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PostPosted: Tue May 19, 2009 10:01 pm 
Dirt Disciple

Joined: Fri May 08, 2009 9:31 am
Posts: 47
Hiya,

So I've built-up my Bob Jackson. I've ridden it for 5 miles, and it feels slow!

The total build only weights 0.5Kg more than my semi-carbon CX bike. I run knobbly tyres on my CX bike (so in theory it should feel slower?!).

Here's the spec:

Copy of Campag Record headset
Cinelli Bars & Stem
Tektro medium drop front caliper
Dia Compe long drop rear caliper
Shimano R400 brake levers
Shimano R400 downtube shifters
Shimano R500 wheels
Shimano 105 front derailleur (double)
Shimano Ultegra SL rear derailleur
Shimano M520 pedals
Shimano HG50 chain
FSA Gossamer Mego Exo double crankset ( 34/48 )
SRAM 8 speed rear cassette
Specialized Pave SL seatpost
Specialized Rival SL seat
Specialized All Condition Sport 28x700 tyres


Now can ANYONE think of a reason why this thing feels slow? I dont get it!

:(


PS I ws running 120psi in the tyres.

PPS Wheels were brand new... but I don't believe that the bearings require 'bedding in'?


Last edited by Oms on Sat May 23, 2009 10:54 pm, edited 2 times in total.

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PostPosted: Tue May 19, 2009 10:03 pm 
Retro Guru

Joined: Mon Mar 02, 2009 1:33 pm
Posts: 281
My bet would be the wheels - not the lightest out there - but still shouldn't affect it that much


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PostPosted: Tue May 19, 2009 10:20 pm 
Dirt Disciple

Joined: Fri May 08, 2009 9:31 am
Posts: 47
joe1983 wrote:
My bet would be the wheels - not the lightest out there - but still shouldn't affect it that much


They're only a smidgeon more in weight to the Roval Pave's that I run on my CX bike...

...but I doubt the bearings are as good. They're also a lot stiffer.


I guess the brearings are causing a bit of drag? Perhaps the weight of the tyres (@370g each)?

PS Might be phychological, but it feels a wee bit better on the big chainring for some reason.


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PostPosted: Wed May 20, 2009 12:06 pm 
Old School Grand Master

Joined: Tue Oct 09, 2007 1:55 pm
Posts: 8202
Location: New Forest, UK
Have you put on a speedo and checked?

My guess is a slightly more relaxed geometry, and a steel frame that has a bit more vibration damping so feels less buzzy and bumpy - and so slower!

It's like driving a go-kart: it's only 30 mph, but feels like 130! Get back in a normal (refined car) and 80mph feels like a standstill.


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PostPosted: Wed May 20, 2009 12:15 pm 
South East AEC
South East AEC
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Joined: Wed Oct 03, 2007 3:39 pm
Posts: 3882
Perhaps its just the differance between the two bikes, or perhaps is because your running Shimano, put campag on and it will be faster.


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PostPosted: Wed May 20, 2009 12:40 pm 
Retro Guru
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Joined: Sat Feb 14, 2009 12:49 am
Posts: 516
Location: Nederland
My guess is that it is just the difference between the two bikes, in geometry and tubing (vibration). Bearings could be, but with already new bearings in the wheels, you should be able to feel the drag on the other parts, if that would be reason of what you feel in cycling. Weight is accoording to me not an issue at all. Maybe on long trips, but just cycling around, I would be very impressed if a non prof could feel the difference of a kilo extra weight. Acceleration would be just over 1% slower (with the same force) and extra drag would be neglectable with the fluctuation of tire pressure.


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PostPosted: Fri May 22, 2009 9:48 pm 
Dirt Disciple

Joined: Fri May 08, 2009 9:31 am
Posts: 47
Hiya,

Thanks for the replies.

I noticed that the tyres were facing the wrong way... however I don't believe that would have affected 'dry' running.

The geometry is completely different - I agree that may have some effect on the 'feel' of the bike.

I've sent it for the respray anyway... I just need to figure out what's holding it back. I expect it's something simple.

:)


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PostPosted: Sat May 23, 2009 10:09 pm 
retrobike rider
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Joined: Fri Oct 28, 2005 1:10 am
Posts: 4473
Location: Bristol
How much do you weigh? My Bob Jackson goes like a jack-in-the-box but has strengthened 531 tubes. I'm 18 stone ( I'm built like a cave troll ) and 6'6" so all that weight and leverage, I'd guess, facilitates the springyness. If you're light, you might not be " activating " it's qualities.


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PostPosted: Sat May 23, 2009 10:24 pm 
Dirt Disciple

Joined: Fri May 08, 2009 9:31 am
Posts: 47
Agency_Scum wrote:
How much do you weigh? My Bob Jackson goes like a jack-in-the-box but has strengthened 531 tubes. I'm 18 stone ( I'm built like a cave troll ) and 6'6" so all that weight and leverage, I'd guess, facilitates the springyness. If you're light, you might not be " activating " it's qualities.



I'm 10 stone... the bike is a 531, and has extra long lugs.

It's pretty darn stiff... well, certainly feels so compared to my E5+carbon CX bike.

I'm not an experienced roadie so it's difficult for me to have a point of reference... I'm sure that's part of the problem!


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PostPosted: Sat May 23, 2009 10:41 pm 
Retro Guru
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Joined: Tue Aug 05, 2008 1:10 pm
Posts: 1743
Location: Peoples Republic of Scunny
Maybe you were just on an 'off' day and anything would feel slow :)


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