# Brake locks front wheel resulting in flying over the handlebars



## Freddy92 (11 Mar 2012)

Some of you will wonder why I am posting this but it will become clear later.

My youngest daughter is a student at Sussex University. She has a Dawes Ladies Bike which she loves. It is a fairly early model with centre pull brakes made of some sort of engineering plastic. One side of the front brake broke under extreme braking. Not good and I am sure the reason no one seems to make brakes out of plastic any more. Shame on you Dawes for ever choosing it. Anyway, not to prolong this, she takes her bike to a cycle shop in Brighton and asks if they can fit a new front brake which they do. Now here is the real story. Friday night she is cycling down a hill - probably rather faster than she should - someone walks across the road and she slams on the brakes. The front wheel locks up and she does a superman impression flying over the handlebars and landing on her front in the road. Luckily she does not seem to be injured other than bruises. She blames herself for 'braking too hard'. On picking her bike up she finds the front wheel will not rotate, being locked by the front brake. I say it should be impossible to apply the brakes so hard that the front wheel is permanently locked. The brakes must have been installed incorrectly by the bike shop. She keeps blaming herself.


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## downfader (11 Mar 2012)

Does sound as if a mechanical failure might be the cause. How is the front wheel? Could it have buckled upon the crash thus jamming one side? Un-clamp the brake and try and free spin it, does it wobble?

Many front brakes can lock a front wheel under the right circumstances (eg hitting a small rut in the road or a kerb at the exact moment, something I did as a kid a few times). A rider also has to learn the limits of braking and how to control their body to avoid the bike becoming unbalanced.


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## ColinJ (11 Mar 2012)

Applying the brakes should not 'jam them on' but are you sure that the brake was not damaged in the crash, with that causing it to get stuck?

It is perfectly possible to go over the handlebars with over-enthusiastic braking of properly maintained brakes, however. 

Can you see why the brake is stuck on?


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## simon.r (11 Mar 2012)

It's easy enough, with a well set up brake, to lock the front wheel. Just think how easy it is to do a rear wheel skid - it's the same priciple.

Not sure what you mean by _'...the front wheel is permanently locked'_ though? The only thing I can think is that the blocks have gone under the rim somehow? Any photos, or a better description?


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## sidevalve (11 Mar 2012)

Forgive my confusion but if you mean the wheel is permanently jammed [as opposed to just locking up when she hit the brake] then something is seriously wrong. I can only think of three things 1- lever pivot breaking sticking lever on. 2- cable sticking or 3- actual brake arm pivot bending or possibly twisting [and thus tightening up] preventing arms releasing. If the brake is still stuck on I'd go back to the shop and start jumping up and down.


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## derrick (11 Mar 2012)

If the front brake did not lock up on the mtb, i would noy be able to do stoppies. have not tried it on the road bike though.
Though they should not stay locked on.


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## Ian H (11 Mar 2012)

simon.r said:


> It's easy enough, with a well set up brake, to lock the front wheel. Just think how easy it is to do a rear wheel skid - it's the same priciple.


Hmm. I've never managed to lock a front wheel on a dry road.


> Not sure what you mean by _'...the front wheel is permanently locked'_ though? The only thing I can think is that the blocks have gone under the rim somehow? Any photos, or a better description?


That sounds like a possibility.


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## simon.r (11 Mar 2012)

Ian H said:


> Hmm. I've never managed to lock a front wheel on a dry road.


 
Boris can (at 51s)


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## Freddy92 (11 Mar 2012)

When she picked the bike up the front wheel would not rotate. I asked the same question - is it jammed? I asked her to take pictures - the one I will upload is less than I would have liked but shows the type of brake. She took the bike back today and she says the guy in the shop did something quickly to the brake and immediately it released the wheel so it was not buckled. What has really annoyed me is he then persuaded her that she needed a full bike check for £20! I am a professional engineer and I know all the usual brake designs and I don't think any of them should jam the wheel like this. It can only happen if the brake shoes rides over the rim onto the tyre which means it was not adjusted correctly in the first place. From the picture I guess this is what has happened on the RHS.


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## Freddy92 (11 Mar 2012)

As I explained in a later post the guy in the bike shop made some adjustment and all was working again so there was no permanent damage. All I can think is that either the brake shoe had ridden over the rim. This can only happen if the brake shoe was adjusted to be too high. I cannot think of anything else.


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## simon.r (11 Mar 2012)

That's a standard V brake, as you know, so enough power to lock the front wheel if applied sharply.

Did something happen to the brake as a result of the crash? If the shop guy did 'something quickly' that suggests to me that it's something like the noodle being dis-placed rather than the pads being re-aligned. Even a good mechanic will take a couple of minutes to re-align pads. TBH I think you're leaping to conclusions when you say that 'The brakes must have been installed incorrectly by the bike shop'. They may have been, but, IMO, you can't definitely state that from the information you have.


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## boydj (11 Mar 2012)

simon.r said:


> That's a standard V brake, as you know, so enough power to lock the front wheel if applied sharply.
> 
> Did something happen to the brake as a result of the crash? If the shop guy did 'something quickly' that suggests to me that it's something like the noodle being dis-placed rather than the pads being re-aligned. Even a good mechanic will take a couple of minutes to re-align pads. TBH I think you're leaping to conclusions when you say that 'The brakes must have been installed incorrectly by the bike shop'. They may have been, but, IMO, you can't definitely state that from the information you have.


Have to agree. Sounds like something fairly basic - and easily corrected - went wrong with the brake as a result of the crash. The crash itself was probably caused by over-enthusiastic braking.


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## downfader (11 Mar 2012)

..and to add, even if you're unsure of what we tell you perhaps take it to a second shop for a second opinion.


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## HLaB (11 Mar 2012)

I could be wrong but it seems to me the original brakes were pants but she was used to that and the new brakes actually worked and it simply caught her out; I'm glad she's OK though.


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## simon.r (11 Mar 2012)

A thought has just popped into my head - you say the bike originally had a 'centre pull' brake, (by which I assume you mean a cantilever), which has been replaced by a V brake:






Was the brake lever replaced at the same time? When V brakes were introduced I seem to remember dire warnings about using them with levers designed for cantis.

To quote Sheldon:

'Direct-pull cantilevers (_i.e. V brakes_) have a very high mechanical advantage, which makes them unsuitable for use with conventional levers. If you do use conventional levers with direct-pull cantilevers, braking may be too abrupt"

As I say, just a thought.


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## snailracer (12 Mar 2012)

Freddy92 said:


> As I explained in a later post the guy in the bike shop made some adjustment and all was working again so there was no permanent damage. All I can think is that either the *brake shoe had ridden over the rim*. This can only happen if the brake shoe was adjusted to be too high. I cannot think of anything else.


If so, you should be able to see a mark on the tyre sidewall.


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## lulubel (12 Mar 2012)

simon.r said:


> A thought has just popped into my head - you say the bike originally had a 'centre pull' brake, (by which I assume you mean a cantilever), which has been replaced by a V brake:
> 
> 
> 
> ...


 
This was my first thought too. Cantis replaced with Vs, and the levers not replaced.

Maybe that's what happened?


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## Tim Hall (12 Mar 2012)

Freddy92 said:


> As I explained in a later post the guy in the bike shop made some adjustment and all was working again so there was no permanent damage. All I can think is that either the brake shoe had ridden over the rim. This can only happen if the brake shoe was adjusted to be *too high*. I cannot think of anything else.


 
No, it can happen if the pad is marginally too low. Apply brake, pad dives under rim. Release brake, pad can't fly back, wheel is jammed. This happened to one of the riders on the FNRTTC, just after the tea stop. It was the rear wheel, so no acrobatics were involved. A couple of minutes with an allen key and all was well.


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## Linford (12 Mar 2012)

There is also a risk that the casting is getting pinched by a washer and is interfeering with the free movement of the lever on its pivot.


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## Freddy92 (12 Mar 2012)

HI everyone. I really appreciate your help here. Managed to get another picture from daughter today. What do you think about the brake cable run?


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## Freddy92 (12 Mar 2012)

Actually thinking about what you guys said about changing from a V brake to a side pull and not changing the lever. You are right - the pull on the brake cable per mm is going to move the pads in towards the rim more in the V brake than the cantilever. (I had no idea until now there was more than one type of brake lever.)


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## Smokin Joe (12 Mar 2012)

Freddy92 said:


> HI everyone. I really appreciate your help here. Managed to get another picture from daughter today. What do you think about the brake cable run?


I'd run the front brake from the left lever, much smoother curve of the cable.


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## Linford (12 Mar 2012)

Freddy92 said:


> HI everyone. I really appreciate your help here. Managed to get another picture from daughter today. What do you think about the brake cable run?


 
Not much wrong with that IMO . If you drop the cable off you can see if it is stiff in action in the sheath, and also you can move the levers on the fork legs to make sure they aren't partially seized.


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## Freddy92 (12 Mar 2012)

Re running the cable from the left lever - can the brake be turned around the other way so as to keep the front brake on the RH lever??


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## Smokin Joe (12 Mar 2012)

Freddy92 said:


> Re running the cable from the left lever - can the brake be turned around the other way so as to keep the front brake on the RH lever??


No


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## oldroadman (12 Mar 2012)

Brake hard enough on any decent set up and it's possible to lock up. If the wheel would not move then investigation, not speculation, is needed to se why. Whilst respecting the "professional engineer" quote, it shows a lack of understanding of braking systems if anyone believes that brakes cannot be locked up - one reason for ABS on motor vehicles. All that said, do hope the lady is OK.


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## simon.r (12 Mar 2012)

Linford said:


> Not much wrong with that IMO . If you drop the cable off you can see if it is stiff in action in the sheath, and also you can move the levers on the fork legs to make sure they aren't partially seized.


 
+1

Ideally it looks as if the outer could do with being a liitle bit shorter, but it's OK as it is.


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## rualexander (12 Mar 2012)

The tops of the brake arms look to be rather far apart with a lot of bare cable between the rubber boot an the cable anchor bolt, maybe the washers on the pads need to be swapped around so that the narrow washer is on the inside which will bring the arms closer together. For a better cable run to the noodle pipe you can get a noodle with a tighter angle.


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## mickeydrippin60 (14 Mar 2012)

i work in a bike shop i am also an engineer ( HNC in mechanical engineering ) and tbh ime sick of hearing the old am an engineer so i know about bike's malarkey it dont mean anything you can either set up a bike or you cant simple as that if you dont want your daughter to be able to lock up her front wheel simply get her one of these http://www.ebay.co.uk/itm/Tektro-V-...keparts_SR&hash=item2ebc1d0722#ht_1999wt_1270 it should help. if that sounded abit ranty ime sorry just tired


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## Sheffield_Tiger (15 Mar 2012)

My theory is that I firstly wouldn't want to arm-wrestle your daughter! 

Just kidding, but it sounds like she has a, shall we say, firm grip, managing to bust a front canti. My reckoning is, the brakes being harsher than she is used to, the front wheel locked under emergency braking with the added leverage of the original brake lever - maybe with a small rut or similar to help it lock up.

The fall somehow managed to dislodge the return spring out of one arm, leaving no opposing force to balance the brake leaving one arm tight to the rim.

The "quick job" done to sort it was releasing the noodle, popping the return spring back in place and re-inserting the noodle into the stirrup


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## YahudaMoon (15 Mar 2012)

Reading the OP post it looks like he / she is looking at every avenue possible to find blame on the mechanic other than the daughters miss judged calibration on the new brake set up ....

Or is it just me ?


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## Sheffield_Tiger (15 Mar 2012)

Reading the OP's post it sounds like he is doing the exact same as the rest of us. Trying to work out what MAY have happened without actually being able to see the bike.


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## YahudaMoon (15 Mar 2012)

Sheffield_Tiger said:


> Reading the OP's post it sounds like he is doing the exact same as the rest of us. Trying to work out what MAY have happened without actually being able to see the bike.


 

That being the old brakes were poor so got replaced with brakes that do work.


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## lulubel (15 Mar 2012)

YahudaMoon said:


> Reading the OP post it looks like he / she is looking at every avenue possible to find blame on the mechanic other than the daughters miss judged calibration on the new brake set up ....


 
Even if that is what he's doing, it seems perfectly natural to me. He's a dad, she's his daughter. Isn't that what dads do?

Or maybe it's just my Dad who's overprotective.


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## fossyant (16 Mar 2012)

YahudaMoon said:


> That being the old brakes were poor so got replaced with brakes that do work.


 
Like it.

My son, on getting a decent first 20" MTB commented, oh brakes that work - he was about 6 at the time ! Having gone from a basic toddler bike.

V brakes and non specific levers will certainly be good. Hmm might have to try that with my MTB - just replace the Canti's with V's. Stop on a sixpence.

TBH If you pull the brakes hard enough you can easily endo any bike - I can even do it on my fixed with fully loaded panniers if I brake hard.


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## fossyant (16 Mar 2012)

lulubel said:


> Even if that is what he's doing, it seems perfectly natural to me. He's a dad, she's his daughter. Isn't that what dads do?
> 
> Or maybe it's just my Dad who's *overprotective*.


 
Probably. 

Bike riding is not for ninnies ! Fall off, get up and check the bike, and ride. Worry later on if your leg falls off !


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## mcshroom (16 Mar 2012)

There is definitely a canti hanger on the front of the bike which suggests that the bike used to have cantis at some point.

To be honest under emergency braking in the wrong conditions any brake setup could lock the front wheel up, but I would check that the levers on the bike are appropriate for the brakes that are on there if the shop has just changed from cantilever to v-brakes.


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## Linford (16 Mar 2012)

I would want to see the brakes being efficient enough to lock the wheels at speeds of up to 20mph. It is then up to the rider to use that wisely.


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## MontyVeda (16 Mar 2012)

i know two people who've done the same thing with the front V brake, one had a broken arm and collar bone, the other just had a broken arm. IMO, they are too efficient.


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## YahudaMoon (16 Mar 2012)

lulubel said:


> Even if that is what he's doing, it seems perfectly natural to me. He's a dad, she's his daughter. Isn't that what dads do?
> 
> Or maybe it's just my Dad who's overprotective.


 

Nothing wrong with that  I just glad Im not the mechanic that fixed the bike lol


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## albion (16 Mar 2012)

Is this a vote to make anti-lock brakes compulsory?


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## simon.r (16 Mar 2012)

Any news from the OP? I'm intrigued as to what the outcome of this is going to be.


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## Freddy92 (20 Mar 2012)

Fair point Simon - about time I re-entered the fray and maybe summed it all up. 

I don't know why I have to apologise for being an engineer but there you go. At least one contributor seems to think this is necessary. I put this in because I think you need to know I have a good technical background but other than looking after my own bikes am not a bike specialist and people who specialise always know more than those who don't. On the other hand non specialists can have a view from the outside. I would like to thank the numerous people who have responded in a very positive way and I think this thread is one of the most fruitful I have ever initiated. Oh - for those who find my initial posting controversial - it was intended to be. We wouldn't have 3 pages of discussion if it hadn't been :-)

I want to get this out of the way first - I think that in all probability the brake was not fitted badly, or that if one of the brake shoes was a little high this was not the cause of locking the front wheel in the first place. It is pretty clear that the combination of a V-brake with a cantilever brake lever is perfectly capable of locking the front wheel at a pull that would nowhere near lock the wheel with a cantilever brake. Therefore having a cantilever brake replaced with a V-brake is potentially dangerous for a non technical rider.

My working life is made something of a pain by our company having to produce risk assessments for just about every activity. I have always thought these a waste of time until this incident with my daughter. If the bike shop or maybe better - the brake manufacturers - had done a risk assessment on replacing cantilever brakes with V-brakes then these problems would have surfaced and every V brake sold separately would come with warnings about checking the brake lever can be adjusted for lower leverage and replace if necessary. Also to warn the user about the greater braking effect. Now it is a fact that if my daughter had been injured or worse, then she or I would have come after the bike shop that fitted the brake. There are those that have contributed here that won't like this but I can assure them that under current health and safety legislation the bike shop would be liable and so would the brake supplier if they had not included instructions as I have suggested.

For my daughter I want to thank mickdrippin60 for leading me to the device that limits the cable tension and thereby reduces the efficiency of the V-brake. I note this device is made by a brake manufacturer so they obviously know the problem. I would say this whole thing comes down to what type of rider you are. If you are an experienced downhill enthusiast who understands exactly how your brakes work and can think fast enough in all situations to never pull too hard for the conditions then you should be able to install whatever you like. On the other hand if you are a bicycle commuter who does not understand the mechanics and hardly ever has to pull up fast then some sort of tension limiter on a front V-brake is essential. It is very like the argument for abs on cars.


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## albion (20 Mar 2012)

The fact is that one gradually adjusts to ageing brake blocks so new blocks always give that initial surge.
Its seems like it was just unfortunate timing of use.


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## TheDoctor (20 Mar 2012)

The manufacturers have done a risk assessment - that's why you get V-brake levers and 'other' levers. I'm not certain I can do a stoppie on my road bike, but I certainly can on my MTB. With all respect, I think it's simply that the brakes were improved out of all recognition and the rider didn't know, or didn't take that into account.


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## Freddy92 (21 Mar 2012)

I have not seen a risk assessment. Could someone upload the instructions or links to the instructions that come with V-brakes for after market installation? We could then all have a look at what they say.


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## mickeydrippin60 (21 Mar 2012)

tis ok freddy happy to help


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## simon.r (22 Mar 2012)

Freddy92 said:


> I have not seen a risk assessment. Could someone upload the instructions or links to the instructions that come with V-brakes for after market installation? We could then all have a look at what they say.


 
http://techdocs.shimano.com/media/t...tem/BRM750/SI-B650A_v1_m56577569830611886.pdf

Above is a link to a random Shimano V brake 'Service Instruction'. It's a while since I bought any Shimano parts, but IIRC they always come with a printed sheet similar to the doc above. Bottom left of the document is a clear instruction to use the V brakes with compatible levers.


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## YahudaMoon (22 Mar 2012)

This



YahudaMoon said:


> Reading the OP post it looks like he / she is looking at every avenue possible to find blame on the mechanic other than the daughters miss judged calibration on the new brake set up ....
> 
> Or is it just me ?


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