Hybrid Bicycles - Add multiple chainrings crank to bike

I found this Marin Bridgeway and it looks quite interesting.
http://www.marinbikes.com/2010/bike_specs.php?serialnum=1644

Is it possible to add another chainring and front derailleur to this bike? The gearing is quite low as is, but a 26T chainring or so will be very helpful for some of these San Francisco hills.

I don't think it would be possible to do that.

If you were to do such a conversion, you'd need to swap out the crank and BB (the spindle will need to be longer), add a front derailleur and shifter, and remove the chainguard. Also, you need to check the total gear range of the rear derailleur: difference between low and high rear cogs + difference between low and high chainring.

...or you just buy a bike with similar geometry and more gears. You can probably get a 21 speed for about the same price.

Most people who would consider a bike with a chain guard love the chain guard. I agree that while you could do it, you would lose the chain guard so that may not be what you want to do. You could also end up spending more money than a bike with the gears you want would cost. You could just put a smaller chain ring on the bike but then you would lose your top end gears and that may not be what you want either. SRAM makes a three speed "dual drive" rear hub that you use with your 7 (or 8, or 9) speed cassette and which gives you in effect a triple chain ring. You could go that route but be prepared to spend some money as you have to buy the hub and shifter and then have your rear wheel rebuilt. And you would lose the quick release attachment of the rear wheel, it will be a bolt on. If money is no object it would give you a bike that looks almost identical to the stock bike but with 21 gears. I don't know the price for sure but I think you would be in the $300 - $500 range when all was said and done.

The cheapest way to go would be to say goodbye to the chain guard and get a bike geared as you need it. Keep looking, you may find a bike with the right gearing and a chain guard but I doubt it.

Ken

Contrary to the above comments, it is an easy conversion, and will run you about $75- plus labor. The neet thing is that low end mountain triple cranks use the same axle length as the low end single cranks. I did a similar conversion on a Raliegh.

You will need; or similar; plus some tools:
http://www.amazon.com/Shimano-M131-Crankset-170mm-48/dp/B003ZMDJW6/ref=sr_1_2?s=cycling&ie=UTF8&qid=1308885738&sr=1-2

http://www.amazon.com/Origin8-Clamp--Frame-Cable-Stop/dp/B003BC7MZK/ref=sr_1_1?s=cycling&ie=UTF8&qid=1308885781&sr=1-1
appropriate for the cable routing and tube diameter. You will need a total of three. For a top pull derailluer, two along the top tub, and one on the seat tube. For a bottom pull, two along the down tube and one on the seat tube.

http://www.amazon.com/SRAM-front-derail-B-pull-uni-band/dp/B000NNQJ7C/ref=sr_1_5?s=cycling&ie=UTF8&qid=1308885844&sr=1-5

http://www.amazon.com/Sram-Shifter-Front-Twist-Speed/dp/B000NNX2UE/ref=sr_1_4?s=cycling&ie=UTF8&qid=1308885925&sr=1-4

http://www.amazon.com/SRAM-P-Link-Bicycle-Chain-8-Speed/dp/B00161FWJG/ref=sr_1_4?s=cycling&ie=UTF8&qid=1308886379&sr=1-4

and some cable housing.

You will have to pull of the left grip, or use a different style of shifter. I used an old style Shimano lever from Crosslake Sales; and eBay vendor. I also got my front derailleur from them.

As noted, you will loose the current chain guard.

Chain guard removal kills it for me. I'd love to keep the chain guard and have at least two chainrings since I'm in a hilly area. Even going to the grocery store means a 7% climb with 10-12% sections. I probably won't use it for commuting since that involves short sections of 20% grades.

I did test ride the bike, and loved the geometry and chain guard but there are no hills near the shop. Is it not possible to put a chain guard on a bike with a front derailleur because the chain moves around too much, in addition to having to clear the derailleur itself? Some bikes have a plastic cover over the big chainring, how well do those work? (I'm guessing not as well as the full length cover on the Marin Bridgeway.)

The 175 and 199 mm versions of the German-made SKS Chainboard (http://www.sks-germany.com/?l=en&a=products&r=chainguards) have cutouts for front dérailleurs:

http://www.bike-x-perts.com/images/images_2010/41pNAWLa0fL%5B1%5D.jpg

Of course, rarely do I find bike accessories that are truly universal so it may require some minor surgery to fit your application.

The 175 and 199 mm versions of the German-made SKS Chainboard (http://www.sks-germany.com/?l=en&a=products&r=chainguards) have cutouts for front dérailleurs:

http://www.bike-x-perts.com/images/images_2010/41pNAWLa0fL%5B1%5D.jpg

Of course, rarely do I find bike accessories that are truly universal so it may require some minor surgery to fit your application.
and available from Amazon.

The rings work fairly well. The crankset I suggest above has them. On a couple of bikes, we have Driveline branded aluminum chain guard rings - do a search on ebay, they are from Taiwan. They are on our tandem and the blue project bike.