Does weight and climbing cause strain on bike?

Question

I‘m a heavy (260 pound) male rider using my 2011 NORCO 24 gear hybrid to commute to and from work. It’s a 6 mile trip each way with a +450 foot climb in the last 2-3 miles coming home. The ride is all on hard surfaces with an occasional curb. I have ridden this commute about 80-100 times.

I have been having issues with the rear-shifter and chain. Also with spokes on the rear rim. Started with the rear-shifter breaking off but despite three visits to the dealer’s shop and one to a different place, new cables, replaced spokes and so on I still have problems. After a couple of rides the spokes rattle and the gears go out of sync. The issues with the gears seem to happen when going up the hills (when I assume the most pressure is on the bike).

Two questions: If I assume the two repair shops are competent then what might be causing the gears from going out of sync 3-4 trips after I get them adjusted? What’s causing the spokes to loosen up? I suspect the strain on the bike climbing (taking in mind my weight). What type of bike would be appropriate considering the combination of climb and level riding plus the weight?

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To answer some questions and some further info:

What do you mean by "the gears go out of sync"??: The gears don’t correspond to the setting I have. I gear but see the chain hasn’t moved. I might have to switch back and forth before I get the desired setting. Chain falls off the gears. There is also a lot of creaking and groaning (and not from me!).

Do you change the gears while climbing / fast pedaling? Not so much while fast pedaling but definitely while climbing. It’s not a steady climb so I try to gain as much speed as possible and then drop the gears fast while climbing.

have you replaced the chain and rear cluster yet? No. I probably need to change the chain. There is a chink in the chain after the last fail.

I’m ready and willing to replace parts if required. However if the cost start mounting I wonder if I’m better off getting a more robust bike.

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Thanks for all the great suggestions and ideas! Since it’s a rather spread and open question I can’t really pick any one as best but I wanted to post one final question and my action plan: I will go back to the dealer and replace the chain and rear rim with higher performance items, plus have the bike overhauled. Think his mech is competent but will insist on talking to him directly. So yes – I intend to extend the life of my NORCO.

For my type of riding – paved roads, occasional curb, hill climbing… is the hybrid the ideal bike-form?

Answer 1

The spokes and gears are likely unrelated issues. You have done 2000km on the bike - have you replaced the chain and rear cluster yet? At you weight and those hill climbs, I would not be surprised if they are just worn out. It is also possible that at your weight and that distance the spokes have come out of adjustment, and/or now have fatiguied to the point of breaking or stripping threads on the nipples. I would also be checking for a broken axle and the bearings not being adjusted properly.

The bike shops should have picked up all these issues, however, are they aware of the distance you are riding? Many such bikes do 50 miles a year and they may be servicing it based on that assumption. It is a mistake to presume that any LBS is competant, servicing is and art and a passion, and (putting it politely) some mechanics are better than others.

What to do - ask around for recommendations on bike shop. If you are comfortable, take it back to one you have used, but make sure you let them know how much use the bike has had. Talk to the mechanic directly, don't be fobbed off by front counter salesmen (And walk out if you cannot get access to the mechanic). Ask him to measure the chain and check the cluster and chain rings. Check the spokes/bearings and axle. Be prepared to replace parts.

Answer 2

With regard to the shifting, you do need to understand proper shifting procedure.

First off, with any derailleur-style bike the chain and sprockets need to be moving when you shift. (You're no doubt aware of this, but it bears mentioning.)

Prior to the advent of "indexed" shifters, it was not possible to shift "under load" at all. To shift you had to reduce the force on your pedals to essentially zero (but keep pedaling) while shifting. Indexed shifting was made possible by adding "ramps" to the sides of the sprockets so that when the chain is moved against a larger sprocket the projecting pins of the chain engage the ramps and the chain is lifted to the larger sprocket.

A big advantage of indexed shifting is that these ramps allow, to a degree, shifting "under load", such that you don't need to completely reduce force on the pedals when shifting.

But the chain pins can only resist a certain amount of force before slipping off the ramps, and if you apply too much force while shifting the chain will not shift. "On the flat", it's fairly easy and natural to reduce force a little, but when climbing it takes a bit of planning -- you have to plan to shift ahead of needing the lower gear, so you can do it when you're not applying so much force to the pedals.

Answer 3

It sounds like you have two separate problems. I'll comment on the spoke breakage, speaking as someone who's had trouble with rear wheels in the past. Bike wheels are surprisingly complex. Essentially if you have a wheel that's been perfectly built, with the spokes at a high and even tension, it should stay true for a long time, without any spokes loosening on their own. Most wheels are imperfectly built but are good enough as long as you're using one appropriate to your weight and riding style. A quality 36 spoke wheel can support someone much heavier than you without spoke loosening or breakage, but unfortunately you're more likely to see issues than a lighter person.

What essentially happens is that, once spokes start to loosen on a wheel you can have a cascade of problems. A spoke that is under low tension will tend to loosen itself more as you ride. Spokes under very low tension will tend to break quite quickly from fatigue, and spokes neighbouring loose spokes will pick up additional stresses. So a single undertensioned spoke can end up causing multiple spoke breakages if it's not caught early enough.

Why are some spokes loose in the first place? Most of the time wheels are built with spoke tension at the low end of acceptable (it takes a lot more time to get them to a high tension and true them), and with slightly uneven spoke tension. You also see problems with spoke windup, where spokes are twisted and untwist as soon as you ride the bike. You see this when less competent/careful mechanics true wheels. If a wheel makes lots of pinging noises when you first ride it, you should carefully monitor that wheel.

What can you do about this? Well, prevention is the best cure: have wheels that have high and even spoke tension, and are appropriately stress relieved before riding. If you've ridden a wheel with broken/loose spokes for a while, it's more of a headache since additional spokes may be close to failure from fatigue. Essentially you need to replace the bad spokes as they break, and keep a close eye on the wheel for trueness and loose spokes - that needs to be addressed promptly to avoid the same cascade of failures. Before replacing spokes, you can try to "stress relieve" your current spokes by grabbing sets of four spokes and pulling apart with your hands. This can break any that are near to breaking already, and will reduce the chances of others loosening later on.

Answer 4

There have been a bunch of good suggestions so far, I just wanted to pick up on your specific point about maybe getting a new bike. This should be unnecessary - unless you specifically wanted one ;-)

Bikes do come with weight limits, so it may be worth checking the spec of your bike to see if it "should" support you. You might possibly have some leverage from the warranty point of view.

But over and above that, I'd have a chat with your LBS. Wider tyres, stronger wheels etc. are all cheaper alternatives to a new bike.

Answer 5

If you're having that much problems with spoke breakage on a reasonably built wheel (32 spokes 3x lacing ), then it's more than likely that your rim is bent in some fashion and the uneven tension required to compensate for the flaw in the rim is causing spokes to break. Ask the shop to check the tension in the spokes and see if it's even[1]. If they don't know how to do this, find a different shop.

260 is a lot for a light racing bike, but any reasonably built hybrid should be stout enough.

[1]- On a rear wheel, the spokes will have much different tension on drive vs non-drive sides, but it should be similar on all spokes on a side. You can sort of ball park this by plucking the spokes if you have a good ear, all the spokes should have roughly the same tone.