Cycling UK Forum

I slipped at a turn on my Trek 1.7 triple road bike and fell heavily on the right / drive side last week.

The bike seemed fine, and I rode home. But today I was checking the chain and realised that the chainset is badly loose.

It could be damage from the crash, as the right pedal was the only part of the bike that took a heavy hit.

It could be I damaged the bottom bracket bearings.

It could be the bottom bracket was shot anyway (it has lasted 12 years!), and I had not noticed: I rode this bike 60 miles three days ago, after the crash, and noticed nothing amiss. (I didn't feel any knocking from the BB at all, although it must have been loose.)

Of course, making a visual alignment with the front gear shifter cage, the largest chainring seems to veer off, but as the whole thing is loose this is not telling me much.

I have ordered a new BB along with a whole load of unrelated parts, including a Hollowtech II spanner. (I have only ever done square tapered ones in the past.)

Is there a good technique for checking whether the chainrings are still true?

Bice wrote: ↑1 Feb 2022, 4:56pmIs there a good technique for checking whether the chainrings are still true?

I'd want to check both whether they are bent and whether they are true to the frame.

Visual inspection from all angles.

And how about taping a pencil to the frame so that the tip just touches the ring, and then rotating the ring. As in wheel truing.

Jonathan

PS: Are you OK?

I once clipped the road with the pedal whilst leaning too far on a corner without stopping pedalling, but there was no harm done so I carried on and never gave it any more thought. After a few hundred miles the pedal spindle failed with a fatigue fracture, but since it bent before the fracture had propagated all the way through the spindle, I was able to ride it home carefully then replace the pedals. Still the penny didn't drop.

Then after a few hundred more miles, the fatigue fracture that had been growing in the crank let go whilst I was honking, and I had a big crash as the right pedal disappeared from under my foot.

Bice wrote: ↑1 Feb 2022, 4:56pm Is there a good technique for checking whether the chainrings are still true?

Just turn it, and watch for movement.

axel_knutt wrote: ↑1 Feb 2022, 5:31pm Just turn it, and watch for movement.

Yes, I will do that, after I have fitted a new bottom bracket. I think one of the bearings must be mashed, as turning the crack in either direction is also quite noisy.

Jdsk wrote: ↑1 Feb 2022, 5:09pm PS: Are you OK?

Kind to ask. It was a fast, heavy fall but on open road into a car park, so I did not end up hitting anything. Cuts to right knee, hip and elbow, and a heavy bash to the head, which has hurt my neck. I thought the bike was almost completely unscathed, apart from a bit of bar tape shredded.

I think it must have done for the bottom bracket. I have never done a Hollowtech before, so hope it is not a complication.

That's good to hear.

I've only replaced one Hollowtech II. Used that thin double-sided tool and a torque wrench and followed the instructions. No particular problem.

Jonathan

40 years ago when crashing I bent cranks and pedal spindles. Latterly they don't seem to bend so the energy must be dissipated somewhere. I've just carried on using chainsets after a crash but I do inspect them when washing the bike; normally after every ride.

I have never done a Hollowtech before, so hope it is not a complication.

In my experience the great thing about Hollowtech is that they are quick and easy to replace

The bad thing about them is you need to do it frequently

The last time I replaced mine I splashed out on the Ultegra version as it was on special offer. Seems to have lasted longer than the cheaper ones but I am astonished yours lasted 12 years. There are previous threads somewhere here about prising off the seals and adding more grease before fitting to make them last longer.

This is the tool you need https://www.wiggle.co.uk/park-tool-bott ... tool-bbt-9 Depending on which model you but you may also need an adaptor as the fancier ones have a smaller diameter. To work properly the two halves need to be in alignment so bottom bracket shell needs to be properly faced. As your last one survived so long I assume that is not a problem on your frame.

I saw a bloke not long ago walking a bike along with a crank in his hand, it was a Hollowtech 2 type and the crank and/spider had split in two. I had a search when I got home and found a couple of articles, (linked below with photographs). The crank is made in two U-section parts-(hence Hollowtech) and bonded together somehow . If your 105 uses the same two-piece system, it might pay to remove the cranks and give them a detailed inspection, it may possibly explain your bike's symptoms.
I was quite surprised that this is how cranksets are made these days
https://road.cc/content/tech-news/shima ... nks-287827
https://www.bikeradar.com/features/shim ... k-failure/
Edit; I had a further look around the web and found this post, apparently the 105 uses a different one-piece construction, apologies for muddying the waters above.
Link below has pictures of the differences in construction.
https://handsonbike.blogspot.com/2016/1 ... o-105.html

Steve O'C wrote: ↑2 Feb 2022, 10:42pm

I have never done a Hollowtech before, so hope it is not a complication.

In my experience the great thing about Hollowtech is that they are quick and easy to replace

The bad thing about them is you need to do it frequently

The last time I replaced mine I splashed out on the Ultegra version as it was on special offer. Seems to have lasted longer than the cheaper ones but I am astonished yours lasted 12 years. There are previous threads somewhere here about prising off the seals and adding more grease before fitting to make them last longer.

This is the tool you need https://www.wiggle.co.uk/park-tool-bott ... tool-bbt-9 Depending on which model you but you may also need an adaptor as the fancier ones have a smaller diameter. To work properly the two halves need to be in alignment so bottom bracket shell needs to be properly faced. As your last one survived so long I assume that is not a problem on your frame.

I generally use the Trek 1.7 in winter, and the Italian steel frame in summer. It has certainly had considerable use, and I have replaced chains and cassettes.

I have not noticed the bottom bracket knocking at all. It might have been pretty worn out and the crash has skewed the bearings: it was wobbling when I pulled one of the cranks. I have now removed the cranks and bottom bracket and I am waiting for a Tiagra replacement.

I think I prefer the simplicity of square tapered bottom brackets - especially hearing that some people break these Hollowtech II ones open to add more grease! - and have replaced a Campag Chorus one on the steel frame, again once in 10 years or so. I am about 73 kilos.

I think some people can be far too eager to swap out bottom brackets, but that's usually those fretting about creaking etc.

colin54 wrote: ↑3 Feb 2022, 10:15am I saw a bloke not long ago walking a bike along with a crank in his hand, it was a Hollowtech 2 type and the crank and/spider had split in two. I had a search when I got home and found a couple of articles, (linked below with photographs). The crank is made in two U-section parts-(hence Hollowtech) and bonded together somehow . If your 105 uses the same two-piece system, it might pay to remove the cranks and give them a detailed inspection, it may possibly explain your bike's symptoms.
I was quite surprised that this is how cranksets are made these days
https://road.cc/content/tech-news/shima ... nks-287827
https://www.bikeradar.com/features/shim ... k-failure/
Edit; I had a further look around the web and found this post, apparently the 105 uses a different one-piece construction, apologies for muddying the waters above.
Link below has pictures of the differences in construction.
https://handsonbike.blogspot.com/2016/1 ... o-105.html

Fascinating links to Hollowtech 2 failings.

Mine's a triple (below), which means it may have additional reinforcement for the granny. In any case, I cannot see any bend. If it is a goner, I would be inclined to replace with a square taper oldie, and lower gearing.

Bottom bracket was simple to fit and well within the capability of a modest DIY bike mechanic. With a new chain the bike is flying (except I have issues with the STIs, as discussed elsewhere).