Something tightens on a hill

[Martinsnos]

Hi all,
Was hard to know which thread to put this in.
So the quip is that it is my age but honestly I noticed it again today - it is definitely a mechanical ‘thing’ can anyone throw any light on it?
I have a well serviced (as in I don’t think it’s a broken spindle) Giant hybrid bike with cable disk brakes and, when I cycle up a steep hill, something definitely adds resistance to (what I think is) the back wheel.
If I had to guess it feels something like the disk is flexing and rubbing on the pads - is that possible? When I look down I can’t see that the wheel is flexing enough to rub on the frame (and also there is no rubbing noise).
There are no issues on the flat and it definitely seems related to the high torque [correct terminology?] on a steep hill - the worst time!
My bike mechanic said he could find nothing (and looked at me with the - you are just getting old theory - look!!!].
It is doing my head in because it is deffo the bike!!!
Thanks for listening!!!

 

[sevenfourate]

Can you first of all get a friend to do ‘the same ride’ to see you both come up with the same conclusion ?

Just possible - if so - they may also see a possible problem and solution !

Good luck.

 

[craigwend]

Gravity?

 

[fossyant]

Yer legs.

 

[Martinsnos]

Can you first of all get a friend to do ‘the same ride’ to see you both come up with the same conclusion ?

Just possible - if so - they may also see a possible problem and solution !

Good luck.

But will they share the ability to put down the awesome power that I generate

Yes - not a bad idea.

 

[sevenfourate]

But will they share the ability to put down the awesome power that I generate

Yes - not a bad idea.

Ease up if the Tarmacadam starts to ripple….

 

[ColinJ]

If you can't hear any strange noises from the bike, how can you tell that the difficulty isn't just from the steepness of the hill?

Sometimes it IS due to the bike though... I once did a 200 km audax event and felt that the whole day was hard work. I got off my bike at the finish and tried wheeling it to my mate's car, only then realising that the rear brake was rubbing!

Another time I overtightened a rear quick release and that caused the bearings to bind.

In both cases the rear wheel would not spin if I lifted it off the ground and gave it a flick. It would just stop dead.

I know people who have pulled rear wheels over on steep climbs because the rear QR was not tight enough, but that is pretty obvious and the wheel doesn't go back by itself afterwards so I'm sure that isn't your problem or you would have spotted it.

 

[a.twiddler]

I definitely feel something tighten when going downhill, especially if it's steep and poorly surfaced.

 

[Cycleops]

I definitely feel my a**e tighten when I see some of the prices being asked for new bikes.

 

[Martinsnos]

If you can't hear any strange noises from the bike, how can you tell that the difficulty isn't just from the steepness of the hill?

Sometimes it IS due to the bike though... I once did a 200 km audax event and felt that the whole day was hard work. I got off my bike at the finish and tried wheeling it to my mate's car, only then realising that the rear brake was rubbing!

Another time I overtightened a rear quick release and that caused the bearings to bind.

In both cases the rear wheel would not spin if I lifted it off the ground and gave it a flick. It would just stop dead.

I know people who have pulled rear wheels over on steep climbs because the rear QR was not tight enough, but that is pretty obvious and the wheel doesn't go back by itself afterwards so I'm sure that isn't your problem or you would have spotted it.

You just know. If I was on my road bike I’d have a smooth change in the feeling of effort but this is literally like the brakes have come on, so it is either the brakes or some weird ‘reaction’ of the spindle (or the bit that goes through the crank - not sure what that it called).
It seems to be totally related to very high power going through the ‘crank’.

Thanks for trying to help.

It felt like much more and the bike would stop (whereas I wasn’t particularly out of breath and I know I have the power to get up there normally without this feeling). I was in middle chainring, 2nd ring from easiest on block. I sense that if I was in smallest chainring it wouldn’t happen - this is why I feel that it is power making ‘something’ flex.

 

[Tenkaykev]

I definitely feel my a**e tighten when I see some of the prices being asked for new bikes.

Mine does that going down a steep hill on my Brommie.

 

[Cycleops]

Mine does that going down a steep hill on my Brommie.

You should get a kiddie wheeler with discs like.my Bike Friday.

 

[figbat]

QR or TA? If QR, is it tight? And fully located in the dropout?
How‘s the bottom bracket?

 

[cyberknight]

QR or TA? If QR, is it tight? And fully located in the dropout?
How‘s the bottom bracket?

I'm thinking similar ,also are the wheel bearings nipped up enough as play in the hub could cause it to wobble under high load

 

[ColinJ]

It felt like much more and the bike would stop (whereas I wasn’t particularly out of breath and I know I have the power to get up there normally without this feeling). I was in middle chainring, 2nd ring from easiest on block. I sense that if I was in smallest chainring it wouldn’t happen - this is why I feel that it is power making ‘something’ flex.

I had a quick search and other cyclists mentioned tight bearings...

As mentioned in my previous post, having the quick release ridiculously tight can cause problems.

I recently replaced a bearing in my freehub and found that the difference in adjustment between too loose (wheel rattles and wobbles) and too tight (FRICTION!) was surprisingly subtle.

I can imagine that if your hub or QR was a smidge too tight then the extra force acting on the bearings might result in unwanted friction.

As for rubbing disks... I have had that problem but even though my hearing is poor, I have always been able to hear it.