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I initially bought a MTB which has 29x2.4" MTB tyres, then I noticed this is really hard to use on roads. My best average speed was 16Km/h from it.

Then I bought a second-hand 2016 Specialized Sirrus hybrid bike. The tyres are "Giant 700x28C" and the rear cassette is 12-21T (3X8 Shimano gears). The average speed increased up to 19.5Km/h. But this is from my fullest effort.

I'm more concerned with average speed. Can I increase my average speed more from this Sirrus bike by doing any modifications or shall I go for another bike to increase the average speed? For example, Giant Escape R3, Merida, etc...?

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    The first comment “28 tires should be narrow enough to give you pretty good performance -- just make sure they're inflated to sidewall pressure (if not a little over)” is so much against current so-called common knowledge it’s almost funny
    – ojs
    Commented Jul 14, 2022 at 15:45
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    (the comment above was response to a deleted comment with a link to similar question asked 10 years ago)
    – ojs
    Commented Jul 14, 2022 at 15:56
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    16km/h??? I can ride a unicycle at that pace. Sorry, the bike or the tyres surely aren't the problem. If you're sure that the indicated speed isn't in miles/h, then either your technique, or fitness are the problems. Keep on riding, it will get (much) better. Commented Jul 15, 2022 at 13:36
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    1) If you lift the front wheel off the ground and spin it, does it spin freely for a minute at least? How about doing the same for the rear wheel? Just to check the basic state of the bearings and that the brake pads are centred and not rubbing. 2) Does it seem difficult to walk the bike along when you're not on it? (Front/rear axle alignment in the other axes check.) Commented Jul 15, 2022 at 22:05
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    3) What is the intent of using the bicycle: is it for shopping, commuting, pleasure, or as an aid to fitness? If the latter, what sort of fitness? 4) What you call a road might be different from what other people call a road: are you talking about a smooth surface that you could skateboard on or something challenging to an agricultural tractor? Commented Jul 15, 2022 at 22:21

4 Answers 4

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You can certainly buy more speed with either new components or a new bike, but it wouldn't be my recommended course of action.

In terms of buying speed, aerodynamics and rolling resistance are the two key factors. You can certainly get some speed improvements (at the cost of puncture resistance) by changing to a high quality 28C road tyre. Likewise you could get significant speed improvements on your MTB by switching to a high quality XC race tyre.

However, the speeds you have mentioned indicate quite poor aerobic conditioning. I'd strongly recommend not spending more time and money looking for speed improvements through components and instead just ride your bike consistently and the improvements will come by themselves.

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  • Excellent Reply.Yes I spent lots of time on this.I guess the Giant Brand mentioned tyre was not so good than I think.There are much better tyres than this..!!
    – Joseph
    Commented Jul 14, 2022 at 16:03
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    I don't think the difference in tyre quality was intended to be the main take away from this answer.
    – Holloway
    Commented Jul 15, 2022 at 8:27
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First of all: Make sure your tyre pressure is high enough, but not too high. As a rough reference point: A 75kg cyclist with a 10kg bike on 28mm wide tyres needs around 4.2bars of pressure. You’ll need more if you are heavier, slightly less if you are lighter.

Second: Make sure your bike is properly maintained. This means the wheels spin freely (no brake rub, no bad bearings), shifting works properly and your chain is lubed and relatively clean.

Third: Make sure your seating position is good. This allows you to output the maximum amount of power and avoids overuse injuries. As a rough rule of thumb, if you place your heel on the pedal your leg should be fully extended when the pedal is in the lowest position.

Only after you’ve done those three things would I think about upgrades. There are three main factors: Rolling resistance (always important), aerodynamic drag (important at higher speeds, above ~25km/h) and weight (important for acceleration and when going uphill).

Rolling resistance is mainly determined by tyres. I don’t think Giant makes any really bad road tyres, so there is probably not much you can improve here.

A big part of aerodynamic drag is your seating position and clothing. This could be easy and cheap to optimize. You can probably lower your handlebars for a more aerodynamic position (if it’s okay for your hands and back). Wear tight fitting clothes. At your relatively low speeds it probably doesn’t make much sense to spend money on aerodynamically optimized components (like high-profile aero wheels).

As for weight: This is where you can spend a lot of money on lighter components. But first of all I’d make sure to remove unnecessary components. If you don’t need the rear rack or mudguards (I think the Sirrus comes with those), remove them.

Next time you buy a new bike, consider getting a road bike or gravel bike. They are usually much lighter and aerodynamic than a hybrid.

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  • Do you think Giant makes tires at all or that 28mm road tires existed in 2016?
    – ojs
    Commented Jul 14, 2022 at 22:06
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    @ojs I'm pretty sure there were 28mm tires back in the 1980's. Commented Jul 15, 2022 at 3:15
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    @Joseph that’s a great list of things that you can fix right now, and everything except clothing is free. There’s absolutely no reason to not learn to stop with saddle at correct height.
    – ojs
    Commented Jul 15, 2022 at 3:59
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    @Joseph that is true. It's a common beginner mistake to think that taller gear gives more speed for free, but as you found out it just gives different trade off between force and rotation speed. Too low saddle makes it just more difficult than it needs to be.
    – ojs
    Commented Jul 15, 2022 at 10:10
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    @Willeke: That’s why I wrote “If you don’t need them”. And some people are already on the lower end of normal weight and can’t lose any without worsening their W/kg.
    – Michael
    Commented Jul 15, 2022 at 16:27
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This is in response to some discussion in the comments, but deserved to be an answer:

Get the saddle height right, and get used to riding like that.

  • If you can put both feet down while still on the saddle at a stop, it's definitely too low.
  • If you can put one foot flat without quite a tilt it's probably too low (almost definitely on a hybrid).
  • A decent fit for a hybrid like that (or mine) will probably mean you can keep the bike upright with your toes on the ground. If you know you're stopping for longer, you can come off the saddle - I stand normally with the toptube between my legs and the saddle nose against my tailbone, when I know I can't go anywhere.
  • This isn't how you set saddle height, but describes where you're very likely to end up. Your leg should be almost but not straight at the bottom of the stroke.
  • You may want to work your way up in small increments rather than a big jump.

Note that this effect will be no better, and may even be worse, on a "faster" bike.

Even 1-2cm (less than an inch) makes a big difference. I know because I consciously set my saddle that much too low when I had a child seat on the back, for stability with a high centre of gravity. Any lower than that and you're working far harder than you should be. This is a bigger effect than flappy clothing (I commute in bike lycra sometimes, sports kit other times, and there's no real difference in speed in urban traffic).

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  • Note that if you really need to be able to put both feet down and stay on the saddle, there are city bikes with a much larger seat tube angle. I saw some in Intersport in France a few years ago. They didn't look built for speed so probably wouldn't help you. The classic shopping bike style is a step in this direction
    – Chris H
    Commented Jul 15, 2022 at 12:51
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    A dropper post might be a good choice in that case. The ones with a lever under the saddle would work fine.
    – MaplePanda
    Commented Jul 15, 2022 at 17:19
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    @MaplePanda good thinking. Overkill for me personally, but could be the solution. Or on the other hand an extra thing to fiddle with in stop start traffic
    – Chris H
    Commented Jul 15, 2022 at 18:48
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First and foremost, look at what you can do without spending money.

The two biggest things here are tire pressures, and seating position.

Tire pressure has a significant impact on rolling resistance, which in turn impacts effective acceleration and top speed. Most MTBs run low tire pressures, because they need the large ground contact area this creates when riding on the trails they were designed for, but using the same pressure on a road will just make things more difficult for you. Even just 10-15 PSI difference in pressure can have a huge impact on things (for example, I average about 2-4 km/h faster on the hybrid 3-speed I use as a commuter when running at 60 PSI (the max rating on the tires) compared to 45 PSI (the minimum rating on the tires)).

Seating position is more a matter of efficiency of your own body. Too high or too low, and you can’t use your leg muscles as efficiently. The general recommendation I typically use to get things close is that your leg should end up almost but not quite straight at the bottom of the stroke when pedaling. On a hybrid at least, this will usually mean you cannot put more than one foot flat on the ground when stopped and will have to tilt the bike to put that one foot flat. Getting this right will not only improve your average speed, but also help you be more comfortable while cycling.

Additionally to that, double check your wheel bearings and brake alignment. With each wheel lifted off the ground, you should be able to spin it freely and should hear no rubbing from the brake pads. If you do see issues here, you may need to spend some money to fix them, but checking is definitely free.

Beyond all that, the next biggest thing is probably how fit you are. This has a much bigger impact than many newer cyclists seem to think, but the plus side is that it will improve over time without needing significant effort from you. Over the past year since I started cycling again, I’ve increased my average speed by about 5 km/h without even really trying, and that’s with me cycling on average no more than 10 km a week. I’m bringing this up specifically because your quoted 19.5 km/h average is really low even for a big clunky hybrid with low tire pressures, and suggests that you’re not in the best condition (for reference, I manage about 22.5 km/h average on the hybrid 3-speed I use as a commuter, and that’s even with the fact that I have a lot of scar tissue in my lungs).

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