How difficult/expensive would it be to replace the front and/or rear gears on my mountain bike? I have a standard Schwinn 21-speed mountain bike, and I want to go faster! I know, I know, I need to get a road bike.
My main problem, I think, is that my legs (my bicycling muscles, anyway) are considerably stronger than my bike was designed to accomodate. This is due to not owning a car for about 13 years and living in a hilly town. Even in my highest gear, on level ground, I can get moving so fast that I simply can’t increase my speed by pedaling faster. Once I’m up to speed, the cars on the road don’t pass me all that quickly. I get going faster than my highest gear can keep up with, and so my pedaling is contributing nothing to my speed.
I just counted the teeth on my gears: largest front gear - 44 teeth; smallest rear gear - 14 teeth. Would a larger front gear and smaller rear gear be impractical on a mountain bike?
This isn’t the question that you’re asking, but if that’s true, then you need to start racing.
Anyway, on to the actual question. I know almost nothing about mountain bikes, but in road bikes, the highest gearing you can normally get is a 53x11. Maybe somebody somewhere makes something bigger, but I doubt it.
You should theroretically be able to put a road cassette on your MTB giving you a 44x11 or an extra 30% in speed or so, but I wouldn’t recommend trying to put a bigger chainring on, it probably won’t work with your front dereilleur. Go to a shop and ask for a 11x23 cassette.
I don’t have a simple answer for you. What changes you can make to a bike’s gearing are an interplay of the frame, the derailleur, and the existing gearing.
I did a quick search of mountain bike front derailleurs, and found that most of them could handle a maximum of 46 teeth (46T) cogs. That’s not much more than you have now. In the rear, most mountain derailleurs seem to have a minimum of 11T and a maximum of around 34T, but you also have to consider what type of front derailleur you’re using, what front cogs you’re using, and what the range of rear cogs is.
After all that, my guess is you might end up spending $200 (or more) to “upgrade” your mountain bike, only to find that you’re still too fast on it for your gearing. After all, the way to decide your gearing is usually not the “fastest” you can go, but the “slowest”. If you’re never using the smallest chainring (front) even when you go up steep hills offroad, then maybe you need a change in that gear rather than in your fastest gear.
You’re never gonna be as fast as a good road bike and rider on a typical mountain bike. Mtn bikes are heavier, and much of the extra weight is in the wheels and tires where it counts the most. Bikes with full suspension are less efficient since you inevitably expend energy that translates into up and down motion on the shocks. Worst of all, you get much higher rolling resistance from big tires, even if they’re “slicks”.
Having given you all these warnings, I suggest you take the bike into the town’s best mountain bike shop and ask what they can do for you. They might have some good suggestions, but don’t be surprised if they tell you to get a road bike.
I know that it sounds like ridiculous, only-in-America extravagance, but most of my “super” mtn bike buddies also have a road unit. Train on the road, and ride on the trail…
Above all, don’t buy the “typical” dual-suspension mountain bike for riding around town/on the roads. They’re not designed for it, and you’ll be unhappy. You now have the choice of getting single-speed or geared “cruisers” that are sturdy, easy to ride, and fit well for casual cycling. Think about it: if you have to run the kids to school and soccer practice, do you automatically run out and buy a off-roading Jeep complete with jack and shovel? Do you buy a Ferrari with a 12-cylinder gazillion valve engine? Or do you buy the Honda Accord sedan? Fortunately for you, the American bike world has finally woken up and started making sedan-style bikes!
You can definitely increase your gearing, but you might have to get a whole new set of front chainrings to have it work very well. 44 on the front is pretty small, in my opinion, but it’s pretty normal for mountain bikes these days. Back when I first started riding mountain bikes (late 80’s), it was common for the front chainrings to be something like 28-38-48, and the rear sprockets would be in the neighborhood of 13 - 30. So your highest gear would be 48:13, which is 17% “faster” than 44:14. Nowadays I guess most people prefer really low gearing.
So at any rate, you can definitely find a 48 tooth chainring for the front, and I’ve seen them as high as 52 that would work on a mountain bike crankset, but the problem is that when your big gear is that tall, shifting from the middle to the big one gets difficult and may not work at all. So you’d probably need to increase the size of the middle one (and possibly the small one for the same reason) in order to lessen the difference in size. You’ll also definitely have to move the front derailleur up higher on the seat tube in order to accommodate the larger chainring, which means readjusting the whole setup (which you may or may not be proficient at, but it’s not exactly brain surgery – you can get the hang of it pretty easily if you’re mechanically inclined), and it may mean buying a new derailleur cable, since the old one might not be long enough to accommodate moving the derailleur farther up the tube.
Oh, and you might need to lengthen your chain. This is another reason you can’t have too wide a range in gears – the rear derailleur folds up as you shift to the smaller gears (lower gears in front, higher gears in back) in order to take up the slack in the chain. If your chain is long enough to accommodate a 52-tooth big chainring, then a 20-tooth small chainring in the front is probably going to leave more slack than the rear derailleur can take up.
I’ve never had to lengthen my chain before, so I don’t really know what to do if you need more links for it, but maybe you’ll get lucky and the local bike shop would have some leftover links from your particular type of chain if they’ve installed some of them recently.
phase42 I’m sure you’ve heard the one about the guy who gets lost in rural Ireland. Eventually, after driving round in confusion for half an hour, he pulls up next to a farmer and says “how do I get to Donegal?”. The farmer scratches his head, hems and haws for a a bit then says eventually, “Well now, if you’d be wantin’ to be goin’ to Donegal, you wouldna’ start from here.”
You need to learn to spin but that won’t seem natural to you for a while. One thing that may make it more difficult is the length of the crank arms as it is common for mountain bikes to have arms that are 175mm long while a road bike might have 170mm arms. It may not seem like a lot but it is. The number may be stamped on the inside of the crank arms.
Could you post all the gear teeth numbers so we can make some other suggestions? Perhaps a new cassette with a 13t small cog would get you the higher gear you seem to think y ou need with the fewest hassles.
No, if you’re spinning the pedals at 100rpm in a 44/14 gear with 26" tires, you’re going 24mph regardless of level ground, etc. In a 52/11 gear with 27" tires, 100rpm gets you 38mph. Unless I did my math wrong, which is entirely possible.
In my experience, most people who think their bikes aren’t geared high enough aren’t spinning their pedals very fast, but the OP may not be most people.
That’s my experience, too. If the OP rides on some long, fairly steep downhill sections, he might spin out (can’t peddle fast enough to add more power to the wheels), but the gearing he has is plenty for flat terrain.
100 rpm is a bit high, but you should be able to do 90 rpm without much trouble if you’re in the right gear. If the OP really wants higher gears, just pop on a new rear cassette with a 12-tooth gear and that should about do it. The chain should be able to handle that fine. An 11-tooth gear on a mtn bike doesn’t make a lot of sense for recreational riding.
Ah, but you see, I smoke too I’ve got good acceleration, blazing speed for relatively short distances, and I have uphill power, but I can’t maintain that pace for extended rides.
I rarely go offroad (another argument for a road bike), but I do have some fairly steep hills in town. I indeed never use my smallest front gear, and in fact I hardly use the middle one either, except when I’m riding home from work (all uphill) and I’m more tired than usual.
I discovered that with my previous bike, which had full suspension. (I knew when I bought it that I didn’t really need the rear shock, but it was an inexpensive emergency purchase after I broke the rear axle on the bike before that). What actually brought it to my attention was that I had to borrow my roommate’s bike one day, which has no shocks. It was much easier to ride than mine, and I made the mental connection with my rear suspension absorbing my energy.
Yeah, I discovered the full-suspension problem, as mentioned above. Are these “cruisers” the ones that have the mountain-bike-style handlebar and skinny road bike tires? If so, I was looking at a nice one like that a few weeks ago. In fact, that’s what’s been in my mind for my next purchase.
Explain, please
Front: 24-34-42 (I miscounted the first time)
Back: 14-16-18-20-22-24-28 and I just discovered that I have a broken tooth on the 22.
Crank arms are 170mm.
My biggest problem actually comes on the very long stretches of road around here that have just a slight incline. What happens is that if I stop pedaling when going downhill, I gradually lose momentum. But if I pedal, it doesn’t take long to spin out.
This city is built along a river, in a valley, so the long, slight inclines run parallel to the river. These are the main streets. The steep hill streets are all perpendicular to the river, and there is a stop sign or light at every intersection as I go up or down, so I never get the chance to build up much gravity-assisted speed on those.
I think my best bet is going to be upgrading to a quality road bike. I think I’m leaning toward a Specialized. Both Specialized and Trek are in my price range, but I’d rather buy from the local Specialized dealer. On my one visit to the Trek dealer, the staff seemed to be just a little bit too impressed with themselves. When I took my Schwinn in to the Specialized dealer to have some minor adjustments made to the rear derailleur (I was fouling it up every time I tried to do that myself), the repair guy actually took the time to show me how to do it myself.
You should be able to pedal this bike at 22mph or higher. If you can’t, you should learn to pedal faster (though not necessarily stronger). For most people, maximum power output occurs somewhere around 90 or 100 rpm.
If you want to pedal faster than that on a downhill, just replace the cassette with a smaller one, as many people here have already suggested.
IMO you don’t need a new bike. If your knobby tires are slowing you down, just replace the tires with high-pressure slick tires. (That’s the most significant difference between a MTB and road bike anyway.) Of course if you want a new bike, I won’t try to stop you.
Spinning means using a lower gear and faster cadence than you are probably used to. It may feel unnatural until you adjust to it but it’s much more efficient than pushing big gears and causes much less stress to your knees. Don’t think of it as pushing the pedals against your body weight but spinning them in a circle where your legs are doing work all the time though at somewhat less effort.
The 170mm cranks should be fine unless you have really short legs. The other biggest item is having the correct seat height. It’s common for recreational bikers to have the saddle too low. Setting the correct seat height is a little bit of black art and the best way is to have an experienced coach watch you and adjust. There are a lot of other rules but for now I’ll just say that the seat should be as high as you can get it without causign you to start bouncing at high cadences. You may also want to move the seat forward a bit as mountain bikes tend to have relaxed angles but the height is more important.
You might also want to consider using clip in pedals as they make spinning more efficient. Modern clipless pedals are much safer than the toe clips and straps and you can get clip in shoes with a recessed cleat that allow normal walking.
That’s an excellent idea. I did a few short Mtn Bike triathlons not that long ago, and none of the biking part was technical and most it was actually on pavement. I put on some slicks that could hold 90 psi, and they worked really well.
Clip-in pedals are a good addition to, unless changing shoes at the other end is a problem.
I’ve got good acceleration, blazing speed for relatively short distances, and I have uphill power, but I can’t maintain that pace for extended rides.
