Bike Forums - An introduction and a question

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An introduction and a question

Hi all, I have just found this forum through reading a review posted at Mountain Equipment Co-op. I haven't much to say about myself besides that I am a Canadian man, from SW Ontario, who commutes to work by bike about 50% of the time. .
I am the happy owner of a new Trek Allant and my commute has taken a whole new level of pleasure due to this bike. There is one minor issue I have with it, which is the size of the tires. I don't know if this is just my perception, but it seems that when I bike, the tires ride very low. They are 700c 35c tires that came with the bike, pumped to 70psi. I am a bit of a bigger guy (6', 245lb) and I have a 20lb bag that carries all my work and bike stuff.
I guess my question is: Is this just my perception from the vantage point while riding, or should I get bigger tires? They are not uncomfortable, but just don't feel right. The person who sold me the bike said that it might take a while to get used to it.
So in conclusion: it's nice to be here, and I'm looking forward to your replies.

Try more air. 70 seems low for someone of your size. Not sure what the max pressure for your tires are but my 700X32 tires are rated at like 90 or some such thing and I normally put them to 105. I'm down to 205 now but was 230 when I got this bike and the extra air pressure does make a difference. Also check them often as most bike tires loose air fairly fast, at least at high pressure. I top mine off every couple of days and the rear is normally the one that needs the most. I'd say go up by 10 psi until you find what feels right.

Yeah, you can try adding 5 psi at a time till they feel right to you. Also, bear in mind that your gauge may not be accurate and causing you to run lower pressure than you think you are. The gauge on my Topeak JoeBlow Pro floor pump reads 15 PSI higher than my handheld gauge and 10 lbs higher than my Topeak RoadMorph G pump.

And welcome.

I'm a big guy (220) and I sometimes feel like my back tire is squishy or flat even when I know for a fact that it is at full pressure. Its usually on days when I'm not feeling tip-top. I'll keep looking down at my tire to see if I've sprung a leak! Inflate them to max PSI, top off every day or every other day, especially if there are big temperature changes outside.

+1 on increasing your tire pressure (check your pressure regularly & keep them inflated)

Looking at the specs for the Allant it looks quite similar to my commuter bike - it came with pretty low end OEM Kenda 700x35c tires and I recently replaced them with a Schwalbe Marathon 700x32c which, with the narrower tire at higher pressure, improved the feel of the bike IMO and was a very affordable "upgrade".

You may have to experiment a little yourself to get what you're looking for. (BTW -MEC has some really great prices - eg my CO2 inflator - and some not so great prices - tires are way cheaper on-line)

I will increase the air pressure, which means I have to get a pump with a pressure gauge.

Regarding the comment about upgrading to smaller tires, this seems counterintuitive to me. Can you explain the logic?

Thanks for the replies all, I'm really liking this forum, and it will probably become a great resource as I bike more and more.

Quote:

Originally Posted by doc0c (Post 11591742)

lower rolling resistance on the skinnier tire. Really will be noticeable if you make a 5mm jump. As a big guy for a commute, I wouldn't go smaller than 25.

A home floor pump with gauge should be the second most important purchase (A bike the first). I check my tire pressure every few days. Under inflated tires can cause pinch flats and increase rolling resistance.

Alright, so I'm gonna keep these tires for now and just pump them up nice and high. Hopefully I won't kill anyone with the pebbles that shoot out every now and then :)
And I'll go get a nice pump of course. Any that you guys own that you would recommend?

Quote:

Originally Posted by doc0c (Post 11592502)

For these types of purchases I usually do the following:

1. Go to bike store
2. Ask for three suggestions
3. Don't get the most expensive one or the cheapest one.
4. Scan the barcode on my iPhone and read online reviews :)

The size of the tire shouldn't be a problem. Most of our 700x35 tires have a load rating of at least 90kg/tire (198lbs.) at max. psi. I could not find the load rating for the Bontrager tire that comes stock on the bike, but one would assume that it's nearly the same.

I would definitely pump up your tire to max psi in the rear, and maybe a bit less in the front. I would respectfully disagree with the concept of going to a narrower tire. A wider tire has a higher load capacity. A larger volume tire will deflect more, but will still roll nicely and will support more weight.

If you intend to retain the fenders, going to a wider tire may not be possible. I'd take a very careful look at your bike where the tire/frame/fender clearance may be an issue and see if there is any wiggle room to get a wider tire on the bike. You may be limited to the width of the tire that you have. That said, you should have no problems with a good 700x35 tire.

As for pump recommendations, get a good floor pump (with or without attached gauge), and get a good hand-held (separate) gauge. Hand-held gauges are much more accurate. Dallas Sox Fan's approach seems like a sound one. A good pump should be available for 20-30 bucks.

I'm thinking in the range of 90 PSI rear, 50 PSI front, based this article, PSI Rx. Here's how I worked the numbers.

Based on your weight of 245, 20 lbs of cargo and a 30 lb bike (the Allant's a nice bike, BTW) you need to work from 295 lbs total load. With a city bike like the Allant, it's safe to estimate 65% of the weight on the rear, figure 190 lbs. I interpolated between the 32 and 37 mm lines, then extrapolated beyond the 70kg/154lb range. That left 35% (105 lbs) on the front, interpolating again, I get about 50.

I've found this graph to be a useful starting point. I experiment from there.

You can also see from the article and graph that narrower tires would probably be a mistake.

Quote:

Originally Posted by doc0c (Post 11591742)

Don't even think about skinnier tires unless you completely understand why that would or wouldn't make sense. Skinnier, higher pressure tires do not automatically have lower rolling resistance.

Welcome. As you've notice, tire choices are affected by a number of variables and can be pretty subjective. Getting a good floor pump is a great idea, have you asked them at the shop about how things feel when you ride?

Quote:

I have bought a Topeak JoeBlow 2 floor pump with integrated gauge. I pumped up the tires to 100 psi in the back and 90 in the front. Went for a 6 mile test ride over pavement and packed gravel and it seemed to handle much better. It does feel stiffer, due in part to the Allant's lack of shock absorbers, but it is a much more pleasant ride. The max psi on the stock tires is 90, so I feel that the 10% increase shouldn't pose that much of an issue. I pump up my car tires well beyond the max rating on the sidewall and haven't had a single issue in 3 years. If they do pop at some point due to the higher pressure, I will use the opportunity to get nicer tires (35s again) with a higher pressure rating.

Quote:

Originally Posted by no motor? (Post 11594821)

I have asked at the shop, but the guy seemed stumped by my question. I was surprised because the shop specializes in bikes, but maybe they don't see too many overweight riders.

Nice work doc,

Now, what you may want to do (and this is where a handheld gauge comes in handy) is drop 5 lbs. front and rear, and see if that improves the ride quality without diminishing the rolling/handling of your bike. If you don't like it, put the 5 psi back in, or maybe bump it up a bit more and again, is it better worse? The more you play with it, the better chance you'll have of honing in on what works best for you.

Incidentally, a nicer tire won't necessarily have a higher psi rating. When choosing a tire, make sure that you figure out your budget, and then determine what characteristics are going to be important. You'll get a lot of opinions, but what works best for someone else, may be a nightmare for you. There are always trade-offs.