tag:blogger.com,1999:blog-3052588339740303416.post7488352064329014032..comments2023-05-31T11:18:01.609-04:00Comments on The Velomobile Observer: Efficiency (2)Luc On The Gohttp://www.blogger.com/profile/06270789105989269682noreply@blogger.comBlogger15125tag:blogger.com,1999:blog-3052588339740303416.post-33761953961364094482021-08-26T13:49:43.777-04:002021-08-26T13:49:43.777-04:00As a general rule, I find not puncturing to be qui...As a general rule, I find not puncturing to be quicker! 20 mins by the roadside (in the rain), fixing a flat really impacts my speeds...Chrishttps://www.blogger.com/profile/02792513508757117847noreply@blogger.comtag:blogger.com,1999:blog-3052588339740303416.post-47350530312359507432021-08-26T13:47:45.115-04:002021-08-26T13:47:45.115-04:00That is my experience too - chip and seal surfaces...That is my experience too - chip and seal surfaces are better with lower pressures.Chrishttps://www.blogger.com/profile/02792513508757117847noreply@blogger.comtag:blogger.com,1999:blog-3052588339740303416.post-89887329773728820012020-07-13T07:39:23.615-04:002020-07-13T07:39:23.615-04:00Thanks for writing such a good article, I stumbled...Thanks for writing such a good article, I stumbled onto your blog and read a few post. I like your style of writing... <a href="https://everyonebmx.com/" rel="nofollow">Mountain bikes</a><br />razzaqhttps://www.blogger.com/profile/08885144633074105635noreply@blogger.comtag:blogger.com,1999:blog-3052588339740303416.post-1058147264624678172017-08-01T07:54:23.201-04:002017-08-01T07:54:23.201-04:00Very important informations. Thanks from Brasil......Very important informations. Thanks from Brasil....Anonymoushttps://www.blogger.com/profile/12441614957404719500noreply@blogger.comtag:blogger.com,1999:blog-3052588339740303416.post-15245333783863701952017-05-09T09:47:06.569-04:002017-05-09T09:47:06.569-04:00I didn't see anywhere where you gave a relativ...I didn't see anywhere where you gave a relative percentage of all the various forces working against a velomobile - relative to speed. That would be hard to generalize - but might give even more in depth discussion.demetriushttps://www.blogger.com/profile/06616879523176780543noreply@blogger.comtag:blogger.com,1999:blog-3052588339740303416.post-53333354935069848622017-05-07T08:57:40.692-04:002017-05-07T08:57:40.692-04:00If you look closely at the road surface and closel...If you look closely at the road surface and closely at a tyre tread then unless you've got much better roads than I have then the road lumps are much bigger than any tread pattern I've seen on road/touring tyres...<br />And 'gaps' between bits of tread have no contact with the road so provide NO traction... :(<br />Oddly I've had success riding soft 'rubber' slicks on my delta trike in the snow.Robhttps://www.blogger.com/profile/16094081689229845843noreply@blogger.comtag:blogger.com,1999:blog-3052588339740303416.post-31646041857149697882017-05-07T08:54:40.679-04:002017-05-07T08:54:40.679-04:00The "rubber" compound is important - for...The "rubber" compound is important - for most road riding the tread is just decoration that customers in shops like to feel - this came from the Schwalbe Rep...<br />I've found Kojak too 'hard' so gets slippy on wet roads where as Durano and Scorcher are a softer 'rubber' and so grip better in the wet.<br />My comparison based on rear wheel 559s on my EvoK - and no doubt Schwalbe change the rubbers every season - I heard the Duranos can now be slippery but they were my grippy tyre of choice....Robhttps://www.blogger.com/profile/16094081689229845843noreply@blogger.comtag:blogger.com,1999:blog-3052588339740303416.post-11278051639051604622017-05-07T08:28:06.411-04:002017-05-07T08:28:06.411-04:00Well I was surprised initially when I saw that the...Well I was surprised initially when I saw that the Shredda (with threads) had a lower rolling resistance than say a Kojak or a Durano but when you think about it, the tread is only one aspect of tire construction. The compound, the number of threads, etc. are probably larger contributor to making a fast tire. Do not underestimate the threads when riding on wet or dirty roads. Recently I rode a brevet where the road was covered with sand used for providing winter adherence on snow and ice. I was drifting through the curves and I was spinning on steep hills (10%+). I used to race Karts when I was younger and driving with slicks under wet conditions was like driving on roller bearings so threads under certain conditions can be important. If you ride normally on mostly straight flat roads, it would not be a problem in wet conditions.Luc On The Gohttps://www.blogger.com/profile/06270789105989269682noreply@blogger.comtag:blogger.com,1999:blog-3052588339740303416.post-34760146167573028792017-05-07T04:06:33.096-04:002017-05-07T04:06:33.096-04:00That is another matter : do cycle tires really nee...That is another matter : do cycle tires really need tire threads/profile ? <br /><br />Below a certain speed and above a certain weight thus wheel pressure and ofcourse how large the tire-road contact surface is it is not necessary to have tire threads/profile to prevent a water film under the tire. <br /><br />Downside of tire threads is they give higher rolling resistance. Even a bit more air resistance too. Plus side is they probably prevent some leaks if the sharp object isn't able to punch through far enough. <br /><br />It will only really be needed if you cycle through sand, mud or snow. I use summer and winter tires so the summer one can be "flop on/flop off" folding slicks that can be changed without tools in about 3 minutes and are easy to store in the velomobile. In winter i go for anti leak tires that do have tire threads/profile. Quezzzthttps://www.blogger.com/profile/13340009785237362388noreply@blogger.comtag:blogger.com,1999:blog-3052588339740303416.post-81976191431183449292017-05-06T15:26:25.232-04:002017-05-06T15:26:25.232-04:00This is a very complex subject that keep tire engi...This is a very complex subject that keep tire engineers working. Formula One tire manufacturers have been designing tires for specific tracks under wet and dry conditions taking into consideration the expected temperature. Tires for velomobiles are in different categories and as riders we need to experiment to find the best combination of tire and pressure that will be a compromise for rolling resistance but also for handling, puncture protection and durability. A rider who expects to have a cushy ride and never have a flat tire will have to compromise on rolling resistance but there are still options open to him or her. Hopefully this post and comments will enable that rider to make an informed decision.Luc On The Gohttps://www.blogger.com/profile/06270789105989269682noreply@blogger.comtag:blogger.com,1999:blog-3052588339740303416.post-32375831448260412092017-05-06T14:05:54.962-04:002017-05-06T14:05:54.962-04:00Exactly so Luc...
The shake-and-bake here means I...Exactly so Luc...<br /><br />The shake-and-bake here means I am particularly keen on a velo with suspension that handles high-frequency vibration.<br /><br />But as the season progresses 'fresh' shake-and-bake goes one of two ways...<br />1) At junctions/farm entrances/lorry turnings it gets ripped up and ends up rutted - it deteriorates into field like ruts that needs very soft suspension to cope with, or<br />2) The 'shake' stones melt into the surface gradually improving into that race-like surface.<br /><br />So even after very careful testing on ONE road the conditions vary over the season and testing is thus a forever ongoing event :(<br /><br />Reading the tyre testing of Wim and some of the Dutch riders they are finding variations in behaviour of a tyre between 10C and freezing - with some tyres behaving just the same as normal and others getting very much worse.<br /><br />There are many, many variables - no wonder the tyre manufacturers often choose to blind us with tread patterns and fancy names for their 'technologies'...! <br />Robhttps://www.blogger.com/profile/16094081689229845843noreply@blogger.comtag:blogger.com,1999:blog-3052588339740303416.post-85712771122973826362017-05-06T13:31:36.716-04:002017-05-06T13:31:36.716-04:00Thank you for your comments, I tend to agree with ...Thank you for your comments, I tend to agree with Rob that you could see difference in rolling resistance depending on road conditions and tire pressure but it is hard in the abstract to say if it would be better at a given pressure in every case. The impact of a specific velomobile suspension has on rolling resistance is an unknown but it should mitigate the bouncing effect to some extent. <br /><br />Roads are very different, on a given ride you can go from a smooth repaved surface to something looking like the course of the Paris-Roubais. Do you set the pressure based on the worst or best conditions you are expecting to encounter? <br /><br />Rob made his tests using one particular tire and one would have to check if other tires behave the same before we could come to a conclusion.<br /><br />As I said in the post above, there is a lot of research that can be done to demystify the importance of tire pressure on rolling resistance on several road surfaces and condition validated with several different types of velomobile.<br /><br />This post is not the definitive thesis on rolling resistance but it provides the basic elements that riders should consider in their quest for the best rolling resistance.Luc On The Gohttps://www.blogger.com/profile/06270789105989269682noreply@blogger.comtag:blogger.com,1999:blog-3052588339740303416.post-52539366189067397192017-05-06T08:57:18.725-04:002017-05-06T08:57:18.725-04:00I performed the 50-60psi tests riding an unfaired ...I performed the 50-60psi tests riding an unfaired Greenspeed trike on a downhill that I did most every ride in the last couple of miles coming home. I deliberately varied the tyre pressure every ride and stopped at a given location. From there I let the trike roll and noted where I rolled to a stop about 1/2 of a mile later. The surface was very broken in places. I was using Tioga Comp Pools - sadly no longer made.<br />On *broken* surfaces the suspension effect from the softer tyres was significant with the optimal pressure being around 60psi, with a drop off in distance for both harder and softer pressures.<br />On another local section of road with beautiful brand new tarmac I did get the more usual expected 'higher is better' results.<br />My conclusion was that it is important to balance pressure for the anticipated road conditions - as mentioned a race track can be considered 'perfect', a mixed surface ride is difficult to optimise for, a known rough ride benefits from the lower pressures.<br />I note that this does seem to read across to velomobiles - I have a QV with soft air suspension and an EvoK with an air shock that is set to give a fairly harsh ride. The QV's airshocks appear better tuned to eliminate road shock from high frequency uneven surfaces and give a noticeably smoother and faster ride over broken pavement where as the EvoK which seems more tuned to handle pothole type bumps is generally (as would be expected from a 'sports' machine) a faster machine as long as the road surface agrees with it.<br />Unfortunately it is very common here for roads to be top-dressed (shake-and-bake) where the road is painted and small stones thrown at it, some sticking to the surface.<br />The softer, higher frequency suspension is happier on this material.Robhttps://www.blogger.com/profile/16094081689229845843noreply@blogger.comtag:blogger.com,1999:blog-3052588339740303416.post-54249427170953187782017-05-06T06:54:23.326-04:002017-05-06T06:54:23.326-04:00I add that most velomobile owners probably can exc...I add that most velomobile owners probably can exceed 50 km/h or 31 mph but will generally not spend most or their riding time above that speed, so it will in fact not be a very important factor. Quezzzthttps://www.blogger.com/profile/13340009785237362388noreply@blogger.comtag:blogger.com,1999:blog-3052588339740303416.post-52053890897059093992017-05-06T06:49:59.162-04:002017-05-06T06:49:59.162-04:00Tires that have very high pressure start to bounce...Tires that have very high pressure start to bounce. Bouncing wastes energy and make your wheel(s) with traction (micro)slip.<br /><br />Shockabsorbers will eat (bouncing) energy but keep the traction wheel(s) from slipping, but without shock absorbers you will have more (micro)slip between your traction wheel and road surface. <br /><br />So losses on variable road surfaces with high pressure tires no matter what. One would expect that the more rigid a vehicle is ( and the more wheels is has ) the more it will have bouncing losses. <br /><br />The exception being race tracks with continuous smooth road surface. No bouncing there so no shockabsorbers needed and you will go faster with high pressure tires.<br /><br />On uneven surfaces ( real world roads ) broad tires with lower pressure will give lower rolling resistance. In velomobiles you can get away with the higher air resistance of wide tires because they are covered in your streamline for 70 %.<br /><br />I do wonder if there is a speed within the general velomobile <br />riders perfomance envelope where wide tires actually are worse then small tires due to increasing air resistance. I suspect it will not occur for most riders as not many will exceed 50 km/u or 31 mph, and it is only a very high speed competion racing thing. <br /><br />It would be a common misconception to interpret the fastest racing condition tires to make you faster on normal roads. <br /><br /><br /><br /><br />Quezzzthttps://www.blogger.com/profile/13340009785237362388noreply@blogger.com