Help with upgrading/buying a casette
 

I recently purchased a Trek FX 7.1 just to commute to school and also to get back into exercising. I usually bike around 20 miles once a week on relatively flat terrain. Hopefully I will eventually be able to bike much further.

One gripe I have about the bike is that the gear ratios are tailored towards mountain bike style gearing, and I find it way too slow for me. I am usually always on the highest possible gear ratio and still pedaling too fast. I can hardly go faster than 20-25mph without being completely winded from pedaling too fast. My legs at that point don't feel tired at all.

The configuration on my bike is stock: 28/38/48 on the crank, 7-speed 14-34 teeth cassette with a HUGE first gear (I never use this)
So I want to upgrade to something that will fit my needs better: making this hybrid bike act a bit more like a faster road bike than a hill-climbing mountain bike.

I found a few Shimano 7 speed cassettes with a lower sprocket of 12 teeth online, but I'm not sure if I can still keep my chain, or if I need to do anything with my derailurs, or anything else to consider. I figured that the lower teeth number on the cassette would help me to be faster whole maintaining a more comfortable cadence. If I went from 14 teeth to 12 teeth, how much faster would I go? Is it even worth the upgrade at that point?

Shimano CS-HG20 7-Speed Cassette, 12-28T (Amazon, apparently I can't post links until I've posted 10 times in this forum...)
Shimano CS-HG200 7-Speed Cassette - 12-32 (Amzn)
SRAM Pg-720 7Sp 11-25T Cassette (Amzn)


Also a question before buying anything, do I have to use Shimano cassettes since I have Shimano Acera derailurs?

Any tips or recommendations would be greatly appreciated. I'm a complete beginner to the bike customization world. I've been riding old cheapo bikes for as long as I can remember. Thanks in advance!

Generally if you replace your rear cassette you should also be replacing your chain at the same time.

Your Trek FX 7.1 probably has a freewheel rather than a cassette. Trek specs show it's a SunRace, and there are a few variations with smaller large cogs and closer spacing. The 14-34 is like the Shimano Megarange, for old loafers like me riding heavy comfort hybrids.

If I'm reading correctly the SunRace and Shimano freewheels are interchangeable and mutually compatible with the rest of your components -- derailers, chain, shifters. While Shimano freewheels can be founder cheaper (especially on Jenson USA), SunRace offers a larger variety. Check the SunRace specs for the 13-25 and 13-28 freewheels. By now you probably have a good idea of which cogs you use most often and which you'd prefer which one or two fewer teeth to suit your strength and speed.

I think you need to improve your spin rather than changing the gearing. I spin at 20 mph in a 39/14 combo on a roadbike. With a 48/14 on a hybrid you have plenty of gear being a rider that rides 20 miles once a week. Improve your spin and adopt a high cadence. Bigger gears wont do much for you at this point.

With 35-622 tires and 48-14, 25mph is 90rpm. You can do 20-25mph on the flats but can't handle 90rpm? :eek:

This could increase your top end gear by 7.6%:
https://www.amazon.com/SunRace-7sp-F...dp/B002FB2Y88/
Or you could give this a shot, it'll improve your high gear by 27%, but it'll require an uncommon DNP freewheel removal tool if you ever need to take it off (whereas the tool for Shimano and Sunrace freewheels is very common):
https://www.amazon.com/DNP-Epoch-Fre...dp/B007A8RWV0/

I'd disagree that the OP needs to improve his technique. My comfort hybrid has exactly that same setup: 28/38/48 chainrings; 14-34 megarange freewheel. I can spin out on downhills and some flats with wind assistance. And, at age 59 with only 18 months back in the saddle after 30 years away, I'm not even a very strong cyclist anymore. A stronger cyclist on a lighter bike could easily outgrow the 48 front, 14 rear combo on the right terrain and wind conditions.

Not everyone is comfortable with a cadence above 80 rpm, especially without clipping in. I still prefer platform pedals and can manage a fairly fast cadence, but that's due to experience and 18 months of hard work getting back into the groove.

And almost every time I ride I'm passed by stronger roadies who are mashing rather than spinning. Looks hard on the knees but some of those fellows are my age and they're much stronger and faster than I am.

Also, that 14-34 freewheel is, frankly, a pain in the neck. There's a huge jump from the 28 to 34 cogs. It's not awful when downshifting for steep climbs with a loaded bike, but the shift back from 34 to 28 is awkward, every time. To spin up fast enough for a relatively smooth shift I need to spin at nearly 100 rpm, and time it perfectly. Any less and there's a knee-jolting shift. But it's occasionally helpful with my loaded errand bike. If I had a lighter bike that wasn't loaded down with up to 50 lbs of groceries I'd skip the 14-34 freewheel in favor of a 13-28. A younger, stronger rider could handle a 13-25, especially on a reasonably lightweight hybrid. The closer spaced cogs would be much smoother for an aggressive rider.

Like the mighty cat of cankles, I have 48/38/28 with a 14-34 on my grocery/tour bike. and yes, there are some huge leaps. You Need a triple with that cluster. Unlike the OP, I don't regularly cruise at 24.2 mph (90 rpm in 48x24.) If he can do that without tapping his legs .... I am wondering how he tracks his speed, and I am wondering what cadence he rides .... and a lot of stuff .... cruising at 20 mph and above and he only rides 20 miles, once a week." Is he a weightlifter or a 440-yard sprinter the rest of the week? Not if he runs out of wind.

The easiest answer is to simply shop online for a 7-speed freewheel with better gearing,. If his bike is new he shouldn't even need to change his chain .... not sufficiently worn yet, I;'d imagine, to damage the new cluster.

His other option is a new crankset---and again, he can use the same rest of the drive train.

A better ides would be to get a new rear wheel with a freehub and cassette.

The best idea is to look into competitive cycling if he can cruise for 20 miles at 20 mph without his legs getting tired at all.

All i can say is that if you are maxing out that gearing on flat ground on that bike, you are my hero!

I think that this is just if its worn out? If the OP has a fairly new bike with a new chain, no no need to replace. Now, if you increase the front chainring you may need extra links. May be easier to buy a new chain at that point. But if you buy a smaller rear sprocket, that may be the cheapest way to get more speed/less cadence.

Anyway, Sunrace offers a 13-28, which gives you an approximatelyl 8% increase in speed. I'd probably look for a 12-28 (~17%), though. In another brand. Or even an 11-24 (~27%). Not sure what the freewheel threads are on a FX 7.1.

Getting more expensive, you could change cranks to get a larger front chainring, or find new chainrings that fit your crank to replace the old. Going from 48-38-28 to 50-40-30 gets you an additional 4% in top end. Then you may need a few extra links to your chain.

I'm 59 and weight 240 and I would spin out a 48/14 on regularly on my rides. Yesterday I hit 41mph (downhill, of course), which corresponds to a cadence of about 108 with a 53/11. Same cadence with a 48/14 is 29mph which my extravagant bulkitude* allows me to reach on many of the slight downhill grades. And I don't like spinning at 110. Much prefer 95-100 for most of the speedier intervals. So I understand the OP's feeling. Were I younger and in better shape, I'd go back to the 54 large ring.

And to the OP: you can use different freewheels with your Shimano Acera RD. When you get up into the 10 and 11 speed drivetrains, it becomes less interchangeable.

*There is some justice in the world in that the slow climb caused by being a large-body is compensated by the fast downhill. Wheee!

Keep in mind, you don't have a cassette, you have a thread on freewheel. Not the same as a cassette. Whatever you buy, make sure it is a freewheel, not a cassette, or it will not work. (BTW, this is one reason why when people ask me, I always suggest when people buy new, they go with a freehub/cassette rather than a freewheel, because if or when they decide to upgrade, they can, whereas most freewheels are lower end products.

The big gear is 93 gear inches, or 25 mph at 90 rpm cadence. If you are winded, your aerobic conditioning could be improved. Changing the gearing might improve things, but realistically, you can't make a silk purse out of a sow's ear. The upright riding position of the hybrid is the biggest thing that will slow you down, and if you can maintain 25 mph on a hybrid, you are a strong rider indeed. But as you already said, you get winded maintaining that speed,

If it is a freewheel, you might consider one of these DNP Epoch 7 Speed Freewheel > Components > Drivetrain > Freewheels | Jenson USA

choice of 11/28, 11/30 or 11/32

I would call myself a "strength" type bike rider. I usually do leg press workouts at 250lbs and can max out at around 500-550lbs. My cardio is laughable which is probably why I get winded at around 90rpm (that sounds about right). I track speed using a smartphone gps counter so I realize that that may have some inaccuracies.

Looks like my bike has a freewheel. Are there recommendations of freewheels that have lower teeth?

I didn't realize that this kind of speed was so difficult to achieve. Yes, I do regularly work out and like I said before I am mostly a "strength" type bike rider, if that makes sense. I'm definitely trying to improve my cardio, however, by riding for longer distances and really pushing my cadence. But it really sucks when I can't try as hard with my legs while I get winded on my bike. I'd like to be at around 70-80rpm most of the time, 60rpm if I want to ride comfortably. Also keep in mind that I said I could BARELY get to 25mph without feeling completely winded. I definitely do not regularly cruise at 25mph, but that would be a good goal to have! :)

Any freewheel recommendations? Is it ok to shop for different models of freewheels, or should I stick with Shimano? Is there any way to change out the freewheel without changing anything else (RD, chain, etc.)? I bought this bike used, but everything is in near new condition

Whether you mash or spin, Cycling is primarily an aerobic activity.

Thanks, I realized as more and more people told me that my bike has a freewheel instead of a cassette. Should have waited longer to see if I can find a deal on the FX 7.2 :(

:foo: :foo: How much lower teeth do you want than 11********** AGAIN, the link for freewheels with 11 teeth and up.....

DNP Epoch 7 Speed Freewheel > Components > Drivetrain > Freewheels | Jenson USA