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Old 02-11-09, 12:36 PM   #1
dynaryder
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2009 Dahon Speed Pro TT Brakes

I've been considering getting a Pro TT. I test rode one at a local dealer and liked everything about it except the brakes. They weren't strong at all. I had one of the mechanics tweak them and took the bike for another ride,and while the brakes were better,they still weren't good enough. I live in a very hilly area,so this is a big deal to me. I checked the forums on Dahon's site,and it seems to be the general consensus that the brakes are underperformers. One poster noted that the '09 models now have V brakes,and Dahon's listing for the bike confirms this. But the shop claims the bike I rode is an '09,and it def had dual pivot calipers.

Can anyone out there confirm that the '09's do have V's? None of the other shops that carry Dahon have Pro TT's in stock. And has anyone ridden one and can confirm that the braking has been improved? It's a shame that the brakes are so bad as the rest of the bike rocked. It was light,had a nice gear spread,handled well,and had a comfortable ride. I'd have bought it if the brakes were up to the level of the rest pf the bike. Thanks in advance.
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Old 02-11-09, 12:54 PM   #2
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The o9 Speed Pro TT is a very differant animal .. Indeed it has V brakes and it share the frame with the Vitesse bikes..i.e. it is an alloy frame versus the steel 08 Speed Pro TT with caliper brakes....

And yes the brakes are not as strong as V brakes and some ( not all by all means) people really do not like them, while others are used more to caliper brakes and find them adequate.

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Old 02-11-09, 01:08 PM   #3
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More pictures of the 2009 model can be found here:
http://www.dahon.com/intl/speedprott.htm
Dahon SpeedPro TT 2009 arrives
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Old 02-11-09, 01:12 PM   #4
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Also, with smaller wheels, you get less leverage, so the braking is inherently less effective than with larger wheels. Even on my high-end 20" wheeled bikes, I just don't get the same level of braking as with my 700C road bike.
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Old 02-11-09, 10:59 PM   #5
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Quote:
Originally Posted by SesameCrunch View Post
Also, with smaller wheels, you get less leverage...
Hmm... never thought of that before. At first I thought since the axle-road leverage is also reduced, they cancel each other out.

Let's see...

For a 700x23c:
* axle-road distance = 311mm + 23mm = 334mm
* axle-brake distance = 311mm - 5mm = 306mm
50N braking force => 46N decelerating force

For a 20x1.5:
* axle-road distance = 203mm + 38mm = 241mm
* axle-brake distance = 203mm - 5mm = 198mm
50N braking force => 41N decelerating force (11% less)

For a hypothetical 23-406:
* axle-road distance = 203 + 23mm = 226mm
* axle-brake distance = 198mm
50N braking force => 44N delerating force (4% less)

So yes smaller wheels = less effective braking, but not because of the size of the wheel per se, it's due to tyre thickness becoming a significant fraction of wheel diameter.
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Old 02-12-09, 12:13 AM   #6
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My initial reaction? How in the world did they manage to use V-Brakes with conventional brake levers?

I would think that the cable pull would not jive correctly.

http://www.sheldonbrown.com/canti-direct.html

I actually did manage to use Sora brifters with V-brakes with QBP Travel Agents and they work just fine.
However, it was quite a bit of a hassle to set up and sometimes I wonder if low-profile cantilevers would have worked better, but hey, they work fine now.

And I know that it's been said many many times before...I believe if you change the stock brake pads with the salmon colored Kool Stop pads, you will see a significant increase in braking power.
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Old 02-12-09, 08:45 AM   #7
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Good to know the new one really has V's. Don't know how they're set up,but I could always drop in a set of Problem Solvers Travel Agents. Used them on a cross bike I converted to V's and they worked really well. Also,I realise smaller wheels will mean less effective rim brakes,but the V's on my FlyBy work much better than the calipers that were on that Pro TT I rode. Thanks for the responses folks.
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Old 02-13-09, 04:15 PM   #8
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Quote:
Originally Posted by SesameCrunch View Post
Also, with smaller wheels, you get less leverage, so the braking is inherently less effective than with larger wheels. Even on my high-end 20" wheeled bikes, I just don't get the same level of braking as with my 700C road bike.
I don't think it's anything to do with leverage. With similar tyres, the force is the same.

The shape of the tyre contact patch would have more to do with the perception of braking forces.
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