Flexible gravel/road bike - 38c to 25c - Will I really notice the difference?

aarondown

I have a gravel/tourer bike that was built for me last year as a new commuter (having used my old hardtail for the preceeding 20 years!).

The spec is:
Light Blue Darwin frame -https://www.thelightblue.co.uk/Sport/FMLBDD1K/Darwin-Frame-Set (link is external)
Wheels - 29" Halo Vapours - https://www.ison-distribution.com/engli ... t=WHHAV9SK (link is external) - with a dynamo on the front to power lights
Tubeless Schwalbe 38c G-One tyres
Shimano S106 hydro disc brakes
Compact 11 cassette with twin chainrings

I love the bike as I can pretty much take it anywhere without worrying about it. However, I've started to do some sportives, the longest of which was 80 miles and I'm considering whether I could improve my setup with a second set of more road-specific wheels which I'd switch out for sportives or other long road rides.

Within my budget this tubeless setup is available:

Wheels - https://www.ison-distribution.com/engli ... =WHHAWDF7K (link is external)
Tyres - Probably Schwalbe Pro-One 25 Discs and cassette to match the existing

The question is - am I going to see much difference by switching the wheels, tyres and the loss of dynamo etc? It's not an insignificant amount of money and I want to be sure I'll be glad to have spent it.

imposter2.0

You can obviously ride sportives on any bike, but if you are planning on doing more of that type of event in the future, I'd be thinking seriously about buying a more road-focused bike.

aarondown

I won't be doing enough of them to justify yet another bike. At max it will be 1 a month but probably more like 1 every 2 months.

veronese68

I've no interest in doing sportives but I've ridden a 200km audax on my cross bike with either 28mm or 32mm tyres on it. Can't remember what it had on at the time. I'm usually running 32mm Vittoria Voyager Pro Hyper and find they roll plenty fast enough for me and are comfortable with plenty of grip. The bike will be fine with something like that on.

aarondown

Thanks @Veronese68. I think we're departing from the question somewhat. Simply switching my 38 tyres for 32 isn't gonna do much, I'm pretty confident on that. Plus my 29er rims probably wouldn't take it.
I figure I need to make a reasonably large change (hence the new wheels and tyres without the dynamo etc) to justify the money, time, effort. My rough calcs suggest a saving of around 500g in weight and I imagine much less rolling resistance from 25c tyres BUT is this going to be that noticeable on a steel framed bike? Having ridden MTBs exclusively for 25years I just don't know what affect these sort of changes make as in the past I've just found a steeper hill if I want to go faster!

veronese68

aarondown wrote:

Thanks @Veronese68. I think we're departing from the question somewhat. Simply switching my 38 tyres for 32 isn't gonna do much, I'm pretty confident on that.

It's not the weight or size of the tyres but the type of tyre that will make the biggest difference, and switching tubeless tyres is a pain in the aris so get a spare set of wheels. I just changed from a pair of CX tyres at 30psi to the road tyres mentioned above at 80psi, both at 32mm and the difference is marked. Tyre pressure accounts for some of that I grant you, but tread pattern and tyre construction also makes a difference. No need to go as thin as a 25mm, that's not the biggest difference. Go for something a bit bigger enjoy the comfort and you won't have to worry about every little bump.
With regards to the 500g difference, weigh a full water bottle. It'll help a bit, but in the great scheme of things...

kingdav

I've kind of gone the other way round.
Previously I had 25mm tyres on both my old allez beater and my carbon sunday special
I put a hyrdaulic disk commuter together based on a caadx frame and have 2 sets of wheels, one with 32mm road tyres and the other with 31mm cx knobblies.

The difference in feel is quite marked, I feel slower on the 32mm road tyres than I do on the more focused road frames with 25mm tyres, but I'm not convinced I actually lose much in time (i.e. I can still keep up with friends). I feel it much more noticeably so on the cx tyres. On the cx tyres I feel the additional effort required and I'm sure I am actually slower because I can't keep up with a mate on his road bike like I can on the 32mm road tyres. So - even though the cx tyres are rated narrower at 31 mm they are slower than 32 road tyres.

Hope this ramble helps!

roger_merriman

aarondown wrote:

I have a gravel/tourer bike that was built for me last year as a new commuter (having used my old hardtail for the preceeding 20 years!).

The spec is:
Light Blue Darwin frame -https://www.thelightblue.co.uk/Sport/FMLBDD1K/Darwin-Frame-Set (link is external)
Wheels - 29" Halo Vapours - https://www.ison-distribution.com/engli ... t=WHHAV9SK (link is external) - with a dynamo on the front to power lights
Tubeless Schwalbe 38c G-One tyres
Shimano S106 hydro disc brakes
Compact 11 cassette with twin chainrings

I love the bike as I can pretty much take it anywhere without worrying about it. However, I've started to do some sportives, the longest of which was 80 miles and I'm considering whether I could improve my setup with a second set of more road-specific wheels which I'd switch out for sportives or other long road rides.

Within my budget this tubeless setup is available:

Wheels - https://www.ison-distribution.com/engli ... =WHHAWDF7K (link is external)
Tyres - Probably Schwalbe Pro-One 25 Discs and cassette to match the existing

The question is - am I going to see much difference by switching the wheels, tyres and the loss of dynamo etc? It's not an insignificant amount of money and I want to be sure I'll be glad to have spent it.

Can’t really say about Dynamos drag though I thought it was quite low now?

I have a Norco Search Gravel bike, with GravelKing SK 32/35mm tyres which are reasonably similar to the G-ones. I’ve found that that bike with those tyres is at worse equal to the road bikes I had with full on road tyres. In terms of speed, measured.

Quite different feel really, I personally like that the wider gravel tyres ride out potholes and what not, and cope with rougher roads much better, equally more rubber on road makes them feel much more sure footed. But road bike tyres do have that zing, and different feel.

DeVlaeminck

Yes I reckon your plan to get different wheels with 25mm tyres is a good one. I certainly notice a huge difference between my Croix DeFer with 38mm hyper voyagers (didn't realise quite how wide that was!!) and my road bike with 25mm Open Corsas. In fact it's only about 2mph but it feels huge!

aarondown

DeVlaeminck wrote:

Yes I reckon your plan to get different wheels with 25mm tyres is a good one. I certainly notice a huge difference between my Croix DeFer with 38mm hyper voyagers (didn't realise quite how wide that was!!) and my road bike with 25mm Open Corsas. In fact it's only about 2mph but it feels huge!

Thanks for your thoughts. I do love the feel of my g ones but 2mph over 80 miles makes a pretty big difference.

aarondown

roger merriman wrote:

Can’t really say about Dynamos drag though I thought it was quite low now?

My LBS that fitted it reckoned it usually feels like going up about 1 tyre size. I hadn't been riding the bike long before I decided to switch the hub to a dynamo so it was hard to judge the difference tbh.

antonyfromoz

your bike looks to be very similar to my commuting/do everthing bike, which is a Norco Indie Drop steel frame which I have fitted with halo vapour 29er wheels. My advice would be to firstly try fitting a set of good folding 28mm tyres to the wheels you have to see if that gives you at least some of the benefit you are looking for. Should you wish to get another set of wheels after that then you can still use the tyres so there is minimal risk. I have been riding with more gravel oriented tyres for a while - 32mm MSO Xplor on the front and a 35mm Gravel King on the rear at the moment - but this is just to cope with mud, leaves and grass shortcuts as well as allowing me to try some bridal paths if I get the urge. In the past i have used 28mm tyres on the same wheels and they do definitely feel faster but I have never tried to test this.Incidentally, the vapours are not really very heavy and are available as single wheels rather than as a set so why not just buy a single wheel to replace the one with the dynamo hub so you can swap it out for the sportives as required?

aarondown

kingdav wrote:

I've kind of gone the other way round.
So - even though the cx tyres are rated narrower at 31 mm they are slower than 32 road tyres.

Surely that's due to the massive difference in rolling resistance of knobblies vs slicks no?

aarondown

antonyfromoz wrote:

My advice would be to firstly try fitting a set of good folding 28mm tyres to the wheels you have to see if that gives you at least some of the benefit you are looking for.

This is a very messy process with tubeless (plus wasted sealant each time), and my LBS is recommending against putting anything much narrower on those rims.

antonyfromoz wrote:

Incidentally, the vapours are not really very heavy and are available as single wheels rather than as a set so why not just buy a single wheel to replace the one with the dynamo hub so you can swap it out for the sportives as required?

I agree, the wheel weight difference between the vapours and the white lines is quite low, most of the 500g is in the tyres. However, running a 25/28 up front and a 38 on the back will be a bit odd I think.
Essentially, I'm thinking go for biggest improvement I can in one hit, rather than trying small incremental ones that probably don't represent much value for the regularity of long rides that I do.

aarondown

oxoman wrote:

You would be better running 28s as a bit more comfortable than 25s. I would imagine the weight difference would be noticeable as well.

Thanks, that seems like a good compromise. I've just never ridden a full-on road bike more than 100m round a cul-de-sac so this is all new territory for me!

veronese68

aarondown wrote:

kingdav wrote:

I've kind of gone the other way round.
So - even though the cx tyres are rated narrower at 31 mm they are slower than 32 road tyres.

Surely that's due to the massive difference in rolling resistance of knobblies vs slicks no?

Yes, type of tyre and pressure makes the biggest difference. I'd go with at least a 28 though as speed difference is debatable and a bit of extra comfort after a long day in the saddle is something you will really appreciate.

stavgold

This is an interesting article
https://janheine.wordpress.com/2018/01/ ... re-slower/

I’ve been using compass 38mm tyres for a couple of years now for club runs. Not slower but very comfortable and more grip. I run them at about 40-50psi

aarondown

Stavgold wrote:

This is an interesting article
https://janheine.wordpress.com/2018/01/ ... re-slower/

I’ve been using compass 38mm tyres for a couple of years now for club runs. Not slower but very comfortable and more grip. I run them at about 40-50psi

Very interesting. Some of their 'myth-busters' seem more theoretical and anecdotal but this one does seem to be backed up by quite a lot of their own physical research. Although I do question the comments on the weight difference being minimal, my 38mm G-ones are almost twice the weight of a 25mm Pro-One.

However, definitely food for thought, thanks. I'm a sucker for decisions based on actual tests/quantifiable experience, as opposed to anecdote and theory.

kingdav

aarondown wrote:

kingdav wrote:

I've kind of gone the other way round.
So - even though the cx tyres are rated narrower at 31 mm they are slower than 32 road tyres.

Surely that's due to the massive difference in rolling resistance of knobblies vs slicks no?

Yes, agreed, just reinforcing the point that the type of tyre and tyre choice within the type might well have more impact than the width measurement.