# Timing Chain Ground Clearance



## Lelandjt (Feb 22, 2008)

I'm trying to figure out how to get the bottom brackets lower for better handling without further compromising ground clearance. I'm switching from 34 to 32t timing rings but that's as small as I can go. I've seen people make skid plates for the bottom tube but it's the chain that I'm worried about. I want to be able to ride over rocks and ledges without worrying that all the weight of the bike is going to rest on chain. Has anyone run the lower part of the chain up over two rolls so it's even with the bottom tube and a skid plate goes below both of them?


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## PMK (Oct 12, 2004)

I designed a tandem with single bike clearance. Inquired about having one custom built but did not bother. The majority of the design was on clearance and also minimal flex lengthwise.

As for a conventional tandem setup and raising the chain, with some ingenuity rollers could be rigged up.

FWIW, we have folded more chainrings than had chain concerns. We have many times gone over all sorts of features dragging the chain with no issues. Possibly the worse that has happened is a derailment if the tandem slides.

I have made a carbon glide plate which is great for protecting the frame. I would like to build a spine style protector to protect both chainrings and give the chain some protection. Not difficult and easy to attach, but will require drilling the downtube and bottom tube.

Unless you ride a lot of rocks, I would not worry about the chain, be more concerned you will bend a crank arm spider.

PK


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## Lelandjt (Feb 22, 2008)

Well yeah, the idea is to be able to ride trails with rocks and have no concerns, like on my taco equipped single bikes. I decided rollers would be too heavy so now I'm thinking steel 22t timing rings on triple cranks with BMX chain. Plasti skid plate attached to bottom tube that extends under the chain.


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## TandemBear (Aug 18, 2013)

I always seem to slam my front timing chainring. That's where I'd put a bash guard, UNDER the chainring to protect it and the spider. But not too low, because you're just reducing your clearance over obstacles THAT MUCH MORE!


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## reamer41 (Mar 26, 2007)

I've used 24t rings on a right side timing set up. Worked great. I used stainless rings and an 8spd chain.


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## DHMASTER (Oct 12, 2010)

This set-up has worked quite well. Steel 24 tooth timing rings, a trials bash ring for the front and a full length skid-plate.


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## switchbacktrog (May 10, 2013)

We use 32 tooth rings with an On-One bash ring. The skid plate is a piece of 70mm rain guttering reduced in width by about 30% then covered in carbon fibre effect self adhesive plastic.

The underside of the keel-tube is covered with clear heli-tape, with the plastic skid plate stuck to that with thin double-sided tape that's normally used for sticking plastic trims to car doors.

The chain is a one piece KMC X1 singlespeed.........KMC CHAINS Tandem Crossover Chain Nickel Plated 160 Link KMC X1 - £40.00 - Components - Chains & Spares - JD Tandems


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## PMK (Oct 12, 2004)

LelandJT, curious, knowing you work for Santana, is Santana planning to build a serious off road tandem? 

Not saying it can't be done, but the current mainstay production tandems in the US (Fandango and ECDM 26 or 29) are well proven reliable and work very well for the intended purpose.

PK


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## Lelandjt (Feb 22, 2008)

We're always playing with new bikes and different ideas. We've got a hardtail 27.5" wheel prototype that we showed at Interbike. I live with another pro DH racer and we've been riding it a lot and tweaking geometry but we both wish we could ride with abandon over ledges and rocks the way we do on our taco bash equipped single bikes.


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## PMK (Oct 12, 2004)

Lelandjt said:


> We're always playing with new bikes and different ideas. We've got a hardtail 27.5" wheel prototype that we showed at Interbike. I live with another pro DH racer and we've been riding it a lot and tweaking geometry but we both wish we could ride with abandon over ledges and rocks the way we do on our taco bash equipped single bikes.


Good luck...the wife and I have ridden some stupid stuff on the Ventana, and even our Fandango. Also bent a couple of front chainrings, one rear, never had a timing chain problem except derailing. I just tell her, most stuff is simply a controlled crash.
PK


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