Putting smaller tires on a Hybrid Bike

Last summer I purchased a Specialized Sirrus Hybrid bike. There are currently 700x32c tires on the bike. Someone had recommended that I would notice a significant difference if swapped the original tires out for 700x28c tires, and still be able to keep my current rims. I was told that if I went down to as far as 700x25c tires, I would be "pushing it," and would have to purchase new rims as well. I'm not sure what was meant by "pushing it." If it means having such small tires could damage frame, then I definitely do not want to go with the 25s. What would be the best option? Sadly, purchasing a road bike would not be feasible at this time. Maybe down in future when I have more funds and space to have both bikes. Also, I would rather not trade in my current bike toward a road. It was a wedding gift to myself and it's my companion.

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Permalink Reply by Far'arned Retrogrumpalunkus #63 on February 24, 2012 at 1:29am

Road bikes accellerate faster because of the difference in the position of the rider and the geometry of their legs and upper body with relation to the cranks and the bars.  There is a give and take between comfort and efficiency in pedaling where the road bike is slanted in one direction and the hybrid toward the other.   This fact has more to do with such acceleration differences than tire size or even the weight/design of the wheel/tire/rotating mass on the two bikes which is mostly coincidental. 

Sheldon went into this many times during his writing career.  

Putting road bike tires on a hybrid bike is NOT going to make it accelerate like one.  In order to be able to put the kind of power to the cranks that produces road-bike-like acceleration one is going to have to put up with road-bike-like riding stance.  This is simple physics. 

If you want a more comfortable upright-type seating position then you are going to have to give up some pedaling efficiency and that will show up in the fact that comfort bikes just don't accelerate very fast.  You can put all unobtanium components and race wheels on a hybrid bike and get the weight down to 15lbs and a 30lb 70's tank K-mart road-bike will still accelerate faster with the drop bars down low and the rider in a position to be able to pull up on the bars and put her legs under her to really crank on the pedals. 

Permalink Reply by Melanie K on February 24, 2012 at 1:59am

I'm not a technical expert, but just from practical experience, I have a hybrid that came with 38 x700 tires. I thought it would be nice to go a little faster and was told go to a skinnier tire, so I went with 32 x700  (still fat, but not as fat as I had). The ride was harsher and only a tiny bit faster than with the 38's. I then decided to put on some 35x700 cross tires (knobby on the edges/flat in the middle)- surprise surprise, the ride is actually smoother, overall nicer, and the bike even seems a bit faster.  I don't expect to be racing with road bikes as I have a hybrid, but I am happier with the performance of the 35s, the grip and cushier ride for commuting, and once in a while I even can keep up with the "fast" bikes out there.

Permalink Reply by koala on February 24, 2012 at 2:50am

I think Michael A had it right -- going to smaller tires can help a bike feel "snappier" because the tires have less mass.  It's not so much a rolling resistance/top speed issue as it is an effort-to-get-up-to-speed issue.  Smaller tires, smaller tubes, less rotating mass all reduce the effort it takes to get up to speed, making the bike feel quicker, even if top speed is unchanged.  

To the OP -- If you change down a size or two, but the new tires are just as heavy or heavier than your current ones, you might not be pleased with the change.  Go lightweight before you go narrow.

Permalink Reply by Tony Adams on February 24, 2012 at 3:41am

This is a great point! Moving to slicks (or something relatively slick) from knobbies will make a much larger different than moving down a few sizes in width. And increasing psi - which, has been noted already, will cost you some comfort. I always get tires that can handle 100 psi - I pump them up to that once every few weeks, but in between the pressure falls as low as 60 sometimes - the difference is HUGE.

Melanie K said:

I'm not a technical expert, but just from practical experience, I have a hybrid that came with 38 x700 tires. I thought it would be nice to go a little faster and was told go to a skinnier tire, so I went with 32 x700  (still fat, but not as fat as I had). The ride was harsher and only a tiny bit faster than with the 38's. I then decided to put on some 35x700 cross tires (knobby on the edges/flat in the middle)- surprise surprise, the ride is actually smoother, overall nicer, and the bike even seems a bit faster.  I don't expect to be racing with road bikes as I have a hybrid, but I am happier with the performance of the 35s, the grip and cushier ride for commuting, and once in a while I even can keep up with the "fast" bikes out there.

Permalink Reply by Duppie on February 24, 2012 at 3:49am

Interestingly, nobody has asked yet which specific tire you have on your bike. The tire itself makes all the difference. Compound, weight, sidewall structure, etc. all play a big role.

If you have a tire with more than just a cosmetic thread and you go to a tire without any thread like a Marathon Supreme, I bet you will notice a difference, even without going to a narrower tire.

 

Also, like everything else, you get what you pay for. You pay more money, you get tires with better compounds, lighter weight, better flat protection etc.

 

My standard tire these days is a Marathon Supreme. I have them on every bike, except my beater. None of them is narrower than 35C. They are expensive but are comfortable, light weight, smooth rolling, and provide excellent grip on wet pavement.

 

 

Permalink Reply by Lanterne Rouge on February 24, 2012 at 4:31am

I ride 23C all the time without many problems. I guess it's a personal comfort thing? Actually, I don't think my Jamis can accept 25C, as the chainstay is stupidly narrow.

 

My Trek 7.3 FX feels like a luxury Cadillac compared to my Jamis, due to the upright geometry and 32C tires. I have to put WAY more effort into going very fast as compared to my road bike. For a long time, I thought that if I put smaller tires on, I'd go faster. But, after reading about all the things James mentions in his post, I understand that it's not the tires, but the overall bike. I may put some 25C or 28C tires on my Trek just for fun after my Bontragers wear out, though.

Permalink Reply by Matt Talbert on February 24, 2012 at 5:57am

Thank you everyone for your helpful feedback! Seems like 25s would be completely unnecessary, and per a few comments, 32s or 28s would be just fine if the treads are right for the streets of Chicago. I guess I could also look into a few more aftermarket alterations that were mentioned, such as a drop down handlebar. I plan to attend the bike swap on next weekend. Perhaps I'll make some alterations and get some more tips.

Tony Adams said:

This is a great point! Moving to slicks (or something relatively slick) from knobbies will make a much larger different than moving down a few sizes in width. And increasing psi - which, has been noted already, will cost you some comfort. I always get tires that can handle 100 psi - I pump them up to that once every few weeks, but in between the pressure falls as low as 60 sometimes - the difference is HUGE.

Melanie K said:

I'm not a technical expert, but just from practical experience, I have a hybrid that came with 38 x700 tires. I thought it would be nice to go a little faster and was told go to a skinnier tire, so I went with 32 x700  (still fat, but not as fat as I had). The ride was harsher and only a tiny bit faster than with the 38's. I then decided to put on some 35x700 cross tires (knobby on the edges/flat in the middle)- surprise surprise, the ride is actually smoother, overall nicer, and the bike even seems a bit faster.  I don't expect to be racing with road bikes as I have a hybrid, but I am happier with the performance of the 35s, the grip and cushier ride for commuting, and once in a while I even can keep up with the "fast" bikes out there.

Permalink Reply by Far'arned Retrogrumpalunkus #63 on February 24, 2012 at 6:19am

Going from MTB-type bars to drops will create some issues with lever/shifter compatibility.  Drop levers can be found quite reasonably but it'll be tougher to get thumbies to fit on the road bar, twist-shifters are out, and going to road levers may cause issues with your front MTB derailleur if they are indexed.   Talk to your mechanic at your LBS and he can fill you in on the options and things you will need to change to do this.  It's not impossible but sometimes it can get pricey. 

Permalink Reply by Kevin C Dormant on February 24, 2012 at 6:28am

I'd also caution you about trying to turn a particular type of bike into something it's not. I got my first hybrid in December 2008, and I love it. It's not a racing bike, it's not a touring bike and it's not a mountain bike. It's a terrific commuter, grocery-getter, errand-runner and while capable of longer distance group rides at faster speeds, it's not particularly well-suited for those types of rides. 

Permalink Reply by Matt Talbert on February 24, 2012 at 7:53am

That is indeed true. I certainly do not want to do anything to cause damage to the frame or relinquish all comfort. The bike is perfect in that it's fulfills my need for transportation and recreation. However, I wouldn't be against just a few tweaks to increase some speed, but I don't need to convert this into a racer. How insane would it be to have two sets of tires? Perhaps a winter set and a summer set?

Kevin C said:

I'd also caution you about trying to turn a particular type of bike into something it's not. I got my first hybrid in December 2008, and I love it. It's not a racing bike, it's not a touring bike and it's not a mountain bike. It's a terrific commuter, grocery-getter, errand-runner and while capable of longer distance group rides at faster speeds, it's not particularly well-suited for those types of rides. 

Permalink Reply by Kevin C Dormant on February 24, 2012 at 8:33am

Lots of people do two or more sets of tires. I have three sets of tires for my mountain bike; i.e. wide knobbies, wide slicks, and narrow slicks. There are certainly also people who have multiple wheelsets for their bike(s) though this is more often a set for training vs. a set for racing.

The question that only you can answer is how much money are you willing to spend turning this bike (and you haven't mentioned which Sirrus model you have; $400 or $900?) into a facsimile of another kind of bike. 

I think your money would be better spent waiting until you can afford to get a used version of the different type of bike that you covet. 


Matthew Talbert said:

That is indeed true. I certainly do not want to do anything to cause damage to the frame or relinquish all comfort. The bike is perfect in that it's fulfills my need for transportation and recreation. However, I wouldn't be against just a few tweaks to increase some speed, but I don't need to convert this into a racer. How insane would it be to have two sets of tires? Perhaps a winter set and a summer set?

Kevin C said:

I'd also caution you about trying to turn a particular type of bike into something it's not. I got my first hybrid in December 2008, and I love it. It's not a racing bike, it's not a touring bike and it's not a mountain bike. It's a terrific commuter, grocery-getter, errand-runner and while capable of longer distance group rides at faster speeds, it's not particularly well-suited for those types of rides. 

Permalink Reply by Matt Talbert on February 24, 2012 at 8:52am

Well I don't need to go bananas. I'll shop and chat about tires at the swap next week and see what I can get that will work with the rims I already have, or maybe determine that I don't need new tires at all. I don't think I need to buy new wheels. Seems like the bike swap could be a good opportunity to find what I might be searching for at a good price.

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