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I have recently joined the cycling world after committing to losing weight. I am a heavy rider at about 28st (390 lbs) and have after some advice gone for a GT Avalanche. I have had the bike less than a month and only have around 15 miles on the bike.

I use the bike to travel to work which varies from light off road to road.

I was riding back from work and realised that the wheel had started to buckle. Upon getting home I have noticed that some of the spokes were loose. Is this normal and if not is it due to the weight the bike is being asked to carry? Will a home fix be enough to mend the issue?

Update:

I have contacted the seller who has advised me to get booked for their free 6 week service where they can service the bike and they can also true the wheels.

The question I have now is until I am able to get the bike serviced am I able as a temporary measure able to fix this at home and use it as I use the bike for getting to and from work?

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    Do you carry a backpack or any other items which can be left out? Your wheel is probably not rated for the requirements, so its failing slowly. On the other hand - you're doing the right thing with your commitments, which will help. Persevere with riding, don't let this put you off. – Criggie Apr 10 at 11:46
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    Note that it's common (depending on manufacturing methods) for spokes to loosen as the wheel "breaks in". Your weight is forcing this to happen over a period of 15 miles instead of 500, but the loosening, in itself, is not unusual. You need to get the spokes re-tightened and the wheel realigned and see if that fixes things for you, at least for the short-term. Long-term, you may need a new wheel. – Daniel R Hicks Apr 10 at 12:16
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    I never stop to be impressed how the imperial system is overly complex for nothing. Thank you for introducing me to yet another weight unit. – Puck Apr 10 at 12:37
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    Bravo on your commitment to losing weight John! Chapeau. – Daniel Shillcock Apr 10 at 13:03
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    @DanielRHicks In this particular case one might recommend at least 36-spoke wheels built with tandem-grade spokes, rims and hubs. Tandems or even triples have to cope with heavier loads than 390lbs. – Carel Apr 10 at 14:24
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Unfortunately, most bikes are only rated to 300lbs or less. However, if this is a new bike, you should take it back to the shop and get them to fix it. They can't claim they didn't know you were a heavy rider when they sold you the bike.

You might need to get more substantial wheels with more spokes. Wheels designed for touring bikes might be more appropriate. Also, when riding, you need to be careful to avoid potholes and other bumps in the road and don't go up and down kerbs. If you can't avoid a bump, lift your weight off the saddle so your legs and arms are acting as suspension – this applies to riders of any weight and it's more comfortable for you as well as the bike!

  • You have a good point, would it not be worth trying to tighten or make sure they are tight before every journey or would this not have much of an impact? – John Apr 10 at 9:44
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    I don't know a huge amount about wheels, to be honest. But having to tighten spokes regularly indicates that there's a deeper underlying problem. Hopefully somebody with more direct knowledge will chime in – David Richerby Apr 10 at 10:54
  • Usually you’ll notice loose spokes because the wheel goes out of true. With rim brakes this is very noticeable because the rim will rub against the brakes. – Michael Apr 10 at 15:18
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    Needing some spoke adjustment after initial usage is fairly typical of machine-built wheels. One of the steps of hand building a wheel is to relieve some of the initial stress before final truing, making subsequent adjustment less necessary. If instead that stress relief happens on the road, then the wheel needs truing again after. The asker's situation may well have gone beyond this, but it may not have - it is hard to tell from words alone. Getting it looked at is indeed the start of what needs to happen. – Chris Stratton Apr 11 at 2:05
  • Thanks, @ChrisStratton and welcome to the site! – David Richerby Apr 11 at 8:53
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I completely agree with the accepted answer of @David Richerby from personal experience.

As a heavier rider (~22 stone) for many years, I also found with a couple of different bicycles that the rear wheel tended to come out of true, especially when hitting bumps and potholes.

My solution was to replace the rear wheel with a touring wheel with more spokes, and I can ride over speed bumps etc. with less worry, although I do ride them standing on the pedals to reduce the force through the seatpost.

I also learned how to true a wheel reasonably, and to keep it trued and correctly tensioned, because shocks have less effect on a properly balanced wheel. It needs mostly patience and care, and something simple to act as a reference marker.

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    And I agree with your answer. 😀 Welcome to the site! – David Richerby Apr 10 at 15:25
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    What an elder long-gone fellow rider used to call 'dynamic' seating, filtering the bumps with the legs! – Carel Apr 11 at 7:37
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Spokes getting loose is not a laughing matter. The more spokes get loose or break, the more uneven the load is distributed to the spokes, and the more likely other spokes are to get loose or break. Accumulate enough failed spokes, and your wheel fails. And failed spokes after only 24km means that something is very wrong with the wheel's built.

As such, your wheel definitely needs to be rebuilt immediately.

When the wheel is rebuilt, it needs to be rebuilt such that no spoke can ever loose tension when you use it. Most importantly, that means that the spokes must have even tension, but also that their tension must be high enough. I'd recommend giving the wheel to a professional builder, and to tell them that the wheel is supposed to carry you. Hopefully, they'll be able to produce a built of high enough quality to avoid repetition of the failure.

What you can do to reduce the likelihood of failure, is to avoid accelerating too hard: The force you can put on the chain is much higher than the force a 70kg person can put on the chain. And that force on the chain is directly proportional to the torque that your spokes need to deliver to the rim. If you put your bike in first gear and then stand on your pedal to accelerate, you'll pretty much kill any rear wheel. Just try to take acceleration a bit more slowly until you have lost weight.

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    "If you put your bike in first gear and then stand on your pedal to accelerate, you'll pretty much kill any rear wheel." - over-egging the pudding here?? – Lamar Latrell Apr 10 at 10:40
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    @LamarLatrell I know how I used to kill spokes until I learned to build my wheels with near perfect even tension, and the OP is a lot heavier than I ever was. If you assume that the chain-wheel radius is half the length of the crank, that's 353kg of tension on the chain. Multiply with a sprocket radius of 10cm, and you get 347Nm torque on the wheel. Assume 36 spokes at a 10% angle and an inner rim radius of 30cm, and you arrive at a dynamic load of about 320N per spoke (about 32kg). For the unloaded spokes to retain 60N tension, the loaded spokes must endure 700N. Much more for a dished wheel. – cmaster Apr 10 at 11:00
  • Circumference of a 10cm radius rear cog = 2π100 = 628mm. 628/12.7mm = 49 tooth cog.... – Lamar Latrell Apr 10 at 12:11
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    An explanation for the downvotes would be nice... – cmaster Apr 10 at 16:04
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    "And failed spokes after only 24km means that something is very wrong with the wheel's built." - Nothing is very wrong on a BSO wheel build with a 400 pound rider. It's amazing it even made it 24m let alone 24km. This is well beyond any BSO. This needs huge spoke count wheels built. – sjakubowski Apr 11 at 19:25
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For your weight, you either need to find reliable wheel builder who will make wheels for you, or you need to become one. Possibly both in that order.

Wheel will be most important part of your bicycle and you should strive to put best components in it, and be sure it is built with your weight in mind.

Unwinding of spokes is almost certainly result of not enough of tension on them for your weight. To be able to put enough tension, you need as many spokes as you can, and very strong rim. It should have no less than 36 spokes, heavy duty rim like rigida sputnik or andre, and double butted spokes.

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It is possible to re-tension loose spokes at home, using a spoke key and the frame of the bicycle as a truing stand. In your case I would not do so.

If the wheel started to fail so quickly from new, I think it would fail again even faster with a home repair. In the worse case the wheel could fail catastrophically injuring you and damaging the bike. In the best case you get stranded.

When you take the bike in for service, the repair shop will hopefully be able to re-build the wheel. They may be able to build it to a higher strength than it was originally by increasing the spoke tension, but it may fail again of course. If the wheel can't be re-built or fails again, you can consider getting a stronger replacement wheel with a higher spoke count and heavier gauge spokes.

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Loose spokes and buckling wheels on a new bike are definitely not normal.

That could be incorrect assembly but may also be a result of the weight of the rider and not getting the right advice:

The design specifications in the GT tech manual book list "330 lbs / 150 kg" as the maximum weight limit for that model. Although not explicitly mentioned for the Avalanche I assume that is the limit for the combined weight of the rider and all gear.

  • Okay, initially would a home fix work or would i need to get it looked at? – John Apr 10 at 9:33
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    On a brand new bike I would expect a reputable seller to take responsibility for this and sort it out for you. – HBruijn Apr 10 at 9:39
  • I agree and i am in the process of getting them to sort it however i need to be able to ride the bike in the meantime as it's used for commuting to work – John Apr 10 at 10:27
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    I wouldn't bother with a home fix. It's dangerous if you don't know what you are doing and won't really help. Take the bike back to the shop asap! Ask them to help you straight away. It sucks not being to able to ride your new bike. – user2705196 Apr 10 at 15:31
  • Buckling is not normal, but some loosening of spokes is, because machine built wheels end up with residual stresses that work themselves out in initial usage, leaving uneven tension. That's part of why you get that initial tune up. – Chris Stratton Apr 11 at 2:02
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I would suggest that if visited the shop and they helped you choose the bike then they should exchange the bike for something more appropriate. Clearly the bike is not suitable otherwise the issue you raised would not have occurred.

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Upon getting home I have noticed that some of the spokes were loose. Is this normal and if not is it due to the weight the bike is being asked to carry? Will a home fix be enough to mend the issue?

In my experience, loose spokes are not typical but can happen. Any decent bump (especially for a big guy like I am) can remove pressure from a spoke and if it is twisted, it will unscrew a bit. But twisted spokes imply that the wheel was not built properly.

When building a wheel, I was taught to over-tighten the spokes and then back them off specifically to reduce spoke twisting. You want the spokes to be under tension but not twisted. See this answer for more details: https://bicycles.stackexchange.com/a/29696. I also was trained to grab the parallel spokes and squeeze them to help untwist the spokes while truing a tire. This page explains the squeezing well.

I also know some wheel builders who use Loctite solution on the spokes to hold them better although I've never found this to be necessary.

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