Thorn Cycles Forum
Technical => Wheels, Tyres and Brakes => Topic started by: ianshearin on February 10, 2021, 09:11:51 PM
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Hi all,
Long time since I posted here, not sure why.....
I am the proud owner of a Mercury which I picked up several months ago and hoping to do a JOGLE when it's possible (crossed fingers for June)
It came with tubeless tyres but they were a bit worn and I ended up changing them to tubes with 700c x 32 for winter riding (I'm in UK)
To be honest I am a little worried about the miles I will put in each Day as I'm not getting any younger ;p...
Do you think it will make life easier, i.e. get more miles in per day for the same time if I swap to 700c x 28's ?
Ian
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I ended up changing them to tubes with 700c x 32 for winter riding (I'm in UK)...Do you think it will make life easier, i.e. get more miles in per day for the same time if I swap to 700c x 28's ?
In a word..."No". :)
In my experience, the wider tires will have you ending each day less fatigued because the larger volume tires can be run at reduced pressure for greater comfort. In any case, I don't think they will hold you back.
I use the Android Berto Tire Pressure app to adjust my tire pressures for load and riding position (the app extends the work of the late US petroleum engineer and bike magazine technical editor Frank Berto. In numerous interviews with bicycle tire engineers, he found the "sweet spot" between rolling resistance and comfort came from tire pressures that allowed a 15% drop in rim height under load). It works well for my needs and has indeed resulted in a measured 15% rim drop for me under stated loads. For comparison, here are some figures for identical loads and on-bike position for 25mm vs 28mm vs 32mm tires (by actual measured mounted width):
25mm: F: 84psi R: 105psi
28mm: F: 70psi R: 87psi
32mm: F: 58psi R: 71psi
Wrt to reduced vibration helping with increased comfort and endurance, I fitted my two primary randonneur bikes with Thudbuster ST suspension seatposts and found myself ending my 300-400km day rides feeling more refreshed. Completion times were about the same for similar conditions, but I felt better After -- less achey and fatigued -- especially if the roads were rough/chip-sealed or included gravel.
For reference, I'm nearly at my 61st birthday. Impressions from a 321km ride in January 2020 as almost no riding after 1 February due to Covid and restrictions for same. Still haven't recovered my pre-Covid breathing capacity and have ongoing symptoms.
Best,
Dan.
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due to Covid
Ach, Dan, sorry to hear that you got hit. It's a nasty business for sure. Seems like recovery is often slow... get rest, what can a person do?!
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"For reference, I'm nearly at my 61st birthday" mere spring chicken ! :)
Get well soon.
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I'm at least as fast (Or slow) on my Mercury with 35f - 40r Schwalbe Supremes as I am on any other bike with any other tyre, so much so that I sold my dedicated Audax bike a couple of years ago because the 28's were not adding any benefit. I've ridden several consecution 100 mile days and a few Audax up to 400km on it and some lightweight touring. I'm not claiming to be the fastest, but that isn't about the bike.
That's not to say that someone else might not be faster or more comfortable on something else. I sometimes ride with someone who thinks 28's are unnecessarily wide! There's only one way to be sure and that's to try, luckily tyres are cheap enough to experiment with. But as they say, size isn't everything. What 32's are you using? Tyres have changed over the last few years, it used to be an assumption that if you wanted wide then speed wouldn't be a high priority. We have the popularity of Gravel and adventure style bikes to thank for the increased range.
Good luck with the E2E.
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My own attempt to extrapolate from Berto's scheme: https://interdependentscience.blogspot.com/2019/11/rotta-model-for-bicycle-tires_38.html (https://interdependentscience.blogspot.com/2019/11/rotta-model-for-bicycle-tires_38.html).
Narrow tires at high pressure are better on smooth surfaces, especially for track racing. The rougher the surface, the wider you want the tire and the lower pressure. For sure the suspension will shake you less so you feel less fatigue. But the shaking absorbs energy from your forward motion. The bike will roll more efficiently when there is enough suspension to reduce the amount of shaking.
The biggest thing with tires is the construction. The tire flexes where it hits the road. If the flexing absorbs energy, that will slow you down. If the flexing is low friction, then you'll roll easy. I just switched from Marathon Plus to Marathon Supreme. The Supremes flex with much less friction. Quite a nice change... now if I just don't pay for it with flats!
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For reference, I'm nearly at my 61st birthday. Impressions from a 321km ride in January 2020 as almost no riding after 1 February due to Covid and restrictions for same. Still haven't recovered my pre-Covid breathing capacity and have ongoing symptoms.
Sorry to hear that Dan, hope you recover well.
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See page 33 onwards of the Thorn bible http://www.sjscycles.com/thornpdf/thorn_mega_brochure.pdf. One reason I bought my Mercury was that it came with 50mm wide tyres which definitely help with comfort and a bit of bounce makes the rough surfaces of an increasing proportion of UK roads much more bearable. The thought of spending all day riding on hard narrow tyres horrifies me. I would be thinking in terms of the widest tyres with good rolling resistance which would fit the frame.
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Do you think it will make life easier, i.e. get more miles in per day for the same time if I swap to 700c x 28's ?
Probably not. I've recently swapped from 35 mm to 42 mm (manufacturer's size, the real sizes are slightly smaller) on my Raven Sport Tour. As far as I can tell I don't go any slower, but the bike is significantly more comfortable. I go further when I am comfortable.
In a given size the model of tyre can make a lot of difference. The 700c x 28 Schwalbe One tyres on my old derailleur bike are both faster and more comfortable than the (already reasonably good) 700c x 28 Michelin tyres they replaced. But if I ever need to replace these Schwalbe One (I no longer use this bike much) I will be getting the fattest lightweight tyre I can fit, probably 32 or 35 mm.
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I've recently swapped from 35 mm to 42 mm (manufacturer's size, the real sizes are slightly smaller) on my Raven Sport Tour. As far as I can tell I don't go any slower, but the bike is significantly more comfortable. I go further when I am comfortable.
My bike was purchased (used) with 622-32 tyres on it. Switching to 622-40 has added so much comfort . I was getting lower back pain at around 12km on my daily ride with the boneshaker thinner tyres and the wider tyres gave comfort without noticeable loss of speed and the back pain is gone on my 16km commute and rarely surfaces any more even on longer rides.
At moment I’m riding spikes, which do slow me down, but even then not that much. But with 622-42 these still give a comfortable ride if you can ignore the spike noise and slightly higher rolling resistance.
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In my opinion. 28mm will make the ride easier.
John
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In my opinion. 28mm will make the ride easier.
John
I guess it depends on what easier means to you, and as well as the way your bike is set up, e.g. with/without suspension, saddle type/ height etc.
If easier means more comfort and perhaps a slight loss of speed due to extra weight and rolling resistance, wider might be easier if you reach your goal still feeling good.
If easier means reaching goal in shortest time and comfort is less of an issue (or you are someone lucky enough not to feel the bumps as much as others) then a narrower tyre may well be easier and better suited for such needs.
Now, what frame colour is the most comfortable on the eyes 8)
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In my opinion. 28mm will make the ride easier.
John
I guess it depends on what easier means to you, and as well as the way your bike is set up, e.g. with/without suspension, saddle type/ height etc.
If easier means more comfort and perhaps a slight loss of speed due to extra weight and rolling resistance, wider might be easier if you reach your goal still feeling good.
If easier means reaching goal in shortest time and comfort is less of an issue (or you are someone lucky enough not to feel the bumps as much as others) then a narrower tyre may well be easier and better suited for such needs.
Now, what frame colour is the most comfortable on the eyes??? 8)
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Thanks all for the informed replies.
Hope your feeling better Dan.
I have schwalbe Marathon Tyres which I am happy with, so looking at the advice I will stick with them.
I might experiment a little with the tyre pressures though looking at Dans post.
Ian
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Just looking at those Thudbuster Seatposts Dan referenced, never really knew about them but they look like a good purchase for my ride.
Will the Thudbuster ST sold on the SJS site fit my Mercury?
Ian
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I have schwalbe Marathon Tyres which I am happy with, so looking at the advice I will stick with them.
If they're the standard Marathons, they're quite slow, that's both my experience and shows up in testing. They have other attributes so may still be your choice, but the same size in a different tyre such as a Supreme will be make more difference than the same tyre in a different size.
The Berto testing that Dan linked to is quite old and although it makes a decent starting point it doesn't take fully into account the way tyres have developed. There's isn't enough weighting given to the way a tyre reforms and the energy it absorbs in doing so, the effect of suppleness as it's often described. It isn't mistaken, it's just there's more variation in tyre construction. You might find this makes interesting reading
https://www.renehersecycles.com/how-wide-a-tire-should-i-ride/
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Just looking at those Thudbuster Seatposts Dan referenced, never really knew about them but they look like a good purchase for my ride.
Will the Thudbuster ST sold on the SJS site fit my Mercury?
Ian
Mercury is 27.2 seatpost so the answer is probably yes.
But the Mercury is an extremely comfortable frame, if you think the comfort of yours needs improving, then wider tyres ought to be top of the list.
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I have schwalbe Marathon Tyres which I am happy with, so looking at the advice I will stick with them.
I might experiment a little with the tyre pressures though looking at Dans post.
Schwalbe Marathon are quite a good tyre, but there are others in the same 700C x 32 size that roll better.
Continental Grand Prix 5000 is supposed to be very free rolling, while retaining a degree of puncture resistance, but would be more fragile than your current tyres. I reckon I would be OK with these with a lightly loaded bike on good road surfaces, they are rated better, for both rolling resistance and puncture resistance, than the Schwalbe Ones I currently have on my old derailleur bike.
While a lot heavier than the Continental Grand Prix 5000, the Schwalbe Marathon Supreme is significantly lighter than the standard Marathon, with less rolling resistance and (in my experience in other sizes) good puncture resistance and durability. I have Supremes on several bikes, but in fatter sizes than 700C x 32. I noticed the improvement in comfort and rolling resistance when going from standard Marathons to Supremes on my old utility bike (650B x 42).
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In my opinion. 28mm will make the ride easier.
John
I guess it depends on what easier means to you, and as well as the way your bike is set up, e.g. with/without suspension, saddle type/ height etc.
THORN cycles are not fitted with suspension! 28mm tyres roll better than 32mm tyres in my opinion as a long time Thorn cycle owner/user of some knowledge,
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THORN cycles are not fitted with suspension! 28mm tyres roll better than 32mm tyres in my opinion as a long time Thorn cycle owner/user of some knowledge,
Opinion is always interesting, but I prefer to hear about experience.
Maybe you'd say what your opinion is based on? Which wider tyres have you used and how did you find them? Have you used any of the more recent ones? How do you think they compare with wider tyres from a generation ago? I'm not suggesting you shouldn't express your opinion, but unless you say what it's based on, it can only be treated as theory.
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In my opinion. 28mm will make the ride easier.
John
I guess it depends on what easier means to you, and as well as the way your bike is set up, e.g. with/without suspension, saddle type/ height etc.
THORN cycles are not fitted with suspension! 28mm tyres roll better than 32mm tyres in my opinion as a long time Thorn cycle owner/user of some knowledge,
I am not a Thorn owner, but a Rohloff rider on other brand with suspension fork. I also have a non suspension 28“ trekking bike and a 26“ non suspension MTB bike and have experimented with a number of tyre sizes over the years.
I don’t dispute that a Thorn will have its own riding dynamics which will be different from my bikes. But it is feasible that two Thorn owners with same model bike will have customised their bikes to suit their riding preferences. I don’t know if a suspension fork can be added, but certainly seat post suspension or sprung brooks seat would give different riding dynamics and perceived feel while riding same tyres on a bike with fixed saddle post and gel saddle as an example.
Apologies if I have offend you or other Thorn users by sharing a general biking opinion which is true at least for my 3 non Thorn bikes on what makes for easier riding. For me easier remains a combination of speed and of comfort and trying to get a balance between the two.
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Thanks guys, what a wealth of information there is on these Forums.
I have decided on the following plan:
I will stick with 32 and look at some other options for tyre make and model.
I won't bother with a thudbuster, they are expensive and I'm just not sure they are for me.
I have decided to get a professional Bike fitting, there is place not far from me.
I will Train as much as I can on putting the miles in before the trip so as to find out where my weaknesses are.
I will stop watching youtube videos of Cats...
Ian
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Sounds like a good plan, though there's always time for videos of cats.
I had a bike fitting about twenty years ago, I found it very worthwhile, it made some changes to my riding position that I wouldn't have made for myself. I wasn't immediately convinced, I had to be persuaded not to change them straight back, I'm glad I didn't as that information has been the basis of all my bike set ups since.
A couple of years ago, I also had a go at re-doing it with some instructions I'd read. I came to pretty much the exact same conclusions. You might find them useful
https://wheel-easy.org.uk/wp-content/uploads/bike-set-up-2017a.pdf
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Thanks PH, thats an interesting text.
Ian
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Here is an interesting link comparing rolling resistance of same model tyre across different tyre width. It is not just the width of tyre but the air pressure you pump it to that make some results suggesting narrow is not always least rolling resistance.
https://www.bicyclerollingresistance.com/specials/schwalbe-marathon-32-37-40-47 (https://www.bicyclerollingresistance.com/specials/schwalbe-marathon-32-37-40-47)
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THORN cycles are not fitted with suspension! 28mm tyres roll better than 32mm tyres in my opinion as a long time Thorn cycle owner/user of some knowledge,
Opinion is always interesting, but I prefer to hear about experience.
Maybe you'd say what your opinion is based on? Which wider tyres have you used and how did you find them? Have you used any of the more recent ones? How do you think they compare with wider tyres from a generation ago? I'm not suggesting you shouldn't express your opinion, but unless you say what it's based on, it can only be treated as theory.
I am certainly not 'one' who is a 'nerd' and so experience is experience. I wrote of my experience. My life has never had time like you and another couple of 'nerds' of this Forum to spend day upon day spouting statistics!
Get a life....