Components query

[PioRow]

Looking for a little bit of help with chosing some components. I'm rebuilding an old MTB with all new parts but I am a bit confused!

On a chainset you have "170mm 4-Bolt 22.32.44"
What does the 170mm refer to?

On the front mech you have "28.6/34.9mm Dual Pull - 44T"
What does the 28.6/34.9mm refer to and what is dual pull?

I've tried to match up all the new components with the old ones, just need to make sure I'm not buying the wrong stuff.

Any help most appreciated.
Thanks

 

[RecordAceFromNew]

170mm is the length of the crank from the centre of pedal axle to centre of bottom bracket axle. Cranks usually come in 170mm, 172.5mm or 175mm.

28.6/34.9 are diameters of the seat tube the front mech clamp is designed to fit in mm, some front mechs come with shim(s) that enable them to fit more than one seat tube size. 44T is the number of teeth of the largest chain ring on the chainset the particular front mech is designed for. You need to measure the size of the seat tube to be sure a new front mech's clamp fits.

Dual pull means that front mech will work with either cable running down from the top tube or up from under the bottom bracket.

If you are rebuilding a bike with all new parts, you will have to ensure that any new chainset has a matching bottom bracket that delivers the right chain line for the new front mech. Likewise many other components are inter-dependent.

 

[PioRow]

Thank you so much for the advice.
The current chainset is a Shimano Deore from about 8 years ago so I was going to go for a current Deore, I assume they will still be compatible? I could buy a new bottom bracket but I'd rather not as I have never swapped one out before.

Also as I think about it the current cassette is a 7 speed and I am putting in a 9 speed. Will I need to change out the rear gear changer??

Thanks
Row

 

[RecordAceFromNew]

I am sorry to have to tell you that a 7 speed shifter will definitely not work properly with a 9 speed cassette.

Are you sure you have a 7 speed cassette and not a 7 speed freewheel? Please read this if you are unsure. Cassettes and freewheels are not interchangeable.

There have been numerous versions of Deore chainsets over the last 8 years, even in the same year they come in different models requiring different bottom brackets. A way to progress, if you do not want/need to change the bottom bracket (ask if you don't know how to tell whether a bb is worn/need adjustment), is to have the chainset's precise model code (usually stamped on the inside of the crank arm), and a visual confirmation of the type of bb, so that the current bb model/size can be guesstimated, and from which a new chainset can hopefully be matched. The more certain way is to observe the type and measure the length of the bb spindle (after removing the chainset).

To make any change to the chainset or front mech it is always best to know what the chainline is first.

 

[PioRow]

Again thanks for the help.

I think you are correct that I currently have a freewheel. This wont be a problem as I am getting new wheels which will fit a cassette, right?!

I think my best bet is to get a new bottom bracket, the shimano deore is only £14 and I have to learn how to change the BB at some point! At this stage the only thing left from the old bike is the brake levers and the frame, everything else will be new. Cant wait to get started.

I'll list my components below and if you could let me know what mistakes I am making:

http://www.chainreactioncycles.com/Models.aspx?ModelID=34674
http://www.chainreactioncycles.com/Models.aspx?ModelID=40496
http://www.chainreactioncycles.com/Models.aspx?ModelID=31059
http://www.chainreactioncycles.com/Models.aspx?ModelID=40542
http://www.chainreactioncycles.com/Models.aspx?ModelID=22972
http://www.chainreactioncycles.com/Models.aspx?ModelID=22973
http://www.chainreactioncycles.com/Models.aspx?ModelID=656
http://www.chainreactioncycles.com/Models.aspx?ModelID=20685
http://www.chainreactioncycles.com/Models.aspx?ModelID=40547

 

[PioRow]

Also is there a danger that my old frame will not support a 9 speed rear caseete. Is there any way to measure this?

Thanks
Rowan

 

[RecordAceFromNew]

At this stage the only thing left from the old bike is the brake levers and the frame, everything else will be new.

I hope I am not dampening your enthusiasm, but building up from new bits can end up more expensive than buying a new bike - you still have many components missing... I do however appreciate there can be good reasons to do what you are planning to do.

Modern mtb cassette wheels have distance between rear dropouts of 135mm. You should check what you have. Is the frame alloy or steel?

You wouldn't need to buy a separate bb. That chainset comes with one.

As you know one should pick components based on what use the bike is intended. Quality wheels and tyres are places where particular attention should always be paid, imho. Those wheels e.g. are well over 1kg heavier than a good pair of wheels for XC purpose.

 

[PioRow]

Thanks for the tips.

I think your right, the wheels are a bit to heavy, I have decided to go with the Shimano MT15 instead.

The reason I am rebuilding the bike is that the frame, forks and brakes are all good. Everything else needs replacing so rather than spend £400 on a new bike I thought I would spend it on doing this bike up. I looked at the spec on a £400 bike and it didnt look as good as my old bike with new parts.


Its a steel frame I think. I measure the rear drop out and its 136mm so I should be OK on that front. Are there any other pitfulls I should be looking out for?

 

[RecordAceFromNew]

I am not sure if these are pitfalls, and I am sure others will come along with excellent suggestions:

* Don't forget tools. If you don't have many bike specific tools, you might want to consider getting a bike tool kit such as this, which costs less than just a couple of the individual tools. A good cable cutter will also come in handy.

* The thing about inexpensive tools, is that the steel won't be that good so it is doubly important to be careful, to ensure e.g. they don't slip on the components.

* Those MT15 are disc specific and don't have braking surfaces I think and are therefore no good for rim brakes.

* I wouldn't get those Shimano chains. Chains from kmc or sram e.g., with reuseable links, are much more handy and imho better value.

* If the current fit is not perfect, now is the golden opportunity to improve it by e.g. picking the right stem/bars/seatpost.

Just for curiousity sake I quickly look up CRC to see what one gets for 400 notes. I have no idea whether it is any good, but within seconds this popped up kitted out with lots of deore bits with £1 to spare.

 

[PioRow]

Thanks for the heads up on the wheels. Can you recommend some good wheels then? £150 max total if possible.

 

[RecordAceFromNew]

I like Mavic factory wheels. I don't have these particular models, but they are probably what I would get if I only want to spend £150 on a pair of new V brake wheels. Alternatively these and these, if I also want to cater for disc brakes in the future, at the expense of additional weight.

You might want to be aware that while these factory wheels are strong and light for the money, it is achieved at the expense of easy maintenance when required - e.g. they have custom spokes, and not many per wheel, meaning they are all under high tension.