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Commuting Bicycle commuting is easier than you think, before you know it, you'll be hooked. Learn the tips, hints, equipment, safety requirements for safely riding your bike to work.

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Old 03-03-10, 11:38 AM   #1
elkfuzz
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Mountain Bike Commuter Conversion

I have a 2008 Specialized Rockhopper. This was/is a decent mountain bike, but I would like to convert it into more of a commuter/urban bike. I attempted to sell this bike for a dedicated commuter bike, but didn't get any reasonable offers. I was wondering what the best options would be to speed this bike up.

My thoughts so far are replace the tires with some slicks, change the suspension fork to a straight rigid fork.

Does anyone have any ideas about what I can do to speed this bike up? Is it possible to safely replace the fork on a bike like this? Will replacing the fork make a significant impact on bike speed for commuting purposes and will the changed geometry of a rigid for be safe on a bike like this? Please let me know if you have any ideas, I am trying to keep the conversion cost under $250.
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Old 03-03-10, 01:15 PM   #2
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Does anyone have any ideas about what I can do to speed this bike up?
Always running late to work?
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Old 03-03-10, 01:41 PM   #3
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Changing to some thinner/slicker tires will make a huge difference. I'd do that first and see how you feel about it after that.

Changing the fork to a suspension-corrected solid fork (Surly makes some nice ones) would lighten the bike up a bit. I'd try the tires first though to see if the fork swap is worth it to you.
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Old 03-03-10, 01:46 PM   #4
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If you can lockout the fork that may be enough. You still may want to take this bike off-road now and then.
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Old 03-03-10, 01:55 PM   #5
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Running narrow slicks will make a big difference, and is probably the most cost-effective change you can make- it will feel like another bike.
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Old 03-03-10, 02:07 PM   #6
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I concur with others on going with narrow slicks, preferably at max pressure. I converted an MTB this way and it made a huge difference.

My MTB had higher bars than yours, and so reducing wind resistance would have been my next suggestion, but you may already be as low as you want to go.

By changing forks you might save a little weight, and maybe save a little energy if you are cranking hard, but not much. Ride it on slicks as others have suggested and see how it feels.

It's possible you'll want a larger top gear on roads going downhill. Wait until that actually happens before bothering to do anything about it.
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Old 03-03-10, 02:11 PM   #7
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My MTB based commuter, rigid fork, Continental Town and Country tires or studded tires for Winter, Topeak Supertourist rear rack, Axiom waterproof panniers, Planet Bike Freddy fenders, Magic Shine headlight, etc:



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Old 03-03-10, 03:08 PM   #8
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Thanks for the help. Any advice for what typy of high pressure slick tire would work well with the stock rims that come on this bike. The rims one this bike are "Specialized/Alex RH 26."

The bike currently has 26x2 in wheels. Will I need new tubes for the slicker/thinner tires??
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Old 03-03-10, 03:27 PM   #9
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I used to commute on my Trek 6700 and retained the suspension fork but ran two sets of wheels with different tyres and cassettes... my road gearing was a little higher and tighter.

I was pretty happy running 2.0 semi slicks at 75 psi as quite often my on road commute would turn into an off road adventure... I ran and still run Schwalbe Hurricane Sport tyres as they roll out fast and have been bulletproof over at least 10,000 km and still have lots of life left in them.

You could go with a suspension corrected fork and then the high pressure skinny tyres may prove to be too harsh as you will lose your front suspension and the bike was designed to perform and ride best on wider higher volume tyres.

There is a little bit of tyre myth out there in that people think that a wider tyre can't roll out fast and much of this has to do with tyre compounds and tread design and when commuting it is also nice to be able to blow through potholes and not worry about your wheels.

I use 1.5 Schwalbe Marathons on my mtb / touring conversion and the guys have clocked me at 35 kmh while I was cruising along at a happy pace... their bulletproof construction and flat resistance are a huge plus.
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Old 03-03-10, 03:32 PM   #10
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My mountain bike conversions... these 2 Kuwaharas have excellent road geometry as they were built in the 80's when mountain bikes were really touring frames designed for 26 inch wheels.

Summer:



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Old 03-03-10, 03:38 PM   #11
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Since no-one else mentioned it, a lot of MTB rims have a very low max PSI rating. Find out what yours is before you put a 110PSI tire on it. Some can be as low as 60PSI. The risk you take is the sidewall of the rim blowing off, which can lacerate you badly, or cause a nasty crash.

As for a tire, find something ~400 grams or so, with at least 60 TPI (120 is better) and a dense rubber compound for flat protection (not kevlar.)
If flat protection doesn't matter, you'll likely get a tire that's ~300 grams or less for fairly cheap. Sub 220lbs with good roads? 28C would be great.
Bad roads or over 220lbs? 32C to 35C would be a good size.
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Old 03-03-10, 05:00 PM   #12
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I say put a rigid fork on and some slick or touring tires. Suspension forks are not necessary for urban riding and with a rigid fork you can still go do some off road trails . Touring tires roll good on pavement and can also be used for mild off roading. Maybe even change the handlebars to a straight bar with bar ends and get rid of the riser bar. that's just my opinion.
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Old 03-03-10, 07:05 PM   #13
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The reason I picked Continental Town and Country tires is that they roll smoothly on pavement and yet retain some basic off-road abilities. I run them at 60psi which is hard enough for smooth rolling yet soft enough to provide shock absorption. I'm willing to pedal a little harder to get better comfort. They can go up to 80 psi but then the ride is too hard for my liking. They also work great at 35psi for off-road or snow riding. They're also puncture resistant. They also look cool. I had 1.75 tires before and they look weird on a MTB, I prefer fatter tires for comfort, traction and looks


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Old 03-03-10, 07:13 PM   #14
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and a dense rubber compound for flat protection (not kevlar.)
Dense rubber versus Kevlar? Are you quite sure about that? Because I'm not.

Adam
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Old 03-03-10, 08:22 PM   #15
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On my hardtail I have Specialized Fatboys (26*1.25 100psi). I love them. Since I have a relatively short commute I kept the suspension fork (it does not have a lockout). The only time I notice a bob effect is when going up a steep incline.

I also use PowerGrips pedal straps. I have them on both my hardtail and tourer. I like them alot also.

I also have Ergon Grips Gr1 or 2's I think (cant remember off hand). I find them to be rather comfortable when angled correctly. They have a built in short magnesium barends. So far I havent had a need for longer ones, but they are available.

Since you may be spending more time in the saddle you may want to change that out as well. I've been looking into a Brooks B17 for mine, but the funding hasn't been there.

Like others have stated the tires will make the difference so change that out first and work from there.
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Old 03-03-10, 08:45 PM   #16
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Dense rubber versus Kevlar? Are you quite sure about that? Because I'm not.

Adam
Find a video of Kevlar vests Vs. a knife, and remember those are several times thicker and still easily stabbed through with a knife tip. They're alright for stopping large things getting through, but thin, narrow, or sharp objects will punch through/cut the fiber fairly easily.

Kevlar is great for some protection without a lot of weight, but dense rubber (see Marathon Plus and tire liners) are where real flat protection lies.
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Old 03-03-10, 09:13 PM   #17
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+1 on the tires. I run 26*1.5" Kenda Kwest tires on my rigid Raleigh and it rides like a completely different bike than it does with the 2.125" knobbies. Another suggestion would be to use a longer stem with a more severe angle to stretch you out into a more aerodynamic riding position. An adjustable stem like this one would allow you to try different angles to dial in the best balance between comfort/speed. New handlebars/aero bars could also be a consideration. Even with tires, stem, and bars you should be able to stay well under your budget limit.
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Old 03-03-10, 09:24 PM   #18
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What is your commute like?

If it's urban stop-and-go or shorter distance commuting then you'll be happy with swapping out the tires on the rockhopper and then perhaps putting on a rack.

If you are looking at 15 miles of high-speed country roads or bike paths then you'll eventually want a true road bike of some sort or perhaps a cyclocross bike with slick tires.
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Old 03-04-10, 04:53 AM   #19
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Find a video of Kevlar vests Vs. a knife, and remember those are several times thicker and still easily stabbed through with a knife tip. They're alright for stopping large things getting through, but thin, narrow, or sharp objects will punch through/cut the fiber fairly easily.

Kevlar is great for some protection without a lot of weight, but dense rubber (see Marathon Plus and tire liners) are where real flat protection lies.
I run 26x1.5" City Jets which have a kevlar band. I ride over some pretty bad roads covered in glass and small sharp stones and get about 1 flat every six months or so. They are lighter than the Marathon Plus by about 200grams and much easier to get on and off the rims so they have their benefits.

Having said I will be getting a pair of Marathon Plus when these wear out, they are the best commuting tyre out there.
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Old 03-04-10, 05:54 AM   #20
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Find a video of Kevlar vests Vs. a knife, and remember those are several times thicker and still easily stabbed through with a knife tip. They're alright for stopping large things getting through, but thin, narrow, or sharp objects will punch through/cut the fiber fairly easily.

Kevlar is great for some protection without a lot of weight, but dense rubber (see Marathon Plus and tire liners) are where real flat protection lies.
Most good Kevlar tires also have additional layers of protection. Kevlar isn't the only material used. They're just generally referred to as Kevlar tires. Tires like Marathon Plus simply use a thick layer of hard rubber (5mm or so) so the trick lies in the thickness of the rubber more than its density.



Just like Kevlar it can be punctured by an object sharp and long enough to penetrate the rubber. In both cases it's extremely rare.

With any Kevlar tires I ever used I experienced less than one puncture a year and that had to be something extreme. The only unreliable Kevlar tires were Armadillos. My Maxxis Refuse tires survived two years of NYC commuting with zero punctures, my estimate is 3000-5000 miles, mostly through poorly maintained streets full of debris. The outer layers were so cut up in the end that chunks of rubber were falling off exposing the inner protective layers, and even then I had no punctures.

They looked like this during the last few weeks and still no punctures:



Adam
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Old 03-04-10, 07:11 PM   #21
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before...


after Peformance Slick City 1.25" tire (and tube). I just use it for the trainer but today it worked pretty good in the slushy snow with the default front tire (same as "before" pic).
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Old 03-05-10, 07:14 PM   #22
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The tire swap and the change to rigid fork would likely be all you need and can be done for much less than $250. Even changing the tires alone would have a pretty significant impact; the rigid fork is just icing on the cake. Most rigid forks I think would be suspension-corrected for 80-100mm travel bikes - more than likely you could do a straight swap with minimal effect on geometry/handling.

From my own experience, the Kona P2 rigid fork does an awesome job as a replacement. Couple that with a decent set of 1.5" street tires and you're good. I have had the greatest success with the Specialized Armadillos, personally. I've found this setup to be more than enough for the pothole-laden streets of SF. And the fact that it is still a mountain bike means that you can still throw on some knobbies if you felt like it, say during the longer days of summer, and look forward to any shortcuts/urban trails on your way home if you have any.
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Old 03-05-10, 07:16 PM   #23
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