Frame flex and broken spokes.

[Brother D]

I'm fairly new to riding, having purchased a road bike (trek 1.5) over a year ago, but two things I've noticed is that its apparently not normal to get through spokes at the current rate of one a week, and that the frame massively flexes when I first get on it. I only weigh 90kgs, and was surprised about the amount of lateral movement when first starting off.

I had the shop replace the first few spokes, but I now carry out the work myself, and I've followed all the guides on setting them up.

Are there any tips on caring for your spokes? Its a road bike so it doesn't see and off road work and I'm not jumping off kerbs etc.

Thanks in advance/

[Parrot of Doom]

A properly-built wheel will not suffer from broken spokes, full stop.

[timbo48]

"A properly-built wheel will not suffer from broken spokes, full stop"

+1

I've had a road bike for a year now and only broken one spoke and that was when I hopped off a kerb. Said spoke then went into the rear mech and broke that, an expensive mistake which I won't be repeating. You could get your wheels rebuilt with some decent spokes, yours shouldn't be breaking at that rate.

[itsnotarace]

Once a couple of spokes have gone the wheel will usually need a full rebuild. Don't keep replacing spokes on it now. Maybe consider a 32 spoke custom build

[okgo]

Parrot of Doom said:

A properly-built wheel will not suffer from broken spokes, full stop.

Depends how much power you can put through it doesn't it?

I've snapped spokes on strong wheels when climbing steep hills.

[louiebaby]

itsnotarace said:

Once a couple of spokes have gone the wheel will usually need a full rebuild. Don't keep replacing spokes on it now. Maybe consider a 32 spoke custom build.

This is exactly what I had built. I'm only about 300 miles in, but it's doing grand at the moment. If you let us know where you are, (OP), I'm sure someone will be along to advise on a specialist that is well versed in this, the darkest of all the dark arts.

If it's London, speak to Andy at On Your Bike near London Bridge.

[Brother D]

Cheers chaps, I'm just replacing the latest one. What I am surprised at is the wheel (bontrager ssr 24 spoke) has the spokes so they don't follow a natural path from hub to rim, but are 'braided' so each spoke has to bend around the other.

Just seems a strange way to build a wheel


From an engineering perspective you are just inducing fret-wear on the spokes?

p.s. wow the flash really shows the dirt up!

[Gooby]

I would be concerned about the frame flex. Check the frame for hairline cracks.

[b2hbm]

Brother D said:

Cheers chaps, I'm just replacing the latest one. What I am surprised at is the wheel (bontrager ssr 24 spoke) has the spokes so they don't follow a natural path from hub to rim, but are 'braided' so each spoke has to bend around the other.

From an engineering perspective you are just inducing fret-wear on the spokes?

The 'braiding' is a normal practice as far as I know, I always do that anyway. You can get wear on the intersection, especially if the spoke tension is low, but I've never seen a spoke seriously worn or broken in that area.

I've also had problems with factory built,low spoke count wheels but even so, it's not normal to break so many spokes on a regular basis. When you're replacing them, are you getting an even tension ? I realise you're probably fitting the spoke & then tightening it until the rim is true, but you can get that condition with slack spokes as well as properly tensioned ones. The aim is to get an even tension on the spokes, hard to explain but I tend to "ping" a spoke and aim for similar sounds across the spokes. You can buy a tool to measure spoke tension (spoke tensometer ?) but it's probably not worth it unless you're building high cost wheels for resale.

As a complete aside (and a theory open to ridicule) when you ride out of the saddle, what sort of angle do you lean the bike to ? The reason I mention it is because I'd guess the greater the angle of lean, the more vertical stress goes on to a spoke - after all, a wheel is designed to give it's greatest strength when loads are applied along the rim/hub axis and not at a tangent ?

Brian

[Rouleur]

I had a problem with the spokes going on the rear wheel of the Trek I bought in 2009, and after having 2/3 replaced I got the dealer to source a new wheel. Since then I've had no problems at all, so it looks as though there are some bad batches of Trek wheels out there. As mentioned, you need to start from scratch and get a good wheel builder on to it.

Re the frame - there's no way someone of your weight should be able to feel it flexing so I'd get a decent shop mechanic to look it over ASAP. Give it a clean too!

[AVeryNaughtyBoy]

Rouleur said:

Re the frame - there's no way someone of your weight should be able to feel it flexing so I'd get a decent shop mechanic to look it over ASAP. Give it a clean too!

I have to disagree.

The OP is talking about lateral flex, which I take to mean that the bottom bracket swings (exaggeration of true movement) from left to right with each pedal stroke.

90kg is a fair weight for a rider (similar to me) and if he is either very powerful in the saddle (unlikely for a new rider) or gets out of the saddle a lot then it is quite probable that he will exert enough force to flex the frame noticeably.

I have a brand-x (courtesy of CRC) frame on my work bike. It was the cheapest alloy frame I could find to put my spare parts on and it feels horrible. The frame has fairly high vertical stiffness, making it uncomfortable, and cock all lateral stiffness, making it inefficient. It is basically the opposite of the ideal stiffness characteristics of a bike.

A simple test of holding the bike upright, leaning it away from you and pushing your foot on the centre of the chainset (not too hard!!) will make any flex rather obvious. I would be shocked to find that it differs from any other Trek 1.5 of the same vintage. Chances are that Trek just did not get the frame design right, probably by pushing for weight saving and assuming that the average owner of what is a fairly entry level road bike would not notice or care. If this is the case then there is no fix, other than a new (different) frame / bike.

The other possibility is that the OP is not feeling frame flex but can feel his, presumably faulty, rear wheel squirming and flexing. I would certainly push for a new wheel from the shop that supplied the bike or failing that stump up for a new wheel myself before thinking about changing bike / frame.

[Rouleur]

I know where you're coming from, but I've got a better model of Trek with the same frame as the OP and I weight 85kg, plus I'm pretty fit, and I can't feel any flex in it during riding. I'm sure you're right about it being down to the wheel moving around, but I think he should get the frame checked just in case.

[AVeryNaughtyBoy]

I suppose that a good wash and a thorough visual check of all of the welds / joints would be a good idea, particularly as your frame seems totally different on feel. It also makes me more convinced that the rear wheel is the problem.

Slightly off topic but I remember reading a review of a very lightweight FS Gary Fisher (Name??) that has so much lateral flex that the rear mech ghost shifted up to a couple of cogs under hard acceleration!! Bet that felt nice...

[Brother D]

Been away from the PC. Yes I was referring to the lateral flex, I compared it to a mates brand new carbon jobbie, and although theres a bit, mine just seems a bit excessive. It doesnt feel like there is a lot of flex when you are riding thou (and pushing on the crank from the side will sho it up). I did check the joints, but I don't think you can get away with a bike that light with skinney tubes without reducing stiffness!

I semi re-built the rear wheel, I guess time will tell, and if I do pop another spoke I'll take it in to get looked at...

Thanks again for the input.

[okgo]

Frame stiffness is almost nothing to do with how thick or heavy the metal is, its in the design and geometry

[graememac]

I have a Trek 1.5 and I've never noticed any flex in the frame, i'm 80 kgs. As for the wheel i kept breaking spokes on the rear wheel which i put down to once one has broken it weakens others resulting in further breakages later on. I had the wheel fully rebuilt and it hasn't happened since

[Brother D]

Three spokes gone in less than a week, after over two months of trouble free cycling following a complete home rebuild.

However, think the cause (in my case) is probably clicking out of the cleats and catching a spoke...

I'm wondering if it is ok to ride to the shop to get more spokes being 3 down on a 24 spoke rim, as two are next to each other!

[timbo48]

Second spoke gone a couple of weeks ago in same wheel. Broke at the nipple end as I was "just riding along". Took wheel in to dealer where bike came from just over a year ago and found there is a fault with the nipples on the wheels of that bike (a scott Speedster 2010) and Scott are replacing them was what I was told. Apparently it's down to alloy nipples rather than brass ones. Must admit I was a bit surprised at breaking spokes, I've been mtb'ing since the early 90's and never broken one, but the roads in Southampton are pot holed, multi patched etc so not really surprised that they break.

[b2hbm]

Brother D said:

Three spokes gone in less than a week, after over two months of trouble free cycling following a complete home rebuild.

However, think the cause (in my case) is probably clicking out of the cleats and catching a spoke...

I'm wondering if it is ok to ride to the shop to get more spokes being 3 down on a 24 spoke rim, as two are next to each other!

If you're 3 spokes down on a 24 spoke rim, with 2 being adjacent, then I'm amazed that it still goes round. If the spoke tensions are anywhere near correct then in my experience having a single spoke go on such a wheel would be enough to have the tyre hitting the chainstay. In fact that's one of the reasons I use 32 spoke home-builds in my (very thin) carbon frame.

Would I ride it ? I'd ride it to get home at 10mph but wouldn't be surprised if I ended up walking.

[itsnotarace]

Brother D said:

I'm wondering if it is ok to ride to the shop to get more spokes being 3 down on a 24 spoke rim, as two are next to each other!

Not unless you want to damage it further, the tension on the surrounding spokes would be immense and you will just break more.

Seriously, as I said back in January - either get a full rebuild done by a professional with a complete set of new spokes using your existing hubs and rims, or buy a set of handbuilt 32 spoked wheels. Don't keep throwing good money after bad.