more than I should have been doing - and also very dangerous :eek: Now that I've done it, I'll be pressing the brakes - rather than the pedals - harder the next time.

I wonder will I ever be able to reach that speed when heading in the Roundwood direction :P

Anyone going for speed records on the Old Long Hill, please be very wary of cars emerging from the Djouce woods car park at the bottom - even if they spot you they will probably fail to appreciate quite how fast you might be going (and it's narrow enough if you have to swerve).

Ruprecht

Greyspoke wrote: »

That's interesting - The only thing I can think of now is that you are going pretty fast along the hard shoulder of what is often a very busy road so it's quite possible that you are getting buffeted by the passing of faster traffic on your outside - probably a far more likely cause of what you are experiencing than a deficient road surface.

Interesting theory Greyspoke. Yes the traffic there is heavy and the hardshoulder narrow enough considering most of the artics etc are going close enough about 120kmh. I got upto 52kmh there the last time when I had to pull back, so it could well be that and a combination of the ensuing impact on the bike of my uneasiness.

DirkVoodoo

I agree with Greyspoke, it's a nice hill to go down but having driven out of that car park it's not the most visible approach for drivers. Plus, you get a lot of tourists going hiking and I have seen far too many cars come out of side roads or petrol stations and turn onto the wrong side of the road.

route66

DirkVoodoo wrote: »

I agree with Greyspoke, it's a nice hill to go down but having driven out of that car park it's not the most visible approach for drivers. Plus, you get a lot of tourists going hiking and I have seen far too many cars come out of side roads or petrol stations and turn onto the wrong side of the road.

:eek: and :eek: again.

Ok, that's it. No more speeding down this hill anymore.

Anyone want to comment on their speed in the opposite direction? I'll start with 7 KMP/H Beat that!

Safe too ...