StreetNameJim

I have a bike that my father in law picked up for $30 at an auction or something (specs from Wal-Mart):
700c Men's Mongoose Paver Commuter Bike

Aluminum commuter frame
Rigid fork
SRAM/Shimano 7-speed shift system
V-brakes and alloy levers
36-spoke alloy rims
Rear rack and ergonomic metro bars
Kickstand
Quick release seat
Model: R4874WM
Walmart No.: 000778353
Shipping Weight (in pounds): 35.5
Product in Inches (L x W x H): 53.1 x 7.9 x 28.3
35 tooth chainring
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Changed the handlebars to flat bar from another bike, removed the rear rack. It weighs about 27lbs ish.

I'm committed to riding this thing to make sure that I'm going to stick with it before I spend hundreds on a decent bike. So far I've got 150 miles in on it (started from 2-3 miles a day, up to 10-15 in about 5 weeks) I average about 12-13mph on flat steady pavement for 10miles. I'd like to know how I can get it to go faster? I think I can change the SINGLE chainring and increase the speed, but I'm not sure. I rarely go out of 6th or 7th gear, so if 1st gear is "harder" than it is now, that'd probably be more useful to me than it is now.

I counted the teeth and it has a 35 tooth chainring on it now... just looking for some guidance on what I need to consider if I change it and where I could buy the right thing.

It has 45c tires which seem tough to find tubes for. Can I put a different sized tire on the same rim?

Any direction other than "buy a real bike" is much appreciated.

Retro Grouch 

Other than a more powerful motor, better tires will yield the most help.

The width of your rims will limit how skinny you can go. Smooth tires are faster and grip just as well on the road, even through puddles. Thin treads are faster than thick treads but will puncture more often. Higher pressure, up to around 110 psi - 120 psi, helps. Above that, higher pressure is generally detrimental.

StreetNameJim

Thanks Retro!! Since this is only a 7 speed bike (no FD), I can't really pedal a lot faster than I do. I'd like to make it harder to pedal in 7th gear... which is why I was thinking of the chainring.

How do I determine how skinny I can go on the tires? Does the 45c give an indication of the width of the rim? or is there some other marking on the rim to look for?

painkiller

some pics of your crank and rear cluster would help.If your rear clusters small cog is an 13 tooth an 11t would help and a bigger front ring if it can be replaced would help 42 to 48 maybee,however these mods come at a cost You will need a chain,11t 30t rear cluster and front chainring and new tubes and tires. probably $150.00 bucks or so
I would say make sure you want to ride and invest in another bike more your style. even then you might want to make similar changes to suit your needs. if you stick to around 700c x 28 to 700c x 32 tires you would probably be fine

Retro Grouch 

35 tooth is a pretty wimpy chainring. If it was my bike and I wanted to go faster I'd probably be looking for something around 48 teeth. 2 issues:

1. Bolt circle diameter. Your new chainring (obviously) has to have the same bolt pattern as your old one. The easiest way to determine what you have now is to measure between any 2 adjacent chainring bolts and check Sheldon Brown's website to convert that dimension into BCD.
2. Chain length. If you get a chainring that much bigger, you're also going to need a new, longer chain. Sheldon't site will also tell you how to determine how long your new chain has to be.

Tire width. 700c rims aren't all the same width. Real wide ones won't handle real skinny tires very well. Guess where you can find how skinny your rims will tolerate. That's right! Sheldon Brown's website.

Andy_K 

A 35T chainring will get you 20 mph at around 100 rpm even if your smallest rear gear is 14T. If you can't comfortably pedal at 100 rpm, work on that and your speed will improve. If you can, then definitely change the gearing. You can get a 12-28 freewheel for a reasonable price. To change the chainring, you'll probably need to change the entire crank. You may as well put on a double if you do that.

You'd probably notice a difference with 700x28 slick tires.

Drew Eckhardt 

500-1000 base miles in your legs, training plan incorporating hard intervals and rest days/weeks/months as required, training log to adjust ramp rate and recovery to suit your physiology, high cadence intervals to improve your spinning ability.

LesterOfPuppets

I'd probably swap out that high rise stem for something like a 90°, 100mm unit in an effort to get the bars level with saddle or lower. Might wanna go with different stem length than 100 depending on your bodily dimensions.

And there's no way I could hammer effectively on that saddle.

I'd run the stock tires until they wear out. You can run some 700c x 32-38 tubes in there, they're close enough and available at most bike shops.

sonatageek

I would go with a 32 or 35mm tire that will let you run 85-90psi. Narrower, but still wide enough to help soak up the road bumps.

StreetNameJim

So here are some pics (I think they'll show up?).

I don't see any bolts attaching the chainring to anything. It looks like its attached to the crank somehow. So maybe changing that isn't so practical?

Counting the times I pedal per minute seems tough to do... is it a full circle? or perhaps each foot to the top? I can see me pumping away with my iphone out trying to start a timer and count and not pay attention to traffic/kids/dogs/parked cars. Is there a good method for doing this? I am glad to know that there is a target for this kinda thing though. I've just been trying to beat my last times and get my mph up.

I'm glad to know that the 35 tires are still an option if the crank is out of the question. I've ridden a couple of bikes with 35s and they seem a lot faster than mine.

I've changed the handlebars and raised them up and the seat and it was 10x more comfortable than the original config.

I appreciate the help guys.

LesterOfPuppets

Higher bars make you slower, as a general rule. I'd go for 28mm tires after yours wear out. That's my favorite road tire width on bikes that they'll fit. Have to get by with 26 on my pinarello.

Hard tellin' what that chainring situation is. Might be some kind of BMX style 3-pc crank. If so there's a slight chance that some BMX chainrings would fit. That's just a totally wild guess, though. I'm not hep to current BMX stuff.

StreetNameJim

I guess part of my challenge is that I don't like getting horizontal to the road. I like to sit up or lean forward some and keep pedaling away. I tried a road bike out and it wasn't comfortable and it responded to EVERYTHING in the road. I think the "hybrid" is the way for me.

note the cracks in the tire on pic 2... does that pose a significant threat? This bike laid out in the winter weather for several months before I took it in.

LesterOfPuppets

Oh yeah, those tires are rotten.

If you're on a budget, these are likely the cheapest tires around at the moment, if you can handle 28s. Unfortunately they're pretty roadish tires so you will feel the road somewhat, but....
Stradas for $7.50

If you want big meat, then Performance has these 35s for $13

StreetNameJim

Thanks!! I think I'll go with the big meat... It looks like something that I can carry forward to the next bike if they last that long.

Not knowing what you don't know sure is an uphill battle, but places like this are encouraging.