Problem with Deore Hollowtech chainset on road bike?

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CMC-24
Posts: 20
Joined: 1 Mar 2012, 8:30pm

Re: Problem with Deore Hollowtech chainset on road bike?

Postby CMC-24 » 7 Apr 2012, 11:42am

Hi Malcontentus,
The relevant measurements, rounded to the nearest millimetre, are as follows:-

Thickness of drive side crankarm - 14mm
Distance from inside of drive side crankarm to outside of frame downtube - 58mm
Width of down tube (incl. thickness of paint) - 29mm
Distance from outside of down tube to inside of crank arm on non-drive side - 63mm
Thickness of non-drive side crank arm - 14 mm

By my calculation, that would give a Q factor of something in the order of 178mm. In reality, it could be up to about a millimetre wider than that due to me rounding sizes to the nearest millimetre. My ruler isn't accurate enough to measure in less that mm segments.

Based on the above measurements:-
Distance from outside of drive side crankarm to centre of downtube - 86.5mm
Distance from outside of non-drive side crankarm to centre of downtube - 91.5mm
Therefore, each pedal is 2.5mm away from it's ideal position for that crankset.

I had a quick measure of my other two road bikes and mountain bike and the only one that has perfect alignment is my old Raleigh Special Products titanium frame which is currently fitted with a Campagnolo Mirage Ultra-torque crankset. The Ultra-torque crankset is a compact and, understandably, has a very much lower Q factor. The Raleigh is a great bike but not up to loaded touring.

Cheers.
Colin.

Brucey
Posts: 42890
Joined: 4 Jan 2012, 6:25pm

Re: Problem with Deore Hollowtech chainset on road bike?

Postby Brucey » 7 Apr 2012, 12:22pm

CMC-24 wrote: By my calculation, that would give a Q factor of something in the order of 178mm.

.............. and the only one that has perfect alignment is my old Raleigh Special Products titanium frame which is currently fitted with a Campagnolo Mirage Ultra-torque crankset. The Ultra-torque crankset is a compact and, understandably, has a very much lower Q factor


the mirage ultra torque was so good they, er , are stopping making it..... :roll:

I have the non-compact version and (bearing issues and lack of chainline adjustability aside) I think it is an excellent piece of design...

I guess you could respace the deore to get the Q factor symmetric but that might mess up the chainline.. ho hum.... I wonder if you could reduce the length of the BB spindle any? How much longer are the spindle splines than they need be?

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

CMC-24
Posts: 20
Joined: 1 Mar 2012, 8:30pm

Re: Problem with Deore Hollowtech chainset on road bike?

Postby CMC-24 » 7 Apr 2012, 6:44pm

I am quite happy that I have got the Chainset working acceptably well with my Tiagra levers and Tiagra front mech so I'll probably leave it exactly as it is for the time being and see how I get on.
I am doing LEJOG starting on Tuesday 10th April so that will a test of how well everything, including me, peforms. I am doing the route with a friend on another Hewitt Cheviot SE. He has the same chainset with Tiagra levers but has a Deore XT front mech. He has the spacers as per the Shimano recommendation (two on drive side and one on non-drive side) but has had some issues with his front mech. LEJOG will let us compare each of the setups over a good few miles. We will be laden, as we are camping, so any weaknesses will quickly show up.
Cheers.

User avatar
Chris Jeggo
Posts: 203
Joined: 3 Jul 2010, 9:44am
Location: Woking

Re: Problem with Deore Hollowtech chainset on road bike?

Postby Chris Jeggo » 16 Apr 2012, 10:44am

I bought a Cheviot SE with a Deore Hollowtech triple chainset and the gears worked fine. However, I was not entirely happy with Shimano's official chain-lines, with the centre chainring being much further out than the centre sprocket. I found that I could remove one of the two right-hand spacers without any problem. Had I removed the second, I would have had to transfer it to the left-hand side as discussed above, and I decided not to do this experiment at the time.

Brucey
Posts: 42890
Joined: 4 Jan 2012, 6:25pm

Re: Problem with Deore Hollowtech chainset on road bike?

Postby Brucey » 16 Apr 2012, 11:24am

I recently boght a SM-BB51 H-II BB unit and I notice the following;

1) the centre tube spacer has shoulders on it which limit how close the cups can be installed to one another.

2) the minimum cup spacing is 74.5mm

3) the cup spacers supplied (in total) come to 7.5mm thickness.

Thus the minimum BB shell width should be 74.5mm - 7.5mm = 67.00mm. If installed without some of the cup spacers, 'bad things' will be happening to the centre tube.

I don't know if it will collapse gracefully or not, but it might be a good idea to remove or reduce the shoulder (which isn't very high) on one or both sides of the tube so that the cups will tighten closer to one another without breaking the tube or deforming it so that it binds against the spindle.

For anyone who has an older frame with a 66mm (or less) shell this is important to bear in mind. For other folk it is only of interest if you remove spacers altoghether, rather than put them onthe other side.

cheers
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~~~~~~~~~~~~~~~~~~~~~~Brucey~~~~~~~~~~~~~~~~~~~~~~~~

CMC-24
Posts: 20
Joined: 1 Mar 2012, 8:30pm

Re: Problem with Deore Hollowtech chainset on road bike?

Postby CMC-24 » 1 May 2012, 3:46pm

For those who might be interested in a follow up to my original concerns:- I have just completed LEJOG on my Hewitt Cheviot SE with Shimano Deore Hollowtech triple crankset, Tiagra STIs and a TIagra front mech. I used one spacer on the drive side and two on the non-drive side. The setup performed absolutely faultlessly and did not need any adjustment during the entire trip. My companion used a similar setup, except that he used an XT front mech and had two spacers on the drive side and one on the non-drive side. He experienced some chain rubbing but nothing serious and had to manually adjust his cable tension once during the trip. I am happy with my setup and my riding companion is happy with his – you makes your choice.