Front Derailer on old MTB

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Front Derailer on old MTB

Postby Dan's Avanti » Sat Jan 19, 2013 12:08 pm

Hi All
I been given an old Mongoose NX 7.5 which i really like the look of. The chain, chainring and rear cassette were well past the use by date so i took it to the lbs for new bits. They guys there installed new cheap parts and gave it back saying it also need a new FD. The shifting was aweful. They also charged me heaps and i am pretty unhappy about it... Won't be going back there! I managed to tweak the shifting enough to get 2 of the 3 chainrings OK but can't get the 3rd. It is actually the wife's bike and she is a little grumpy that it is difficult to ride - it doesn't 'just work'.

I want to install a new FD myself. I am looking at replacing a Shimano Deore XT with a Shimano XT M771 from chain reaction. The specs say it will suit 44 - 48 tooth large ring, the bike has 42 tooth (3 x 8 gears). Is this likly to be a problem? I would prefer to not buy the FD to find it doesn't fit.

Dan's Avanti
Posts: 13
Joined: Mon Apr 16, 2012 9:57 am

by BNA » Sat Feb 02, 2013 7:50 am


Re: Front Derailer on old MTB

Postby Dan's Avanti » Sat Feb 02, 2013 7:50 am

I purchased the M771 FD from Crainreaction (good delivery time) and installed. I could not adjust it to suit but not because of the size of the chainring as I asked. The sizing was fine - It turned out that the bottom bracket was too narrow for the frame (111.5mm). Installed a new BB (117.5mm) and problems all solved!

I also installed new Shimano cranks and some DMR pedels to improve the looks a little - the old girls is starting to look good!

Now, for some front shocks, hand grips, decal pack saddle etc etc !!

Dan's Avanti
Posts: 13
Joined: Mon Apr 16, 2012 9:57 am

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