Why is my new bike slower than my old one? Aero?
Discussion
I have two road bikes, and I have now come to the conclusion that my new (and more expensive) carbon bike is slower than my old Alu one when descending. On my old bike I could easily hit 65kph+ and do over 70kph if my nerves were up to it, but on the new one 65 is a real effort, even on a long and flowing Cat 2 or 3 descent.
The new bike is an Eastway RD 1.0, the old one is a Genesis Volant 00, there's about 2kg difference in weight, and the Eastway is now running a set of carbon wheels on Novatec hubs (I had been blaming the old heavy standard wheels for my lack of speed before). Both are on Michelin Pro4 Service Course tyres (25c on the Genesis, 23c on the Eastway)and run at the same pressures. The discs are set up properly on the Eastway so there is no rubbing, and both bikes have a compact chainset and the Eastway has a 11-28 cassette vs a 12-15 on the Genesis so again no reason there for the speed difference.
I'm now wondering if it's rider positioning and aero that is making the difference? The Genesis has a longer stem and slightly racier geometry (it's the 2013 model, not the more relaxed 2014) and also has deeper drop bars. I'm now thinking I need a 130mm stem and some new bars as the Eastway has a ridiculously shallow drop and the stem feels a bit too short. The Genesis riding position feels a bit more comfortable for me, which I think also has something to do with it.
For the record, I'm 186cm tall and weigh 61kg, and am fairly athletic/flexible if it makes a difference. Links to the two bikes below:
http://www.cyclingweekly.co.uk/reviews/touringauda...
http://www.bikeradar.com/road/gear/category/bikes/...
Any suggestions, before I go down the stem and bars route?
The new bike is an Eastway RD 1.0, the old one is a Genesis Volant 00, there's about 2kg difference in weight, and the Eastway is now running a set of carbon wheels on Novatec hubs (I had been blaming the old heavy standard wheels for my lack of speed before). Both are on Michelin Pro4 Service Course tyres (25c on the Genesis, 23c on the Eastway)and run at the same pressures. The discs are set up properly on the Eastway so there is no rubbing, and both bikes have a compact chainset and the Eastway has a 11-28 cassette vs a 12-15 on the Genesis so again no reason there for the speed difference.
I'm now wondering if it's rider positioning and aero that is making the difference? The Genesis has a longer stem and slightly racier geometry (it's the 2013 model, not the more relaxed 2014) and also has deeper drop bars. I'm now thinking I need a 130mm stem and some new bars as the Eastway has a ridiculously shallow drop and the stem feels a bit too short. The Genesis riding position feels a bit more comfortable for me, which I think also has something to do with it.
For the record, I'm 186cm tall and weigh 61kg, and am fairly athletic/flexible if it makes a difference. Links to the two bikes below:
http://www.cyclingweekly.co.uk/reviews/touringauda...
http://www.bikeradar.com/road/gear/category/bikes/...
Any suggestions, before I go down the stem and bars route?
el stovey said:
Is this really a physics question about whether a heavier object will descend faster? 
I think it is a physics question actually. The weight difference in the bikes is minimal when my weight is added in (about 1.5%) but the aero difference could be fairly big.Without pedalling at all I hit 45kph freewheeling down this hill at the weekend on the old bike, I'll try it on the new one when I get time and see how that goes.
http://www.strava.com/segments/5069469
What I'm struggling with, is that the new bike has better hubs, aero rims and spokes, and a more aero frame (disc brakes excluded) so I guess it must be my position on the bike that's causing the issues.
pablo said:
I'd say is probably psychological, you're probably being a little bit more cautious on the new bike given its only 5 kmh difference, in your head you know that it was expensive and carbon breaks if you tumble....
It's absolutely not caution causing the problem, if I break the bike it's just an excuse to buy another new one! The more I think about the physics of it the only real possible cause is drag, and as I think I've isolated mechanical drag it must be air resistance. If I can get lower and more stretched out on the bike then that should help, I'll also go for some slightly narrower bars to reduce frontal area a bit.The old bike feels a bit more comfortable to me as well, so I think that even with a large frame size the geo of the carbon bike doesn't suit me as well. I'm thinking that with a more stretched out position I'll be more aero as well as more comfy so it should be a win/win.
I tend to always be on the drops when descending, as it makes it easier to grab a handful of brake without unsettling the bike when moving from the top of the bars.
I think I will hit Wiggle this evening (after measuring my shoulder width), order a few bits and see what a difference it makes with a change of bars and stem.
I tend to always be on the drops when descending, as it makes it easier to grab a handful of brake without unsettling the bike when moving from the top of the bars.
I think I will hit Wiggle this evening (after measuring my shoulder width), order a few bits and see what a difference it makes with a change of bars and stem.
okgo said:
Why exactly do you care how fast you are going down a hill?
Because I enjoy it. Also, I'm probably missing out on some efficiency on the flat as well and I want to know why, but it's most noticeable going downhill as my Garmin makes it pretty clear that I'm losing a good 5-10kph on a lot of descents.A quick measure up of the two bikes shows the old one has a 130mm stem, the new one a 100mm so that'll be making a bit of a difference. Both have 440mm bars but I'm going to order some 420mm ones with a deeper drop which are more similar in profile to the Genesis ones and see how I get on with them.
A new Garmin is tempting, as I'd like maps but maybe that's one purchase too far, for this month at least...
A new Garmin is tempting, as I'd like maps but maybe that's one purchase too far, for this month at least...
okgo said:
Lets just make clear that a 30mm difference in stems is not going to be costing you 10kph LOL
Of course it isn't, but combined with the ridiculously shallow drops on the standard bars it makes quite a big difference to the tuck position you can adopt when descending. Also, yes, I am very skinny! Always have been, and no amount of pies, toblerone or fondue seems to make a difference to it
Matt_N said:
How do the top tube lengths compare?
How does the bar height compare?
Bar height is the same at the top as I took a couple of spacers out on the new bike to get a bit lower (drops are lower on the old bike as the bar is deeper). Not sure on top tube lengths, they are similar but I'm not at home so can't check at the moment.How does the bar height compare?
I've ordered the new bars and stem, will throw myself down the side of the nearest Alp once they're fitted and report back.
Matt_N said:
Fair enough, just when you mentioned one bike had a 100mm and the other a 130mm, that's quite a difference and was wandering if that was due to just what they came with or trying to match effective length.
It's just what they came with. I bought the new bike online and it's marketed as more of a fast city bike than a racer, hence shallower bars and a shorter stem. My old bike was back in the UK when it arrived so I didn't get a chance to A/B test them but it has now become clear that although it's not uncomfortable the new bike isn't as good a fit for my body shape as the old one was.So maybe the bike is slow, or I just don't get on with it. I took my old bike to work today and cycled home, the first time I've ridden it properly since I got the new one. Lots of PRs, a KOM and a much faster average speed later something is clearly wrong.
This is a flat ride (42m elevation in 16k) so maybe if I try a climb then it might make a difference with the lighter weight of the carbon bike but the 30T cassette on the old one means it's not quite a fair fight there either.
I'm on the verge of selling it, and putting it down to the fact that I just don't get on with the bike - it has been serviced by the LBS, and I'm happy with my position on the bike, I'm mechanically competent and can't find anything wrong with it so I'm not sure what else to do. Luckily I have all the original parts so can put it back to standard spec and hopefully get my money back as it was very heavily discounted when I bought it.
So, the plan I formulated on the way home is to order a 2015 Genesis Equiblibrium disc frame (the new one now has a carbon fork), 11 speed Shimano 105 groupset and some TRP HY/RD calipers, and re-use the carbon wheels and new finishing kit from the old bike. The cost of all of the new bits should be covered by selling the Eastway bike and I get the bike I wanted in the first place but was too tempted by SRAM Force and lots of carbon at a bargain price.
Anyone care to talk me out of it?
This is a flat ride (42m elevation in 16k) so maybe if I try a climb then it might make a difference with the lighter weight of the carbon bike but the 30T cassette on the old one means it's not quite a fair fight there either.
I'm on the verge of selling it, and putting it down to the fact that I just don't get on with the bike - it has been serviced by the LBS, and I'm happy with my position on the bike, I'm mechanically competent and can't find anything wrong with it so I'm not sure what else to do. Luckily I have all the original parts so can put it back to standard spec and hopefully get my money back as it was very heavily discounted when I bought it.
So, the plan I formulated on the way home is to order a 2015 Genesis Equiblibrium disc frame (the new one now has a carbon fork), 11 speed Shimano 105 groupset and some TRP HY/RD calipers, and re-use the carbon wheels and new finishing kit from the old bike. The cost of all of the new bits should be covered by selling the Eastway bike and I get the bike I wanted in the first place but was too tempted by SRAM Force and lots of carbon at a bargain price.
Anyone care to talk me out of it?
okgo said:
You might as well throw £500 off the Severn bridge for all the difference its going to make.
What on earth are you on about? How can one bike be THAT much slower than another over such a short distance?
On any given bit of road I can hold 3-4kph more on the old bike than the new one, it just seems easier to hold a higher speed on the flat as well as downhill. Maybe I need to play a bit more with my position on the new bike and see if that helps because you're absolutely right, there is no rational explanation for me being much faster on an entry level £600 bike than a £2k carbon one which is theoretically 'better' in every possible way.What on earth are you on about? How can one bike be THAT much slower than another over such a short distance?
Gearing is pretty much the same, compact chainset with a 11-28 10 speed on the new one and compact and 11-30 8 speed block on the old one.
As I see it, there are two possible issues - one is that the BB isn't spinning as smoothly as it should be (no noises or noticeable resistance though) or my position on the bike is way off and is stopping me transmitting as much power to the pedals.
The new bars and stem have certainly helped, and I'm more comfortable on the bike now, but it still hasn't fixed the fundamental problem that I don't seem to be able to ride this one as fast.
As I see it, there are two possible issues - one is that the BB isn't spinning as smoothly as it should be (no noises or noticeable resistance though) or my position on the bike is way off and is stopping me transmitting as much power to the pedals.
The new bars and stem have certainly helped, and I'm more comfortable on the bike now, but it still hasn't fixed the fundamental problem that I don't seem to be able to ride this one as fast.
Brakes backed right off, wheels spin freely at both ends, same Michelin tyres (23 on one, 25c on the other) so no rational explanation at all. I'm travelling the rest of the week, but will get the two bikes side by side and see if I can tweak the seat height, stack height etc and see if that helps
WinstonWolf said:
Do you feel strong on the new bike? If you don't feel as strong it's probably just a fit thing.
I don't feel strong on any bike, my BMI is significantly lower than Chris Froome or Nairo Quintana's I think it must be a fit issue, so that's where I'm going to look next. The speedo is a Garmin GPS one so no risk of data corruption there.
I have also stuck an ad on one of the ex-pat websites on the off chance someone wants to give me back what I paid for the bike, as I like shiny new stuff and want this...
https://www.facebook.com/GenesisBikesUK/photos/a.1...
Just to update this, I got the old and new bikes together, and with the new stem and bars the riding position is as good as identical so no issues there.
I have decided that I just need to man up and push the pedals harder, and any difference is in my head, or possibly just that the wind is blowing in a different direction sometimes.
So, I have been reciting rule 5 to myself every night before bed in the hope that it helps (and also because I need to make up for buying full Belkin kit and having a saddle bag).
I have decided that I just need to man up and push the pedals harder, and any difference is in my head, or possibly just that the wind is blowing in a different direction sometimes.
So, I have been reciting rule 5 to myself every night before bed in the hope that it helps (and also because I need to make up for buying full Belkin kit and having a saddle bag).
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