Tuesday, October 19, 2010

Primo Comet Tires on Downtube 8H.

I was getting a little tired of the sluggishness from the Kenda Kwests that came with the Downtube 8H so I picked up some Primo Comet tires. These tires have gotten some good reviews on the Bikeforums community. They are smooth tire with just a very slight line pattern.

Yes, the tires are a big improvement over the Kendas, but I wouldn’t say it is like night and day in terms of change. The tires roll better than the Kendas, but I still detect a little hugging or grippishness (is that a word?) of the road. I think they could be a little nimbler. Another positive for the Primo comets are that they are 100psi tires. This is probably what makes them roll better than the Kendas. The Kendas max out at 60psi.

A caveat is in order, though. I continued the pattern of having a fatter tire in the back vs. the thin one in the front. The Kendas were 20x1.75” rear tire vs. 20x1.5” in the front. The Primos I went with are 1.90” for the rear tire vs. 1.50” for the front.

Why did I do this? I guess I “drank the koolaid” in that Downtube puts a wider tire in the rear for various reasons. I quote from the DT site:

Q Why do you have different front and rear tires on some models?
A This is one of the best features of our bikes. Note the forces on the front wheel are push based, and pull based on the rear. Pushing is "harder" than pulling, hence more energy is wasted up front. Hence we thinned the front tire. Additionally, the seat tube is angled back more weight is distributed towards the rear of the bike. Hence we put a wide rear tire for traction. This configuration is highly efficient, and very safe.

I believe some other bicycle experts also have recommended this, maybe even the late Sheldon Brown, but I’m not 100% sure on that.

Maybe I should have just kept a 1.5” Primo comet in the back (?). In addition, I couldn’t find a 1.75” Primo comet tire for the rear. The next closest size was 1.90” so I went with that. Maybe I installed too fat of a tire.

Another surprise is the weight of these tires vs. the Kendas. I weighed the Primos and the front one weighed 12.5 oz and the rear weighed 20oz. Both of these tires weigh just a little over 32oz, or 2 lbs, together. The Kendas weigh right around 1 lb each. The front Kenda tire was just a smidgen lighter than the rear. Therefore, you’re getting better performing and higher PSI tires for the same weight.

Bottom line: a nice upgrade over the Kenda Kwests, but still could be better. The best rolling tire I have found for a small wheeled bike is the yellow tag Brompton brand stock tires. Those roll very well and are 100psi tires.

Tag: Primo comet tire review.

No comments: