soulshade

I am just now getting into cycling and I have a few questions about how I might do a couple of things. One would be are there any upgrades I can get that will increase my overall speed? Somewhere to start anyhow? I have looked at crankshafts and I currently have 48 tooth and I was wondering if I should go bigger. I have a mountain bike but all I can find that is any bigger is for road bikes. Can you rig that? Thanks for any help.

mechBgon

Can you post a photo of your bike?

John E

Unless you are "spinning out" of your top gear, higher gearing will not make you go any faster. There is nothing wrong with 26" wheels and a 48T outer chainring, with which I use a 13T cog to obtain a perfectly adequate (for me) 96-inch top gear. Dropping to a 12T or 11T cog would increase the gear ratio inverse-proportionately, to 104 and 113 gear-inches, respectively, both of which are higher than I need.

The best way to enhance the on-road performance of a mountain bike is to switch to higher-pressure, smoother-treaded tires. Adjusting the seat height for an optimal leg extension and the handlebar position for a good aerodynamic position will also help.

soulshade

This is the stock photo of the bike. I have made some basic mods, but all of the important hardware is stock.


https://www.marinbikes.com/bicycles_2...z_stinson.html

soulshade

I have times where I do spin out the top gear. I can only seem to get to about 32 miles per hour top speed and about 18 miles per hour average speed.

I adjusted my handlebars and did all the seat adjusting already. I check the tire pressure pretty regularly as well I suppose I just feel like I have hit a plateau and I want to get faster. THanks for the help though, I think I am understanding the correlation between speed and "gear-inches":

longer gear inches = greater speed? Am I gleaming the information correctly?

mechBgon

That's right, for a given pedal RPM, you go faster with a higher gear-inches gear.

For this bike, it appears that the front chainrings are permanent parts of the crankset (you can check, though). The gearing on the rear wheel already has a good high gear back there (an 11-tooth). So I think you'll have to get a new crankset in order to raise your gearing, and possibly a new axle/bearing set (aka "bottom bracket") for the cranks too.

Here's an idea: https://www.nashbar.com/profile.cfm?c...eid=&pagename=
and you'd need one of these too: https://www.nashbar.com/profile.cfm?c...eid=&pagename=

You'd also need some specialty tools to remove the old cranks and bottom bracket and install the new one, and then you'd need to do some adjustment of your front derailleur. But it could be done. Considering how athletic you are, we may also want to get you into one of these: https://www.cycleops.com/products/powertapsl.htm

KevinF

Under what conditions are you "spinning out" the top gear? If you're only spinning out on signifigant downhill stretches, then I wouldn't think you're a candidate for needing higher gear-inches.

Gear inches are a measurement that date back to the days of penny farthing bicycles (i.e., these things). The "gear inches" number is literally the size of the front wheel that would be required on a penny farthing bicycle to match the gear ratio you currently have selected. i.e.,. as you shift, the gear-inches change, which is the equivalent of changing the size of the front wheel on an ancient penny-farthing bicycle. How's that for an obscure measuring method? But it has stuck, and it's what we have.

Essentially "gear inches" are a measurement of how far the bike will travel per pedal revolution. The higher the gear-inches number, the faster you will go -- assuming you can keep pedalling at the same cadence. It gets very hard to continue pedalling at any sort of reasonable cadence as the gear-inches number increases.

operator

Tires are the biggie. Then the drop bars.

soulshade

I can spin out on a flat track if I push it. I maintain it for a bit but mostly I spin out on any slope more tan ten degrees while I am sitting.

soulshade

Thanks for those links. They are even in my price range. All except for that last one. Looks pretty cool though. Thanks for all the help. I have a place to start now.

mechBgon

I was sort of joking about the last item, although you clearly ARE athletic to be riding that kind of pace on a "city" bike If you need any further help, like what tools to pick, just holler and someone will help you out

Bikepacker67

18 mph avg speed with an upright positioned, knobby tyred, heavy azz, MTB?
Cry me a flippin river, young buck!

_dhan_

actually the stinson is listed as having a 7-speed 14-18 cassette (count the # teeth on the smallest cog to be sure). If you go down to 12 or even 11, that'll give you a higher top gear. changing the cassette would be cheaper and give a more dramatic gearing change than changing the bb, cranks and chainring. I rode w/ 48-11 as my top gear and it's plenty fast. now I have an actual road bike that I'm running at 52-12 (I have bigger wheels which makes the difference).

2nd upgrade would be tires. be sure to pump up your current semi-slicks up every couple of days. I used the specialized all condition pro atb for a while. 26x1.0 and 125psi. really zippy. and light too. There are a bunch of different tires available in the 1.0-1.5 range to choose from.

UmneyDurak

At that point might as well go with a a road bike.

Al1943

If you want to go faster buy a good road bike. Nothing wrong with spinning out down hill, 32 mph is faster than Lance Armstrong on a 50K time trial.