Question about new wheel rim vs tire size

Aug 10, 19 2:15

Post #1 of 31 Views: 2893

Hi! I registered here about a year ago when I was buying my first road bike but haven't posted anything before now.

I have a 2019 Specialized Tarmac SL6 Disc Sport and love it. I recently decided to upgrade my wheels for races and bought a set of Shimano WH-RS770 Ultegra wheels. They haven't been delivered yet.

I also purchased some Conti GP5000 TL 28mm tires. Here is where I think I messed up. I figured because the roads here in Hawaii are awful and I'm reasonably heavy (200lb) I could use the extra cushion on a high-speed descent. But with my relative inexperience I hadn't thought about frame clearance, aero (I'm probably not a fast enough rider to really need aero, but it's still a factor), etc.

The tires arrived before the wheels and I can return them for some 25s. I'd really rather not open the package at $70/tire and then find out they are useless.

I know "tire width" questions are about as welcome as a political debate, but I could really use some experienced insight. Will these tires fit on my bike at all with this wheelset? If so, ho bad is the profile going to be and will that be a detriment in an olympic triathlon? I'll never do an ironman or even a century ride most likely, but I did buy this bike and tire set to do as much damage as I can and would like to make it count.

Thanks to all for helping. Also, I tried to find where to post this and chose as best I can. No hurt feelings if a moderator needs to move it.

Edit: it may help to know that the stock rims are 20mm internal, but the Shimano wheels are 17mm internal. I know that makes a difference but not sure how. Also, I've read that Specialized says that the Tarmac has 30mm clearance based on actual inflated tire dimensions.

Last edited by: PedalingHertz: Aug 10, 19 2:33

Re: Question about new wheel rim vs tire size [PedalingHertz] [ In reply to ]

Aug 10, 19 8:04

Post #2 of 31 Views: 2830

Why did you pay $70 per tire?

Re: Question about new wheel rim vs tire size [PedalingHertz] [ In reply to ]

Aug 10, 19 8:43

Post #3 of 31 Views: 2812

The wheels you've selected, other that being tubeless, are unlikely to show any noticeable improvement over the stock wheels. You save less than 40 grams, get a 1mm deeper front and 5mm deeper rear, but drop from a 20 to a 17 mm internal width. I don't know if either has been wind tunnel tested, but there are better and cheaper shallow rims available. If you want something deeper and weight isn't an issue for you, save your money a little longer and get Hed Jet+ 4s or 6s when they go one sale.

Re: Question about new wheel rim vs tire size [FatandSlow] [ In reply to ]

Aug 10, 19 10:21

Post #4 of 31 Views: 2790

Thank you. I supposed that is the answer to the question I should have asked: what kind of wheels should I get?

I'm amazed to hear that they wouldn't be a significant improvement at $600 for a set. Not that price is everything, but the reviews were very good and considered a solid "upgrade wheel." Which is obviously a very general and subjective statement.

So, is that a consensus that the wheels are not worth the cost paid? Again, I can return them.

Re: Question about new wheel rim vs tire size [PedalingHertz] [ In reply to ]

Aug 10, 19 10:32

Post #5 of 31 Views: 2785

HED Jet Plus 4 or 6.

Have you ever installed tubeless tires?

Re: Question about new wheel rim vs tire size [jimatbeyond] [ In reply to ]

Aug 10, 19 10:45

Post #6 of 31 Views: 2781

I've never installed them but figured my LBS could. I was going to have them do it because I don't see myself getting sealant right without a huge mess. I wanted tubeless to avoid pinch flats in a race. I can change a tire, but the race will be over and all the food gone by the time I'm done. I know that comes with practice and I've only changed a few.

Re: Question about new wheel rim vs tire size [jimatbeyond] [ In reply to ]

Aug 10, 19 10:57

Post #7 of 31 Views: 2775

I didn't - I misstated the price by accident. I think they had been listed for more on other sites before I purchased where I did. Just looked it up and they were $57/tire. Still more than I care to waste, although from the looks of things that may be the least of my worries now.

Re: Question about new wheel rim vs tire size [PedalingHertz] [ In reply to ]

Aug 10, 19 10:59

Post #8 of 31 Views: 2772

How much does your bike shop charge to install tubeless tires?

Re: Question about new wheel rim vs tire size [PedalingHertz] [ In reply to ]

Aug 10, 19 11:01

Post #9 of 31 Views: 2770

My shameless plug is that I have a brand new set of DT Swiss P1800 wheels if you want em. I bought them and found I couldn’t use them. Long story.

Anywho- everybody is riding 28’s these days if they can. Wider rims are the thing as well as larger tires. I found I couldn’t run continental gp4000 tires on my 2016 tarmac. The tires were just way bigger than other brand 28’s. I now run Vittoria Corsa G+ tires in 28. They appear to be good. I don’t know if the GP5000 is more true to size than the GP4000.

Also, probikekit.com and other online stores have pretty aggressive tire prices that are hard to ignore.

Re: Question about new wheel rim vs tire size [jimatbeyond] [ In reply to ]

Aug 10, 19 11:04

Post #10 of 31 Views: 2768

It depends on what needs to be done but for a new tubeless ready wheel/tire that doesn't need a bunch of sealant cleaned out etc they estimated $100 total.

Re: Question about new wheel rim vs tire size [PedalingHertz] [ In reply to ]

Aug 10, 19 11:18

Post #11 of 31 Views: 2757

Do you feel that $100 to install two tires is a reasonable amount?

Re: Question about new wheel rim vs tire size [jimatbeyond] [ In reply to ]

Aug 10, 19 11:22

Post #12 of 31 Views: 2754

If I can't figure it out it would be lol.

I used to have a little diesel tractor that I loved tinkering on. Rewired it and did all the normal maintenance myself. I was a hundred times more capable working on it than I am these little precise bicycle parts. And I still paid someone else to put new tires on it. :)

I do hate paying for what I could do myself of course.

Re: Question about new wheel rim vs tire size [PedalingHertz] [ In reply to ]

Aug 10, 19 11:53

Post #13 of 31 Views: 2737

How many flat tires do you think you might get each year?

What are you going to do if you get a flat when out on a training ride?

Re: Question about new wheel rim vs tire size [jimatbeyond] [ In reply to ]

Aug 10, 19 12:19

Post #14 of 31 Views: 2724

Not sure how many per year. I had one not long after getting the bike when I hit a Texas pothole. Called my wife for pickup and changed the tire at home myself. Not a problem but it did take a long time.

Hawaii roads are terrible compared to where we lived in Texas. The patched potholes are somehow worse than the actual potholes. There are few bike lanes and they are littered with debris. Flats, especially pinch flats, seem inevitable.

I also figured tubeless at a bit lower pressure might save my back from the vibration of the rough roads.

Re: Question about new wheel rim vs tire size [jimatbeyond] [ In reply to ]

Aug 10, 19 13:53

Post #15 of 31 Views: 2689

jimatbeyond wrote:

Do you feel that $100 to install two tires is a reasonable amount?

At that rate of pay I'm going to pack in my engineering job and move into the tyre replacement industry.

Re: Question about new wheel rim vs tire size [BobAjobb] [ In reply to ]

Aug 10, 19 15:29

Post #16 of 31 Views: 2662

I know it seems steep, but we're talking about Honolulu. Everything here is absurdly expensive. We're paying nearly 4k/mo for rent on a 1700 square foot house and it doesn't even have air conditioning. And that was a pretty good deal for the area we got.

While I do try to limit my spending by buying everyday things on base, etc. I truly don't mind spending my money one of my few chosen hobbies when it's appropriate. And supporting the local bike scene, which is struggling here.

Back to the original post: I have obtained return shipping labels for a whopping $7. I will return them and find something more advantageous. I had previously had a Hunt 30mm/50mm front/rear combo planned but went with this based on price.

I'm concerned about crosswinds with too deep a front wheel. It can get VERY windy here (except on Saturdays when I want to go kiteboarding, apparently). I don't want to get pushed around too hard. Is that a legitimate concern for a rider my weight?

Again, I really appreciate everyone's help. I welcome random shout outs to wheels you think would be good. I looked up the HEDs mentioned and like them so far!

Re: Question about new wheel rim vs tire size [PedalingHertz] [ In reply to ]

Aug 10, 19 15:35

Post #17 of 31 Views: 2658

I would highly recommend Continental GP5000 clincher tires with latex tubes and sealant.

Re: Question about new wheel rim vs tire size [jimatbeyond] [ In reply to ]

Aug 10, 19 18:40

Post #18 of 31 Views: 2621

Tubes AND sealant? In a non-tubeless version? Mind *blown*

I'm assuming the idea is the tubes still work but if they fail there's a good chance the tire will hold pressure? Or is it just to stop small punctures?

What about these wheels? This is what I first had my sights set on before wrongly assuming the Shimano wheels would be just as good at 3/5 the price...

https://www.huntbikewheels.cc/...n-aero-disc-wheelset

Re: Question about new wheel rim vs tire size [PedalingHertz] [ In reply to ]

Aug 10, 19 18:49

Post #19 of 31 Views: 2618

Those Hunt wheels are nowhere close to being as fast as HED.

Re: Question about new wheel rim vs tire size [jimatbeyond] [ In reply to ]

Aug 10, 19 20:18

Post #20 of 31 Views: 2595

Good to know! Can you help me understand why? What specs am I looking for to help me tell which wheel will be faster?

Re: Question about new wheel rim vs tire size [PedalingHertz] [ In reply to ]

Aug 10, 19 20:39

Post #21 of 31 Views: 2582

PedalingHertz wrote:

Good to know! Can you help me understand why? What specs am I looking for to help me tell which wheel will be faster?

Wind tunnel testing, mostly.

Re: Question about new wheel rim vs tire size [PedalingHertz] [ In reply to ]

Aug 10, 19 20:40

Post #22 of 31 Views: 2576

Rim shape.

Re: Question about new wheel rim vs tire size [jimatbeyond] [ In reply to ]

Aug 10, 19 22:18

Post #23 of 31 Views: 2554

That sounds like *not* the sort of thing I would be able to tell from a spec sheet. :/

Is there an equivalent metric to a ballistic coefficient that wheel makers post somewhere? When I was handloading rifle rounds (i.e. when I lived on a land mass large enough to easily practice long-range marksmanship), every bullet had this type of info listed (usually on the box, but certainly on the manufacturer's website). It makes "this vs this" comparisons much easier (until you get into comparisons at different velocities, at least).

Right now, I'm leaning towards the HED Jet 4 plus on the front, and 9 on the back. Is that too excessive? Some people run full disc wheels so it can't be too crazy, right?

Last edited by: PedalingHertz: Aug 10, 19 22:19

Re: Question about new wheel rim vs tire size [PedalingHertz] [ In reply to ]

Aug 10, 19 22:25

Post #24 of 31 Views: 2543

As mentioned by HTupolev, wind tunnel testing don't lie.

Certain rim shapes are significantly faster.

Re: Question about new wheel rim vs tire size [PedalingHertz] [ In reply to ]

Aug 10, 19 22:28

Post #25 of 31 Views: 2540

PedalingHertz wrote:

That sounds like *not* the sort of thing I would be able to tell from a spec sheet. :/

Is there an equivalent metric to a ballistic coefficient that wheel makers post somewhere? When I was handloading rifle rounds (i.e. when I lived on a land mass large enough to easily practice long-range marksmanship), every bullet had this type of info listed (usually on the box, but certainly on the manufacturer's website). It makes "this vs this" comparisons much easier (until you get into comparisons at different velocities, at least).

Right now, I'm leaning towards the HED Jet 4 plus on the front, and 9 on the back. Is that too excessive? Some people run full disc wheels so it can't be too crazy, right?

There's not much disadvantage to running high depth or even discs out back, since it doesn't really affect steering. It does tend to be heavier (a tension-spoked wheel with a shallow rim is a design of absolutely ridiculous structural efficiency), but that's about it.

Re: Question about new wheel rim vs tire size [PedalingHertz] [ In reply to ]

Aug 11, 19 0:03

Post #26 of 31 Views: 1443

PedalingHertz wrote:

I'm concerned about crosswinds with too deep a front wheel. It can get VERY windy here (except on Saturdays when I want to go kiteboarding, apparently). I don't want to get pushed around too hard. Is that a legitimate concern for a rider my weight?

Again, I really appreciate everyone's help. I welcome random shout outs to wheels you think would be good. I looked up the HEDs mentioned and like them so far!

Hello fellow Honoluluian! I run a Tarmac SL6 too and the HEDs would not be that good for 28c tires. If you put those tires on that wheel, it'll probably balloon up to 29-30mm wide and that'll violate the 105% rule. At that point, you might as well be running shallower rims because most of that aero gain of a deep wheel will be lost and you're just running a heavier wheelset.

https://blog.silca.cc/...ure-and-aerodynamics

Aero may not be as big of a deal if you're going with 28c tires but more than anything, running a tire that's too wide for the rim will adversely affect cornering/handling. So, if you want to run 28s, match it with some wide internal rim width rims. Your stock ones are actually pretty good with this regard. This shimanos with 17mm internal rim widths would have been pretty bad with 28s.

I run 28c tires, because like you mentioned, Oahu roads suck. Currently using Conti GP5000s, on these set of 50mm deep 25.5 internal wide wheels built by November and they're awesome.

https://novemberbicycles.com/...disc-chris-king-r45d

These kind of rims are the new generation optimized for 28c tires. Others include the Enve 4.5AR, Hunt 48 limitless, HED Vanquish, Light bicycle Falcon Pro WR50 or WR38

I just finished doing a crap ton of research in buying my wheels so it's fresh in my mind.

Handling crosswinds is a skill/practice thing. Went to Makapuu on those windy days last week with 25mph gusts on those 50 deep rims and was blown around but those wheels handled it really well. I'm about 140lbs so it should be even easier for you at 200lbs.

Last edited by: Montster: Aug 11, 19 0:05

Re: Question about new wheel rim vs tire size [Montster] [ In reply to ]

Aug 11, 19 11:00

Post #27 of 31 Views: 1405

That is some very helpful info! And good to see someone else in the area here!

I may be willing to come down in tire size for a race specific wheel (although I am definitely switching to 28s for my stock/commuting/training wheels). Most races are on closed roads, which gets me off of the shoulder and onto the less treacherous part of the road. That said, the ability of a race wheel to accommodate larger tires is a huge plus for me. It just removes a bit of anxiety for shooting down some of the descents. I hit an invisible pothole coming down Manoa Rd a couple weeks ago. I don't know how the bike stayed together, but more cushion would have been a lot better.

Are the Chris King wheels as aerodynamically sound as the HEDs? Or at least close enough not to worry about it?

Last edited by: PedalingHertz: Aug 11, 19 14:17

Re: Question about new wheel rim vs tire size [PedalingHertz] [ In reply to ]

Aug 11, 19 21:54

Post #28 of 31 Views: 1373

PedalingHertz wrote:

That is some very helpful info! And good to see someone else in the area here!

I may be willing to come down in tire size for a race specific wheel (although I am definitely switching to 28s for my stock/commuting/training wheels). Most races are on closed roads, which gets me off of the shoulder and onto the less treacherous part of the road. That said, the ability of a race wheel to accommodate larger tires is a huge plus for me. It just removes a bit of anxiety for shooting down some of the descents. I hit an invisible pothole coming down Manoa Rd a couple weeks ago. I don't know how the bike stayed together, but more cushion would have been a lot better.

Are the Chris King wheels as aerodynamically sound as the HEDs? Or at least close enough not to worry about it?

Those wheels I linked don’t have to come with Chris King hubs. They branded that line of wheels as “All Road 50s”. You can choose a cheaper, more economical hub too and that line of wheels more describes the rim. I would say they’re close enough to HEDs to not worry about it. As far as aero goes, the most important thing is to match the measured tire size with the rim width. The dimensions of the rim matter more than the design. If you want to run wide AND still be reasonably aero, go for something like the All Roads. Alternatively you can see how much it would cost for them to build you that wheel locally. I assume your LBS is The Bike Shop?

Yea, Manoa road is a death trap right now with all the construction. No amount of wheel width would save you if you bomb down it at speed and hit one of the big holes. With your weight you may break the rim. Be careful out there.

If I were you, just go with the 28 tires on the rim you currently have. The stock wheels that come with the Tarmac are really a good bang for the buck because that internal rim width is good enough to run 28s for now. If you still feel like the wheels are lacking, go for the upgrade.

Re: Question about new wheel rim vs tire size [Montster] [ In reply to ]

Aug 12, 19 0:58

Post #29 of 31 Views: 1353

Thanks. I'm going to keep researching the issue. I like that the November wheels are wider but wonder if I really need the 28s on the race set. If not, I may just go with the heds and use 25s. As you say, I def want them on my stock wheels for everyday use. But I don't think I want to race on my stock set with 28s on them due to weight and aero penalty, so I'll wait until I have a dedicated set of race wheels to do that.

With 2 local tri sprints coming up in the next 2 months, I'd like to get the upgrade done relatively soon. If you make your bike faster and don't race it, you didn't really make it faster, did you. :)

Re: Question about new wheel rim vs tire size [PedalingHertz] [ In reply to ]

Aug 12, 19 1:15

Post #30 of 31 Views: 1348

PedalingHertz wrote:

Thanks. I'm going to keep researching the issue. I like that the November wheels are wider but wonder if I really need the 28s on the race set. If not, I may just go with the heds and use 25s. As you say, I def want them on my stock wheels for everyday use. But I don't think I want to race on my stock set with 28s on them due to weight and aero penalty, so I'll wait until I have a dedicated set of race wheels to do that.

With 2 local tri sprints coming up in the next 2 months, I'd like to get the upgrade done relatively soon. If you make your bike faster and don't race it, you didn't really make it faster, did you. :)

If I was you I'd probably get something like HED Jet 4 or 6 plus, fit 25mm GP5000 tyres and see how they feel. A wider rim increases the air volume compared to the same tyre on a narrower rim. So the HED will be more comfortable than the Ultegra wheel with the same tyre. Also the 25 or 28 label on the tyre is not the whole story. For example GP4000 tyres were far bigger than the labelled size on most rims. GP5000 has apparently dialled it back and is much closer to the labelled size. From what I've seen a GP4000 23 is very close to the size of the new GP5000 25.
You'll find inflated sizes of the GP5000 tyres on a 17mm rim at the link below:

https://www.bicyclerollingresistance.com/...omparison#sizeweight

Last edited by: Ai_1: Aug 12, 19 1:20

Re: Question about new wheel rim vs tire size [PedalingHertz] [ In reply to ]

Aug 12, 19 1:37

Post #31 of 31 Views: 1341

PedalingHertz wrote:

Thanks. I'm going to keep researching the issue. I like that the November wheels are wider but wonder if I really need the 28s on the race set. If not, I may just go with the heds and use 25s. As you say, I def want them on my stock wheels for everyday use. But I don't think I want to race on my stock set with 28s on them due to weight and aero penalty, so I'll wait until I have a dedicated set of race wheels to do that.

With 2 local tri sprints coming up in the next 2 months, I'd like to get the upgrade done relatively soon. If you make your bike faster and don't race it, you didn't really make it faster, did you. :)

Honestly, if you’re doing tris on a tarmac, have you optimized everything else like aero helmet and suit? Otherwise, narrower tires and deeper wheels are not your low hanging fruit. Also about the HEDs. You would actually have to run something like 22s or 23s on that front tire, because again, the 105 rule. A 25 labeled tire would balloon up to 27 or 28ish on those wheels and you run into that problem of have a tire too big for the rim. Those wheels are too old for disc brakes and too narrow with only a 25mm external. It’s a really bad deal actually if you plan on running 25s. If you run 22s, then it’s fine. The whole point of disc brakes is to break free from old rim dimensions. Going with an HED is a bit out of date with disc brakes IMO. There are plenty of other rim options from November, light bicycle, roval etc.

edit: If you're going to spend HED Jet plus money, you're better off going with

https://novemberbicycles.com/...riant=28614804570205

or at the higher end,

https://rovalcomponents.com/products/cl-50

I'm sure there are others but there's a common theme here. 21mm internal, 28+ external, 50ish deep. That's modern dimensions for disc brakes and would be excellent for the tarmac disc. You can run the 25c front tire for race day to be maximum aero and 28c for everyday.

Last edited by: Montster: Aug 12, 19 2:01

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