Wheel Profile..Front v Back

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Paddy Pumpkin
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Wheel Profile..Front v Back

Postby Paddy Pumpkin » Sat Jul 06, 2019 14:18 pm

I am about to buy a BMC Roadmachine which comes with Dt swiss 47mm profile wheels front and back.

I live at the base of a mountain range by the coast. Hence fast windy descents are a regular occurrence for me. None of my friends can consistently ride profiles above 35mm. I am currently using 32mm to enable me to ride every day without having to gauge the wind to decide on wheel depth for the weather conditions. I have seen some visitors to the area on lovely 45 to50 mm wheels twitching dangerously so I am convinced I cannot regularly run the 47mm that come with the BMC.

The strongest rider in our group runs 35mm front and 45mm back

So my question is would you swap both wheels to a lower profile or just the front wheel? If so is there any brand that will sell just a endurance front wheel with a depth of about 32 to 35 mm and is similar quality to the DT swiss 47 mm carbon endurance wheel that come standard on the BMC.

Lastly what do you think my chances of getting the shop to supply the bike with a changed wheel or wheel set?

Imposter
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Re: Wheel Profile..Front v Back

Postby Imposter » Sat Jul 06, 2019 15:07 pm

Paddy Pumpkin wrote: The strongest rider in our group runs 35mm front and 45mm back


Not sure of the significance of this. I imagine he would still be the 'strongest', regardless of whatever wheels he was using..

Unlikely that the shop would swap wheels without some kind of cost implication. Overall though, I can't help thinking you are over-estimating the impact that deep sections (especially the newer profile rim types) have in wind.

cougie
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Re: Wheel Profile..Front v Back

Postby cougie » Sat Jul 06, 2019 19:36 pm

Tbh I'd explain it to the shop and see what they offer. I used to ride 50mm deep but its been so windy that I replaced with normal wheels. I don't regret that.

Odd wheels would just look odd.

Stueys
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Re: Wheel Profile..Front v Back

Postby Stueys » Sun Jul 07, 2019 15:48 pm

Enve seem to have done reasonably well selling different profile wheels front and back, it's the USP of their SES range.

Chat to the dealer and see what he'll do, something like an Enve 3.4 wheel set would fit what you're looking for well if he could do you a deal.

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darkhairedlord
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Re: Wheel Profile..Front v Back

Postby darkhairedlord » Sun Jul 07, 2019 17:21 pm

It's ok to have different front to back, but left to right is when you get problems.

thecycleclinic
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Re: Wheel Profile..Front v Back

Postby thecycleclinic » Sun Jul 07, 2019 22:58 pm

Paddy pumpkin

50mm deep rimmed shells can be fine. I have been out in 40mph winds in mine and you know all wheels are a bit twitchy in those winds, nothing though that I cant handle.

Rim profile, tyre width relative to rim width, how the airflow around the wheel and fork is important. Even front end geometry and weight distribution are important factors. So to state you seen some people on 50mm deep rims and them unable to handle there bike dies not answer why. Drawing the conclusion that it's the rimz fault shows your simply assuming. That also means you'll fall for marketing.
http://www.thecycleclinic.co.uk -wheel building and other stuff.

Paddy Pumpkin
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Re: Wheel Profile..Front v Back

Postby Paddy Pumpkin » Mon Jul 08, 2019 06:48 am

Sorry I am confused by your comment that I fall for marketing.

Do you mean that I fall for the marketing that says I should put shallow rims on? Or the marketing that says I should run deep rims?

philbar72
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Re: Wheel Profile..Front v Back

Postby philbar72 » Mon Jul 08, 2019 07:31 am

I'd just keep the 47s for faster rides and get a pair of decent spec 32 ish mm wheels. if you look around you can get them for a reasonable price. I wouldn't buy enve's. phenomenal looking wheels for sure but, cost the earth.

also anything below 50mm shouldn't be too badly behaved unless you have over 20mph winds. I run 58mm front and rear and they don't twitch too much.

hypster
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Re: Wheel Profile..Front v Back

Postby hypster » Mon Jul 08, 2019 09:01 am

Rider weight is also another factor as lighter riders will tend to get blown around more. I'm 80kg and don't really have much problem with my 46mm wheels.

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Lincolndave
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Re: Wheel Profile..Front v Back

Postby Lincolndave » Mon Jul 08, 2019 09:10 am

If was you I would try the 47s in a cross wind, I ride 50,s and even riding around a relatively flat Lincolnshire where the winds blow across flat fields I have only on very odd occasions been affected , you will never know unless you try them out

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Step83
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Re: Wheel Profile..Front v Back

Postby Step83 » Mon Jul 08, 2019 11:43 am

I ride most of the time with some older style slab side 66mm rims, rear has never been an issue, front only at certain angles but, I can live with it. I did ToC which is very exposed and windy on them, it was liveable.

I would go out an try, climbing you'll not really notice it so on decents just go easy an build, half the time its mind over matter anyway.

As for the strong riders, its more skill and mindset than just strength, try them an see you should be fine.

Paddy Pumpkin
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Re: Wheel Profile..Front v Back

Postby Paddy Pumpkin » Mon Jul 08, 2019 13:24 pm

Thanks for all your inputs but there is no way I can handle the 40mm+ depths in the area I cycle, especially on the front wheel. It is just too windy, especially on the fast desecents, I normally top out at 65-70 km/h (aerodynamics is the limit as I am long past my cadence limit at this speed) and riding 32mm rims I sometimes even back off as the bike moves around too much. The bunch I ride with are pretty experienced (20,000km per year for 1 guy) and they won't ride deep front rims.

So I guess I am stickig with my original question. Does anyone know a brand that will sell a single wheel 35ish mm carbon wheel that is optimised for a 28mm tyre?

thecycleclinic
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Re: Wheel Profile..Front v Back

Postby thecycleclinic » Mon Jul 08, 2019 17:37 pm

Marketers will say shallaower rims handle better well that not always true.
Rider weight is not much of an issue. I know this as I supported a team of light ladies with 50mm deep rimmed wheels and no one them noticed any problems. They race in all weathers and in all conditions. Proper hard lasses.
The rules of thimb wth regards to handling have very little basis in relaity. They are based on broad generaliations and assumptions and conclusion drawn are flawed.

I have some 38mm deep tubular wheels that catch the wind more than my 50mm deep carbon clinchers. Same bike, same rider and both wheels had tyres matched to the rim. So this is what I mean by forget the generalistions and you have to look at rim profile and tyre/rim interface and you have to know what your looking at. If you dont your relying on marketing and most of that is made up.

With such a shallow rims (32mm) you might as well get a Kinlin XR31T built up. Rims that are optinised for 28mm tyres well that depends on the 28mm tyre. A Schwalbe pro one for example on a wide rim (19mm to 21mm internal width) is around 31 or 32mm wide so the rim has to be 33 to 34mm wide externally. It starts to get silly. Other 28mm tyres will be closer to 28mm but are still likely to be 29mm or 30mm wide and that still means a 32mm wide rim.

So what your asking for is not a wise buy. Why would any one make this or even buy it. The rim would be so blunt the air flow around would be turbulant to say the least. It more like an MTB rims in shape.

So back to my orginal suggestion the Kinlin XR31T or get a deeper wheelset that handles better in the wind.
http://www.thecycleclinic.co.uk -wheel building and other stuff.

Paddy Pumpkin
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Re: Wheel Profile..Front v Back

Postby Paddy Pumpkin » Mon Jul 08, 2019 18:43 pm

Thanks, it seems BMC know what they are doing in choosing the wheel for the bike. It satisfies all the criteria you mentioned and seems to be the optimal wheel for the job I want it to do.....now I just need to grow a pair and take the 47mm wheels and trust BMC

Paddy Pumpkin
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Re: Wheel Profile..Front v Back

Postby Paddy Pumpkin » Sun Aug 04, 2019 13:52 pm

So I grew a pair....big big mistake

The bike is twitchy as hell on any descent involving wind. Even worse when you swing around a corner and the wind changes direction....it's a blind guess as to what the bike wants to do when I round a bend at speed. I am fine south of 50kph or 60kph on a straight. I pick up the speed much quicker than before but I find myself braking way more than before. Net result I am slower descending than I was with 32m rims.

I am however noticeably faster on the flats.

These things are a dream on the flat...much smoother and way quicker. Anybody want to buy a set of DT SWISS ERC 47mm and who rarely exceeds 55kph on their bike?

davetex
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Re: Wheel Profile..Front v Back

Postby davetex » Sun Aug 04, 2019 17:55 pm

Drop in a shallower front wheel?

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First Aspect
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Re: Wheel Profile..Front v Back

Postby First Aspect » Sun Aug 04, 2019 21:26 pm

davetex wrote:Drop in a shallower front wheel?

My palm just collided with my forehead.

I love this thread for how completely no one has listened to the OP. "You play tennis? Really? I used to play cricket."

Matthewfalle
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Re: Wheel Profile..Front v Back

Postby Matthewfalle » Mon Aug 05, 2019 08:34 am

Paddy Pumpkin wrote:So I grew a pair....big big mistake

The bike is twitchy as hell on any descent involving wind. Even worse when you swing around a corner and the wind changes direction....it's a blind guess as to what the bike wants to do when I round a bend at speed. I am fine south of 50kph or 60kph on a straight. I pick up the speed much quicker than before but I find myself braking way more than before. Net result I am slower descending than I was with 32m rims.

I am however noticeably faster on the flats.

These things are a dream on the flat...much smoother and way quicker. Anybody want to buy a set of DT SWISS ERC 47mm and who rarely exceeds 55kph on their bike?


why should they be useful only to anyone who never exceeds 55kph?
what if you exceed 55kph on the flat?
what if people don't suffer from the same bike handling deficiencies as you do?


the MFs are confused.

#speedy
#unansweredquestions
Postby team47b » Sun Jun 28, 2015 11:53 am

De Sisti wrote:
This is one of the silliest threads I've come across. :lol:

Recognition at last Matthew, well done!, a justified honour :D

smithy21 wrote:
He's right you know.

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Poptart242
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Re: Wheel Profile..Front v Back

Postby Poptart242 » Mon Aug 05, 2019 09:14 am

I ride 60mm wheels everywhere - it fully depends on the profile of the wheel (and to an extent, the bike itself) as to how much you move around. I used to get blown all over the place on my old 52mm Mavics.

At the end of the day if you're that worried then sell your wheels and buy some box-sections, but try the 47s first. You might be surprised, and you might save a bunch of money.

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First Aspect
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Re: Wheel Profile..Front v Back

Postby First Aspect » Mon Aug 05, 2019 11:05 am

Matthewfalle wrote:
Paddy Pumpkin wrote:So I grew a pair....big big mistake

The bike is twitchy as hell on any descent involving wind. Even worse when you swing around a corner and the wind changes direction....it's a blind guess as to what the bike wants to do when I round a bend at speed. I am fine south of 50kph or 60kph on a straight. I pick up the speed much quicker than before but I find myself braking way more than before. Net result I am slower descending than I was with 32m rims.

I am however noticeably faster on the flats.

These things are a dream on the flat...much smoother and way quicker. Anybody want to buy a set of DT SWISS ERC 47mm and who rarely exceeds 55kph on their bike?


why should they be useful only to anyone who never exceeds 55kph?
what if you exceed 55kph on the flat?
what if people don't suffer from the same bike handling deficiencies as you do?


the MFs are confused.

#speedy
#unansweredquestions
He wasn't asking for advice so he could pass it on to "people" he was asking advice based for himself. "People" can do whatever he wants can't he?

You don't know where he rides and what the nature of the roads are. Other than it's windy and there are long fast descents. Hardly a mystery why deep sections are not to everyone's taste in those conditions.


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