Giant crs 3.0 crankset replacement

leyuzzzz

My bottom bracket was gone in my Giant CRS 3.0 so i decided to replace it (BB 7420) however when I was removing crankset i destroyed the thread therefore I would like to replace it too. It is Shimano crankset and sticker says FC-M191 not only I can't find this particular one on ebay for sale but also I would like a better quality one. Which bottom bracket and crankset should I get for this bicycle?

I will appreciate any help.

cooldad

It's a basic Shimano square taper - Tourney I think, so pretty much any will be an upgrade, but I assume it needs trekking size rings.

leyuzzzz

I just checked they are 20/16/11.5 cm so will any same size work fine from shimano? Should I use same bottom bracket or should I use different depending on crankset I get?

cooldad

The BB and crankset have to match, ie square taper, Octolink, external etc, and a cartridge type has to have the right length axle for the crankset. I would just replace like for like.

leyuzzzz

So what can I do if I am unable to buy this FC-M191? Should I just buy the same size and style shimano crankset (square taper) ? I will try to buy the same BB since those BB7420 are available on ebay. Do I need to know anything more than size and BB matching?

leyuzzzz

So I did some research:

RPM BB-7420

Available on ebay for £8 however they are not recommended because of their quality. Full specs is:
Shell: 68mm
Spindle: 122.5mm
Thread: BC1.37x24
People recommend UN 55 or UN 56
I found Shimano UN55 on ebay 122.5 mm 68 mm for £12.89

As a replacement for FC-M191 i found on internet recommended SHIMANO TOURNEY FC-M171 48-38-28 for £21.99 , is it good or should I look for something better/different? (Tourney don't have best reputation but there is not bashing on internet on it like on RPM BB I have so I guess it will be ok).

I am open to any opinions/help/recommendations especially if you can recommend some other crankset since this UN 55 BB seems good choice unless I overlooked something.

EDIT: I don't know fully rules on this forum, if it is acceptable I can post links to ebay auctions that I found and quote information I found I also have pictures of my removed crankset and BB so if any of this is helpful and it is ok to post it here I can do that.

cooldad

It's fine, as long as you are not advertising commercial stuff, or posting nude pics.

leyuzzzz

cooldad wrote:

It's fine, as long as you are not advertising commercial stuff, or posting nude pics.

Without nude pics it lost whole fun but ok

Old crankset specs:
http://techdocs.shimano.com/media/techd ... 657743.pdf

Recommendations for replacement:
http://www.cycling-forums.com/replaceme ... t1902.html

I already posted BB specs, here is quote of why I shouldn't get it:
"I wouldn't expend any effort in trying to replace the RPM BB-7420 with another of the same, they're not all that good.

Neither would I bother with a Shimano UN-26, they're built for a bike that gets ridden a couple of times a year in the dry.

However a UN55 (or 56) will go on and on and on. bike-discount.com or rose.de have them very cheaply, especially if you can combine the postage charge with a few other items."
written by: s1965c

As you can see I didn't' found much about crankset replacement (at least not something with reasonable quality) so I wrote to rosebikes that I want to buy UN-55 and M-171 and I asked them would they recommend anything different then M-171 from their offer that will fit my Giant CRS 3.0. They are cheaper then ebay sellers but when I add delivery on cheap things like this M-171 it's only few quid difference. I will let you know what they answered hopefully they will have some suggestions from at least Alivio class or higher.

cooldad

UN26 is fine.

leyuzzzz

cooldad wrote:

UN26 is fine.

But there is very little price difference between them (£5 maybe) and I didn't replace BB since I bought bicycle ( approximately 4 years ago) and this OEM one basically fall apart, so I think adding few extra quid is not a big deal since I'm sure for next few years I won't be bother to check it and replace unless something serious happen like now ( I had this nasty sound coming out of BB ).

EDIT: Also I just checked, on ebay they have UN26 but rosebike don't and if they answer my message within 2-3 days and advice me on crankset I am willing to buy everything from them since I appreciate good customer service. We will see if they won't answer maybe I will consider UN26 from ebay, always few quid more in my pocket, especially if all can come from one seller, it;s easier to have both parts at the same time then wait with maintenance till second one arrives.

EDIT2: It is worth mentioning that I am 110 kg, 190 cm which is unusual among cyclists since bicycle saddle OEM on this bicycle broke under me I focus on best quality components I can afford that have good reputation since damage I'm doing to them is significantly bigger then regular person would do.

leyuzzzz

So they answered that M-171 and UN55 are a good choice. Unfortunately when I wanted to order, it was sold out. Therefore I gave them a call and I end up buying UN55 with FC-M411 which should be much better quality. Will update you after I install it on my bike how did it go (BB removal was a nightmare I even tried jumping on pipe attached to it before it let go).

leyuzzzz

Order arrived today I will go back to thread after installation which I should attempt in next few days to report results.

leyuzzzz

Everything went smooth with installing this crankset and BB. Unfortunately I took my bike for second ride today and rear derailleur hanger broke, smashing derailleur into wheel, destroying one spoke and mudguard, it looks like it didn't damage cassette so at least that's good. Some more maintenance waiting for me.